Objectives: Off-pump coronary artery bypass surgery is becoming increasingly popular although its effectiveness remains controversial. Our goal was to investigate the effectiveness of on-pump and off-pump coronary artery bypass surgery on early (30 days) and long-term (5 years) clinical outcome in two groups of patients selected using propensity scores.
Methods: From November 1994 to December 2001, 4381 patients underwent isolated coronary surgery. Applying propensity score matching, 1922 patients were selected (off-pump n=961, on-pump n=961).
Results: Stepwise logistic regression analysis showed that the use of cardiopulmonary bypass was an independent predictor for early death, cerebral vascular accident, early negative primary endpoints (ENPEP), and early major events (EME). Five years freedom from both events was similar in the two groups. However, freedom from acute myocardial infarction (AMI) in grafted areas was higher in the off-pump than in the on-pump patients, a possible explanation being the lower postoperative creatine kinase myocardial band (CKMB) release. Grouping all patients according to CKMB peak release also showed that patients with normal release values had higher freedom from all cardiac events investigated. A subgroup analysis of 59 patients converted from off-pump to on-pump showed higher early mortality, ENPEP, and EME. Conversion, however, did not affect late clinical outcome.
Conclusions: These results suggest that off-pump surgery reduces early mortality and morbidity. Conversion to on-pump carries high in-hospital mortality and morbidity. Long-term clinical outcome is similar in the two groups; however, off-pump patients seemed to have a higher freedom from AMI in the grafted area which might be related to the lower CKMB peak release when compared with patients undergoing on-pump surgery.