Background: The efficacy of coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) in patients with multivessel coronary artery disease (CAD) has been well-defined by randomized controlled trials. However, patients with severe left ventricular dysfunction (ejection fraction <35%; EF) were under-represented in these trials. We sought to compare the outcomes of patients with multivessel CAD and EF<35% undergoing CABG vs. PCI. Methods: We used APPROACH, a clinical data collection initiative, capturing all patients undergoing cardiac catheterization and revascularization in the province of Alberta, Canada, to identify 2477 patients with multivessel CAD and EF<35% undergoing CABG (n=1242) or PCI (n=1235) between 1995 and 2008. Results: Patients undergoing CABG were slightly older (65.8 vs. 65.3 years; p=0.269), more likely to have three vessel CAD (62% vs. 56%; p<0.001), male gender (85% vs. 77%; p<0.001), diabetes (39% vs. 27%; p<0.001), peripheral vascular disease (PVD; 14% vs. 8%, p<0.001), congestive heart failure (CHF; 46% vs. 41%, p=0.012), and COPD (21% vs. 16%, p=0.005). Unadjusted survival at 1, 5, and 12 years in the CABG vs. PCI groups was 90% vs. 86%, 75% vs 71%, and 47% vs. 48%, respectively (p=0.394). After controlling for differences in baseline risk factors, CABG was associated with improved long term outcomes. Multivariable logistic regression identified PCI was significantly associated with a higher risk of death compared to CABG (adjusted hazard ratio, 1.20; 95% CI, 1.03 to 1.40). Other significant predictors of poor long-term survival included COPD (adjusted hazard ratio, 1.19; 95% CI, 1.01 to 1.40), renal failure (adjusted hazard ratio, 2.33; 95% CI, 1.80 to 3.04), CHF (adjusted hazard ratio, 1.19; 95% CI, 1.04 to 1.37), diabetes (adjusted hazard ratio, 1.21; 95% CI, 1.06 to 1.40), PVD (adjusted hazard ratio, 1.31; 95% CI, 1.09 to 1.59), and prior CABG (adjusted hazard ratio, 1.30; 95% CI, 1.04 to 1.62). Conclusion: In patients with multivessel CAD and left ventricular dysfunction, CABG was associated with better survival than PCI after adjustment for baseline risk profile differences. Further research exploring the factors leading to use of a particular revascularization modality is required.