Ischemic heart disease is the set of metabolic, mechanical, electrical, and structural changes produced in the myocardium by an oxygen supply insufficient for demand. It is a pathophysiological definition before it is an anatomical one: the most common cause is atherosclerotic coronary artery disease, but an epicardial stenosis is neither necessary nor sufficient. A stenosis may not limit blood flow, whereas ischemia may occur with nonobstructive coronary arteries because of microvascular dysfunction or vasospasm, or during anemia, hypoxemia, hypotension, and tachyarrhythmia.
The term encompasses reversible manifestations, such as angina and transient contractile dysfunction, and irreversible consequences, such as infarction, scar, remodeling, and ischemic cardiomyopathy. It also includes symptomatic episodes and silent ischemia. Acute and chronic forms are not biologically isolated categories: a patient with stable disease may develop acute thrombosis and, after the event, return to a chronic phase characterized by a different burden of scar and risk.
The distinction among ischemia, myocardial injury, and infarction is fundamental. Ischemia indicates inadequate tissue oxygenation and may resolve without necrosis. Myocardial injury is defined by troponin above the 99th percentile and has ischemic and nonischemic causes. Myocardial infarction requires acute injury associated with evidence of ischemia. Confusing these categories leads to inappropriate diagnoses and treatments.
Clinical relevance depends not only on the presence of ischemia, but also on its intensity, duration, distribution, repetition, and myocardial substrate. A brief episode may cause only diastolic abnormalities; prolonged occlusion of a proximal vessel may produce extensive necrosis, shock, and arrhythmias; repeated episodes may cause adaptation, stunning, or hibernation; previous scars reduce functional reserve and increase electrical risk.
Epidemiologically, ischemic heart disease remains the principal component of cardiovascular mortality worldwide. Statistics based on diagnosed infarction and coronary artery disease underestimate the phenomenon because they do not fully capture silent ischemia, microvascular disease, and subclinical forms. The reduction in age-standardized rates achieved in many countries is offset by population aging and the absolute increase in diabetes, obesity, and kidney disease.
Contemporary assessment must answer separate questions: is the symptom likely to be ischemic? Is acute injury present? What is the mechanism reducing supply? How much myocardium is at risk or already scarred? Does the patient have anatomy in which revascularization can improve symptoms or prognosis? Effective treatment arises from integrating these answers, not from a single stenosis percentage.
Myocardial oxygen consumption is determined primarily by heart rate, contractility, and wall tension. According to Laplace principles, the latter depends on intraventricular pressure, chamber radius, and wall thickness. Tachycardia, hypertension, ventricular dilation, and increased contractility increase demand; hypertrophy may reduce tension per unit of tissue but increases the overall mass to be perfused and is often associated with microvascular rarefaction.
Oxygen supply is the product of coronary blood flow and arterial oxygen content. Content depends primarily on hemoglobin concentration and saturation, while the contribution of dissolved oxygen is minimal. Severe anemia, hypoxemia, and changes in hemoglobin affinity may therefore reduce supply even with patent coronary arteries. Perfusion pressure, diastolic duration, and coronary resistance determine blood flow.
At rest, the myocardium extracts approximately three quarters of the oxygen available in coronary blood. Consequently, increased demand is met primarily by increasing blood flow. Metabolic vasodilation of the arterioles, mediated by a network including adenosine, potassium, nitric oxide, and other signals, can increase blood flow several-fold above baseline. The ratio of maximal to resting blood flow constitutes coronary flow reserve.
Blood flow to the left ventricle occurs predominantly during diastole because intramyocardial pressure compresses the vessels during systole, especially in the subendocardium. Tachycardia is therefore doubly unfavorable: it increases consumption and shortens diastole. Elevated end-diastolic pressure, hypertrophy, and aortic stenosis increase extravascular compression and reduce the subendocardial perfusion gradient.
Normal epicardial arteries offer modest resistance. A stenosis produces a pressure loss that increases nonlinearly with severity, length, and blood flow. Distal arterioles dilate to preserve resting flow; during stress, residual capacity is reduced. Significance cannot be precisely inferred from angiography because vessel diameter, serial lesions, diffuse disease, collaterals, and microvascular resistance alter the anatomy-flow relationship.
Epicardial atherosclerosis may reduce supply chronically or acutely. Plaque growth and healing of subclinical thrombotic episodes progressively narrow the lumen. Rupture, erosion, or a calcified nodule may instead cause rapid thrombosis. A partial, dynamic thrombus produces intermittent ischemia; persistent occlusion causes necrosis if collateral flow is insufficient.
