Myocardial revascularization

Article written and reviewed by Dr Luca Moretti

Myocardial revascularization comprises all procedures aimed at restoring an adequate blood supply to a myocardial territory compromised by coronary stenoses or occlusions. In contemporary practice, the two fundamental strategies are percutaneous coronary intervention, or PCI, and coronary artery bypass grafting, or CABG. Both can improve perfusion, but they do so according to different anatomical principles: PCI directly treats the native-vessel lesion through dilation and, in the great majority of cases, stent implantation; CABG instead creates a new conduit that carries blood downstream of the coronary disease, bypassing one or more diseased segments.

The choice of revascularization cannot be reduced to the presence of an angiographic stenosis. It must answer a precise clinical question: why revascularize this patient, this lesion, and at this time? In acute coronary syndromes, the main objective is to rapidly interrupt thrombosis-related ischemia and limit necrosis. In chronic coronary syndromes, the procedure may be indicated to improve symptoms and quality of life, reduce event risk in high-risk anatomical settings, or obtain prognostic benefit in specific subgroups. In other situations, optimal medical therapy without an initial procedure offers a comparable prognosis and makes a selective approach appropriate.

Revascularization is therefore a component of ischemic heart disease therapy, not an alternative to it. Even technically perfect PCI or bypass surgery with patent grafts does not eliminate systemic atherosclerosis, the risk of plaque progression, thrombogenicity, diabetes, hypertension, or exposure to atherogenic lipoproteins. Procedural benefit must always be accompanied by intensive secondary prevention, risk-factor control, appropriate antithrombotic therapy, and clinical follow-up.
The most recent guidelines have progressively shifted the paradigm from simple 'percentage stenosis' to an integrated assessment of anatomy, physiology, disease burden, ventricular function, clinical presentation, procedural risk, and patient preferences. In intermediate stenoses, functional significance must be defined with FFR, iFR, or other appropriate tools before revascularization, while intracoronary imaging has an increasing role in planning and optimizing complex procedures.

Objectives, indications, and decision-making principles

The objectives of revascularization may be distinguished as prognostic, symptomatic, and myocardial salvage. Prognostic benefit consists of reducing spontaneous death, infarction, or other major events in populations in which the natural risk of disease is sufficiently high and the procedure modifies that risk. Symptomatic benefit primarily concerns reducing angina and improving functional capacity. Myocardial salvage is typical of acute coronary syndromes, in which the speed of reperfusion determines how much myocardium will undergo necrosis.
In chronic coronary syndromes, revascularization is particularly indicated when limiting symptoms persist despite adequate antianginal therapy and a responsible lesion is demonstrated. It is also considered in coronary anatomical settings associated with high risk, such as significant left main disease, complex multivessel coronary artery disease, extensive ischemia in specific contexts, or selected ischemic cardiomyopathy. The indication must be formulated by integrating the expected prognosis with and without the procedure.

The ISCHEMIA trial substantially changed perceptions of revascularization in stable coronary artery disease. In selected patients with moderate or severe ischemia, largely excluding those with significant left main disease, an initial invasive strategy did not reduce mortality or major ischemic events compared with an initially conservative strategy during the principal follow-up, although it improved angina control in symptomatic patients. This does not make revascularization useless, but demonstrates that inducible ischemia alone does not automatically amount to a prognostic indication for PCI.
The 2024 ESC guidelines do not exclude a survival benefit solely on the basis of the absence of significant left main or proximal LAD disease: in patients with chronic coronary syndrome, LVEF >35%, and functionally significant three-vessel disease, revascularization is recommended to improve long-term survival. In ischemic cardiomyopathy with impaired ventricular function, surgical revascularization may instead provide a long-term survival advantage in selected patients.

Decision-making must be proportional to risk. A technically simple single lesion in a patient with refractory symptoms may be managed with PCI after its relevance is documented. Conversely, left main disease or complex three-vessel disease in a patient with diabetes requires multidisciplinary assessment because the difference between PCI and CABG may translate into differences in mortality, spontaneous infarction, stroke, and the need for further procedures.
The Heart Team is the reference model when the strategy is not evident. The clinical cardiologist, interventional cardiologist, and cardiac surgeon should integrate operative risk, anatomy, PCI complexity, probability of complete revascularization, ventricular function, frailty, life expectancy, comorbidities, and informed preferences. The SYNTAX score may help describe anatomical complexity, but does not replace clinical judgment and must not be used in isolation.

Coronary anatomy and physiological significance of stenoses

Invasive coronary angiography remains the anatomical reference for revascularization procedures, but is essentially two-dimensional luminography. A visual reduction in diameter does not directly describe either plaque burden or physiological relevance. The relationship between stenosis and ischemia depends on lesion length, vessel diameter, aortic pressure, microvascular resistance, diffuse disease, collateral circulation, and the amount of subtended myocardium.
Angiographically intermediate stenoses are the setting in which invasive physiology has greatest value. Fractional flow reserve measures the ratio of distal to aortic pressure during maximal hyperemia; a value ≤0.80 is the conventional threshold used to identify a hemodynamically significant stenosis. iFR and other nonhyperemic indices use intervals of the cardiac cycle during which microvascular resistance is relatively stable; the validated iFR threshold is ≤0.89.

The FAME studies demonstrated that selecting lesions on the basis of physiology improves PCI appropriateness compared with angiographic assessment alone. FAME 2 also showed that, in patients with FFR-positive stenoses, PCI primarily reduces the need for urgent revascularization and improves angina control, whereas patients with FFR-negative lesions have a favorable prognosis with medical therapy.
Physiology must not, however, be interpreted as a test of plaque 'biological danger.' An FFR-negative stenosis may have a high atherosclerotic burden and confer long-term risk, whereas a positive FFR documents the lesion's hemodynamic effect. Anatomy, physiology, and plaque biology answer different questions.

Diffuse coronary artery disease may produce a gradual pressure drop along the vessel without one dominant focal lesion. Pressure pullback during FFR or nonhyperemic indices can distinguish a focal pattern, more suitable for correction with a stent, from a diffuse pattern, in which a long series of stents may not normalize physiology and may expose the patient to greater procedural complexity.
In patients with microvascular dysfunction, the relationship between stenosis and flow may be even more complex. Apparently preserved FFR in the presence of an attenuated hyperemic response may require interpretation within the overall context. When the clinical problem is ANOCA/INOCA, revascularization of the epicardial arteries is not the solution in the absence of hemodynamically significant stenoses.

Percutaneous coronary intervention: principles and technology

Modern PCI comprises vascular access, selective coronary catheterization, guidewire crossing of the lesion, plaque preparation, possible predilation, stent implantation, and final optimization. New-generation drug-eluting stents have substantially reduced restenosis and thrombosis compared with bare-metal stents and represent the standard in the great majority of indications.
Radial access is preferred in most procedures, especially in acute coronary syndromes, because it reduces bleeding and vascular complications and, in ACS settings, is associated with better outcomes than routine femoral access. Femoral access retains a role in procedures requiring large-bore sheaths, circulatory support, or for specific anatomies, but must be performed with meticulous technique and complication-prevention strategies.

Lesion preparation is crucial in calcified segments. Noncompliant balloons, scoring or cutting balloons, rotational or orbital atherectomy, and intravascular lithotripsy make it possible to modify calcium and promote adequate stent expansion. Implantation in an unprepared lesion, with an underexpanded stent, increases the risk of restenosis and late thrombosis.
The angiographic result is not always sufficient to assess PCI quality. Underexpansion, malapposition, edge dissections, tissue prolapse, and failure to cover diseased segments may be underestimated. Intracoronary imaging with IVUS or OCT permits more accurate assessment and is now recommended in complex procedures, with particular relevance in left main disease, bifurcations, long or calcified lesions, and restenosis.

