Should we consider beating-heart on-pump coronary artery bypass grafting over conventional cardioplegic arrest to improve postoperative outcomes in selected patients?

Abstract

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether beating-heart on-pump coronary artery bypass grafting (BH-ONCAB) offered superior mortality and morbidity outcomes when compared with conventional on-pump coronary artery bypass grafting (C-ONCAB). Morbidity outcomes consisted of renal failure, stroke (transient or permanent), myocardial infarction, angina, congestive cardiac failure, reintervention and arrhythmias. Best evidence papers investigating BH-ONCAB versus C-ONCAB were considered. Where data were duplicated, the more credible evidence-based and recently published study was included. Two hundred and thirty-one papers were found using the reported search, of which 11 represented the best evidence to answer the clinical question. Two were prospective randomized controlled trials and the remaining 10 observational studies, of which one was propensity-matched. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Five of these studies demonstrated significantly improved mortality following BH-ONCAB; however, one study exhibited better survival after C-ONCAB. Notably, this study incorporated BH-ONCAB patients with significantly more haemodynamic instability, thus possibly explaining the worse mortality outcomes. In terms of morbidity, a slightly more mixed picture is drawn. Five studies report morbidity in favour of BH-ONCAB, whereas three studies include individual outcomes favouring C-ONCAB. The remaining studies showed equivalent mortality and morbidity data. In summary, the results presented here suggest that BH-ONCAB may improve survival following coronary artery bypass surgery. A key observation is that the greatest benefits of BH-ONCAB appear to be in studies including patients with considerably higher risk characteristics at the time of surgery (haemodialysis, end-stage coronary artery disease, emergency surgery, low ejection fraction). There are limitations of the current evidence presented. Only two studies were randomized controlled trials. There was variability in sample size, selection criteria and preoperative risk profiles between the studies. The studies span many years, and the outcomes may have been affected by evolving technologies and differing patient profiles between these periods.

Keywords: Beating-heart; Cardioplegia; Coronary artery bypass; On-pump; Outcomes.