Endothelial dysfunction reduces nitric oxide-mediated vasodilation and may promote paradoxical vasoconstriction during stimulation. In epicardial vasospasm, smooth muscle cell hyperreactivity and abnormal vasomotor regulation produce intense focal or diffuse constriction. The phenomenon may occur in apparently normal vessels or atherosclerotic segments and cause transmural ischemia, arrhythmias, and infarction.
The microcirculation is not visible on conventional coronary angiography. Structural dysfunction includes arteriolar wall thickening, inward remodeling, perivascular fibrosis, and rarefaction. Functional dysfunction includes reduced vasodilator capacity, high resting tone, an abnormal endothelium-dependent response, and microvascular spasm. Diabetes, hypertension, obesity, inflammation, and cardiomyopathies may promote these phenotypes.
Reduced coronary reserve may result from low maximal flow, high resting flow, or both. Tachycardia, anemia, and hypertension increase resting flow and may lower the ratio without severe maximal limitation. Interpretation of CFR must therefore consider hemodynamics. Measurements of microvascular resistance and absolute blood flow help distinguish the mechanisms.
Ischemic heart disease due to a systemic imbalance occurs when a vulnerable substrate encounters reduced supply or increased demand. Sepsis, hemorrhage, hypotension, respiratory failure, hypertensive crisis, and tachyarrhythmias are typical precipitants. When another acute condition causes a supply-demand imbalance, acute myocardial injury, and evidence of ischemia, a secondary myocardial infarction is considered; the diagnosis is confirmed by the presence of obstructive coronary artery disease without acute coronary pathology or by a new regional wall-motion abnormality or loss of viable myocardium. If infarction is not confirmed, the condition is acute myocardial injury.
At the onset of ischemia, decreased ATP impairs diastolic relaxation, which is an energy-dependent process. Anaerobic glycolysis, lactate, protons, and inorganic phosphate increase. Acidosis reduces myofilament calcium sensitivity; impaired ion pumps promote intracellular sodium and calcium overload. Regional systolic function decreases and repolarization abnormalities appear.
The temporal sequence is described as the ischemic cascade: heterogeneous perfusion and metabolism, diastolic dysfunction, regional systolic abnormality, electrocardiographic changes, and symptoms. The order is not rigid in every patient, but it explains why perfusion or wall-motion imaging may detect unperceived ischemia and why the absence of pain does not equate to the absence of risk.
The subendocardium is more vulnerable because it undergoes greater systolic compression, has higher wall tension, and is perfused later in diastole. A moderate reduction in blood flow therefore tends to produce subendocardial ischemia; prolonged occlusion may extend necrosis toward the epicardium according to the wavefront model. Early reperfusion interrupts this progression and salvages myocardium.
Cell death involves necrosis and other regulated injury pathways. Loss of membrane integrity releases troponins. Reperfusion is indispensable for salvage but produces radicals, calcium overload, rapid correction of pH, opening of the mitochondrial permeability transition pore, inflammation, and edema. In clinical practice, the net benefit of timely reperfusion far exceeds the injury it may add.
Microembolization of debris, endothelial injury, edema, and capillary compression may cause microvascular obstruction. In severe cases it is associated with intramyocardial hemorrhage; these lesions can be identified by CMR, predict remodeling, and may explain failure to recover despite TIMI 3 epicardial blood flow.
A brief episode followed by reperfusion may leave reversible contractile dysfunction termed stunning. Blood flow is restored, but radicals, calcium abnormalities, and reduced myofilament sensitivity prolong hypocontractility. Recovery may require hours, days, or weeks and does not imply irreversible necrosis, although small areas of injury may coexist.
Hibernating myocardium is chronically hypocontractile but viable and may recover after revascularization. It may result from a persistent reduction in blood flow or repeated episodes of stunning with metabolic and structural adaptation. Distinguishing it from scar is important in patients with ventricular dysfunction, but the presence of viability does not automatically guarantee that revascularization will improve survival: anatomy, procedural risk, and the overall clinical picture remain decisive.
Ischemic preconditioning describes increased resistance to a prolonged insult after previous brief episodes, mediated by receptor pathways, kinases, and mitochondria. It has major experimental relevance but does not justify inducing ischemia. Attempts to transfer cardioprotection pharmacologically or mechanically have produced less consistent clinical results than preclinical findings because of patient complexity and timing.
