Intravenous enoximone or dobutamine for severe heart failure after acute myocardial infarction: a randomized double-blind trial

Intravenous infusions of enoximone or dobutamine were given, using a double dummy technique, in a randomized, double-blind study, to 18 patients with acute myocardial infarction who had persisting signs of left ventricular failure after treatment with intravenous diuretics. Blood pressure, heart rate and cardiac output, by transcutaneous Doppler aortovelography, were measured and any arrhythmias recorded by Holter monitoring. Eight of the nine enoximone treated patients showed clinical improvement. One patient in the enoximone group failed to respond and subsequently died. Five of the nine dobutamine treated patients showed clinical improvement. The other four patients in the dobutamine group experienced tachyarrhythmias and were withdrawn from the study; one of these patients also deteriorated and died. There were no significant differences in systolic or diastolic blood pressure either within or between the two treatment groups during the study. Enoximone increased cardiac output by 32% (P = 0.003), and dobutamine by 46% (P < 0.001); there was no significant difference between groups. Dobutamine also significantly increased heart rate from a mean of 108 beats.min-1 to 117 beats.min-1 (P < 0.001). There was no difference between the two groups in ventricular ectopic counts, but dobutamine produced significantly more runs of supraventricular and ventricular tachycardia (P = 0.0003). Enoximone was better tolerated with fewer side-effects than dobutamine in doses which produced similar increases in cardiac output. In the setting of an acute myocardial infarction when inotropic therapy is indicated, enoximone is a better choice than dobutamine.