Relationship between beta-blockers and mortality in diabetic patients undergoing coronary artery bypass grafting

Abstract

Background: Beta-blockers have an established role in the management of acute coronary syndromes. Whether beta-blockers also reduce adverse outcomes in the peri-operative setting, including in cardiac surgery, remains controversial. Purpose: We compared characteristics and outcomes of diabetic patients undergoing coronary artery bypass grafting (CABG) by whether they were on beta-blockers peri-operatively. Methods: All diabetic patients undergoing CABG during July 2010-June 2010 were included. Characteristics and outcomes including mortality and morbidities were collected and compared by baseline beta-blocker status. Results: Out of the 306 patients studied, 72.5% (222) were on a beta-blocker at the time of CABG. Not having beta-blocker treatment was associated with being female (41.8% vs 23.4%, P=0.005), intra-aortic balloon pump treatment (50.0% vs 25.4%, P=0.011), history of congestive heart failure (51.9% vs 25.1%, P=0.006), atrial fibrillation (52.4% vs 25.6%, P=0.02), impaired ejection fraction<40% (46.6% vs 23.0%, P=0.001), chronic respiratory disease (40.0% vs 24.7%, P=0.029) and dialysis (26.0% vs 52.9%, P=0.023). Beta-blocker use was associated with reduced operative mortality (0.5% vs 6.0%, P=0.007) and 1-year mortality (99.1% vs 88.1%, log-rank P=0.002), but not other post-operative complications including myocardial infarction or stroke. In multivariate analysis, beta-blocker use was independently associated with reduced 1-year mortality hazards ratio (95% confidence interval) 0.204 (0.063-0.654) but not operative mortality 0.227 (0.009-5.767) or morbidities. Conclusion: Peri-operative beta-blocker use was associated with reduced operative mortality and independently predicted improved 1-year mortality after CABG in diabetic patients. In the absence of contraindications, beta-blockers should be considered in all diabetic patients undergoing CABG.