IVUS has greater penetration depth and makes it possible to define the external elastic membrane, vessel dimensions, plaque burden, and calcium. OCT offers higher resolution and depicts stents, dissections, thrombus, and surface features in great detail, but requires blood clearance with contrast and has less penetration depth. The choice depends on the clinical question and anatomy.
Bifurcation PCI is generally planned with a single-stent provisional strategy whenever possible. Two-stent techniques are reserved for complex bifurcations with a major side branch and extensive disease. In left main bifurcations, the choice among techniques such as DK-crush, culotte, or TAP depends on geometry and operator experience; intracoronary imaging is particularly useful for optimizing expansion and apposition.

Chronic total occlusions require dedicated expertise. Antegrade wire escalation, antegrade dissection and re-entry, and retrograde approaches can achieve high success rates at experienced centers, but with longer procedure duration, greater contrast and radiation exposure, and higher risk than simple PCI. The indication for CTO PCI should be primarily clinically driven by symptoms or ischemia, not by the angiographic presence of the occlusion alone.

Coronary artery bypass grafting: surgical principles and grafts

CABG creates an alternative route for coronary blood flow through arterial or venous conduits anastomosed distal to the stenoses. Its conceptual strength is that a graft can protect an entire coronary segment from events developing in plaques proximal to the anastomosis, whereas PCI predominantly treats individual selected lesions.
The left internal mammary artery used for the LAD is the conduit with the best long-term patency and is one of the foundations of CABG benefit. The radial artery is used as a second arterial graft in appropriate patients and provides better patency than venous grafts in many settings, provided that it is anastomosed to vessels with stenoses sufficiently severe to avoid competitive flow.

Saphenous vein grafts are technically versatile but are more vulnerable over time to degeneration, thrombosis, intimal hyperplasia, and atherosclerosis. Vein-graft failure is not equivalent to stent restenosis: its pathobiology includes changes in the venous wall exposed to arterial pressure and accelerated development of neoatherosclerosis.
Surgery may be performed with cardiopulmonary bypass and cardioplegic arrest or off-pump at selected centers and in selected patients. Universal superiority of one technique over the other has not been demonstrated; outcomes and indications depend heavily on experience. No-touch aortic techniques may reduce embolization in patients with a heavily atheromatous aorta.

The concept of complete revascularization in surgery refers to the ability to bypass all clinically relevant territories. Anatomical completeness may be achieved more readily with CABG in diffuse and complex coronary artery disease, but it is not always necessary or possible in small vessels, diffusely diseased vessels, nonviable territories, or high-risk patients. The quality of the anastomoses and conduits is at least as important as the number of grafts.

PCI versus CABG in left main disease

Significant left main disease has prognostic importance because it jeopardizes a large myocardial territory. For decades, CABG was the predominant standard. Advances in stents, pharmacotherapy, and imaging have made PCI a possible alternative in selected anatomies, but the two strategies are not equivalent in every patient.
The 2024 ESC guidelines confirm CABG as the generally preferred strategy in patients with left main disease, low surgical risk, and suitable anatomy, especially because of the lower long-term incidence of spontaneous myocardial infarction and repeat revascularization. PCI may be appropriate when anatomical complexity is low or intermediate, surgical risk is high, the patient prefers a less invasive procedure, or conditions exist that make bypass surgery less favorable.

EXCEL and NOBLE produced results that were not entirely concordant, partly because of differences in endpoints and definitions. The clinical message is not that either trial ‘invalidates’ the other, but that in left main disease it is necessary to consider the time horizon, spontaneous events, stroke risk, need for further procedures, and anatomical complexity. Discussion with the patient must include these differences and not be limited to immediate risk.
Intracoronary imaging is particularly relevant in left main PCI because angiography may underestimate vessel diameter and disease distribution. IVUS contributes to assessing the severity of intermediate lesions and optimizing the stent; an underexpanded stent in the left main can have catastrophic consequences.

Multivessel disease, anatomical complexity, and diabetes

In multivessel coronary artery disease, the choice must consider the number of vessels, lesion locations and lengths, calcification, bifurcations, CTOs, diffuse disease, and the possibility of achieving complete revascularization. The SYNTAX score quantifies anatomical complexity and has demonstrated value in stratifying PCI versus CABG outcomes, but SYNTAX II and more modern models incorporate clinical characteristics to improve personalization.
Long-term follow-up of the SYNTAX trial showed that the relative effects of PCI and CABG depend on the complexity and distribution of disease. In patients with complex three-vessel coronary artery disease, especially when good-quality arterial grafts are feasible, bypass surgery tends to reduce spontaneous myocardial infarction and the need for further revascularization compared with PCI.

Diabetes mellitus strongly influences this choice because it is associated with more diffuse disease, smaller vessels, accelerated progression, and a higher risk of restenosis and events. In the FREEDOM trial, among patients with diabetes and multivessel disease, CABG reduced death and myocardial infarction compared with PCI using drug-eluting stents, at the cost of a higher risk of stroke. The surgical benefit is particularly relevant in complex and three-vessel disease.
The presence of diabetes, however, does not constitute an absolute automatic indication. Frailty, prohibitive surgical risk, anatomy favorable for PCI, limited life expectancy, or informed preference may alter the decision. The correct recommendation is not ‘CABG for every patient with diabetes,’ but CABG preferred when the expected benefit outweighs the risk and the anatomy is appropriate.

Left ventricular dysfunction and ischemic cardiomyopathy

Ischemic cardiomyopathy represents a setting distinct from stable coronary artery disease with normal ventricular function. Previous infarctions, hibernating myocardium, remodeling, secondary mitral regurgitation, and arrhythmias all contribute to prognosis. Revascularization must therefore be assessed together with heart failure therapy and prevention of sudden death.
STICH and the STICHES follow-up demonstrated that, in selected patients with LVEF ≤35% and coronary artery disease amenable to surgery, CABG added to medical therapy provides a long-term survival benefit despite an initial perioperative risk. The advantage emerges over time and must be interpreted in light of life expectancy and surgical risk.

The REVIVED-BCIS2 trial, by contrast, showed that in patients with severe ischemic ventricular dysfunction and viable myocardium, a PCI strategy did not reduce death or hospitalization for heart failure compared with optimal medical therapy; this result has tempered the idea that documentation of viability alone constitutes a sufficient indication for prognostic PCI.
Viability assessment retains value for understanding the substrate, the likelihood of functional recovery, and procedural planning, but must not be used as the sole gatekeeper. Scar on CMR, ventricular dimensions, residual ischemia, anatomy, symptoms, surgical targets, and comorbidities must be integrated.

STEMI: primary reperfusion and multivessel disease

In STEMI caused by acute coronary occlusion, primary PCI is the preferred reperfusion strategy when it can be performed promptly by an experienced team. The priority is to reopen the culprit artery, achieve adequate epicardial and microvascular flow, and limit infarct size. Total ischemic time remains a fundamental determinant.
Routine manual thrombus aspiration is not recommended because large trials have not demonstrated clinical benefit and have raised safety concerns. It may be used selectively in the presence of a high thrombus burden and specific procedural needs, but not as a mandatory step.

In hemodynamically stable patients with STEMI and multivessel disease, the COMPLETE trial demonstrated that complete revascularization of nonculprit lesions reduces cardiovascular death or new myocardial infarction and further reduces the need for revascularization. Contemporary guidelines therefore recommend a complete strategy, performed during the index procedure or in a staged manner according to anatomy and clinical condition.
The timing of nonculprit PCI must be individualized. A single procedure may reduce hospitalizations and subsequent visits, but immediately increases procedure time, contrast use, and complexity. A staged strategy may be preferable in complex anatomies, impaired renal function, or when physiological reassessment is needed.

The physiology of nonculprit stenoses in the acute phase must be interpreted cautiously because the microcirculation and vascular tone may be altered, but modern studies have supported angiography-guided or physiology-guided strategies. The criterion must be consistent with the clinical picture and must not turn every angiographic irregularity into a procedure.