Autoregulation maintains relatively constant blood flow across a range of pressures through the myogenic response of the arterioles. When perfusion pressure falls below compensatory capacity, blood flow becomes pressure-dependent. In patients with hypertrophy, microvascular dysfunction, or an epicardial stenosis, the lower limit may be shifted toward higher pressures: an otherwise tolerated reduction in blood pressure may then precipitate ischemia.
The left ventricular perfusion gradient is approximated by the difference between diastolic aortic pressure and ventricular end-diastolic pressure. Hypotension, tachycardia, and increased filling pressure may therefore converge. In right ventricular infarction, reduced output lowers aortic pressure, whereas in left-sided heart failure, increased diastolic pressure impedes subendocardial blood flow.
The relationship between blood flow and work is not linear during ischemia. The myocardium may transiently reduce contractility to adapt demand to supply, but this adaptation occurs at the expense of function. If perfusion remains insufficient, metabolite accumulation and ionic instability exceed adaptive capacity. Mechanical function is therefore both an indicator and a modulator of consumption.
Extravascular factors explain ischemia even when epicardial blood flow is preserved. Severe aortic stenosis, hypertrophic cardiomyopathy, and hypertensive hypertrophy increase mass, intramyocardial pressure, and diffusion distance; tachycardia and atrial fibrillation reduce diastolic filling; anemia and hypoxemia lower arterial oxygen content. Ischemic heart disease may therefore overlap with noncoronary structural disorders.
Ischemia does not leave a single anatomical signature. A completely reversible episode may produce no macroscopic changes; infarction causes necrosis with a distribution related to the vascular territory and wall depth; healing produces a fibrous scar. Stunning, hibernation, microinfarctions, patchy necrosis, and remodeling lie between these extremes.
Infarction due to epicardial occlusion tends to begin in the subendocardium and progress toward the epicardium if the occlusion persists. Transmural necrosis is not a perfect synonym for STEMI, nor is subendocardial necrosis for NSTEMI: ECG and anatomy correlate but are not equivalent. Reperfusion may produce a nontransmural infarction even after a presentation with ST-segment elevation.
Circumferential or multifocal subendocardial infarctions may occur during severe hypotension, hypoxemia, or tachyarrhythmia, especially in the presence of diffuse coronary artery disease. Territorial infarctions suggest occlusion of a specific artery. Distal emboli and microembolization may create small disseminated areas of necrosis, sometimes recognizable only by CMR.
In the first hours, fibers become edematous and progressively lose integrity. Neutrophilic infiltration, macrophage removal, granulation tissue, and collagen deposition follow. During the phase of maximal degradation, the wall is vulnerable to mechanical rupture. A mature scar does not recover contractility, but global function may improve through recovery of stunned myocardium and remodeling.
CMR with late gadolinium enhancement recognizes the ischemic pattern as subendocardial involvement with possible transmural extension in a coronary territory. Myocarditis and cardiomyopathies often have nonischemic distributions. The transmural extent of the scar reduces the likelihood of regional recovery after revascularization, although it is not the only decision-making factor.
Hibernating myocardium shows reduced function, metabolic abnormalities, and potentially reversible cellular changes. Thinned segments that are not completely scarred may retain viability. Dobutamine echocardiography, metabolic PET, and CMR assess different aspects, respectively contractile reserve, metabolism, and scar.
Post-infarction remodeling includes dilation of the infarcted area, hypertrophy, and geometric changes in remote myocardium. Wall stress, the renin-angiotensin-aldosterone system, the sympathetic nervous system, inflammation, and extracellular matrix contribute. Adverse remodeling increases volumes, reduces ejection fraction, and promotes functional mitral regurgitation.
Ischemic cardiomyopathy is characterized by ventricular dysfunction attributable to infarctions, scar, chronic ischemia, or combinations of these. Not every patient with coronary artery disease and reduced ejection fraction has an exclusively ischemic etiology; alcohol, genetics, myocarditis, tachycardia, and valvular disease may contribute. Scar distribution and coronary anatomy assist causal attribution.
Repeated ischemia may produce a phenotype of ischemic mitral regurgitation. The valve is often structurally intact, but displacement of the papillary muscles and leaflet tethering prevent coaptation. Acute papillary muscle rupture, by contrast, is a distinct mechanical complication with massive regurgitation and instability.
The scar contains channels of surviving tissue with slow conduction that may sustain reentry circuits and ventricular tachycardia. Residual ischemia may act as a trigger, but revascularization does not necessarily eliminate a mature scar substrate. Assessment of arrhythmic prognosis requires consideration of ejection fraction, scar, documented arrhythmias, and timing after infarction.
