Using the EuroSCORE to assess changes in the risk profiles of the patients undergoing coronary artery bypass grafting before and after the introduction of less invasive coronary surgery

Background. Patients undergoing coronary artery bypass grafting seem to be older and have more comorbidity than patients in prior decades. We retrospectively assessed changes in the predicted mortality risk of patients who underwent coronary artery bypass surgery before and after the introduction of minimally invasive surgical techniques. Methods. Between 1993 and 2002, 345 consecutive patients underwent coronary bypass surgery at Osaka Prefectural General Hospital. Minimally invasive direct coronary artery bypass was introduced in 1997 and off-pump bypass in 1999. Patients were divided into two groups, based on the year of surgery (1993 to 1996 and 1997 to 2002), and mortality risk was assessed with the European System for Cardiac Operative Risk Evaluation (EuroSCORE). Results. The in-hospital mortality was 3% overall (11 of 345), 8% during the early period (6 of 106), and 2% during the later period (5 of 239). Multiple regression analysis identified an emergent operation to be an independent predictor of in-hospital mortality (p = 0.035). Factors associated with higher scores were recent myocardial infarction (p = 0.028), preoperative intraaortic balloon pumping (p = 0.026) and preoperative ventilation (p = 0.026), but not age. Scores were higher in the minimally invasive (6.5 +/- 3.6, P = 0.004) and off-pump (5.0 +/- 3.7, p = 0.04) groups than in the conventional bypass group (4.1 +/- 3.3). The arterial graft in coronary artery bypass graft group was significantly less than in off-pump coronary artery bypass group (0.8 +/- 0.8 vs 1.2 +/- 0.8, p = 0.0001). Despite the increasing risk scores, overall in-hospital mortality decreased. Conclusions. The EuroSCORE was useful for assessing changes in the risk profile of patients undergoing bypass surgery over the past decade. The decrease in in-hospital mortality despite the increased risk might reflect the introduction of less invasive coronary surgery in highrisk patients. (c) 2005 by The Society of Thoracic Surgeons.