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.