Hemodynamic effects of intravenous diltiazem in patients with acute myocardial infarction

Experimentally, diltiazem has demonstrated favorable effects on acute myocardial infarction in animals. In this study, we administered diltiazem intravenously to 11 patients with acute myocardial infarction within 24 hours from the onset and examined the hemodynamic changes. Dose was 20 minutes of 0.5 mg/min and 20 minutes of 1.0 mg/min (i.e., total 30 mg). Hemodynamic results were decrease in heart rate, blood pressure (systolic, diastolic), mean arterial pressure, double product (p less than 0.01), and systemic vascular resistance (p less than 0.05). On the other hand, stroke volume index increased (p less than 0.01). There were no significant changes in mean pulmonary capillary wedge pressure, cardiac index, and stroke work index. Serum diltiazem concentrations during intravenous administration in our study were near the steady-state plasma concentrations in which oral multiple-dose administration of diltiazem 60 mg twice or thrice daily resulted in 2 to 3 days. It is concluded that diltiazem can be administered safely to patients with acute myocardial infarction in acute phase and has two favorable hemodynamic effects on acute myocardial infarction. One is decrease of afterload, as evidenced by the decrease in systemic vascular resistance and in mean arterial pressure. Second is the decrease of double product as an index of myocardial oxygen consumption.