Comparison between off-pump and on-pump coronary artery bypass grafting in patients with severe lesions at the circumflex artery territory: 5-year follow-up of the MASS III trial

Abstract

Background: Several studies comparing Off-Pump Coronary Artery Bypass surgery (OPCAB) with On-Pump (ONCAB), in various patients populations, fail to demonstrate a superiority of a technique over the other in long term outcomes. The technical difficulty in the revascularization of the Circumflex Artery (CXA) territory with off-pump surgery may compromise the outcome of this method in clinical follow-up. Objective: To evaluate cardiac events in patients with stable Coronary Artery Disease (CAD) that had an obstruction on CXA (or their major branches) greater than 70% undergoing CABG with or without cardiopulmonary bypass. Methods: The MASS III was a single-center study that evaluated 308 patients with multivessel CAD and preserved ejection fraction randomized to ONCAB (153) or OPCAB (155). Of this total, 260 (84.4%) patients had on coronary angiography at least a 70% obstruction in the circumflex artery territory. (141 ONCAB and 119 OPCAB). The combined outcome was death, myocardial infarction, target vessel revascularization (angioplasty or surgery), or hospitalization for cardiac causes. Variables with possible association (P <0.2) were included in multivariate analysis. Results: The two groups were well matched for demographics, clinical and angiographic characteristics. After 5 years of follow up, OPCAB had higher combined events than ONCAB: 25 (21%) vs 17 (12%), hazard ratio 1.88, 95% CI 1.02 to 3.48, P = 0.041. In the multivariate model the following variables were included: age (P = 0.09) and presence of diabetes (P = 0.18). OPCAB remained as a predictor of combined events in 5 years, P = 0.032. There was no advantages of complete revascularization over incomplete revascularization in the combined endpoint at 5 years: 22 (17.1%) vs 20 (15.3%) P = 0.68, respectively. Conclusions: In patients with multivessel CAD and severe lesions in the CXA territory, off-pump coronary bypass surgery resulted in a higher frequency of cardiac events in 5 years, regardless of achieving complete revascularization.