A propensity score analysis on the effect of eliminating cardiopulmonary bypass for coronary artery bypass grafting

Aim. The aim of the study was to investigate if the off-pump technique could reduce the hospital mortality after coronary artery bypass grafting when compared to the standard cardiopulmonary bypass (CPB) technique. Methods. An observational study with propensity score matching analysis was performed in a university teaching hospital in 2 899 consecutive patients undergoing elective coronary artery bypass grafting. No intervention was performed. Major perioperative complications and hospital mortality were noted. Results. The overall hospital mortality was 1.3% (39/2 899) with no difference between the off-pump (16/802, 2.0%) and the CPB group (23/2 097, 1.1%) P=0.09. Since the off-pump group included patients at high risk, a propensity score analysis was then performed and off-pump patients matched 1: 1 to CPB patients in order to have the same pre-operative variables identified by a multivariate analysis as associated to surgeon propensity to operate off-pump: (age, chronic renal failure and low ejection fraction) and the same number of graft performed. The results of the propensity matching still showed no difference in hospital mortality between off-pump and CPB group (1.6% vs 1.1% P=0.6). The off-pump technique showed advantages in terms of transfusion of blood products (P < 0.001) and reduction of surgical re-exploration (P=0.04). Conclusion. No difference in hospital mortality in coronary artery bypass grafting patients could be observed between patients operated off-pump or with the standard CPB technique.