NSTE-ACS and the invasive strategy

In NSTE-ACS, invasive coronary angiography is recommended during hospitalization in patients at intermediate or high ischemic risk, with the intent to perform revascularization when appropriate. Hemodynamic instability, persistent ischemia, life-threatening arrhythmias, and other risk criteria may require a more rapid approach.
The choice between PCI and CABG depends on coronary complexity and comorbidities. A clearly identifiable culprit and favorable anatomy are frequently treated percutaneously; complex left main or multivessel disease may require stabilization, Heart Team discussion, and surgery after appropriate management of antithrombotic therapy.

The 2025 ACC/AHA guidelines recommend a complete revascularization strategy also in ACS with multivessel disease, but the method must be tailored to the anatomy. Complete revascularization does not necessarily mean ‘stenting everything’ during the same session: it can be achieved with staged PCI, CABG, or appropriate combinations.

Cardiogenic shock and circulatory support

Cardiogenic shock after myocardial infarction radically changes the risk-benefit relationship. The CULPRIT-SHOCK trial demonstrated that, in patients with shock and multivessel disease, a strategy of immediate PCI of all lesions is unfavorable compared with PCI of the culprit lesion alone, with the option of subsequent procedures. Guidelines therefore maintain urgent revascularization of the culprit lesion and advise against routine immediate multivessel PCI.
Mechanical support may be considered in selected patients. The microaxial flow pump has received renewed attention after recent trials in infarction-related shock, with signals of reduced mortality in selected populations but increased bleeding, limb ischemia, and kidney injury. Patient selection, timing, vascular access, and management by experienced shock teams are critical.

Venoarterial ECMO, temporary ventricular assist devices, and the intra-aortic balloon pump have different hemodynamic profiles. No device should be used indiscriminately. The objective is to create a window for revascularization, recovery, or advanced therapy without causing complications that outweigh the benefit.

Complex PCI: calcium, bifurcations, CTOs, and grafts

Severely calcified lesions are among the principal causes of mechanical stent failure. Imaging makes it possible to define the arc, length, and depth of calcium and select the modification technology. Calcium modification is not an objective in itself, but a means of achieving proper device expansion.
In bifurcations, post-stenting geometry may alter the carina, side-branch ostium, and strut distribution. Proximal optimization technique, distal rewiring, and kissing-balloon inflation when indicated contribute to the result. Two-stent strategies must be planned before implantation when the probability of losing a major branch is high.

CTO PCI can improve angina and quality of life in appropriate patients, but no broadly generalizable survival benefit has been demonstrated. Selection must therefore be rigorous and include symptoms, ischemia, viability, probability of success, and procedural risk.
PCI of degenerated vein grafts is associated with a high risk of distal embolization and no-reflow. Whenever possible, treatment of the native vessel may be preferable, especially if the center's expertise permits CTO PCI. If the graft is treated, the friable nature of the atheroma requires particular caution.

Antithrombotic therapy during and after PCI

PCI intentionally causes endothelial injury and implants thrombogenic material; antithrombotic therapy is therefore an integral part of the procedure. Aspirin, P2Y12 inhibitors, and parenteral anticoagulants are selected according to the clinical presentation, timing, and bleeding risk.
In patients with ACS undergoing PCI, ticagrelor or prasugrel are generally preferred to clopidogrel when appropriate. DAPT for approximately 12 months remains the default strategy when bleeding risk is not high, but abbreviated strategies and P2Y12 monotherapy may be adopted in selected patients.

In chronic coronary syndromes after PCI, DAPT duration is generally shorter and may be adjusted according to ischemic risk, procedural complexity, and bleeding risk. Contemporary stents permit shorter durations in many patients without compromising safety, but complex PCI may shift the balance toward greater ischemic protection.
In patients who require oral anticoagulation, for example for atrial fibrillation, triple therapy significantly increases bleeding. Modern strategies minimize the duration of aspirin and continue an anticoagulant plus clopidogrel for the appropriate period, with individualized risk assessment.

Complications of PCI

Acute complications include coronary dissection, perforation, vessel closure, distal embolization, no-reflow, periprocedural myocardial infarction, arrhythmias, tamponade, and access-site complications. Risk varies with anatomy, age, renal function, the presence of shock, and lesion complexity.
No-reflow is inadequate microvascular perfusion despite reopening of the epicardial vessel. Microembolization, edema, ischemia-reperfusion injury, vasoconstriction, and capillary obstruction contribute to the phenomenon. It is associated with larger infarctions and a worse prognosis.

Stent thrombosis may be early, late, or very late and frequently presents as severe ACS. Underexpansion, malapposition, residual dissection, premature discontinuation of antiplatelet therapy, and prothrombotic conditions increase the risk. Intracoronary imaging is useful for identifying its mechanism.
In-stent restenosis is primarily due to neointimal hyperplasia or neoatherosclerosis. Treatment depends on the pattern and mechanism: drug-coated balloons, a new DES, correction of underexpansion, and calcium-modification techniques are selected on the basis of imaging.

Complications of CABG

CABG entails a higher perioperative risk than PCI because of its invasiveness, anesthesia, and cardiopulmonary bypass. Bleeding, sternal infection, atrial fibrillation, kidney injury, stroke, and perioperative myocardial infarction are the principal complications. Age, diabetes, obesity, peripheral vascular disease, and frailty increase the risk.
Perioperative stroke results from aortic embolization, atrial fibrillation, and hypoperfusion. Surgical strategies that reduce manipulation of the aorta may be useful in patients with severe atheromatous disease. Carotid assessment should not be performed indiscriminately but guided by the clinical profile.

Postoperative atrial fibrillation is common and increases hospital length of stay and thromboembolic risk. Prevention and treatment depend on the context; the need for anticoagulation must be individualized by considering arrhythmia duration and embolic and bleeding risks.
Early graft failure may result from thrombosis or technical problems; late failure reflects degeneration, atherosclerosis, and progression of native-vessel disease. Statin and antiplatelet therapy is essential to preserve the surgical benefit.

Completeness of revascularization and the concept of residual risk

Complete revascularization may be defined anatomically, functionally, or clinically. Purely anatomical completeness may lead to treatment of irrelevant lesions; functional completeness aims to correct the segments responsible for ischemia. The concept must be adapted to the clinical presentation and the technology used.
In stable multivessel ACS, complete revascularization reduces events compared with a culprit-only strategy. In chronic disease, by contrast, the benefit depends on the quality of the indication and does not justify indiscriminate treatment of every stenosis. Residual atherosclerotic burden remains a strong predictor of events even after complete revascularization.

Incomplete revascularization may be acceptable when some lesions involve small vessels, scarred territories, or vessels that cannot be treated, or when the risk of completing revascularization outweighs the benefit. The decision must be explicit and documented, avoiding incompleteness that is merely the consequence of inadequate planning.

Follow-up after PCI and CABG

Follow-up does not require routine serial coronary angiography in asymptomatic patients. Assessment focuses on symptoms, functional capacity, adherence, blood pressure, lipid profile, diabetes, smoking, and ventricular function. New symptoms require an appropriate diagnostic pathway and do not automatically lead to repeat angiography.
After PCI, persistent or recurrent angina may be due to restenosis, progression of other lesions, vasospasm, microvascular dysfunction, or noncardiac causes. After CABG, graft disease, progression of native coronary artery disease, and ischemia in non-bypassed territories must be considered.

Cardiac rehabilitation after ACS, PCI, or CABG improves functional capacity, adherence, and risk-factor control. It is not an ancillary intervention, but part of the revascularization strategy in the broadest sense because it consolidates the benefit obtained from the procedure.

Prognosis and individualized choice

Prognosis after revascularization depends on the clinical presentation, ventricular function, completeness of treatment, renal function, diabetes, atherosclerotic burden, quality of medical therapy, and complications. Immediate angiographic success does not equate to the prognosis at ten years.
PCI offers faster recovery and less invasiveness, but entails a higher likelihood of further revascularization in many complex anatomies. CABG involves a higher initial risk and longer recovery, but may offer more durable protection in complex multivessel disease, diabetes, and selected left main disease.

