Effects of verapamil and nifedipine on rate of left ventricular relaxation in coronary arterial disease patients

Abstract

We have evaluated the effects of nifedipine and verapamil on rate of left ventricular relaxation in 26 patients having coronary arterial disease with normal ejection fraction and normal left ventricular contractility. None of the patients had myocardial infarction. All patients showed normal contractile indices and abnormally high values of T constant, neg, dP/dt and left ventricular protodiastolic pressure, suggesting an impairment of left ventricular relaxation. Nifedipine, injected intravenously (15 micrograms/kg) in 14 patients induced a significant reduction of afterload parameters and an increase of contractility. Nifedipine also improved left ventricular relaxation, as it induced a reduction of the T constant from 42 +/- 2 msec to 33 +/- 2 msec (P less than 0.01). It induced a tendency to a reduction of negative dP/dt and protodiastolic pressure without reaching statistical significance. Verapamil, injected intravenously in the remaining 12 patients (0.1 mg/kg as a bolus followed by chronic infusion of 0.005 mg/kg/min for 3 min) induced a reduction of the T constant from 43 +/- 10 to 37 +/- 6 msec (P less than 0.01). It reduced the negativity of dP/dt from 2302 +/- 273 to 2021 +/- 252 mm Hg/sec (P less than 0.05) and of left ventricular protodiastolic pressure from 3.2 +/- 1.4 to 1.5 +/- 1.1 mm Hg (P less than 0.01). Verapamil, like nifedipine, reduced the afterload parameters although to a lesser extent. It did not substantially affect the left ventricular contractility. These data suggest that abnormalities of left ventricular relaxation may precede changes in systolic function and that nifedipine and verapamil favourably modify the indices of left ventricular diastolic function in patients with coronary arterial disease.