EFFECTS OF ATENOLOL ON REST AND EXERCISE HEMODYNAMICS IN PATIENTS WITH MITRAL-STENOSIS

Beta-blocker therapy remains controversial in patients with mitral ste nosis. In this randomized, double-blind, crossover, placebo-controlled study, the effects of atenolol (50 and 100 mg/day) were assessed in 1 5 patients (aged 46 +/- 11 years) with mitral stenosis (mean valve are a 1.0 +/- 0.4 cm(2); New York Heart Association class II or III) at re st and during upright bicycle ergometry. Doppler echocardiography was used to compare heart rate, cardiac and stroke volume indexes, diastol ic filling period, and peak and mean transmitral gradients; a metaboli c cart was used to obtain maximal oxygen consumption, carbon dioxide p roduction, and anaerobic threshold. Beta-blocking therapy did not impr ove 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%, respectivel y, 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 p lacebo. The data suggest that despite lower trans-valvular pressure gr adients, little benefit in exercise performance is achieved with beta- blocker therapy in patients with severe mitral stenosis.