Plomondon and colleagues19reported a significant reduction in mortality rates (2.7% vs 4.1%, respectively) and morbidity rates (8.8% vs 14%, respectively) with OFFCABG in a retrospective analysis of 680 patients undergoing OFFCABG and 1,733 patients undergoing ONCABG. Magee and colleagues20 conducted a retrospective study of 1,983 OFFCABG procedures and 6,466 ONCABG procedures from two US centers in a higher risk surgical population. Of these patients, the mean age was 64 years, 48% had impaired left ventricular function, 30% had diabetes, and about 20% had significant comorbidity (including 5% with renal failure and 5% undergoing repeat CABG). The authors used propensity score analysis, and included statistical compensation for the nonrandomization of patients. They showed that the OFFCABG group had a higher preoperative risk. Despite this, the ONCABG group had higher mortality than the OFFCABG group (odds ratio of CPB as a predictor for postoperative mortality, 1.9; 95% confidence interval, 1.2 to 3.1). In addition, the OFFCABG group showed a reduction in findings for morbidity that was consistent with the results of previous trials.