The Influence of On-pump Versus Off-pump Surgery on Short- and Medium-term Postoperative Coronary Flow Reserve After Coronary Artery Bypass Grafting

Abstract

Background Although several clinical trials have compared surgical outcomes between off-pump and on-pump coronary artery bypass grafting (CABG), whether there is a difference in the early- and medium-term postoperative coronary microvascular functions is not fully understood. We compared short- and medium-term coronary microvascular function after off-pump and on-pump CABG. Methods A prospective study of patients undergoing off-pump and on-pump CABG. Eighty-two patients scheduled for CABG were recruited: 38 underwent off-pump surgery and 44 on-pump surgery. Each participant's coronary flow reserve (CFR) and diastolic function were measured with transthoracic Doppler echocardiography six and 12 months after surgery. Results Baseline and hyperaemic diastolic peak flow velocity in the left anterior descending artery were similar in both groups, as was CFR (2.22 +/- 0.66) in the off-pump group compared with (2.13 +/- 0.61) in the on-pump group, (P = 0.54). Coronary flow reserve was significantly and inversely correlated with high sensitivity C-reactive protein concentration (r = -0.416; P < 0.001) and positively correlated with mitral E/ A-wave velocity ratio (r = 0.247; P = 0.02). Stepwise linear regression analysis revealed that only high sensitivity C-reactive protein concentration was independently correlated with CFR (beta = -0.272, P = 0.02). Conclusions Heart-lung bypass technique had no medium-term influence on the coronary microcirculation, despite a possible initial unfavourable effect. Serum hs-CRP concentration was an independent predictor of medium-term coronary microvascular dysfunction.