The best decision is therefore not the technically simplest procedure, but the one that maximizes net clinical benefit over time. A young patient with diabetes and complex three-vessel disease may accept an initial surgical risk to obtain a more durable benefit; a frail patient with multiple comorbidities may prioritize targeted PCI or medical therapy.
Finally, modern revascularization is inseparable from precision coronary medicine: physiology to select lesions, imaging to optimize the procedure, scores to describe risk, the Heart Team to integrate perspectives, and intensive prevention to reduce residual risk; this integration, more than the abstract opposition between ‘stent’ and ‘bypass,’ represents the central scientific principle of contemporary coronary artery disease management.

Preprocedural planning, CCTA, and the Heart Team

The quality of revascularization begins before the patient enters the procedure room. Preprocedural assessment must clarify the clinical question, identify the territory responsible for symptoms or risk, and determine whether the anatomy is best managed with PCI, CABG, or medical therapy. In stable patients, CCTA can provide a noninvasive map of the coronary tree, show lesion calcification and length, and, in appropriate cases, help predict the complexity of the invasive procedure.
Planning must include ventricular function, valvular disease, renal function, blood count, bleeding risk, the presence of peripheral artery disease, and vascular access. In candidates for CABG, available conduits, the ascending aorta, pulmonary function, and the risk of surgical complications must be assessed; in candidates for complex PCI, catheter support, plaque-modification techniques, imaging, and the potential need for mechanical support must be anticipated.

The Heart Team is particularly important when the decision affects prognosis: left main disease, complex multivessel disease, diabetes, severe comorbidities, reduced ventricular function, previous procedures, and patients in whom both strategies are technically feasible. The discussion should produce an understandable recommendation and compare not only 30-day risk, but also spontaneous myocardial infarction, stroke, repeat revascularization, and long-term quality of life.
Surgical risk scores such as STS or EuroSCORE II estimate operative mortality and some complications, but do not determine the decision by themselves. Frailty, cirrhosis, a ‘porcelain’ aorta, malignancy, disability, and life expectancy can alter actual risk in ways not fully captured by scores. Similarly, the SYNTAX score describes anatomy but does not measure the center's ability to perform complex PCI or the expected quality of grafts.

Intracoronary imaging: evidence and optimization criteria

Intracoronary imaging has evolved from a predominantly diagnostic tool into an active component of procedural optimization. The RENOVATE-COMPLEX-PCI trial demonstrated a reduction in target-vessel events with an IVUS- or OCT-guided strategy compared with angiography alone in complex lesions. The benefit derives from the ability to identify true vessel dimensions, calcium distribution, landing zones, and mechanisms of a suboptimal result.
The OCTOBER trial showed that OCT guidance reduces events compared with angiographic guidance in complex bifurcations. ILUMIEN IV, by contrast, showed a larger minimum stent area with OCT without a significant difference in the primary clinical endpoint at two years, although with less stent thrombosis; these results indicate that the effect of imaging depends on lesion type, the optimization protocol, and baseline risk.

With IVUS, proper stent expansion is assessed relative to the lumen or external elastic membrane of the reference segments. OCT can identify underexpansion, malapposition, edge dissection, and tissue protrusion at a resolution on the order of tens of micrometers. Not every finding requires correction: the decision must focus on abnormalities associated with clinically relevant risk.
In left main PCI, imaging is particularly useful because the vessel is large, angiography can be misleading, and stent failure would have severe consequences. Assessment of the circumflex ostium, expansion in the polygon of confluence, and the transition toward the LAD and LCx allows more precise optimization than angiographic impression alone.

Chronic kidney disease and prevention of kidney injury

Chronic kidney disease simultaneously increases ischemic risk, calcification, bleeding, and procedural complications. Patients with advanced CKD must be assessed while avoiding two opposing errors: withholding potentially life-saving revascularization because of concern about contrast or performing extensive procedures without considering renal vulnerability.
Prevention of contrast-associated kidney injury is based primarily on minimizing contrast volume, appropriate management of volume status, discontinuation or review of nephrotoxic medications when appropriate, and avoidance of closely spaced repeat exposures. Hydration with isotonic solution is adjusted according to congestion risk. Universal pharmacological ‘renoprotective’ strategies have not replaced these principles.

IVUS can enable ultra-low-contrast PCI at experienced centers, which is particularly useful in patients with severe CKD. OCT generally requires a larger amount of contrast medium to clear blood and may be less favorable in this setting, except in selected cases and with selected techniques.
The choice between CABG and PCI in CKD must consider operative risk, the need for dialysis, anatomy, and expected survival. In advanced disease, randomized evidence is less robust, and generalizing trials conducted in populations with better renal function may be inappropriate.

Advanced age, frailty, and multimorbidity

Chronological age is not a contraindication to revascularization, but absolute benefit depends on life expectancy, frailty, cognition, independence, and the patient's priorities. An independent 80-year-old with STEMI may derive major benefit from primary PCI; a patient with severe frailty and minimally symptomatic stable disease may not benefit from a complex procedure.
The FIRE trial demonstrated that, in patients aged at least 75 years with myocardial infarction and multivessel disease, a strategy of physiology-guided complete revascularization reduced the composite endpoint compared with a culprit-only strategy. This finding is important because it demonstrates that advanced age does not eliminate the benefit of treating nonculprit lesions in selected stable patients.

Frailty increases bleeding, delirium, functional decline, and mortality after both procedures. With CABG, the risk of prolonged recovery must be considered; with PCI, lengthy multivessel procedures may still entail high contrast volume, radiation exposure, and complex access. A ‘less invasive’ strategy is not automatically less risky if it is technically very demanding.

Sex, vessel size, and differences in presentation

Women with coronary artery disease often undergo revascularization at an older age and more frequently have diabetes, CKD, or heart failure. Smaller average vessel size may increase technical complexity, and bleeding risk may be higher in relation to body weight and vascular access.
These differences do not justify discriminatory treatment thresholds. Indications must be determined by the same assessment of risk, anatomy, and symptoms. Systematic use of radial access, antithrombotic doses appropriate for body weight, and imaging when indicated may reduce some of the procedural differences.

Patients with previous CABG

Recurrent ischemia after CABG may result from progression of native-vessel disease, graft occlusion, vein-graft degeneration, or distal stenoses. Repeat revascularization is often more complex because the patient is older and the anatomy has been altered by previous surgery.
Whenever possible, PCI of the native vessel is frequently preferable to PCI of a degenerated vein graft because grafts contain friable atheroma and carry a higher risk of embolization. However, the native vessel may be a calcified CTO and require extensive expertise. The decision must compare the risk and probability of success of the two routes.

Redo CABG carries a higher surgical risk than the initial operation because of adhesions, existing grafts, and reduced conduit availability. It is reserved for selected patients with anatomy unfavorable for PCI and a substantial expected benefit.

Hybrid revascularization and combined strategies

Hybrid coronary revascularization combines a mammary-artery graft to the LAD, often through a minimally invasive approach, with PCI of the other arteries. The objective is to use the durability advantage of the mammary artery-to-LAD graft while avoiding a full sternotomy or multiple vein grafts.
The strategy is technically attractive but requires precise anatomical selection, coordination between cardiac surgery and interventional cardiology, and complex management of antiplatelet therapy. Evidence on long-term outcomes is less extensive than for conventional CABG and standard PCI, so it does not represent a universal solution.

Perioperative medications in CABG

Medical therapy is not conceptually discontinued when the patient enters cardiac surgery. Statins are continued or initiated as indicated; aspirin is generally continued or resumed early after surgery unless contraindicated. Management of P2Y12 inhibitors, however, requires a drug-dependent discontinuation interval before elective surgery to reduce bleeding.
After CABG for ACS, the need to complete a period of DAPT may persist and must be balanced against postoperative bleeding risk. In vein grafts, platelet inhibition is particularly important in the early phase, when thrombosis represents a significant cause of failure.

Perioperative glycemic control, infection prevention, and early mobilization are essential, especially in patients with diabetes or obesity. Excessive hyperglycemia increases sternal infections, whereas overly aggressive control can cause hypoglycemia.

