Effects of preemptive therapy with milrinone or amrinone on perioperative platelet function and haemostasis in patients undergoing coronary bypass grafting

Preemptive therapy with a phosphodiesterase III inhibitor preserves cardiac function and oxygen transport after cardiac surgery, and its safety on platelet function and haemostasis must be verified. We examined the effects of preemptively administered milrinone or amrinone on platelet function and haemostasis. In 45 cardiac surgery patients, we randomly administered milrinone 50 microg/kg plus 0.5 microg/kg/min for 10 hours, amrinone 1.5 mg/kg plus 10 microg/kg/min infusion for 10 hours, or placebo at release of aortic cross-clamp. Whole blood platelet aggregation, haematological values, and postoperative chest drainage were examined. Three patients in the placebo, 1 patient in the amrinone, and 2 patients in the milrinone groups received allogenic blood transfusion (654 +/- 365 ml) intraoperatively, but no patient postoperatively. The mean platelet counts 3 days postoperative in the milrinone and amrinone groups did not significantly differ from the placebo group (10.9 +/- 3.3 and 12.1 +/- 3.8, vs. 12.1 +/- 3.4x10(4) per cubic millimeter, respectively), and chest-tube drainage in the first 24 hours did not significantly differ (450 +/- 156 and 391 +/- 184, vs. 448 +/- 140 ml, respectively). Although there were changes in platelet aggregation consequent to surgery there was no significant differences in platelet aggregation or other haematological values among the three groups. Preemptive therapy of milrinone or amrinone does not deteriorate perioperative platelet function and haemostasis beyond surgical interventions.