Causes of valvular heart disease

Article written and reviewed by Dr Luca Moretti

Valvular heart diseases are not a single disease, but the hemodynamic outcome of different biological and mechanical processes. Calcific aortic stenosis in an older adult, mitral regurgitation caused by chordal rupture, a rheumatic valve, and tricuspid regurgitation due to right ventricular dilatation can produce similar symptoms while requiring different prevention, imaging, timing and treatment. A complete diagnosis must therefore answer two distinct questions: what dysfunction is present, and what process caused it.

The etiology is identified by integrating the distribution of valve involvement, the morphology of the leaflets and subvalvular apparatus, age at onset, rate of progression, and family, infectious, medication and oncologic history. No isolated finding is infallible. Calcification may be part of common degeneration or radiation exposure; functional regurgitation may coexist with organic damage; and a vegetation may develop on a prosthesis or on an already degenerated valve.

Defining the cause is not merely descriptive. It determines whether there is a treatment capable of halting the process, whether other organs or family members should be evaluated, whether repair is likely to be durable, and whether the disease process will continue to damage a prosthesis. It also prevents a consequence from being mistaken for the primary disease: tricuspid regurgitation may be a late manifestation of left-sided valvular heart disease, pulmonary hypertension or atrial fibrillation.

The frequency of causes varies with geography, age and access to care. In high-income countries, calcific aortic degeneration and degenerative mitral disease predominate; rheumatic heart disease remains a leading primary cause in many resource-limited areas and vulnerable populations. Aging, cancer survivorship, intracardiac devices and valve procedures have also created increasingly common iatrogenic and prosthetic phenotypes.

Etiologic classification and mechanisms of damage

Congenital causes include valves formed with an abnormal number, size or insertion of cusps or leaflets, endocardial cushion defects and dysplasia of the subvalvular apparatus. The bicuspid aortic valve is the paradigm of an abnormality that combines architecture, mechanical stress, early calcification and possible aortopathy. A malformation may be isolated or part of connective-tissue syndromes and requires a lifelong perspective.

Genetic etiologies do not necessarily correspond to an obvious malformation at birth. Variants that alter the extracellular matrix, valvular development or connective tissue predispose to mitral valve prolapse, aortic dilatation and degeneration. Variable penetrance and expressivity explain why relatives carrying the same variant may present at different ages and with different severity. A family history of dissection, early valve surgery or sudden death guides counseling, but genetic testing should be requested only when its result can be interpreted and can alter management.

Degeneration should be regarded as an active biological process, not simple wear and tear. In the aortic valve, endothelial injury, lipid retention, inflammation, osteogenic transformation of interstitial cells and mineralization progressively stiffen the cusps; in the mitral valve, by contrast, collagen and proteoglycan abnormalities may cause myxomatous expansion, chordal elongation and prolapse, whereas fibroelastic deficiency is associated with thin tissue and focal rupture. For this reason, grouping all these phenotypes under the single label of “degenerative” without describing their anatomy means losing information that is also relevant to the surgical strategy.

Mitral annular calcification involves the annulus and may extend to the leaflets, myocardium and conduction system. Age, renal failure, mineral disorders and mechanical stress promote its development. It can cause stenosis, regurgitation or both and can make surgery hazardous. It should not be equated either with rheumatic stenosis, in which the commissures and chordae are predominantly affected, or with aortic cusp calcification.

Rheumatic heart disease results from the immune response to group A streptococcal infection and the cumulative damage caused by recurrences. Fused commissures, thickened leaflets and a shortened subvalvular apparatus mainly produce mitral disease, often with aortic and tricuspid involvement. The multivalvular distribution and combination of stenosis and regurgitation reflect a process different from age-related calcification.

Infective endocarditis may affect native valves, prostheses, devices or repair material and damage them through vegetations, perforations, abscesses, fistulas and destruction of the supporting apparatus. The most typical hemodynamic manifestation is acute regurgitation, although bulky vegetations or prosthetic obstruction may cause functional stenosis. Urgency and treatment therefore depend on the microorganism, site and local extent of disease, as well as on the presence of embolism and heart failure; a negative culture, especially after antibiotics or in the presence of intracellular pathogens, is not sufficient to exclude the diagnosis.

Immune-inflammatory diseases include lupus with Libman-Sacks endocarditis, antiphospholipid antibody syndrome, vasculitides, Behçet disease and other rare conditions. Sterile deposits, thickening, retraction or root dilatation produce different phenotypes. Systemic activity and thrombotic risk modify treatment and prosthesis choice; automatically attributing regurgitation to a known autoimmune disease is hazardous unless infection and degeneration have been excluded.