Radiation, contrast, and occupational safety

Complex PCI, especially CTO and multivessel procedures, can involve high radiation doses. The ALARA principle requires collimation, reduced frame rate, optimization of projections, and dose monitoring. High skin doses may require specific follow-up because of the risk of radiation-induced injury.
Protection of the operator and staff is part of procedural quality. Shields, distance, correct tube geometry, and protective equipment reduce cumulative exposure. Increasing PCI complexity makes this issue clinically relevant also for the occupational sustainability of catheterization laboratories.

Refractory angina and patients without conventional options

Some patients remain severely symptomatic despite maximally tolerated medical therapy and are not candidates for further PCI or CABG because of diffuse disease, small vessels, or unfavorable anatomy. Before diagnosing refractory angina, nonischemic causes must be excluded, and adherence and true pharmacological optimization must be verified.
In selected patients, specialist strategies such as the coronary sinus reducer may be considered; evidence supports improvement in angina among ‘no-option’ patients. The benefit is symptomatic and must not be confused with a demonstrated reduction in mortality or myocardial infarction.

Multidisciplinary programs for refractory angina can integrate pharmacological optimization, rehabilitation, psychological support, and selected interventional techniques. Quality of life becomes a primary outcome once prognostic risk has been addressed and anatomical options have been exhausted.

Technological perspectives

Coronary technology continues to evolve toward stents with thinner struts, more biocompatible polymers, drug-coated balloons, co-registered imaging, and angiography-derived physiology. Drug-coated balloons are established primarily for restenosis and are being studied in selected de novo lesions, but they do not universally replace stents.
Fully bioresorbable devices have an attractive theoretical rationale, but first-generation devices showed an excess of events and tempered initial enthusiasm. New scaffolds and materials require robust evidence before being incorporated into routine practice.

Artificial intelligence and computational modeling may improve anatomical quantification, bifurcation planning, and interpretation of physiology. Their clinical value will depend on demonstrating that the additional information changes decisions and outcomes, not merely on the algorithm's technical accuracy.

Stent biology, vascular healing, and neoatherosclerosis

A stent is not simply a passive tube. Implantation compresses plaque, injures the endothelium and media, and initiates a healing response characterized by fibrin deposition, inflammation, smooth muscle cell migration and proliferation, and progressive endothelialization. In drug-eluting stents, local release of antiproliferative drugs reduces neointimal hyperplasia but may delay some aspects of healing, which is why design, strut thickness, polymer, and drug kinetics influence outcomes.
Contemporary drug-eluting stents primarily use analogues from the ‘limus’ family and thin-strut platforms. Reducing thickness decreases flow disturbance and the amount of exposed material, while more biocompatible or biodegradable polymers aim to reduce chronic inflammation. Technological improvements have permitted shorter DAPT durations in many patients without reproducing the risk of late thrombosis observed with early generations.

Neoatherosclerosis consists of the formation of foam-cell macrophages, lipid deposition, and sometimes fibroatheroma within a stent's neointima. It may contribute to restenosis and very late thrombosis. OCT is particularly well suited to identifying features compatible with neoatherosclerosis, but treatment must be guided by the overall mechanism and not by an isolated image.

Restenosis: mechanisms and treatment

In-stent restenosis is not a single disease. It may result from mechanical underexpansion, neointimal hyperplasia, neoatherosclerosis, stent fracture, or edge proliferation. This distinction is fundamental because simply placing another stent inside an underexpanded platform may worsen the problem.
IVUS or OCT should be used whenever possible to identify the mechanism. If underexpansion due to deep calcium predominates, high pressures, intravascular lithotripsy, or other modification techniques may be necessary. If the problem is proliferative with good expansion, a drug-coated balloon or new DES may be appropriate.

Diffuse, recurrent, or multilayer restenosis may make PCI progressively less effective. In patients with suitable anatomy and an important territory, CABG may become the preferable option. The decision should avoid an unplanned so-called full metal jacket, in which successive layers of stents turn a long segment into a rigid structure that is difficult to treat.

Periprocedural myocardial infarction and myocardial injury

PCI may be associated with troponin release due to small-branch occlusion, distal embolization, dissection, or no-reflow. The universal definition distinguishes simple procedural myocardial injury from procedure-related myocardial infarction, which is defined by clinical and objective criteria of ischemia or a procedural complication and not by a fixed multiple of biomarker thresholds.
Prognostic importance depends on the size and mechanism of the event. Small isolated troponin elevations are not equivalent to a large spontaneous myocardial infarction; by contrast, loss of a major branch or acute occlusion can have severe clinical consequences; this distinction is also essential when interpreting trials comparing PCI with medical therapy.

After CABG, procedure-related myocardial infarction follows criteria comparable to those applied to percutaneous procedures, albeit in the setting of frequent postoperative myocardial injury. Diagnosis is not based on a fixed biomarker threshold: it requires acute myocardial injury with evidence of ischemia and confirmation by coronary and/or cardiac imaging according to the timing and context of the complication. Indiscriminate use of troponin without context would lead to overdiagnosis.

Revascularization and ischemic mitral regurgitation

In secondary ischemic mitral regurgitation, the fundamental problem is ventricular remodeling, which displaces the papillary muscles and prevents proper coaptation. Revascularization may improve regional function and reduce regurgitation in some patients, but does not guarantee correction when remodeling is advanced.
In patients undergoing CABG who have severe mitral regurgitation, the valvular strategy must be planned by the Heart Team. Repair or replacement depends on geometry, recurrence risk, and ventricular function. In moderate disease, the benefit of additional surgical correction at the time of CABG is less consistent and must be individualized.

In patients who remain symptomatic after revascularization and heart failure therapy, transcatheter edge-to-edge repair may be considered when the phenotype corresponds to the efficacy criteria demonstrated in trials. The therapeutic sequence must therefore address the coronary arteries, ventricle, and valve as parts of a single system.

Revascularization of viable myocardium and scarred territories

A completely scarred territory cannot recover contractility after revascularization. CMR with late gadolinium enhancement, PET, and other techniques can estimate viability and scar, but the decision must not be based on a simplistic threshold. Even a nonrecoverable territory may be supplied by a vessel whose revascularization protects more distal viable myocardium or collaterals.
The concept of hibernating myocardium describes chronically reduced function associated with inadequate flow or reserve but with the potential for recovery. In the past, it was used as a strong rationale for revascularization. STICH and REVIVED showed that viability alone does not identify patients who derive prognostic benefit from CABG or PCI.

Assessment must therefore integrate scar, symptoms, ischemia, anatomy, and the mode of revascularization. The presence of a large transmural scar reduces the probability of functional recovery, but the clinical decision remains multidimensional.

Revascularization and ventricular arrhythmias

Acute ischemia can cause ventricular tachycardia or fibrillation, and urgent revascularization of the culprit vessel is part of causal therapy. For arrhythmias occurring during ACS, correcting ischemia, electrolyte abnormalities, and hemodynamic instability takes priority over a chronic antiarrhythmic strategy.
In chronic ischemic cardiomyopathy, by contrast, monomorphic ventricular tachycardia often results from re-entry circuits within scar. Revascularization of stable stenoses does not necessarily eliminate the scar substrate and does not replace an ICD or ablation when indicated.

Before VT ablation, it is nevertheless appropriate to establish whether active ischemia is present in suitable patients because an ischemic trigger can increase electrical instability. Optimal management integrates electrophysiology and coronary artery disease without confusing trigger and substrate.

Timing of surgery after P2Y12 therapy

When coronary angiography for ACS identifies anatomy requiring CABG, recent P2Y12 administration influences surgical timing. Prasugrel, ticagrelor, and clopidogrel have different durations of platelet effect; elective surgery is generally delayed to allow hemostatic recovery unless there is an urgent need.
This is one reason why indiscriminate pretreatment with P2Y12 inhibitors before the anatomy is known is not appropriate in all patients with NSTE-ACS scheduled for early coronary angiography. A drug administered before the angiogram may delay necessary surgery or increase bleeding.

