Diabetes and outcomes of coronary artery bypass graft surgery in patients with severe left ventricular dysfunction: results from The CABG Patch Trial database

OBJECTIVES We examined the relationship between diabetes mellitus and outcomes after coronary artery bypass graft (CABG) surgery in patients with severe left ventricular (LV) dysfunction. BACKGROUND Although diabetes is associated with poor outcomes after CABG surgery among unselected patients, the relationship between diabetes and mortality after CABG surgery among patients with LV dysfunction is less certain. METHODS Using data from The CABG Patch Trial, a study of implantable cardiac defibrillator therapy, we analyzed 900 patients with ejection fraction <0.36 who underwent CABG surgery from 1990 to 1996. RESULTS Diabetics comprised 38% of the patients, and 48% of diabetics were prescribed insulin. Diabetes was associated with hypertension, peripheral vascular disease, history of stroke, clinical heart failure and rales on physical exam. Diabetics were at higher risk for postoperative superficial sternal wound infection and renal failure. With an average follow-up time of 32 ± 16 months, actuarial all-cause mortality 48 months after CABG surgery was 26% in diabetics and 24% in nondiabetics (p = 0.66, log-rank test). Diabetes was not associated with long-term mortality in Cox multiple regression analyses. Actuarial re-hospitalization rates 48 months after CABG surgery were 85% in diabetics and 69% in nondiabetics (p = 0.0001, log-rank test). Diabetics had a 44% higher risk of re-hospitalization for any cause (p = 0.0001) and a 24% higher risk of re-admission for cardiac causes (p < 0.05). Unexpectedly, fewer arrhythmic events were found in diabetics. CONCLUSIONS Diabetes was not a predictor of mortality after CABG surgery among patients with LV dysfunction despite associated comorbidities. However, diabetes was associated with increased postoperative complications and re-hospitalization.