Effects of diltiazem on left ventricular diastolic behavior in patients with hypertrophic cardiomyopathy: Evaluation with exercise pulsed Doppler echocardiography

To estimate the effects of diltiazem on the left ventricular diastolic abnormalities in patients with hypertrophic cardiomyopathy, transmitral flow velocity during diastole was studied before and immediately after dynamic leg exercise with the pulsed Doppler technique combined with two-dimensional echocardiography. Seventeen patients with hypertrophic cardiomyopathy and 24 apparently healthy men performed bicycle ergometer exercise in the supine position with the target heart rate set at 120 beats/min. The patients with cardiomyopathy were directed to perform the exercise at the same intensity after receiving 30 to 60 mg of diltiazem, three times daily, for 1 or 2 weeks. The pattern of transmitral flow velocity in diastole had two components, one corresponding to the rapid filling phase in early diastole and the other to the atrial contraction phase in late diastole. To assess left ventricular diastolic behavior, the following variables were analyzed: peak velocity in the rapid filling and atrial contraction phases, the ratio of peak velocity in the atrial contraction phase to that in the rapid filling phase, and pressure half-time. The changes in peak velocity in the atrial contraction phase, pressure half-time and the ratio of peak velocity in the atrial contraction phase to that in the rapid filling phase with exercise differed significantly between patients with hypertrophic cardiomyopathy with no medication and control subjects. After diltiazem, the response of these variables to exercise was almost identical in the two groups. These results suggest that diltiazem can lessen the left ventricular diastolic abnormality in patients with hypertrophic cardiomyopathy on dynamic exercise of mild intensity.