Microvascular dysfunction may be primary or secondary to hypertrophy, diabetes, cardiomyopathy, aortic stenosis, or infarction. After reperfusion, destroyed capillaries and microvascular obstruction produce a phenotype different from chronic INOCA. The same general expression must therefore not obscure different mechanisms and treatments.
From a clinical perspective, recognizable phenotypes include chronic forms with exertional angina, silent ischemia, ANOCA or INOCA, ischemic ventricular dysfunction, and patients stabilized after ACS; acute phenotypes with STEMI, NSTEMI, and unstable angina; and systemic imbalance phenotypes, including secondary myocardial infarction and nonischemic injury that must be distinguished. Each phenotype requires a specific diagnostic question.
The distribution of necrosis also reflects the relative duration of occlusion and reperfusion. Very early reperfusion may leave edema with minimal necrosis; intermediate reperfusion creates a salvaged border around a necrotic core; late reperfusion may restore the vessel without substantially reducing the infarction. The area at risk and myocardial salvage index are useful concepts in studies, but their clinical estimation requires standardized methods.
The right ventricle has less mass, lower systolic pressure, and lower demand than the left ventricle and is perfused during systole as well. It may therefore recover substantially after reperfusion, but acute right ventricular infarction impairs left ventricular filling and may cause shock. Dilation shifts the septum and further worsens output, especially with positive-pressure ventilation or excessive fluids.
Scar is not uniform tissue. The dense fibrous core is electrically inert, whereas the border zone contains surviving myocytes separated by fibrosis. Slow, anisotropic conduction permits reentry circuits. The extent of the heterogeneous zone on CMR may add prognostic information beyond ejection fraction alone, although it does not replace validated criteria for prevention with a defibrillator.
Healing also modifies the matrix of remote myocardium. Fibroblast and neurohormonal activation may produce diffuse interstitial fibrosis, increase stiffness, and reduce diastolic reserve; this helps explain symptoms and arrhythmias in patients whose focal scar does not appear sufficient to account for the entire functional picture.
Ischemia may be asymptomatic or present as angina, dyspnea, arrhythmia, heart failure, or sudden death. Perception depends on intensity and duration, innervation, individual threshold, neuropathy, and attention to the symptom. The relationship between the amount of ischemia and pain is imperfect: silent electrocardiographic episodes may be extensive, whereas intense pain may occur with limited ischemia.
The history of chest discomfort must define its character, location, duration, radiation, and precipitating factors. Exertional retrosternal pressure, tightness, heaviness, or burning is suggestive. Pain that is reproducible on palpation, instantaneous, or strictly pleuritic lowers the probability but does not eliminate it. Response to nitrates is not specific because esophageal spasm may also improve.
Exertional angina occurs when demand exceeds available reserve. The threshold may be fixed in stable stenoses or vary with vascular tone, temperature, meals, anemia, blood pressure, and heart rate. First-effort angina, in which the symptom diminishes when activity is resumed after a pause, may reflect warm-up, collateral recruitment, and preconditioning.
Vasospasm often causes episodes at rest, at night, or with a circadian pattern, sometimes with palpitations or syncope. It may cause transient ST-segment elevation but also depression. Microvascular dysfunction may produce symptoms during exertion, after exercise, or at rest, with prolonged duration and an incomplete response to nitrates. Mixed phenotypes are common.
Dyspnea is an important ischemic equivalent. Impaired relaxation rapidly increases filling pressure and may cause congestion before a marked reduction in ejection fraction. In older adults or patients with diabetes, it may be the only symptom. Fatigue, nausea, sweating, and epigastric discomfort are less specific but clinically relevant.
An acute presentation includes new or worsening pain, an episode at rest, a prolonged symptom, or instability. Distinguishing STEMI, NSTEMI, and unstable angina requires ECG and troponin. The absence of ST-segment elevation does not exclude an occlusion; diffuse ST-segment depression with elevation in aVR may suggest global ischemia but must be interpreted in context.
During extensive ischemia, hypotension, pulmonary edema, altered consciousness, and shock may occur. Right ventricular infarction may produce hypotension with relatively clear lungs and jugular venous distention. Papillary muscle ischemia may cause transient mitral regurgitation; papillary rupture causes severe acute mitral regurgitation.
Palpitations, presyncope, and syncope may result from ventricular tachyarrhythmias, bradyarrhythmias, or blocks. Inferior ischemia may activate vagal reflexes; extensive anterior ischemia may damage the intraventricular conduction system. Arrhythmia may precede pain, and sudden death may be the first manifestation.
