The use of intravenous milrinone in chronic symptomatic ischemic heart disease

Abstract

To evaluate the antiischemic effects of intravenous milrinone, 20 patients with angiographically proved coronary artery disease and stable angina were studied at rest and during exercise under control conditions and after an intravenous loading injection of milrinone (50 micrograms/kg/10 min) followed by an infusion with 0.5 micrograms/kg/min. Hemodynamic parameters, epinephrine, norepinephrine, and atrial natriuretic factor were assessed. Control ergometry revealed ischemia; however, during exercise with intravenous milrinone, ischemia was eliminated. Because of unloading effects, there was also a significant decrease in ST segment depression (p less than 0.001). Heart rate increased significantly (p less than 0.001) at rest but increased significantly less after exercise testing (p less than 0.001). The changes in mean arterial pressure, cardiac output, and myocardial oxygen consumption during exercise were not significantly different between the milrinone and control phase. Intravenous milrinone delayed the onset of angina (p less than 0.001) and significantly shortened the duration of anginal attacks (p less than 0.05); exercise duration in the milrinone phase was longer than in the control phase (p = 0.051). Because of vasodilatation, a mild secondary increase in norepinephrine was observed during the milrinone phase, and there was a significantly smaller increase in atrial natriuretic factor during exercise while receiving milrinone as a result of preload reduction (p less than 0.05). Intravenous milrinone produced beneficial hemodynamic and antiischemic effects in patients with coronary artery disease, stable angina, and reproducible ST segment depression probably by enhancing myocardial contractility and reducing preload and afterload.