In emergencies that cannot be deferred, ischemic risk may exceed bleeding risk, and CABG is performed despite residual antiplatelet effect, with appropriate hemostatic and transfusion preparation. The decision is individualized and depends on clinical stability.

Preprocedural planning, risk, and revascularization strategy

Revascularization planning must precede the choice of device or technique. The first step is to establish whether the procedure is indicated for prognostic benefit, symptom control, acute myocardial salvage, or a combination of these objectives. The same anatomy may therefore lead to different decisions in a patient with evolving STEMI, a person with refractory stable angina, or an asymptomatic individual with an incidentally discovered intermediate stenosis. Assessment must integrate the extent and distribution of coronary artery disease, ventricular function, the proportion of myocardium at risk, comorbidities, frailty, bleeding risk, renal function, life expectancy, and the probability that the procedure will produce truly complete and durable revascularization.

The operative risk of CABG is estimated with validated tools, including Society of Thoracic Surgeons scores and, in Europe, EuroSCORE II, but no score replaces clinical assessment. Frailty, cirrhosis, malignancy, advanced pulmonary disease, aortic calcification, previous sternotomies, conduit quality, chest anatomy, and rehabilitation potential can alter risk in ways not fully captured by models. Similarly, PCI feasibility depends on characteristics that cannot be reduced to percentage stenosis: tortuosity, calcium, bifurcations, chronic occlusions, vessel accessibility, lesion length, diameter, diffuse disease, and the quality of the distal bed.

Anatomical complexity can be described with the SYNTAX score, originally developed to quantify the complexity of left main and multivessel coronary artery disease. The score has descriptive and prognostic value and may contribute to the choice between PCI and CABG, but it has interobserver variability and does not incorporate numerous clinical determinants; contemporary guidelines therefore recommend integrated rather than automatic use. In patients with complex disease, especially when diabetes, ventricular dysfunction, left main disease, or three-vessel coronary artery disease make different strategies plausible, multidisciplinary Heart Team discussion remains the most appropriate method.

Preprocedural assessment also includes a complete blood count, renal function, electrolytes, coagulation status when indicated, blood typing in surgical or high-risk cases, echocardiography for ventricular and valvular function, and review of antithrombotic therapy. The presence of anemia, thrombocytopenia, renal failure, recent bleeding, or the need for chronic anticoagulation may alter both the choice of strategy and the duration of subsequent antithrombotic therapy. In surgery, symptomatic carotid stenosis, aortic disease, peripheral artery disease, or respiratory failure may require a dedicated assessment pathway.

In patients with chronic kidney disease, iodinated contrast and the possibility of procedure-associated kidney injury are particularly important. The approach must include a realistic assessment of the benefit-risk relationship, minimization of contrast volume, correction of volume depletion when present, avoidance of unnecessary nephrotoxic drugs, and subsequent monitoring of renal function. Renal failure is not, however, an absolute contraindication to coronary angiography or revascularization when the expected benefit is high, for example in myocardial infarction with persistent ischemia or hemodynamic instability.

In elective procedures, the decision must be shared with the patient in understandable terms. Communication should clearly distinguish the probability of improving symptoms from potential prognostic benefit, describe the risks of procedural myocardial infarction, stroke, bleeding, kidney injury, restenosis, stent thrombosis, or surgical complications, and explain the possibility of subsequent revascularization. Truly informed consent is particularly important when PCI and CABG are both technically feasible but differ in immediate invasiveness, recovery time, and long-term durability.

Lesion preparation, coronary calcium, and stent optimization

The success of PCI depends largely on lesion preparation. The objective is not simply to cross the stenosis, but to obtain a sufficient lumen and geometry that allows the stent to expand symmetrically and adhere to the vessel wall. Inadequate preparation, especially in calcified lesions, increases the risk of underexpansion, malapposition, dissection, restenosis, and thrombosis. The choice among noncompliant balloons, cutting or scoring balloons, rotational atherectomy, orbital atherectomy, and intravascular lithotripsy depends on the distribution and depth of calcium, vessel diameter, the ability to cross the lesion, and operator experience.

Rotational atherectomy uses a high-speed diamond-coated burr primarily to modify superficial calcium and facilitate lesion expansion. It should not be interpreted as a technique for completely removing plaque: the objective is to modify segment compliance and create a pathway that permits subsequent dilation. Orbital atherectomy uses a different principle, with an eccentric orbit of the device that produces progressive calcium modification. Both require careful case selection, specific anticoagulation management, and attention to slow flow, perforation, dissection, and thermal or mechanical injury.

Intravascular lithotripsy uses acoustic pressure pulses generated by emitters mounted on a balloon to create fractures in superficial and deep calcium, thereby improving vascular compliance. It is particularly useful when imaging shows circumferential or deep calcium that makes adequate expansion with a balloon alone unlikely. Its conceptual advantage over ablative techniques is the ability to modify calcium without requiring directional ablation of the luminal surface; limitations include lesion crossability, the need for a compatible profile, and cost.
IVUS and OCT make it possible to quantify the arc, length, and thickness of calcium and recognize conditions associated with underexpansion. Thanks to its higher resolution, OCT provides particularly detailed visualization of calcium fractures after plaque preparation, whereas IVUS offers greater penetration and may be preferred when the entire vessel architecture must be assessed. The choice of modification technique should be guided not only by angiography but, in complex lesions, by a three-dimensional understanding of the substrate.

After stent implantation, optimization includes verification of expansion, apposition, complete lesion coverage, and the absence of significant edge dissections. Marked underexpansion is one of the most important mechanical determinants of thrombosis and restenosis. Postdilation with an appropriately sized noncompliant balloon can correct part of the problem, but resistant underexpansion in the presence of unmodified calcium may require advanced strategies. Prevention is therefore preferable to late correction.
Contemporary randomized trials have strengthened the role of intracoronary imaging in complex PCI. RENOVATE-COMPLEX-PCI showed that IVUS or OCT guidance in complex lesions reduces the risk of target-vessel failure compared with angiography alone. ULTIMATE had already demonstrated a benefit of IVUS in a broader population undergoing DES implantation. The effect derives from the ability to select the correct stent dimensions, recognize calcium and dissections, achieve greater expansion, and correct problems not apparent on angiography alone.

Left main disease, bifurcations, and complex anatomies

Left main disease warrants separate assessment because it jeopardizes an extensive myocardial territory and because the angiographic percentage of stenosis can be difficult to estimate, especially with ostial, diffuse, or calcified lesions. In intermediate stenoses, IVUS and physiology can avoid both unnecessary revascularization and deferral of truly significant lesions. Minimum lumen area on IVUS can contribute to the decision, but thresholds must be interpreted in the context of body size, the reference population, and concordance with physiology.

When left main disease requires revascularization, CABG retains a reference role, especially in the presence of complex anatomy or associated multivessel disease. PCI may be a reasonable alternative in selected patients with low or intermediate anatomical complexity and the possibility of achieving an equivalent percutaneous result. EXCEL and NOBLE produced results that were not completely concordant because of differences in endpoints and definitions, but overall confirm that the choice cannot be based on a single trial: anatomical complexity, diabetes, age, surgical risk, and preferences must be integrated.
Bifurcations are among the principal causes of procedural complexity. The default strategy for many noncomplex bifurcations is provisional stenting of the main branch, with treatment of the side branch only if necessary; this approach reduces metal, overlap, and complexity compared with a systematic two-stent strategy. However, complex true bifurcations, large side branches, long ostial disease of the secondary branch, or distal left main anatomy may require a planned two-stent technique.

