Effect of Intraoperative Milrinone on Left Ventricular Diastolic Function in Critically Ill Patients Undergoing CABG: A Transesophageal Echocardiography Study

Introduction: This study evaluated whether intraoperative milrinone improves cardiac diastolic and systolic function in patients undergoing elective on-pump CABG.Method: In this prospective study, ۳۰ patients undergoing elective on-pump CABG were allocated equally to a milrinone group (n=۱۵) or a control group (n=۱۵). After anesthesia induction and before CPB, the milrinone group received a loading dose of ۵۰ µg/kg over ۱۰ minutes, followed by an infusion of ۰.۵ µg/kg/min continued for ۶ hours postoperatively; the control group received an identical volume of normal saline. TEE was performed at two time points: after induction (baseline) and after separation from CPB. Baseline diastolic function was characterized using standard Doppler indices; however, patients were not preselected or stratified by diastolic dysfunction grade, which represents a limitation of the study design. Echocardiographic indices (fractional area change [FAC], pulmonary venous flow velocity [PV], deceleration time [DT], E/PV, A-wave duration [Adur], atrial reversal duration [ARdur]), hemodynamic variables, vasoactive requirements, and intensive care unit (ICU) length of stay were compared between groups.Result: Baseline characteristics, including age, sex, weight, height, comorbidities, left ventricular ejection fraction (p=۰.۱۰), surgical duration (p=۰.۱۸), and CPB duration (p=۰.۱۰) were comparable between groups. Milrinone significantly increased FAC after CPB relative to control (۵۵.۳۹±۱۰.۸۶% vs ۴۵.۷۱±۱۲.۰۴%; p=۰.۰۲۸) and relative to its own baseline (vs ۴۲.۷۷±۱۱.۲۷%; p<۰.۰۰۱). Pulmonary venous flow velocity after CPB was significantly higher in the milrinone group than in controls (۹۶.۹۵±۳۱.۰۸ vs ۷۶.۰۳±۲۲.۵۴ cm/s; p=۰.۰۴۹) and higher than its own baseline (vs ۶۳.۵۹±۲۰.۷۲ cm/s; p<۰.۰۰۱). No significant between-group differences were observed in DT, E/PV, Adur, or ARdur. Hemodynamic parameters, norepinephrine requirement during CPB (p=۰.۹۲), inotrope and nitroglycerin dosing, cardiac rhythm, and ICU length of stay did not differ significantly between groupsConclusion: Intraoperative milrinone significantly improved systolic performance (FAC) and pulmonary venous flow in patients undergoing elective on-pump CABG, with a relative improvement in selected diastolic indices and no adverse hemodynamic effects. However, because patients were not preselected for baseline diastolic dysfunction, the study was underpowered to detect a dedicated diastolic benefit. These findings suggest a potential role for milrinone in the perioperative management of CABG patients, particularly those with preexisting diastolic dysfunction. Adequately powered multicenter trials are warranted to confirm a dedicated diastolic benefit and to evaluate its impact on clinical outcomes, particularly in higher-risk or critically ill subpopulations.

کلیدواژه ها:

Milrinone ، diastolic dysfunction ، TRANSESOPHAGEAL ECHOCARDIOGRAPHY ، Coronary artery bypass grafting ، Cardiopulmonary bypass