[Hemodynamic effect of intravenous diltiazem and nifedipine in acute myocardial infarct. A randomized study]

In a prospective, randomized trial of 28 patients with acute myocardial infarction nifedipine or diltiazem were administered intravenously and hemodynamic parameters and drug plasma levels measured for 24 hours. Both drugs lowered arterial blood pressure and peripheral resistance. Only diltiazem reduced heart rate and the heart rate x arterial pressure product, as pointer to a reduction in myocardial oxygen consumption. On the other hand, nifedipine is more likely to cause a (reflex) increase in heart rate. In no patient was there evidence of drug-induced hemodynamic impairment. Left ventricular filling pressure was reduced in those patients in whom it had been elevated. While a steady-state plasma concentration was quickly reached with nifedipine, in some patients diltiazem infusion produced a continuous rise in plasma concentration and, in two patients with posterior-wall infarction, high-grade a-v block (reversible after discontinuation of the drug). The results indicate that under ECG control both drugs can be used intravenously without much risk. The hemodynamic profile of diltiazem (reduction in peripheral resistance and heart rate) would seem to be particularly favorable in acute infarction, while nifedipine is preferred in acute infarction plus hypertension. The possible effect on a-v conduction is to be watched on intravenous administration of diltiazem, while in normotensive patients nifedipine may cause an undesirable (reflex-mediated) sympathetic activation.