Among two-stent techniques, DK-crush, culotte, and TAP address different geometries. DK-crush has particularly robust evidence in complex distal left main disease when performed by experienced operators, but requires a rigorous sequence of steps, rewiring, and kissing-balloon inflation. Intracoronary imaging is particularly useful for verifying expansion and apposition in proximal and overlap segments, where suboptimal geometry may promote restenosis or thrombosis.
The proximal optimization technique, or POT, corrects the discrepancy between the proximal and distal diameters of the main vessel in bifurcations. Proper proximal expansion facilitates side-branch rewiring and reduces malapposition. The sequence of POT, possible side-branch opening, kissing, and re-POT is adapted to the technique used; these procedural details are important because failure of bifurcation PCI often results more from final stent geometry than from the initial lesion.

Graft disease requires specific strategies. Degenerated vein grafts frequently contain friable, thrombotic atheroma, with a high risk of distal embolization and no-reflow. When technically feasible, treatment of the native vessel may be preferable to intervention on a degenerated vein graft. Intervention on an internal mammary artery, by contrast, requires particular caution because of the risk of dissection or spasm and the prognostic importance of the conduit.

Chronic coronary occlusions and revascularization of diffuse disease

A chronic total occlusion, or CTO, is a complete coronary occlusion of presumed duration of at least three months, characterized by TIMI 0 antegrade flow and progressive fibrotic and calcific changes. The decision to treat it must begin with symptoms, the amount of viable and ischemic myocardium, ventricular function, collateral quality, probability of technical success, and procedural risk. The presence of a CTO alone does not constitute an automatic indication for PCI.
CTO PCI is a highly specialized discipline. Strategies include antegrade wire escalation, antegrade dissection and re-entry, and retrograde approaches through septal or epicardial collaterals. The choice depends on the morphology of the proximal cap, occlusion length and composition, quality of the distal landing zone, the presence of usable collaterals, and previous failure. Dedicated algorithms, including the hybrid algorithm, encourage an early switch from an ineffective strategy to a more suitable one.

CTO procedures involve greater radiation and contrast exposure and a higher risk of perforation, tamponade, collateral ischemia, and vascular complications than standard PCI. The most consistently demonstrated benefit concerns improvement in angina and quality of life in appropriately selected symptomatic patients; a universal prognostic benefit has not been demonstrated; the procedural threshold should therefore be higher, and the procedure should be performed at centers with expertise and the ability to manage complications.
Diffuse disease is a different problem from CTO. When the vessel has a long, progressive reduction in caliber, the pressure drop may be distributed without a single focal point. Pullback of FFR or nonhyperemic indices can distinguish diffuse from focal physiology. In a diffuse pattern, implantation of long or multiple stents may produce an apparent angiographic result without normalizing flow and may increase the risk of restenosis, thrombosis, and the need for prolonged DAPT.

CABG has a conceptual advantage in diffuse disease because a distally anastomosed graft can bypass multiple proximal lesions and provide a form of protection against progression in upstream segments, especially when the arterial conduit maintains good patency; this principle helps explain the greater surgical durability observed in some populations with complex multivessel disease and diabetes, in whom the entire coronary tree frequently has diffuse disease rather than only focal stenoses.

Surgical revascularization: technique, conduits, and durability

In CABG, the conduit with the best evidence of durability is the left internal mammary artery anastomosed to the LAD. Its high long-term patency depends on biological properties of the vessel wall, endothelial production of vasoprotective mediators, and lower susceptibility to atherosclerosis compared with vein grafts. Whenever possible, the LIMA-to-LAD graft is the cornerstone of surgical revascularization and contributes substantially to the long-term benefit of bypass surgery.
The radial artery is a second arterial conduit of major interest. Randomized and meta-analytic data show better patency and fewer graft-related events than with the saphenous vein in selected patients. Selection requires assessment of upper-limb circulation, the history of radial access, the potential future need for a hemodialysis fistula, and the severity of the target coronary stenosis because competitive flow may promote arterial graft closure.

Saphenous vein grafts remain widely used because they are available, versatile, and suitable for reaching numerous territories. Their biology is less favorable, however: after implantation in the arterial circulation, they develop adaptation, intimal hyperplasia, and subsequently accelerated atherosclerosis, with an increasing risk of degeneration and occlusion over time. Secondary prevention with statins, antiplatelet agents, blood-pressure control, and smoking cessation is therefore essential also for graft durability.
Revascularization may be performed with cardiopulmonary bypass and cardioplegic arrest or, in selected cases, on the beating heart using an off-pump technique. Off-pump surgery may reduce some complications related to aortic manipulation or cardiopulmonary bypass in selected patients, but it is technically more demanding and has not demonstrated a universal advantage. The quality of the anastomoses and completeness of revascularization are more important than an ideological preference for one technique.

Manipulation of the ascending aorta is a potential source of cerebral embolization in patients with aortic atheroma. Anaortic or no-touch strategies, when technically feasible, may reduce this risk in selected patients. Epiaortic ultrasonography can identify plaques not adequately recognized by palpation and guide the cannulation and clamping sites; these strategies are particularly relevant in older adults with advanced aortic atherosclerosis.
Surgical completeness depends on the ability to identify target vessels of adequate caliber with a viable distal bed. A diffusely diseased or very small coronary artery may not provide an effective target. Coronary endarterectomy is used rarely and at experienced centers when severe diffuse disease prevents a normal anastomosis, but it increases complexity and requires specific antithrombotic management.

Periprocedural myocardial infarction, myocardial injury, and systemic complications

An increase in troponin after PCI or CABG is common and is not automatically equivalent to a periprocedural myocardial infarction. The Fifth Universal Definition does not use fixed biomarker thresholds for procedure-related myocardial infarction: in the presence of acute myocardial injury and compatible symptoms or ECG changes, confirmation requires coronary and/or cardiac imaging according to the timing and context of the complication. Distinguishing simple procedural myocardial injury from infarction is important because prognostic significance increases with the extent of injury and the presence of a documented ischemic complication.
During PCI, side-branch occlusion, dissection, thrombosis, distal embolization, slow flow, and no-reflow can cause necrosis. In surgery, cross-clamp ischemia, inadequate myocardial protection, embolization, graft problems, or supply-demand mismatch can contribute to injury. Prevention includes meticulous technique, adequate anticoagulation, hemodynamic control, and early treatment of mechanical complications.

Bleeding is one of the principal prognostic complications of revascularization. After PCI, risk arises from vascular access and antithrombotic therapy; after CABG, surgical hemostasis, coagulopathy, hypothermia, and platelet dysfunction are additional factors. Adoption of radial access, correct selection of antithrombotic doses, and abbreviated DAPT strategies in high-risk patients have reduced the bleeding burden without sacrificing ischemic protection when appropriately applied.
Postoperative atrial fibrillation is common after CABG and results from inflammation, adrenergic stress, electrolyte abnormalities, and atrial vulnerability. It can prolong hospitalization and increase thromboembolic risk. Management includes rate or rhythm control according to stability and symptoms and an individualized assessment of anticoagulation, taking early bleeding risk and arrhythmia duration into account.

Neurological complications include ischemic stroke, hemorrhage, and delirium. In CABG, stroke may result from aortic embolization, atrial fibrillation, hypoperfusion, or preexisting cerebrovascular disease. In PCI, the absolute risk is lower but not zero, especially during complex left main procedures, aortic manipulation, or in patients with advanced atheroma. Neurological risk is one of the central elements in the PCI-CABG comparison because bypass surgery tends to carry a higher procedural stroke risk but may reduce some long-term spontaneous events in specific subgroups.
Acute kidney injury may follow either strategy. In PCI, contrast, hemodynamic instability, and comorbidities contribute; in CABG, cardiopulmonary bypass, systemic inflammation, and changes in perfusion are additional factors. Prevention requires identification of high-risk patients, optimization of volume status, minimization of nephrotoxic exposure, and careful hemodynamic control. In patients with advanced kidney disease, renal risk must be balanced against the risk of not treating prognostically critical coronary anatomy.

