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Effects of atenolol on rest and exercise hemodynamics in patients with mitral stenosis
B C Stoll1, T L Ashcom, J P Johns
1Department of Medicine, Brooke Army Medical Center, Fort Sam Houston, Texas 78234-6262.
Insights
Beta-blocker therapy, like atenolol, did not improve exercise capacity in patients with severe mitral stenosis. Despite reduced heart rate and lower pressure gradients, exercise performance did not benefit from beta-blockers.
Area of Science:
- Cardiology
- Pharmacology
- Exercise Physiology
Background:
- Beta-blocker therapy is controversial in managing mitral stenosis.
- Mitral stenosis can significantly impair cardiac function and exercise capacity.
Purpose of the Study:
- To evaluate the efficacy of atenolol in improving exercise performance in patients with severe mitral stenosis.
- To assess the hemodynamic and metabolic effects of beta-blocker therapy in this patient population.
Main Methods:
- Randomized, double-blind, crossover, placebo-controlled study involving 15 patients with mitral stenosis.
- Assessment of atenolol (50 and 100 mg/day) effects at rest and during exercise using Doppler echocardiography and a metabolic cart.
- Measured parameters included heart rate, cardiac index, stroke volume index, transmitral gradients, and maximal oxygen consumption.
Main Results:
- Atenolol did not improve exercise time, external work, maximal oxygen consumption, or anaerobic threshold.
- Maximal oxygen consumption rate and cardiac index decreased with atenolol compared to placebo during peak exercise (p < 0.05).
- Heart rate was reduced and diastolic filling period prolonged by atenolol, but stroke volume index showed minimal change.
Conclusions:
- Beta-blocker therapy offers little benefit for exercise performance in severe mitral stenosis.
- Despite reduced transvalvular pressure gradients, atenolol did not enhance functional capacity in these patients.
- Further research may be needed to clarify the role of beta-blockers in specific subgroups of mitral stenosis patients.
Abstract:
Beta-blocker therapy remains controversial in patients with mitral stenosis. In this randomized, double-blind, crossover, placebo-controlled study, the effects of atenolol (50 and 100 mg/day) were assessed in 15 patients (aged 46 +/- 11 years) with mitral stenosis (mean valve area 1.0 +/- 0.4 cm2; New York Heart Association class II or III) at rest and during upright bicycle ergometry. Doppler echocardiography was used to compare heart rate, cardiac and stroke volume indexes, diastolic filling period, and peak and mean transmitral gradients; a metabolic cart was used to obtain maximal oxygen consumption, carbon dioxide production, and anaerobic threshold. Beta-blocking therapy did not improve exercise time, external work, maximal oxygen consumption rate, or anaerobic threshold. Compared with placebo, maximal oxygen consumption rate and cardiac index decreased (p < 0.05) > 11% and > 20%, respectively, with atenolol at peak exercise. Although heart rate was reduced > 20% and diastolic filling period prolonged > 40% by atenolol at rest and exercise (p < 0.05), stroke volume index changed little compared with placebo. The data suggest that despite lower transvalvular pressure gradients, little benefit in exercise performance is achieved with beta-blocker therapy in patients with severe mitral stenosis.