Does avoidance of cardiopulmonary bypass decrease the incidence of stroke in diabetics undergoing coronary surgery?

Background: The adverse effects of diabetes mellitus on the coronary circul ation and the higher incidence of cardiovascular events in diabetic patient s are well documented [Johnson 1982]. Improvements in myocardial protection , revascularization techniques, and anesthetic management have had favorabl e impacts on coronary artery bypass grafting (CABG) outcome in diabetic pat ients. Despite that, diabetic patients are significantly more likely to hav e a prior history of myocardial infarction, congestive heart failure, perip heral vascular disease, and hypertension, as well as having a significantly greater baseline serum creatinine. The aim of our study was to record, com pare, and analyze the stroke rate among patients with a history of preopera tive diabetes undergoing "off-pump" CABG (OPCAB) with conventional cardiopu lmonary bypass (CPB) CABG to determine whether the stroke rate in this high er risk population could be decreased by off-pump techniques. Methods: The records of 1,227 patients with a pre-operative history of diab etes undergoing conventional CABG (973 patients, 79.3%) using cardiopulmona ry bypass and off-pump CABG 254 (20.7%) were analyzed from 1995 through 199 9. There were no differences in age, sex, or elective/urgent status of pati ents. Preoperative risk factors (gender distribution, carotid disease, ejec tion fraction, CHF, hypertension, previous MI) were identical in both group s. The goal of the operations were complete revascularization, which was ac hieved via median sternotomy in both groups. Results: Our reported series reveals a stroke rate of 3.6% in the CPB group and 1.2% in the off-pump group. This evidence alone was not statistically significant, but two other high-risk criteria for stroke, re-do CABG and ca lcified aortas, revealed that the off-pump series had a higher percentage o f each (26.4% redos in off-pump vs. 8.7% CPB redos, p < 0.005; 7.1% calcifi ed aorta cases in the off-pump group vs. 2.9% in the CPB group, p < 0.004). The threefold reduction in stroke may be clinically significant in light o f the higher-risk profile of the off-pump group. The limitations of this st udy are that it was retrospective, there were a small number of events, and different surgeons were involved in the two different approaches to these patients. Conclusions: Improvements in myocardial protection, revascularization techn iques, and anesthetic management have made significant, favorable impacts o n CABG outcome in diabetic patients. New diagnostic and therapeutic strateg ies must be developed to lessen the medical and economic implications of st roke. A larger series or a more effective way of analyzing preoperative ris k may well have shown a statistically significant difference in the stroke incidence given the differences in preoperative risk factors/stroke predict ors. Until such advances occur, a threefold reduction of stroke incidence u sing OPCAB certainly makes this technique a favorable one for high-risk dia betics requiring coronary revascularization.