Risk stratification for coronary bypass surgery in patients with left ventricular dysfunction: analysis of the coronary artery bypass grafting patch trial database.

BACKGROUND

Preoperative characteristics may influence morbidity and mortality in patients undergoing coronary artery bypass grafting (CABG). The CABG Patch Trial was designed to assess the impact of prophylactic insertion of an implantable cardioverter-defibrillator in patients undergoing high-risk CABG. This database was used to investigate the influence of symptomatic congestive heart failure (CHF) and angina on morbidity and mortality in CABG patients with ventricular dysfunction.

METHODS AND RESULTS

Data were analyzed for 900 randomized patients with an ejection fraction </=35% and an abnormal signal-averaged ECG. Single-variable and stepwise multiple logistic regression analyses were used for mortality and length-of-stay (LOS) data. Severity of CHF and angina was graded by the New York Heart Association (NYHA) and Canadian Cardiovascular Society (CCS) classifications, respectively. Perioperative mortality was 3.5% in 454 patients without clinical signs of heart failure versus 7.7% in 443 patients with NYHA class I to IV heart failure (P=0.018). By multiple logistic regression analysis, mortality was significantly higher in patients with preoperative symptomatic (NYHA class I to IV) heart failure (odds ratio, 2.4; P=0.01) or reoperation (odds ratio, 3.8; P<0.0001). Mortality was not significantly influenced by age, sex, the presence or severity of angina, hypertension, left main coronary artery disease, pulmonary disease, or severity of CHF (although LOS was increased 0.7 days per NYHA class). Patients with a history of stroke had a higher rate of perioperative stroke (16.4% versus 3.6%, P=0.001) and an increased LOS (by 3.5 days).

CONCLUSIONS

Symptomatic heart failure and reoperation are predictors of increased operative mortality in patients with ventricular dysfunction and a positive signal-averaged ECG. Conversely, patients without heart failure symptoms may undergo CABG with relatively low mortality despite low ejection fraction. LOS is prolonged significantly by advanced age, history of stroke, and the presence and severity of heart failure.