To define the effects of
nicardipine, a new
dihydropyridine calcium antagonist
drug, on exercise- and pacing-induced
myocardial ischemia, 15 men with
coronary artery disease were studied during cardiac catheterization.
Nicardipine was administered intravenously as a 2-mg bolus followed by an infusion titrated to maintain
a 10- to 20-mm Hg decrease in systolic arterial pressure. At rest,
nicardipine decreased systemic and coronary vascular resistances, left ventricular end-diastolic pressure and increased coronary blood flow, heart rate and myocardial oxygen consumption. During bicycle exercise-induced
myocardial ischemia,
nicardipine significantly prolonged exercise duration and time to 1 mm of ST-segment depression. These changes were associated with no alteration in the product of systolic pressure and heart rate, decreased left ventricular end-diastolic pressure, systemic and coronary vascular resistances and increased coronary blood flow, as well as myocardial oxygen consumption. During atrial pacing, the heart rate threshold for
myocardial ischemia was not changed by
nicardipine administration, despite improvement in the ratio of coronary blood flow to myocardial oxygen consumption and hemodynamic changes otherwise similar to those during exercise.
Nicardipine favorably influenced myocardial metabolic state, as indexed by
lactate extraction during pacing-induced
ischemia.
Nicardipine is a potent coronary and systemic vasodilating
drug that improves exercise tolerance and myocardial metabolic response to pacing stress, the mechanism for which appears to be partially mediated through increased coronary blood flow.