Aortic stenosis.

Abstract

SEE PAGE 1225 I t has been known for decades that once symptoms develop in patients with severe aortic stenosis (AS), the prognosis worsens dramatically (1). Asymptomatic patients have a relatively benign course wherein the risk of the most dire complication, sudden cardiac death is fairly rare, occurring <1% per year (2). At the onset of symptoms this risk increases by a remarkable 25-fold. Thus, there is virtually unanimous agreement that symptom onset demands that the only known definitive therapy for AS, aortic valve replacement (AVR), be performed unless comorbidities or other patient factors militate against it. The exact cause of symptoms in AS is unknown, but symptoms are so important because they are a barometer of pathophysiology. They can arise from left or right ventricular diastolic dysfunction, systolic dysfunction, pulmonary hypertension, abnormal coronary blood flow, reduced cardiac output, or any combination of these factors for which no simple test or magic number is applicable (3). But how sharp is this crucial dividing line between symptomatic and asymptomatic patients? The assessment is straightforward when patients develop angina, syncope, or overt heart failure. However, in many cases the decision regarding symptomatic status rests on subtle changes in exercise tolerance or dyspnea for a given patient that seems out of the ordinary for him or her. In this regard, formal exercise testing adds important objective evidence that symptomatic status has changed (4). A positive exercise test indicates AVR with a “2a” level of support from the American College of Cardiology/American Heart Association valve guidelines (5). Likewise increasing levels of