In the chronic form with ventricular dysfunction, dyspnea, orthopnea, edema, reduced functional capacity, and asthenia predominate. The absence of angina does not exclude ischemia or viability. A history of infarction, Q waves, ischemic scar, or multivessel coronary artery disease points toward the etiology.
Physical examination during an episode may reveal tachycardia or bradycardia, hypertension or hypotension, a third or fourth heart sound, crackles, and mitral regurgitation. Outside the episode it may be normal. Examination also looks for anemia, hyperthyroidism, hypoxemia, fever, heart failure, and other causes capable of increasing demand or reducing supply.
Women have a higher prevalence of ANOCA and INOCA and may more frequently receive a premature noncardiac diagnosis; this does not mean that they always have symptoms different from those of men. Age, diabetes, neuropathy, comorbidities, and social factors influence presentation in both sexes and must be considered without stereotypes.
The differential diagnosis includes pericarditis, myocarditis, Takotsubo syndrome, pulmonary embolism, aortic dissection, aortic stenosis, hypertrophic cardiomyopathy, and extracardiac disorders. CMR is particularly useful when troponin and symptoms suggest infarction but the coronary arteries do not show a culprit lesion.
Silent ischemia may be recognized during monitoring, exercise testing, imaging, or because of a previously unknown scar. It is more common in diabetes with autonomic neuropathy but also occurs without neuropathy. Indiscriminate screening of asymptomatic individuals does not automatically improve outcomes; investigation must be reserved for settings in which the result changes prevention or management.
Circadian variability in heart rate, sympathetic tone, blood pressure, and platelet function contributes to the morning concentration of some events but does not allow prediction of the individual timing. Cold, large meals, and stress increase demand and vasoconstriction. Sexual activity generally entails moderate exertion and may be resumed according to stability and functional capacity, with counseling on interactions between nitrates and drugs for erectile dysfunction.
Decubitus angina may occur with increased venous return and wall tension; nocturnal angina requires differentiation among vasospasm, heart failure, and reflux. Response to nitrate does not establish the diagnosis. A diary of symptoms, activity, blood pressure, and medications may reveal useful patterns without replacing medical monitoring.
Examination must also assess peripheral and carotid artery disease because polyvascular disease increases risk and influences access and revascularization. Tendon xanthomas and early corneal arcus suggest familial hypercholesterolemia; their absence does not exclude it. Signs of anemia, thyroid disease, or lung disease may identify treatable precipitants.
Ischemia may be demonstrated clinically, electrocardiographically, functionally, or physiologically. Anatomy clarifies the substrate but does not always prove the consequence. In acute presentations, the priority is rapid recognition of necrosis and occlusion; in chronic presentations, the test is selected according to probability, patient characteristics, and whether the question is to document plaque, ischemia, viability, or microvascular function.
The resting ECG may be normal. Subendocardial ischemia often produces ST-segment depression and T-wave abnormalities; acute transmural ischemia may produce ST-segment elevation. Q waves suggest previous necrosis but have limited sensitivity. Bundle branch block, pacing, and hypertrophy may make interpretation of electrocardiographic stress testing unreliable.
High-sensitivity troponin is central in suspected acute presentations. The temporal pattern distinguishes acute injury from chronic elevation but does not assign the etiology. Diagnosis must integrate symptoms, ECG, imaging, and context. A normal value obtained too early may require repeat testing according to validated algorithms.
General clinical definition of acute myocardial infarction according to the fifth universal definition
Echocardiography identifies regional abnormalities, global function, filling pressure, the right ventricle, valves, and complications. During exercise or dobutamine stress, new hypokinesia indicates ischemia. Quality depends on the acoustic window and expertise; echocardiographic contrast improves endocardial definition when necessary.
SPECT demonstrates reversible perfusion defects and scar, with broad availability but radiation exposure and lower resolution than PET and CMR. Balanced multivessel disease may reduce the relative contrast among territories. Findings such as transient ischemic dilation and reduced function under stress may suggest diffuse risk.
PET measures absolute blood flow and global and regional reserve. It is useful when diffuse disease and microvascular dysfunction are suspected. Reduced reserve in the absence of stenosis may indicate CMD but must be interpreted with resting flow, blood pressure, heart rate, and comorbidities. FDG metabolism may assess viability in selected protocols.
Stress CMR combines perfusion, function, and tissue characterization without ionizing radiation. Late gadolinium enhancement quantifies scar and transmurality; T1 and T2 mapping assists with alternative diagnoses. Limitations include incompatible devices, claustrophobia, availability, arrhythmias, and gadolinium use in specific kidney conditions.