Complete revascularization, future events, and secondary prevention

The concept of complete revascularization may be anatomical or functional. Anatomical completeness entails treating all stenoses considered significant in vessels of adequate caliber; functional completeness aims to correct only lesions that cause ischemia or physiological abnormalities. In contemporary practice, functional completeness can avoid unnecessary procedures, whereas in complex anatomies the ability to achieve complete revascularization influences the comparison between PCI and CABG.
In STEMI with multivessel disease in a hemodynamically stable patient, COMPLETE demonstrated that treatment of significant nonculprit lesions, performed during hospitalization or in a planned procedure, reduces cardiovascular events compared with PCI of the culprit vessel alone. Contemporary guidelines have therefore incorporated a complete revascularization strategy for appropriate patients. The principle changes radically in cardiogenic shock, where CULPRIT-SHOCK demonstrated harm from routine immediate multivessel PCI and supports initial treatment of the culprit vessel alone, reserving possible subsequent procedures until after stabilization.

In NSTE-ACS, the complete strategy must be individualized. The significance of nonculprit lesions may be more difficult to interpret during the acute event because of alterations in vascular tone, microcirculation, and physiology. Anatomy, stability, renal function, contrast volume, and complexity determine whether revascularization should be completed during the same procedure, in a staged procedure, or after functional assessment.
After revascularization, residual risk derives from three categories: procedural risk, risk related to the treated segment, and risk related to untreated atherosclerosis. Stent thrombosis, restenosis, and graft failure belong to the first two; new plaque ruptures, progression in native segments, diabetes, inflammation, Lp(a), and atherogenic lipoproteins belong to the third. No procedure eliminates this last component, which requires permanent systemic therapy.

Secondary prevention after PCI and CABG must include intensive LDL-C lowering, smoking cessation, blood-pressure control, diabetes management, physical activity, a cardioprotective diet, and cardiac rehabilitation. Adherence to therapy is critical to the durability of the result. Premature discontinuation of DAPT after stenting increases the risk of thrombosis, whereas discontinuation of statins accelerates progression of native-vessel and vein-graft atherosclerosis.
Follow-up does not require routine coronary angiography or stress testing in every asymptomatic patient. Investigations must be guided by new symptoms, functional changes, high-risk anatomy, or clinical questions capable of changing management. Systematic surveillance with invasive imaging in the absence of indications can generate a cascade of unnecessary procedures without improving outcomes.

Contemporary revascularization must therefore be conceived as a longitudinally integrated strategy: appropriate patient selection, physiological definition of the lesion, optimal technical execution, proportionate antithrombotic therapy, intensive secondary prevention, and reassessment over time. The quality of the result depends not only on the absence of residual stenosis at the end of the procedure, but on the ability to durably reduce ischemia, symptoms, events, and the need for repeat procedures while maintaining an acceptable procedural risk.

Diabetes, renal failure, advanced age, and previous revascularization

Diabetes mellitus profoundly alters the revascularization problem because it is associated with more diffuse coronary artery disease, a greater atherosclerotic burden, smaller-caliber vessels, microvascular disease, a higher risk of restenosis, and accelerated progression of untreated lesions. In patients with diabetes and complex multivessel coronary artery disease, especially when the LAD is involved and surgical risk is acceptable, CABG frequently provides greater protection from death, spontaneous myocardial infarction, and the need for repeat revascularization than PCI, at the cost of a higher procedural stroke risk and greater initial invasiveness. FREEDOM is one of the pivotal trials supporting this difference.

Surgical superiority does not imply that every patient with diabetes should undergo surgery. Single-vessel or less complex disease, high surgical risk, frailty, major comorbidities, or anatomy favorable for PCI may make the percutaneous approach appropriate. The decision must be individualized and explained in terms of the trade-off among procedural risk, initial recovery, likelihood of repeat intervention, and long-term protection. The quality of glycemic and risk-factor control remains critical regardless of the procedure.
In chronic kidney disease, the choice is complex because both strategies carry specific risks. PCI involves contrast exposure and may require repeated procedures; CABG entails greater hemodynamic and inflammatory stress and a risk of acute kidney injury. Patients with CKD are also at high risk of bleeding and vascular calcification. The presence of kidney disease does not eliminate the potential benefit of revascularization when a strong prognostic or symptomatic indication exists, but requires multidisciplinary planning and kidney-protection measures.

In patients on dialysis, randomized data are limited, and overall prognosis is strongly influenced by comorbidities and calcification. Arterial grafts may offer patency advantages, but radial artery availability must be assessed cautiously if the limb may be needed for hemodialysis vascular access. In PCI, severe calcium may require lithotripsy or atherectomy and increases the risk of stent underexpansion.
Advanced age is not in itself a contraindication to either PCI or CABG. Frailty, cognition, independence, life expectancy, and preferences assume greater importance, however. PCI generally offers faster recovery and may be preferred when the primary objective is to reduce symptoms in a patient with high surgical risk; CABG may remain appropriate in selected robust older adults with complex anatomy and sufficient life expectancy to benefit from greater durability.

In patients with previous CABG, recurrent ischemia may result from native-vessel progression or graft failure. A second sternotomy carries greater risk than the initial operation; PCI is therefore frequently preferred when technically feasible. Treatment of the native vessel is generally preferable to that of a degenerated vein graft when a practicable strategy exists because graft PCI is associated with greater distal embolization, no-reflow, and recurrence.
In patients with previous PCI, repeat revascularization may address restenosis, stent thrombosis, or progression of other lesions. Intracoronary imaging is essential when mechanical stent failure is suspected because it can distinguish underexpansion, fracture, malapposition, neoatherosclerosis, and neointimal proliferation. Treating restenosis without defining its mechanism increases the risk of a second recurrence.

Restenosis, stent thrombosis, and graft failure

In-stent restenosis is a new reduction in lumen within the stented segment, caused by biological mechanisms such as neointimal hyperplasia or neoatherosclerosis or by mechanical causes, especially stent underexpansion. With new-generation DES, its incidence is lower than with earlier technologies, but it remains clinically important in long lesions, small vessels, diabetes, bifurcations, CTOs, and especially when the stent is underexpanded. The angiographic diagnosis should be integrated, whenever possible, with IVUS or OCT to identify the mechanism.
Restenosis due to underexpansion requires mechanical correction of expansion before adding further antiproliferative therapy. High-pressure balloons, intravascular lithotripsy in specific calcific restenoses, or other techniques may be necessary. When the problem is predominantly proliferative, a new DES or a drug-coated balloon may be used according to the geometry, number of metal layers, and available evidence.

Neoatherosclerosis consists of the development of atherosclerotic features within the stent neointima, including lipid accumulation, calcification, and sometimes rupture with thrombosis. It may appear earlier in DES than in historical bare-metal stents. Its presence underscores that the treated segment remains biologically vulnerable and that systemic prevention continues to be necessary even years after PCI.
Stent thrombosis is temporally classified as acute, subacute, late, or very late and represents a potentially catastrophic event, often presenting as STEMI or sudden death. Determinants include premature discontinuation of antiplatelet agents, underexpansion, malapposition, residual dissections, high thrombus burden, small vessels, bifurcations, renal failure, and a prothrombotic state. Management requires urgent coronary angiography, restoration of flow, and identification of the mechanism with imaging whenever possible.

Vein-graft failure follows a distinct natural history. In the first weeks, technical or low-flow thrombosis may predominate; in subsequent months, intimal hyperplasia; and over years, accelerated atherosclerosis. Degenerated vein grafts may contain large amounts of friable and thrombotic material, making PCI high risk for embolization. Selecting the native vessel as the target, when feasible, may provide a more durable result.
Arterial grafts, especially the internal mammary artery, have markedly better patency but may fail because of technical problems, competitive flow, anastomotic stenosis, or distal progression. An angiographic graft stenosis must be interpreted in the context of competitive flow and native-vessel physiology, avoiding interventions on findings that do not explain ischemia.

Management of late failure often requires a new Heart Team assessment. Repeat PCI of the native vessel, graft treatment, redo CABG, and medical therapy may have very different risk profiles. The decision must consider the extent of residual disease, conduit availability, quality of the distal bed, ventricular function, and life expectancy. The mere fact that a previous strategy failed does not automatically imply that it should be repeated.