Less common infiltrative or metabolic causes include forms related to endomyocardial fibrosis, Fabry disease, amyloidosis, disorders of mineral metabolism and other systemic conditions. The valvular finding may be secondary to myocardial and chamber disease. The prevalence of minor thickening does not prove causality; a coherent phenotype and the extracardiac context are required. A rare diagnosis should explain the findings better than more common alternatives.

Toxic, oncologic, ischemic and iatrogenic etiologies

Some molecules activate serotonergic pathways and induce fibrous plaques with retracted leaflets. Fenfluramine and dexfenfluramine, ergot derivatives and some dopamine agonists are historically well-established associations; the magnitude of risk depends on 5-HT2B receptor activity, cumulative dose and duration. Drug-induced valvular heart disease requires a precise reconstruction of prescribed products, weight-loss substances, antiparkinsonian drugs and nonmedical use, rather than an indiscriminate list of exposures.

Carcinoid heart disease shares a fibrogenic pathway mediated mainly by serotonin, but its source is a secreting neuroendocrine neoplasm. The predominance of right-sided involvement, with retracted tricuspid and pulmonary valves, reflects exposure to mediators before their pulmonary inactivation. Neuroendocrine biomarkers, NT-proBNP and oncologic imaging therefore have a significance that does not apply to other valvular heart diseases.

Radiation-induced valvular heart disease often emerges after a long latency. Cardiac dose, treatment field, age at exposure and cardiovascular factors influence risk. Fibrosis and calcification may involve the aorta, aortic root, aorto-mitral continuity and mitral valve, together with the coronary arteries, pericardium, myocardium and conduction system. This combination alters operative risk and makes assessment of the valve alone insufficient.

Ischemic heart disease mainly causes secondary mitral regurgitation through ventricular remodeling, papillary muscle displacement and tethering, even when the leaflets are structurally intact. Papillary muscle rupture after myocardial infarction, by contrast, produces catastrophic acute regurgitation and a lesion of the subvalvular apparatus. Right ventricular ischemia and infarction can contribute to tricuspid regurgitation. The term “ischemic” should therefore specify whether there is acute mechanical damage or chronic remodeling.

In dilated cardiomyopathies, reduced closing force, annular dilatation and tethering cause secondary mitral and tricuspid regurgitation. In long-standing atrial fibrillation, dilatation of the atria and annuli may produce atrial phenotypes with relatively preserved ventricles. The functional mechanism is dynamic and sensitive to volume status, pressure and rhythm; it can nevertheless become self-perpetuating once remodeling exceeds reversibility.

Pulmonary hypertension and left-sided heart disease increase right ventricular afterload and dimensions, promoting secondary tricuspid regurgitation. Lung disease, chronic thromboembolism, shunts and ventricular dysfunction have different prognoses and treatments. Regurgitation is a hemodynamic consequence, but it becomes an independent determinant of congestion when annular dilatation and coaptation abnormalities are severe. Treating the upstream cause does not guarantee late regression.

Chest trauma, endomyocardial biopsy and intracardiac procedures can lacerate leaflets, chordae or papillary muscles. Transvalvular leads cause impingement, adherence, perforation or entanglement of the tricuspid valve, but the mere presence of a lead does not prove causality. After repair, iatrogenic stenosis may result from an undersized ring or an edge-to-edge procedure; residual regurgitation may reflect incomplete repair, progression or new endocarditis.

Prostheses introduce their own categories: structural deterioration, thrombosis, pannus, endocarditis, paravalvular leak and prosthesis-patient mismatch. Although these are not etiologies of a native valve, they enter the differential diagnosis of a new murmur or heart failure. Time since implantation, prosthesis type, antithrombotic regimen and baseline echocardiogram are decisive causal information.

Anatomic phenotype, distribution and differential diagnosis

The etiology often leaves a morphologic signature, although rarely an exclusive one. Commissural fusion and chordal shortening point toward rheumatic disease; calcification at the cusp bases with reduced opening toward calcific aortic stenosis; segmental prolapse and flail toward degenerative mitral disease. Likewise, vegetations, perforation or abscess suggest endocarditis, whereas retracted right-sided leaflets in the setting of a secretory syndrome suggest carcinoid disease. Diagnosis therefore arises from concordance of the entire picture, not from isolated recognition of a single image.

The affected valve narrows the field. Acquired mitral stenosis with fused commissures is almost always rheumatic; in older patients, annular calcification can produce noncommissural obstruction. Aortic stenosis is predominantly calcific in tricuspid or bicuspid valves, whereas isolated rheumatic aortic disease is less common. Tricuspid stenosis suggests rheumatic disease, carcinoid disease or iatrogenic causes and almost always requires a search for other lesions.