CCTA reliably excludes obstructive coronary artery disease in many patients and documents nonobstructive plaque. CT-derived FFR may estimate the functional effect in selected cases. Very dense calcium may overestimate stenosis because of blooming and require a functional or invasive method.
Exercise ECG testing provides functional capacity, blood pressure response, symptoms, and arrhythmias but has lower accuracy than imaging. It remains appropriate in selected patients with an interpretable ECG and the ability to exercise, especially when the overall functional result is clinically useful. It does not visualize plaque, and a negative result does not exclude nonobstructive disease.
Coronary angiography defines the lumen and permits treatment. FFR is the ratio of distal to aortic pressure during maximal hyperemia; the conventional threshold for significance is ≤0.80. iFR and other nonhyperemic indices use phases of the cycle with relatively stable resistance, with an iFR threshold of ≤0.89. Values must be viewed as continuous and interpreted in the clinical context.
Pressure pullback and physiological assessment help distinguish focal from diffuse pressure loss. In serial stenoses, each lesion influences flow through the others, and reassessment after treatment may be necessary. A negative FFR does not make a plaque biologically harmless, but it indicates that the stenosis does not limit blood flow under the test conditions and reduces the rationale for PCI performed solely to relieve ischemia.
Invasive microvascular function may be studied with CFR, the index of microcirculatory resistance, and acetylcholine testing. Reduced CFR and elevated resistance indicate a structural phenotype; symptoms and ischemic changes without epicardial spasm during acetylcholine support microvascular spasm. Reproduction of symptoms without ischemic criteria is insufficient.
Viability is assessed when ventricular dysfunction is present and the result may influence revascularization. Dobutamine looks for contractile reserve; PET identifies preserved metabolism in a hypoperfused area; CMR identifies absent or limited scar transmurality. After STICH and REVIVED, viability must not be used in isolation as a promise of prognostic benefit.
Risk is estimated by integrating ventricular function, anatomy, ischemia, scar, symptoms, and comorbidities. A large amount of ischemia or plaque identifies risk but does not mean that an invasive strategy automatically improves survival. Left main disease, complex anatomy, refractory symptoms, and ischemic dysfunction require dedicated assessment and often a Heart Team.
Pretest clinical probability prevents both unnecessary examinations and false reassurance. The 2024 ESC guidelines use a probability weighted by risk factors in addition to age, sex, and symptoms. In the very-low range, it may be reasonable not to perform testing; in intermediate ranges, CCTA or functional imaging is selected according to the question; with a very high probability and severe symptoms, coronary angiography may be appropriate.
Technical quality modifies the value of every examination. Attenuation artifacts may simulate defects on SPECT; an inadequate chronotropic response reduces the sensitivity of exercise stress; balanced ischemia may mask multivessel disease; calcium and motion degrade CCTA. Discordance between testing and clinical probability must lead to review of quality and mechanism, not to an arithmetic average of the results.
Epicardial and microvascular physiology may be discordant. Normal FFR with reduced CFR suggests diffuse or microvascular disease; abnormal FFR with preserved CFR may reflect a focal gradient with high overall flow capacity; these patterns have different implications for PCI, symptoms, and prognosis and explain why a single index does not describe the entire circulation.
Magnetic resonance imaging for acute pain with nonobstructive coronary arteries should be performed early enough to detect edema and tissue patterns. Subendocardial enhancement supports infarction; subepicardial or mid-wall enhancement suggests myocarditis; edema with a typical contractile pattern and absence of scar supports Takotsubo syndrome. The correct diagnosis avoids unnecessary antithrombotic therapy or omission of prevention.
Treatment pursues four objectives: interrupting acute ischemia, preventing future events, reducing symptoms, and preserving or restoring ventricular function. Priority changes with the phenotype. In acute occlusion, every minute of delay increases necrosis; in the chronic form, systemic risk management is continuous, and revascularization is selected for defined symptomatic or prognostic indications.
Atherothrombotic prevention includes complete smoking cessation, regular exercise, a heart-healthy diet, control of weight, blood pressure, and diabetes, intensive lipid-lowering therapy, and antithrombotic therapy when indicated. Cardiac rehabilitation transforms these elements into a structured program and improves recovery, adherence, and quality of life.
A high-intensity statin is fundamental in atherosclerotic disease. If the target is not achieved, ezetimibe and, according to risk and distance from target, anti-PCSK9 antibodies or bempedoic acid are added early. Therapy acts on the risk of new events and plaque biology, not on immediate pain. Elevated Lp(a) requires more aggressive control of modifiable factors.
