In the vast majority of adults, aortic valve replacement (AVR) is the only effective treatment for severe aortic stenosis (AS). Although there is some lack of agreement about the optimal timing of surgery, particularly in asymptomatic patients, it is possible to develop rational guidelines for most patients.

In the absence of serious comorbid conditions, AVR is indicated in virtually all symptomatic patients with severe AS. There are many ways in which AVR benefits these patients. These depend partly on the patient’s left ventricular (LV) function. The outcome is similar in patients with normal LV function and in those with moderate ventricular dysfunction. The depressed ejection fraction in many of these patients is caused by excessive afterload, and LV function improves after AVR. If LV dysfunction is not caused by afterload mismatch, improvement in LV function and resolution of symptoms may not be complete after valve replacement, but survival is still improved in this setting.

Symptomatic patients with angina, dyspnea, or syncope exhibit symptomatic improvement and an increase in survival after AVR.

In patients who have severe AS, even those with a low transvalvular pressure gradient, AVR results in hemodynamic improvement and better overall patient functional status.

In summary, symptomatic patients with severe AS should undergo AVR. These patients will have improved LV function, reduced or resolved symptoms, and increased survival.

Many clinicians are reluctant to proceed with AVR in an asymptomatic patient, whereas others are concerned about conservative treatment of a patient with severe AS. Insertion of a prosthetic aortic valve is associated with low perioperative morbidity and mortality. Despite this, some difference of opinion persists among clinicians regarding the indications for corrective surgery in asymptomatic patients. Irreversible myocardial depression or fibrosis may develop during a prolonged asymptomatic stage, and this may preclude an optimal outcome. Still others attempt to identify patients who may be at especially high risk of sudden death without surgery, although evidence supporting this approach is limited. Patients in this subgroup include those who have an abnormal response to exercise (e.g., hypotension), those with LV systolic dysfunction, those with marked or excessive LV hypertrophy, and those with evidence of very severe AS.

We recommend that asymptomatic patients with an aortic valve area of less than 0.8 cm ² undergo valve replacement. Similarly, any evidence of impaired LV function (e.g., decreased ejection fraction, LV dilation, or significantly elevated LV diastolic pressure at rest or with exercise) is an indication for AVR. In the absence of symptoms, a peak aortic gradient of 70 mm Hg may be an indication for surgery, but this is controversial.

Patients with moderate or more AS (mean gradient of 20 mm Hg or higher), with or without symptoms, who are undergoing coronary artery bypass grafting should undergo AVR at the time of the revascularization procedure.

Similarly, patients with moderate or more severe AS undergoing surgery on other valves (e.g., mitral valve repair) or the aortic root should also undergo AVR as part of the surgical procedure.

AVR is recommended for patients with severe regurgitation in the presence of symptoms or any evidence of pathologic LV remodeling (e.g., impairment of LV function, LV dilation, significant elevation of LV end-diastolic pressure).

Symptomatic patients with advanced LV dysfunction (ejection fraction < 0.25 or end-systolic dimension > 60 mm) present difficult management issues. Some patients manifest meaningful recovery of LV function after operation, but many will have developed irreversible myocardial changes. The mortality rate associated with valve replacement approaches 10% in these patients, and the postoperative mortality rate over the subsequent few years is high.

AVR should be considered more strongly for patients with New York Heart Association (NYHA) functional class II and III symptoms, especially if symptoms and evidence of LV dysfunction are of recent onset, and intensive short-term therapy with vasodilators, diuretics, or intravenous positive inotropic agents results in substantial improvement in hemodynamics or systolic function. However, even in patients with NYHA functional class IV symptoms and an ejection fraction less than 0.25, the high risks associated with AVR and subsequent medical management of LV dysfunction are usually a better alternative than the higher risks of long-term medical management alone.

AVR in asymptomatic patients remains a controversial topic, but it is generally agreed that valve replacement is indicated for patients with LV systolic dysfunction. As noted previously, for the purposes of these guidelines, LV systolic dysfunction is defined as an ejection fraction below normal at rest.

Valve replacement is also recommended for patients with severe LV dilation (end-diastolic dimension > 75 mm or end-systolic dimension > 55 mm), even if the ejection fraction is normal. Most patients with this degree of dilation have already developed systolic dysfunction because of afterload mismatch and thus are candidates for valve replacement on the basis of the depressed ejection fraction. The elevated end-systolic dimension in this regard is often a surrogate for systolic dysfunction. The relatively small number of asymptomatic patients with preserved systolic function, despite severe increases in end-systolic and end-diastolic chamber size, should be considered for surgery because they appear to represent a high-risk group with an increased incidence of sudden death ; the results of valve replacement in these patients have thus far been excellent. In contrast, postoperative mortality is considerable once patients with severe LV dilation develop symptoms or LV systolic dysfunction.