Exercise capacity in hypertrophic cardiomyopathy depends on left ventricular diastolic function

Some studies have demonstrated that left ventricular (LV) diastolic functio n is the principal determinant, of impaired exercise capacity in hypertroph ic cardiomyopathy (HC). in this study we sought the capability of echocardi ographic indexes of diastolic function in predicting exercise capacity in p atients with HC. We studied 52 patients with HC while they were not on drug s; 12 of them had LV tract obstruction at rest. Diastolic function was asse ssed by M-mode and Doppler echocardiography by measuring: (1) left atrial f ractional shortening, and the slope of posterior aortic wall displacement d uring early atrial emptying on M-mode left atrial tracing; and (2) Doppler- derived transmitral and pulmonary venous flow velocity indexes. Exercise ca pacity was assessed by maximum oxygen consumption by cardiopulmonary test d uring cycloergometer upright exercise, Maximum oxygen consumption correlate d with the left atrial fractional shortening (r = 0.63, p <0.001), the slop e of posterior aortic wall displacement during early atrial emptying (r = 0 .55, p <0.001), age (r = -0.50; p <0.001), pulmonary venous diastolic anter ograde velocity (r = 0.41, p <0.01), and the systolic filling fraction (r = -0.43; p <0.01). By stepwise multiple linear regression analysis, left atr ial fractional shortening and the pulmonary venous systolic filling fractio n were the only determinants of the maximum oxygen consumption (multiple r = 0.70; p <0.001). Exercise capacity did not correlate with Doppler-derived transmitral indexes. Thus, in patients with HC, exercise capacity was dete rmined by passive LV diastolic function, as assessed by the left atrial M-m ode and Doppler-derived pulmonary venous flow velocities. (C) 1999 by Excer pta Medica, Inc.