Off-pump vs. on-pump coronary artery bypass surgery: an updated meta-analysis and meta-regression of randomized trials

The benefits of off-pump coronary artery bypass (OPCAB) continue to be debated, in part due to the fact that pooled effects fail to consider differences in trial and patient characteristics. We sought to analyse the contemporary evidence for OPCAB vs. conventional coronary artery bypass (CCAB), incorporating recent larger trials, and adjusting for differences in trials using a technique known as meta-regression. We systematically reviewed MEDLINE, EMBASE, and the Cochrane database for published and unpublished randomized trials of OPCAB vs. CCAB in which 30-day or in-hospital clinical outcomes were reported. The outcomes of interest were: all-cause mortality, stroke, and myocardial infarction. In addition to measuring the pooled treatment effects using a random effects meta-analysis model, we measured the effect of selected trial-level factors on the effects observed using the meta-regression technique. Fifty-nine trials were included, encompassing 8961 patients with a mean age of 63.4 and 16 females. There was a significant 30 reduction in the occurrence of post-operative stroke with OPCAB [risk ratio (RR) 0.70, 95 CI: 0.490.99]. There was no significant difference in mortality (RR: 0.90, 95 CI: 0.631.30) or myocardial infarction (pooled RR: 0.89, 95 CI: 0.691.13). In the meta-regression analysis, the effect of OPCAB on all of the clinical outcomes was similar regardless of mean age, proportion of females in the trial, number of grafts per patient, and trial publication date. Our meta-analysis incorporating recent trials suggests that there appears to be a beneficial effect of OPCAB on stroke. Moreover, our meta-regression does not support the hypothesis that differences in study populations are responsible for the observed outcomes, although pooled individual patient-data would be better suited to confirm these findings.