Indications for Aortic Valve Replacement
Aortic valve replacement is definitively indicated for any patient with severe aortic stenosis or severe aortic regurgitation who develops symptoms, regardless of left ventricular function. 1
Aortic Stenosis Indications
Class I (Definitive) Indications
Symptomatic severe aortic stenosis is an absolute indication for AVR, even with preserved ejection fraction. 1 The presence of angina, syncope, dyspnea, or heart failure symptoms mandates intervention because untreated symptomatic severe AS carries extremely high mortality risk. 2
AVR is indicated for asymptomatic patients with severe AS and left ventricular systolic dysfunction (LVEF <50%) not attributable to another cause. 1 This threshold recognizes that ventricular dysfunction represents decompensation from chronic pressure overload. 1
Severe AS patients undergoing other cardiac surgery (CABG, ascending aorta surgery, or other valve surgery) require concomitant AVR. 1 This prevents the need for reoperation and addresses the hemodynamic burden during recovery. 1
Asymptomatic severe AS with abnormal exercise testing showing exercise-induced symptoms clearly related to AS warrants AVR. 1, 3 Exercise testing unmasks latent symptoms in patients who may have unconsciously limited their activity. 3
Class IIa (Reasonable) Indications
AVR should be considered for asymptomatic severe AS patients with abnormal exercise testing showing exercise-induced hypotension (blood pressure fall below baseline). 1 This hemodynamic response indicates inadequate cardiac output reserve and predicts poor outcomes. 1
For asymptomatic patients with very severe AS (peak velocity ≥5.5 m/s or mean gradient ≥60 mmHg) and low surgical risk, AVR should be considered even without symptoms. 1, 3 The extremely high gradient indicates critical obstruction with imminent decompensation risk. 3
Moderate AS (not severe) should be addressed during CABG or other cardiac surgery. 1 The moderate stenosis will likely progress, and addressing it prevents future reoperation. 1
Low-flow, low-gradient severe AS with normal ejection fraction requires careful confirmation of severity, but AVR should be considered once severe AS is confirmed. 1 This paradoxical entity requires comprehensive evaluation including valve calcification assessment and potentially dobutamine stress echocardiography. 1
Low-flow, low-gradient severe AS with reduced ejection fraction and documented flow reserve (contractile reserve on dobutamine) should undergo AVR. 1 The presence of flow reserve indicates the ventricle can recover after afterload reduction. 4, 5
Class IIb (May Be Considered) Indications
Symptomatic low-flow, low-gradient severe AS with reduced ejection fraction but WITHOUT flow reserve may be considered for AVR after careful evaluation. 1 These patients have higher operative mortality but may still benefit from afterload reduction, though outcomes are less predictable. 4, 6
Asymptomatic severe AS with markedly elevated natriuretic peptides (confirmed on repeated measurements without other explanation) may warrant AVR in low-risk patients. 1 Elevated biomarkers suggest subclinical decompensation. 1
Aortic Regurgitation Indications
Class I (Definitive) Indications
Symptomatic patients with severe AR require AVR regardless of left ventricular systolic function. 1 Symptoms indicate hemodynamic decompensation with high mortality risk if untreated. 1
Asymptomatic patients with chronic severe AR and LV systolic dysfunction (LVEF <50%) require AVR. 1 Once ejection fraction falls below 50%, irreversible myocardial damage may be developing. 1, 7
Severe AR patients undergoing cardiac surgery for other indications (CABG, ascending aorta surgery, other valve surgery) require concomitant AVR. 1 This prevents progressive volume overload during recovery. 1
Class IIa (Reasonable) Indications
Asymptomatic severe AR with normal LV systolic function (LVEF ≥50%) but severe LV dilatation warrants AVR. Specifically: end-systolic dimension >50 mm or end-diastolic dimension >75 mm. 1 These dimensional thresholds indicate the ventricle is approaching irreversible remodeling. 1 Consider lower thresholds (LVESD >50 mm, LVEDD >70 mm) for patients of small stature. 1
Moderate AR (not severe) should be addressed during other cardiac surgery. 1 The regurgitation will likely progress, and addressing it prevents future reoperation. 1
Class IIb (May Be Considered) Indications
Asymptomatic severe AR with normal systolic function (LVEF ≥50%) but progressive severe LV dilatation (LVEDD >65 mm) may be considered for AVR if surgical risk is low. 1 This is particularly relevant with documented progressive enlargement on serial imaging. 1
Asymptomatic severe AR with evidence of progressive LV dilatation, declining exercise tolerance, or abnormal hemodynamic responses to exercise may warrant AVR. 1 These findings suggest early decompensation despite preserved resting function. 1
Critical Pitfalls and Caveats
The "Gorlin Conundrum" in low-gradient AS: Patients with apparent severe AS (calculated AVA <0.8 cm²) but low transvalvular gradient and low cardiac output present diagnostic uncertainty. 4 The low gradient may reflect true critical stenosis with afterload mismatch OR may reflect mild stenosis with coexistent cardiomyopathy where the Gorlin equation falsely calculates a small valve area. 4 Dobutamine stress echocardiography helps differentiate: patients with flow reserve who increase their gradient with dobutamine have true severe AS and benefit from AVR, while those without flow reserve have worse outcomes. 1, 4
Timing in asymptomatic AR is critical: Approximately 50% of asymptomatic severe AR patients remain stable for 10 years, but 4% per year develop LV dysfunction. 7 Serial imaging every 6-12 months is mandatory once LVEDD exceeds 65 mm or LVESD exceeds 50 mm to detect the transition to dysfunction before irreversible damage occurs. 3, 7
Multidisciplinary Heart Valve Team evaluation is mandatory for all AVR decisions, particularly for TAVR candidates, involving interventional cardiology, cardiac surgery, imaging specialists, and heart failure specialists. 1, 3 This collaborative approach is essential given the complexity of risk stratification and procedural planning. 1, 3
Surgical outcomes in severe LV dysfunction: Patients with severe AS and LVEF <30% without significant CAD or requiring only 1-2 bypass grafts have acceptable surgical outcomes with survival approaching that of heart transplantation. 6 However, those requiring ≥3 bypass grafts have significantly reduced survival, and heart transplantation should be considered. 6 Most survivors experience significant LVEF improvement (from ~28% to ~45%) and functional class improvement. 5, 6