Why the study?
Does chronic beta-blockade improve rest and exercise hemodynamics in patients with mitral stenosis?
Does chronic beta-blockade improve rest and exercise hemodynamics in patients with mitral stenosis?
Chronic beta-blockade in mitral stenosis lowers exercise pulmonary capillary wedge pressure but blunts cardiac output response without improving exercise performance.
Chronic beta-blockade may lower exercise PCWP in mitral stenosis without enhancing performance; leaves open net hemodynamic benefit.
beta-blocker therapy for mitral stenosis is controversial. This study compares right and left heart hemodynamics at rest and supine submaximal 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 cm2/m2). Little benefit was observed with treatment at rest. Although pulmonary capillary wedge pressures (PCWP) were lower during exercise in the beta-blocker group (22 +/- 4 vs. 31 +/- 9 mmHg; P < 0.05), exercise performance was not enhanced and cardiac output response during exercise was reduced (control = 41% increase vs. 12% for beta-blockade). PCWP rose rapidly when diastolic filling periods were < 300 msec in both groups. Pulmonary capillary wedge pressure was found to be a nonlinear functions (P < 0.001) of diastolic filling period (PCWP = 15.9 + 5.84 x 10(5)/dfp2). These data suggest that there is a critical heart rate in patients with mitral stenosis above which hemodynamic compromise rapidly occurs.
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Ashcom et al. (1995) studied this question.