The effect of insulin cardioplegia on atrial fibrillation after high-risk coronary bypass surgery: A double-blinded, randomized, controlled trial

Atrial fibrillation after coronary bypass (CABG) surgery is an important ca use of morbidity and increased resource utilization. Insulin-enhanced cardi oplegia may reduce postoperative arrhythmias by improving aerobic myocardia l metabolism and mitigating the deleterious effects of ischemia. We perform ed a double-blinded, randomized, controlled clinical trial to determine if insulin-enhanced cardioplegia decreases the risk of post-CABG atrial fibril lation in a high-risk patient population. We randomized 501 patients underg oing urgent CABG to receive insulin-enhanced (Humulin R 10 IU/L, Insulin gr oup, n = 243) or standard (Control group, n = 258) blood cardioplegia durin g cardiopulmonary bypass. Patients were monitored by using continuous elect rocardiography for a minimum of 3 days postoperatively. All standard cardia c medications,including P-adrenergic blockers, were continued postoperative ly. Insulin-enhanced cardioplegia did not result in a significant reduction in postoperative atrial fibrillation. Furthermore, we failed to detect a d ifference in the incidence of conduction defects, ventricular tachycardia, or pacemaker requirements between insulin and placebo patients. Atrial fibr illation was the most common arrhythmia, occurring in 31% of all patients. Independent predictors of atrial fibrillation were elderly age, preoperativ e atrial fibrillation, and renal insufficiency. Right bundle branch block w as the most common conduction abnormality. Predictors of right bundle branc h block were elderly age, female sex, and circumflex coronary artery diseas e. The incidence of postoperative ventricular tachycardia, left bundle bran ch block, and permanent pacemaker requirement was small. We conclude that i nsulin-enhanced cardioplegia does not reduce the incidence of postoperative atrial fibrillation in high-risk CABG patients.