Title: Usefulness of Exercise-Stress Echocardiography for Risk Stratification of True Asymptomatic Patients With Aortic Valve Stenosis
Topic: Noninvasive Cardiology
Date Posted: 3/29/2010
Author(s): Marйchaux S, Hachicha Z, Bellouin A, et al.
Citation: Eur Heart J 2010;Mar 21:[Epub ahead of print].
Clinical Trial: No
Study Question: Among asymptomatic patients with aortic stenosis (AS) with a normal response to exercise testing, does exercise stress echocardiography add incremental prognostic value to resting echocardiography?
Methods: A retrospective analysis was performed using data from 186 patients with at least moderate AS (valve area <1.5 cm2, indexed valve area <0.9 cm2/m2) and preserved left ventricular (LV) ejection fraction (≥50%) who underwent exercise stress echocardiography at one of four hospitals. Outcomes were cardiac death or aortic valve replacement (AVR) motivated by development of symptoms.
Results: There was an abnormal response to exercise in 51 (27%). Among the remaining 135 patients with a normal exercise test (53% with severe AS) at a mean follow-up of 20 ± 14 (median 19) months, a cardiac event occurred in 67 (AVR motivated by symptoms in 58, severe symptoms without AVR in four, symptoms awaiting AVR in one, cardiovascular death in three, and cardiac arrest followed by resuscitation and AVR in one). The variables independently associated with events were age ≥65 years (hazard ratio [HR], 1.96; 95% confidence interval [CI], 1.15-3.47; p = 0.01), diabetes (HR, 3.20; 95% CI, 1.33-6.87; p = 0.01), LV hypertrophy (HR, 1.96; 95% CI, 1.17-3.27; p = 0.01), resting mean gradient >35 mm Hg (HR, 3.60; 95% CI, 2.11-6.37; p < 0.0001), and exercise-induced increase in mean gradient >20 mm Hg (HR, 3.83; 95% CI, 2.16-6.67; p < 0.0001).
Conclusions: Exercise-induced increase in transvalvular gradient may be helpful to improve risk stratification in asymptomatic patients with AS and a normal exercise response. Exercise stress echocardiography may provide additional prognostic information over that obtained from standard exercise testing and resting echocardiography.
Perspective: Asymptomatic patients with severe AS traditionally are thought to have a low risk of adverse cardiac events, justifying a conservative philosophy of waiting for symptoms before considering AVR. However, it has become clear that not all asymptomatic patients are at the same low risk. Exercise testing (screening for the development of symptoms, hypotension, or complex ventricular arrhythmias) appears to offer incremental prognostic value. The present study suggests that an increase in AV gradient during exercise also might add incremental prognostic information. Notably, this study included roughly equal numbers of patients with moderate AS and with severe AS, and separate multivariate analyses revealed that an exercise-induced increase in gradient was strongly associated with risk in both categories. In addition, the authors observed that the increase in gradient during exercise did not correlate with resting gradient or any other resting echocardiographic variable. These findings serve to underscore some of the difficulties in determining the true hemodynamic impact of stenotic valve lesions, and the associated clinical challenges in treating patients with valvular heart disease. David S. Bach, M.D., F.A.C.C.
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