A Propensity Score Analysis on the Effect of Eliminating Cardiopulmonary Bypass for Coronary Artery Bypass Grafting

Background: 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 preoperative 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).

Conclusions: 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.