Background: We examined outcomes of patients with ischemic cardiomyopathy (ICMP), defined by left ventricular ejection fraction (LVEF) <35%, compared with patients with better-preserved LVEF, undergoing coronary bypass graft surgery (CABG). In addition, we examined the relative impact of a reduced LVEF in comparison with other comorbidities on long-term mortality in these patients.
Methods and results: We evaluated 1381 patients (114 with ICMP, 1267 with better-preserved LVEF) who underwent isolated CABG at a tertiary Veterans Administration (VA) hospital between 1990 and 2000 using data from the VA Continuous Improvement in Cardiac Surgery Program and other VA databases. The 5-year survival was 74.0% in patients with ICMP and 84.4% in the group with better-preserved LVEF ( p = .005). LVEF <35% remained a significant predictor of long-term mortality in multivariable models (hazard ratio [HR] 1.55, 95% confidence interval [CI] 1.02-2.35). However, the presence of comorbidities, especially renal insufficiency, peripheral vascular disease, and cerebrovascular disease, had a similar or greater impact on long-term mortality. Renal insufficiency (serum creatinine >1.5 mg/dL) was associated with the highest risk of long-term mortality (HR 2.02, 95% CI 1.46-2.80). The use of a left internal thoracic artery graft reduced the risk of long-term mortality (HR 0.72, 95% CI 0.54-0.98).
Conclusion: Even though severely depressed LVEF is associated with an increased risk of long-term mortality, the presence of comorbid factors, especially renal dysfunction and noncardiac vascular disease, increase the risk of long-term mortality by a similar or even larger magnitude. These comorbid factors should be given important consideration when evaluating the risks and benefits of CABG.