Modification of abnormal left ventricular diastolic properties by nifedipine in patients with hypertrophic cardiomyopathy.

The effect of nifedipine on left ventricular isovolumic relaxation and diastolic filling properties and systemic and left ventricular hemodynamics was studied in 15 patients with hypertrophic cardiomyopathy. After nidefipine (10 mg sublingually), the prolonged left ventricular isovolumic relaxation time assessed by echocardiography decreased from 112 +/- 26 to 83 +/- 23 msec (p less than 0.0001), and the left ventricular pressure decay as measured by time constant T improved from 63 +/- 20 to 49 +/- 11 msec (p less than 0.05). Left ventricular filling dynamics also improved as assessed by a return toward normal in the depressed peak rate of left ventricular diastolic filling (dimension change 72 +/- 37 to 101 +/- 39 mm/sec, p less than 0.01) and the peak rate of posterior wall thinning (47 +/- 31 to 68 +/- 36 mm/sec, p less than 0.001). These changes were accompanied by hemodynamic evidence of improved diastolic function shown as a decrease in left ventricular end-diastolic pressure and a downward shift in the left ventricular diastolic pressure-dimension relationship, suggesting improved left ventricular distensibility. After nifedipine, there was a slight increase in heart rate and a decrease in systemic ventricular distensibility. After nifedipine, there was a slight increase in heart rate and a decrease in systemic arterial blood pressure, and no depression of the left ventricular percent fractional shortening or cardiac index. These data indicate that abnormal left ventricular relaxation and diastolic filling rates in hypertrophic cardiomyopathy are dynamic and favorably modified by nifedipine, and that this effect is not related to a depression of left ventricular systolic function.