Calcium antagonists are popular therapeutic agents in the treatment of systemic hypertension. Although these agents have similar antihypertensive efficacy, they have varied effects on left ventricular function at rest in hypertensive patients. The effect of different calcium antagonists on left ventricular function during exercise and on exercise performance in patients with hypertension, however, is less clear. Fifteen patients with essential hypertension (diastolic blood pressure = 95 to 110 mm Hg) were enrolled in a placebo-controlled, single-blinded crossover study comparing nifedipine with verapamil for rest/exercise heart rate and blood pressure, exercise performance, and rest/exercise left ventricular function. Each drug was titrated to achieve resting diastolic pressures less than 90 mm Hg. All patients underwent maximal exercise testing and rest/exercise gated radionuclide ventriculography at the end of 3-week placebo, nifedipine, and verapamil treatment periods. Both calcium antagonists significantly reduced blood pressure at rest and during exercise compared with placebo. Neither calcium antagonist altered resting heart rate; however, both verapamil and nifedipine significantly reduced heart rate at maximal exercise. Verapamil but not nifedipine impaired left ventricular peak emptying rate and left ventricular peak filling rate during exercise but not at rest. Neither verapamil nor nifedipine, however, significantly altered rest or exercise global left ventricular ejection fraction (LVEF) compared with placebo. There was a trend, however, for impairment in the LVEF response to exercise (delta LVEF) in the verapamil treatment group. Exercise capacity was not significantly altered by either calcium antagonist compared with placebo. Thus verapamil but not nifedipine impairs left ventricular function during exercise in hypertensive patients.(ABSTRACT TRUNCATED AT 250 WORDS)