Ventricular arrhythmias following coronary artery bypass grafting for ischemic cardiomyopathy: When to insert an implanted cardioverter defibrillator?

OBJECTIVES

The study objectives were to determine the incidence, predictors, and clinical impact of ventricular arrhythmias after coronary artery bypass grafting and to evaluate the impact of implantable cardioverter defibrillators on the survival of patients with ventricular arrhythmias.

METHODS

We enrolled 498 patients with a left ventricular ejection fraction of 40% or less who underwent coronary artery bypass grafting between 1993 and 2015. Clinical follow-up was completed in 94.0% of patients, with a median follow-up of 58.4 months.

RESULTS

Overall, 212 patients (43%) died, mainly of heart failure (n = 54, 10.8%) or sudden cardiac death (n = 40, 8.0%). The sudden cardiac death rate was highest during the first 6 months, with a monthly rate of 0.37%. Overall, 99 patients (20%) developed postoperative ventricular arrhythmias, and implantable cardioverter defibrillator was implanted in 55 patients. Previous ventricular arrhythmias (hazard ratio, 3.22; 95% confidence interval, 1.98-5.24;  < .001), left ventricular end-systolic dimension (hazard ratio, 1.07; 95% confidence interval, 1.04-1.10;  < .001), and myocardial infarction in the left anterior descending artery territory (hazard ratio, 1.73; 95% confidence interval, 1.10-2.73;  = .02) were independent predictors of postoperative ventricular arrhythmias. Notably, the 5-year survival of patients with ventricular arrhythmias who received an implantable cardioverter defibrillator was significantly higher than that of patients with ventricular arrhythmias who did not receive it (76.1% vs 22.7%,  < .001) and was comparable to that of patients without ventricular arrhythmias (76.1% vs 73.6%,  = .98).

CONCLUSIONS

Sudden cardiac death affects a significant proportion of patients with ischemic cardiomyopathy undergoing coronary artery bypass grafting, most frequently within 6 months postoperatively. To prevent sudden cardiac death, earlier implantable cardioverter defibrillator implantation should be indicated for high-risk patients with scars in the left anterior descending artery territory and excessive left ventricular remodeling.