EFFECTS OF CHRONIC BETA-BLOCKADE ON REST AND EXERCISE HEMODYNAMICS INMITRAL-STENOSIS

beta-blocker therapy for mitral stenosis Is controversial, This study compares right and left heart hemodynamics at rest and supine submaxim al exercise in patients (n=7) receiving chronic beta-antagonists with untreated patients (n=17) matched for age (mean +/-SD = 51+/-12 years) and valve area (0.7+/-0.2 cm(2)/m(2)), Little benefit was observed wi th treatment at rest, Although pulmonary capillary wedge pressures (PC WP) were lower during exercise in the beta-blocker group (22+/-4 vs. 3 1+/-9 mmHg; P<0.05), exercise performance was not enhanced and cardiac output response during exercise was reduced (control = 41% increase v s, 12% for beta-blockade). PCWP rose rapidly when diastolic filling pe riods were <300 msec in both groups. Pulmonary capillary wedge pressur e was found to be a nonlinear functions (P<0.001) of diastolic filling period (PCWP=15.9+5.84x10(5)/dfp(2)), These data suggest that there i s a critical heart rate in patients with mitral stenosis above which h emodynamic compromise rapidly occurs. (C) 1995 Wiley-Liss, Inc.