Regurgitation requires an even more articulated interpretation, because the mechanism always completes the etiologic diagnosis. In aortic regurgitation the lesion may involve the cusps, the root or both, whereas endocarditis and dissection are typical causes of acute forms. In mitral regurgitation, prolapse, restriction, perforation, annular dilatation and tethering must be distinguished; in tricuspid regurgitation, primary disease, the secondary atrial phenotype, the ventricular phenotype and device-related forms must be separated.

Multivalvular distribution provides clues: mitral, aortic and tricuspid involvement in rheumatic heart disease; tricuspid and pulmonary involvement in carcinoid disease; the aorta and aorto-mitral continuity after radiation; mitral and tricuspid regurgitation in cardiomyopathies. However, advanced age makes coexistence of independent processes likely. A patient may have degenerative aortic stenosis, ischemic mitral regurgitation and secondary tricuspid regurgitation without a single unifying etiology.

Chronology distinguishes primary damage from adaptation. Mitral regurgitation that appears after ventricular dilatation is likely to follow remodeling; chordal rupture that precedes dilatation causes it. Retrieving previous imaging makes it possible to reconstruct this sequence. Without chronology, dilated chambers and severe regurgitation can be interpreted in either direction and lead to opposite therapeutic choices.

The history investigates rheumatic fever, recurrent pharyngitis, endocarditis, injection drug use, autoimmune diseases, renal failure, neuroendocrine tumors, thoracic radiotherapy, fibrogenic drugs, ischemic heart disease and previous procedures. Age and country of origin modify pretest probability. The family history explores bicuspid aortic valve, aortopathy, prolapse, sudden death and early surgery; it should not be limited to unspecified “heart disease.”

Physical examination assesses not only murmurs, but also the systemic phenotype: connective-tissue features, skin or vascular lesions, fever, embolic phenomena, flushing, congestion and oncologic scars. Murmur intensity depends on flow and pressures and does not identify the cause. A severe acute lesion may be relatively quiet; a moderately obstructed valve in a high-flow state may be very prominent.

Laboratory tests become meaningful only when guided by the etiologic hypothesis. In suspected endocarditis, blood cultures precede antibiotics, whereas inflammatory markers remain nonspecific; autoantibodies, antiphospholipid profile, calcium-phosphate metabolism, renal function, 5-HIAA or genetic tests should be requested when the phenotype makes them relevant. Indiscriminate panels instead increase false-positive results and may divert attention from the most likely cause.

The risk of apparent causality is high in rare diseases. A drug taken by many patients is not automatically responsible; a neoplasm does not make every regurgitation carcinoid; lupus does not turn every vegetation into Libman-Sacks endocarditis. The strength of the known association, dose and latency, morphology, distribution, alternatives and response after withdrawal of the exposure must be considered methodically.

Imaging and targeted tests to determine the cause

Transthoracic echocardiography defines the valve, mechanism, severity and consequences. An etiologic study describes the number and thickness of cusps, commissures, calcification, mobility, chordae, papillary muscles, annuli and roots; it assesses all valves, not only the dominant lesion. Doppler quantifies the hemodynamic effect, but a gradient or regurgitant volume alone cannot distinguish degeneration, rheumatic disease or toxicity.

Transesophageal echocardiography provides higher resolution for vegetations, perforations, prostheses, the mitral apparatus and procedural planning. 3D imaging provides an en face view of commissures, segments and orifices and clarifies the relationship between a lead and the tricuspid valve. Sedation and reduced afterload may attenuate regurgitation; morphology remains informative, but quantification should be correlated with the awake study.

CT identifies calcium, root and aortic anatomy, coronary arteries, prostheses and perivalvular complications. Calcium distribution helps distinguish annular, cuspal and radiation-associated calcification without being pathognomonic. In bicuspid aortic valve disease, CT clarifies morphology and aortopathy; after radiotherapy, it shows a porcelain aorta and mediastinal fibrosis relevant to surgical access. In endocarditis, CT may demonstrate abscesses and pseudoaneurysms.

Cardiac magnetic resonance measures volumes, flows, function and myocardial tissue characteristics. It is useful when regurgitation and chamber dimensions are discordant, in cardiomyopathies, congenital heart disease and right-sided lesions. Fibrosis or ischemia may support a secondary mechanism, whereas a mass requires characterization. Magnetic resonance does not replace blood cultures or leaflet anatomy and must be interpreted according to the etiologic question.

FDG PET/CT or labeled leukocyte imaging contributes to the diagnosis of prosthetic infection and the search for infectious foci; receptor imaging is specific to neuroendocrine tumors. These techniques answer different questions and are not interchangeable. A metabolic signal must be interpreted in light of preparation, time since surgery and sterile inflammation. The most sophisticated test does not compensate for a low pretest probability or an inadequate protocol.