Antianginal drugs must be individualized. Beta-blockers reduce heart rate, contractility, and blood pressure and are particularly useful after certain acute syndromes, in tachyarrhythmias, and in ventricular dysfunction. An indefinite prognostic benefit must not automatically be extended to every stable patient with normal function and no recent infarction.
Dihydropyridine calcium channel blockers reduce afterload and increase blood flow, whereas verapamil and diltiazem reduce heart rate and contractility but are contraindicated in some forms of systolic dysfunction or conduction disturbance. They are central in vasospasm. Combination with a beta-blocker requires attention to bradycardia and block.
Nitrates reduce preload and consumption and dilate the coronary arteries. Sublingual nitrate treats an episode; prolonged formulations require a nitrate-free interval to limit tolerance. They are contraindicated with phosphodiesterase-5 inhibitors and require caution in hypotension, right ventricular infarction, and dynamic obstructions.
Ranolazine reduces the late sodium current and may improve angina without major effects on heart rate and blood pressure, but requires attention to QT and interactions. Ivabradine reduces sinus rate and is useful only in appropriate settings. Trimetazidine and nicorandil are available in some healthcare systems; indications and contraindications vary.
In microvascular angina with low CFR or elevated resistance, beta-blockers, ACE inhibitors or ARBs, statins, and other antianginal drugs are often used. In epicardial or microvascular spasm, calcium channel blockers and nitrates are the main treatments. Treatment stratified according to invasive physiology has improved symptoms and quality of life compared with unguided therapy, although evidence for hard outcomes remains more limited.
Secondary myocardial infarction first requires correction of the precipitating factor: control of tachyarrhythmia or hypertensive crisis, and treatment of hypoxemia, sepsis, anemia, or hypotension. There is no universal antithrombotic therapy equivalent to that used for primary myocardial infarction due to atherothrombosis. Concomitant coronary artery disease must be investigated proportionately and treated according to risk.
PCI treats one or more focal stenoses; CABG provides conduits beyond diseased segments and may protect territories from proximal disease progression. The choice depends on left main disease, number of vessels, complexity, diabetes, ventricular function, operative risk, and the possibility of complete revascularization. Intracoronary imaging and physiology improve selection and outcome.
In stable patients with moderate or severe ischemia but without significant left main disease, ISCHEMIA did not show a reduction in mortality with an initial invasive strategy compared with medical therapy. It did, however, show greater relief of angina in symptomatic patients. The result does not automatically apply to ACS, refractory symptoms, severely reduced function, or excluded anatomies.
In ischemic ventricular dysfunction, CABG may improve long-term survival in selected patients, as documented by the extension of the STICH study. REVIVED did not show a benefit of PCI on death or hospitalization for heart failure in patients with severe dysfunction and selected viability, emphasizing that PCI and CABG are not interchangeable and that viability alone does not determine the decision.
Heart failure therapy for reduced ejection fraction includes neurohormonal blockade and SGLT2 inhibitors according to guidelines. After infarction, reassessment of ejection fraction at the end of the recovery period and optimal therapy guides any indication for a defibrillator. Protection instituted too early may overestimate persistent risk because stunned myocardium may recover.
Prognosis depends on ventricular function, scar, anatomy, atherosclerotic burden, residual ischemia, arrhythmias, and comorbidities. CCTA showing no plaque confers a favorable prognosis; nonobstructive disease nevertheless increases risk compared with plaque-free coronary arteries. Severely reduced CFR may predict events even without stenosis.
Follow-up must assess the frequency and threshold of symptoms, functional capacity, blood pressure, lipids, kidney function, blood glucose, and adherence. New angina at rest or acceleration requires urgent reassessment. Routine serial examinations without a clinical change do not replace control of causal factors.
Long-term antiplatelet therapy is indicated in clinically documented coronary artery disease according to the history of infarction, PCI, anatomy, and bleeding risk. After ACS, dual antiplatelet therapy is generally maintained for twelve months but may be shortened or modified. In patients with atrial fibrillation, anticoagulation and antiplatelet therapy are combined for the shortest period necessary to prevent thrombosis without excessive bleeding.
Anti-inflammatory therapy does not replace lipid control. Low-dose colchicine reduced events in chronic coronary artery disease and after infarction in selected trials and may be considered after assessment of tolerance, kidney and liver function, and interactions. Canakinumab demonstrated the biological principle of residual inflammation but is not a routine treatment for ischemic heart disease.
