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

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 (β=-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.