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 cause of morbidity and increased resource utilization. Insulin-enhanced cardioplegia may reduce postoperative arrhythmias by improving aerobic myocardial metabolism and mitigating the deleterious effects of ischemia. We performed a double-blinded, randomized, controlled clinical trial to determine if insulin-enhanced cardioplegia decreases the risk of post-CABG atrial fibrillation in a high-risk patient population. We randomized 501 patients undergoing urgent CABG to receive insulin-enhanced (Humulin R 10 IU/L, Insulin group, n = 243) or standard (Control group, n = 258) blood cardioplegia during cardiopulmonary bypass. Patients were monitored by using continuous electrocardiography for a minimum of 3 days postoperatively. All standard cardiac medications, including beta-adrenergic blockers, were continued postoperatively. Insulin-enhanced cardioplegia did not result in a significant reduction in postoperative atrial fibrillation. Furthermore, we failed to detect a difference in the incidence of conduction defects, ventricular tachycardia, or pacemaker requirements between insulin and placebo patients. Atrial fibrillation was the most common arrhythmia, occurring in 31% of all patients. Independent predictors of atrial fibrillation were elderly age, preoperative atrial fibrillation, and renal insufficiency. Right bundle branch block was the most common conduction abnormality. Predictors of right bundle branch block were elderly age, female sex, and circumflex coronary artery disease. The incidence of postoperative ventricular tachycardia, left bundle branch block, and permanent pacemaker requirement was small. We conclude that insulin-enhanced cardioplegia does not reduce the incidence of postoperative atrial fibrillation in high-risk CABG patients.


CONCLUSIONS
We conducted a double-blinded, randomized, placebo-controlled trial of insulin-enhanced cardioplegia in 501 patients undergoing urgent coronary bypass surgery. Insulin did not decrease the incidence of postoperative atrial fibrillation when compared with placebo. We also failed to demonstrate a difference in the incidence of other postoperative arrhythmias between the two groups of patients.
Division of Cardiac Anesthesia and Intensive Care, Toronto General Hospital, University Health Network, University of Toronto, Ontario, Canada.
M
M
Hynninen
M A
MA
Borger
V
V
Rao
R D
RD
Weisel
G T
GT
Christakis
J A
JA
Carroll
D C
DC
Cheng
D000368:Aged; D000768:Anesthesia, General; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology; D002037:Bundle-Branch Block / Q000453:epidemiology / Q000209:etiology; D002314:Cardioplegic Solutions / Q000627:therapeutic use*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007328:Insulin / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D012306:Risk
D002314:Cardioplegic Solutions; D007004:Hypoglycemic Agents; D007328:Insulin