Improvement in left ventricular diastolic function during intravenous and oral diltiazem therapy in patients with hypertrophic cardiomyopathy: an echocardiographic study.

M-mode echocardiography was used to evaluate the acute effect of intravenously administered diltiazem, 10 mg, and the chronic effects of oral diltiazem, 180 mg/day, and propranolol, 60 to 120 mg/day, administered for 2 weeks on left ventricular (LV) systolic and diastolic function in 13 patients with hypertrophic cardiomyopathy. Intravenous injection of diltiazem reduced isovolumic relaxation time from 114 +/- 26 to 99 +/- 21 ms (p less than 0.01) and the time to peak rate of LV dimensional lengthening from 166 +/- 17 to 133 +/- 10 ms (p less than 0.01), without significant changes of LV dimensions or fractional shortening. No significant changes were observed in LV dimensions or fractional shortening, but a significant increase in peak rate of LV dimensional lengthening (from 4.1 +/- 1.5 to 4.8 +/- 1.6/s, p less than 0.05) and a reduction in isovolumic relaxation time (from 105 +/- 26 to 77 +/- 23 ms, p less than 0.01) and the time to peak rate of LV dimensional lengthening (from 156 +/- 23 to 124 +/- 20 ms, p less than 0.01) occurred during the oral administration of diltiazem. In contrast, propranolol caused no significant changes in these values. Thus, diltiazem improves LV relaxation and diastolic filling without altering LV systolic function in patients with hypertrophic cardiomyopathy.