In patients with anemia, correction depends on severity, symptoms, bleeding, and ischemia; a universal transfusion strategy is inappropriate. In hypoxemia, the cause is treated and oxygen is administered, whereas routine oxygen provides no benefit in a normoxemic patient. In tachyarrhythmia, rate or rhythm control may restore balance without a coronary procedure.
The choice between PCI and CABG must also consider the expected duration of benefit and the ability to adhere to therapy. PCI offers rapid recovery but requires DAPT and may leave diffuse disease; CABG is more invasive but may provide more complete revascularization in complex anatomy. Biological age, frailty, cognition, and the patient's goals are part of the decision.
Myocardial necrosis is the primary irreversible complication. Its extent determines contractile loss, heart failure, and electrical risk. Early reperfusion limits the wavefront, but microvascular obstruction and intramyocardial hemorrhage may increase the final infarct size.
Acute ischemia alters membrane potentials, conduction, and refractoriness, promoting ventricular fibrillation and sudden death. Late scar sustains reentrant ventricular tachycardia. Ischemia and scar may coexist as trigger and substrate, which is why revascularization and arrhythmic prevention address distinct problems.
Acute ventricular dysfunction may cause pulmonary edema and cardiogenic shock. Right ventricular infarction reduces left ventricular filling; papillary ischemia causes mitral regurgitation; major loss of left ventricular myocardium compromises output. Management requires urgent echocardiography, reperfusion, and individualized hemodynamic support.
Ruptures of the free wall, septum, and papillary muscle occur during the phase of tissue fragility. They cause tamponade, a shunt, or acute mitral regurgitation. Presentation may be sudden, and the absence of a loud murmur does not exclude the defect in severe shock.
Chronic remodeling leads to dilation, a true aneurysm, functional mitral regurgitation, and ischemic cardiomyopathy. Stasis in an akinetic apex promotes ventricular thrombus and embolism. ACE inhibition, beta-blockade, mineralocorticoid receptor antagonism, and other heart failure therapies reduce remodeling and risk in appropriate patients.
Ischemia may precipitate atrial fibrillation, worsen conduction disturbances, and decompensate valvular disease. Reduced activity because of fear of symptoms produces deconditioning, depression, and loss of quality of life. Safe rehabilitation is part of preventing these consequences.
Chronic ischemic heart disease may progress to refractory angina when revascularization and pharmacological therapy fail to control symptoms. Before defining it as such, adherence, ischemia, microvascular or vasospastic mechanisms, and alternative diagnoses must be assessed. Nonconventional options are reserved for expert centers and have different levels of evidence.
The procedures themselves may cause infarction through branch occlusion, dissection, embolization, no-reflow, or thrombosis. An isolated rise in troponin after PCI or CABG does not automatically equate to procedure-related myocardial infarction: the fifth universal definition does not use a single diagnostic troponin threshold and requires a procedural coronary complication and/or a new regional wall-motion abnormality or loss of viable myocardium, according to the context.
The risk of recurrence persists because revascularization does not remove diffuse atherosclerosis, microvascular dysfunction, or thrombotic predisposition. New lesions, graft failure, restenosis, and stent thrombosis may cause new ischemia. Premature discontinuation of antiplatelet agents after stenting is particularly dangerous.
The ultimate consequence may be death from infarction, shock, arrhythmia, or progressive heart failure. Prognosis is nevertheless highly modifiable: early prevention, rapid recognition of acute symptoms, timely reperfusion, and intensive risk control reduce the likelihood that an ischemic episode becomes permanent myocardial loss.
Ischemic mitral regurgitation may be dynamic and increase during exercise, explaining dyspnea disproportionate to regurgitation at rest. Treatment integrates revascularization when indicated, heart failure therapy, resynchronization in candidates, and surgical or transcatheter valve intervention in selected patients.
A true ventricular aneurysm causes heart failure, arrhythmias, and thrombosis but rarely ruptures late; a pseudoaneurysm is a contained rupture and carries greater risk. Differentiation by echocardiography, CT, or CMR is essential because prognosis and surgical indications differ.
Kidney dysfunction may be a cause, modifier, and consequence. It reduces physiological reserve, increases atherothrombotic and bleeding risk, and limits some procedures; shock and contrast may cause acute kidney injury. Appropriate hydration, the minimum contrast dose, and medication adjustment reduce risk without denying life-saving revascularization.
Brain injury may result from cardiac arrest, hypoperfusion, or embolism from ventricular thrombus and procedures. Prevention includes timely resuscitation, hemodynamic stability, recognition of thrombus, and appropriate use of anticoagulation. Neurological recovery, not coronary success alone, determines the outcome after cardiac arrest.
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