Preoperative β-Blocker Use and Mortality and Morbidity Following CABG Surgery in North America

Abstract

Context  β-Blockade therapy has recently been shown to convey a survival benefit in preoperative noncardiac vascular surgical settings. The effect of preoperative β-blocker therapy on coronary artery bypass graft surgery (CABG) outcomes has not been assessed.

Objectives  To examine patterns of use of preoperative β-blockers in patients undergoing isolated CABG and to determine whether use of β-blockers is associated with lower operative mortality and morbidity.

Design, Setting, and Patients  Observational study using the Society of Thoracic Surgeons National Adult Cardiac Surgery Database (NCD) to assess β-blocker use and outcomes among 629 877 patients undergoing isolated CABG between 1996 and 1999 at 497 US and Canadian sites.

Main Outcome Measure  Influence of β-blockers on operative mortality, examined using both direct risk adjustment and a matched-pairs analysis based on propensity for preoperative β-blocker therapy.

Results  From 1996 to 1999, overall use of preoperative β-blockers increased from 50% to 60% in the NCD (P<.001 for time trend). Major predictors of use included recent myocardial infarction; hypertension; worse angina; younger age; better left ventricular systolic function; and absence of congestive heart failure, chronic lung disease, and diabetes. Patients who received β-blockers had lower mortality than those who did not (unadjusted 30-day mortality, 2.8% vs 3.4%; odds ratio [OR], 0.80; 95% confidence interval [CI], 0.78-0.82). Preoperative β-blocker use remained associated with slightly lower mortality after adjusting for patient risk and center effects using both risk adjustment (OR, 0.94; 95% CI, 0.91-0.97) and treatment propensity matching (OR, 0.97; 95% CI, 0.93-1.00). Procedural complications also tended to be lower among treated patients. This treatment advantage was seen among the majority of patient subgroups, including women; elderly persons; and those with chronic lung disease, diabetes, or moderately depressed ventricular function. Among patients with a left ventricular ejection fraction of less than 30%, however, preoperative β-blocker therapy was associated with a trend toward a higher mortality rate (OR, 1.13; 95% CI, 0.96-1.33; P = .23).

Conclusions  In this large North American observational analysis, preoperative β-blocker therapy was associated with a small but consistent survival benefit for patients undergoing CABG, except among patients with a left ventricular ejection fraction of less than 30%. This analysis further suggests that preoperative β-blocker therapy may be a useful process measure for CABG quality improvement assessment.