Exercise Hemodynamics and Risk Assessment in Asymptomatic Aortic Stenosis

Abstract

More than half a century ago, in the American Journal of Cardiology , Dr Paul Wood aptly described aortic stenosis (AS) as “a simple mechanical fault which, if severe enough, imposes a heavy burden on the left ventricle and sooner or later overcomes it.”1 Our subsequent understanding of the pathophysiology of AS, using more sophisticated tools than those at Dr Wood's disposal, has confirmed his concept. Severe chronic pressure overload and outflow obstruction beget left ventricular (LV) hypertrophy and its attendant myocardial fibrosis and impaired coronary vasodilator reserve, leading to LV systolic and diastolic dysfunction, and progressing ultimately to the anticipated symptoms of dyspnea, angina, and presyncope or syncope, which are harbingers of death within a few years. Once symptoms develop, the treatment strategy is clear, because aortic valve replacement (AVR) improves symptoms, improves LV function, and improves survival. The indications for AVR in asymptomatic patients, however, remain less clear and the subject of ongoing debate.2–4 Although the current evidence-based guidelines recommend a watchful waiting approach for most patients, with no class I indications for surgery in asymptomatic patients with normal LV systolic function,5,6 numerous studies have shown that patients with severe AS have a high likelihood of developing symptoms and requiring surgery within 3 to 5 years,7–10 and some series have reported that asymptomatic patients with severe AS are also at risk of death when managed without surgery.11,12 Because the operative risk of AVR is low in experienced centers,11,13 there is intense interest in identifying the subsets of asymptomatic patients that have the highest likelihood of dying or developing symptoms over the short term and that might benefit from early, preemptive AVR rather than a watchful waiting approach. Article see p 851 Determining …