Milrinone Improves Diastolic Function in Coronary Artery Bypass Surgery as Assessed by Acoustic Quantification and Peak Filling Rate: A Prospective Randomized Study

Objective

To compare the effects of a bolus dose of milrinone, 50 μg/kg, to placebo on diastolic function (active relaxation) in patients undergoing on-pump coronary artery bypass grafting (CABG).

Design

Prospective, randomized, double-blind, placebo-controlled study.

Setting

University hospital.

Participants

Twenty-four patients with stable angina and left ventricular ejection fraction >30%, scheduled for elective CABG using cardiopulmonary bypass (CPB), were included.

Intervention

Patients were randomized to receive either 50 μg/kg of milrinone (n = 12) or placebo (n = 12) after aortic declamping.

Measurements and Main Results

The diastolic function of the left ventricle (LV) was measured as peak filling rate (dA/dt [maximal diastolic area change over time]) with transesophageal echocardiography (TEE) using acoustic quantification (AQ) before CPB and 10 minutes after termination of CPB. The normalized peak filling rate (dA/dt)/EDA was also calculated. Active relaxation was statistically significantly increased in the milrinone group compared with the placebo group after CPB.

Conclusion

Patients undergoing CABG surgery and treated with milrinone after aortic declamping had better diastolic function following cardiopulmonary bypass.

Key Words: myocardial revascularization, CABG, phosphodiesterase inhibitor, milrinone, transesophageal echocardiography, diastolic function