Catheterization is reserved for hemodynamic discordance, coronary assessment or procedural planning. Pressures and cardiac output confirm the impact of the lesion, not its cause. Valve biopsy is almost always available only after surgery and may confirm endocarditis, carcinoid disease or rare disorders; the histologic result must be integrated with microbiology and clinical findings because fibrosis and calcification are shared endpoints.

An integrated report separates certainty from probability. It may conclude “morphology typical of rheumatic disease,” “ventricular secondary regurgitation” or “suspected radiation-induced lesion with concomitant degeneration,” while explicitly stating conflicting data and required investigations. Unsupported absolute labels become particularly dangerous when they determine antibiotic use, withdrawal of an essential drug, family screening or exclusion from repair.

Serial reassessment is part of the diagnosis. Resolution of regurgitation with reverse remodeling supports a functional component; progression despite control of secretory activity documents persistent structural damage; new destruction with fever reopens the suspicion of infection. Changing the hypothesis in light of longitudinal data is not inconsistency, but the correct application of causal reasoning.

Prognostic, therapeutic and preventive implications

The cause changes the natural history. A congenital valve may deteriorate over decades and be associated with aortopathy; endocarditis may destroy tissue within days; radiotherapy may cause effects after many years; functional regurgitation fluctuates with loading conditions but becomes progressive with remodeling. The follow-up interval should reflect severity and etiologic activity, not only a mild, moderate or severe classification.

When a modifiable cause exists, treating it is a priority: antibiotics and source control for infection, secondary prophylaxis for rheumatic disease, carefully considered withdrawal of a fibrogenic agent, control of carcinoid syndrome, heart failure therapy and revascularization when indicated. Such treatment may halt new injury or reduce a secondary component, but it does not dissolve calcification, repair a perforation or lengthen ruptured chordae.

Etiology also directly affects repairability. Localized degenerative prolapse can be repaired durably at experienced centers, whereas diffusely retracted rheumatic or carcinoid valves offer less tissue reserve, and annular calcification or radiation injury increases complexity. In endocarditis, repairability depends on the amount of tissue remaining after debridement; in all cases, a technically feasible repair is not preferable if it leaves stenosis, regurgitation or a high likelihood of reintervention.

Prosthesis choice takes into account recurrence, thrombogenicity, anticoagulation, age and future procedures. Persistent diseases may affect residual tissue or bioprostheses; infection requires microbiological control and prevention; carcinoid disease requires control of secretory activity. In irradiated patients, future surgical access and degeneration of multiple structures favor a lifetime strategy rather than focusing only on the immediate procedure.

Prevention must likewise be tailored to the etiology. Better social conditions, diagnosis and treatment of streptococcal infections and prophylaxis against recurrences reduce rheumatic disease; oral hygiene and control of infectious foci limit bacteremia, whereas antibiotic prophylaxis for endocarditis remains reserved for high-risk categories. Radiotherapy planning aims to reduce cardiac dose and pharmacovigilance to avoid unnecessary exposures; for established calcific aortic stenosis, by contrast, no medical therapy has been proven to halt progression.

The same principle applies to screening. Family screening is appropriate mainly for bicuspid aortic valve, aortopathies and some genetic syndromes, but it is not automatically extended to common degeneration, endocarditis or secondary forms. In cancer survivors, surveillance is adjusted according to dose, field, time elapsed and risk factors, whereas in neuroendocrine tumors it also depends on secretory activity. Applying the same program to every valvular heart disease reduces precision and risks diverting resources from truly vulnerable groups.

Pregnancy represents a hemodynamic and organizational stress test. Rheumatic stenosis may decompensate because of increased cardiac output; a genetic aortopathy introduces aortic risk; prostheses and anticoagulation add maternal-fetal issues. Preconception counseling requires an etiologic diagnosis, assessment of severity and anticipation of events, because two women with the same gradient may have completely different anatomy, progression and options.

The patient should be given an understandable causal diagnosis together with its degree of certainty. A “leaky valve” does not explain whether the problem results from degenerated tissue, infection or cardiac dilatation; “degenerative” should not become synonymous with inevitable and harmless aging. Precise communication improves adherence to prophylaxis, family screening, withdrawal of exposures and prompt recognition of fever or heart failure.

Etiologic reasoning turns a finding into a clinical pathway. It begins with morphology, tests consistency with history and distribution, uses targeted investigations and remains open to the coexistence of multiple causes. This discipline reduces overdiagnosis of rare conditions and neglect of secondary forms, supports a more durable valve strategy and links cardiology to prevention of the disease process that continues to act beyond the valve itself.