Milrinone in the treatment of low output states following cardiac surgery

Abstract

Milrinone is known to have beneficial haemodynamic and clinical effects in patients with congestive heart failure. An investigation into the safety and efficacy of milrinone in patients following heart surgery was undertaken by the European Milrinone Multicentre Trial Group. This paper reports the efficacy, the effects on left heart function, and the adverse events in the study. Ninety-nine adult patients, 61 coronary artery bypass grafting (CABG), 33 valve surgery (VS), and five CABG+VS were studied. Three dosage regimens were investigated sequentially. All patients received a loading dose of intravenous milrinone 50 micrograms kg-1 over 10 min, followed by an infusion of either 0.375 micrograms kg-1 min-1, 0.5 microgram kg-1 min-1, or 0.75 microgram kg-1 min-1 over 12 h. The groups were comparable for age, weight, and surface area; however, in the group receiving 0.5 microgram kg-1 min-1 there were more females and patients undergoing mitral valve surgery. Efficacy criteria of an increase in cardiac index of 30% and/or a decrease in mean pulmonary capillary wedge pressure of 25% were fulfilled by 77 patients at the 60-min measurement. Of the remaining 22 patients, 17 were clinically satisfactory and fulfilled efficacy criteria at some time during the study. At 15 min and 60 min there was a dose-related decrease in systolic and diastolic arterial pressure; however, there was no significant difference in the mean arterial pressure measurements. In all groups there was an improvement in cardiac index at 15 min following the start of milrinone, which was sustained during and up to 4 h after the infusion. This was closely associated with changes in stroke volume index and systemic vascular resistance, and not solely due to a change in heart rate.