Association of Perioperative Beta-Blockade With Mortality and Cardiovascular Morbidity Following Major Noncardiac Surgery
What are associations of early perioperative exposure to beta-blockers with 30-day postoperative outcomes in patients undergoing noncardiac surgery?
This was a retrospective cohort analysis of a population-based sample of 136,745 patients who were 1:1 matched on propensity scores (37,805 matched pairs) treated at 104 VA medical centers from January 2005 through August 2010. Perioperative risk, process, and outcome data from patients undergoing noncardiac surgical procedures were obtained from the VA Surgical Quality Improvement Program (VASQIP) database. Beta-blocker exposure from an inpatient pharmacy database was defined as any prescription ordered on either postoperative day 0 or 1. Data were also linked with outpatient pharmacy records for beta-blockers, and additional data sets were used to classify the six revised Cardiac Risk Index component variables for patients in the cohort analysis. The primary outcome was all-cause mortality and the secondary outcome was a composite of Q-wave myocardial infarction (MI) or nonfatal cardiac arrest assessed at 30 days after surgery.
Overall, 55,138 patients (40.3%) were exposed to beta-blockers. Overall, 1,568 patients (1.1%) sustained the primary 30-day mortality outcome and 1,196 patients (0.9%) the secondary cardiac morbidity outcome. In the matched cohort, a lower rate of mortality was observed in the exposed group (relative risk [RR], 0.73; 95% CI, 0.65-0.83; p < 0.001). There were significant associations of beta-blocker exposure with lower mortality in patients with two Revised Cardiac Risk Index factors (RR, 0.63; 95% CI, 0.50-0.80; p < 0.001); three factors (RR, 0.54; 95% CI, 0.39-0.73; p < 0.001); or four factors or more (RR, 0.40; 95% CI, 0.25-0.73; p < 0.73). When stratified by type of surgery, no significant associations were noted in patients undergoing vascular surgery, regardless of the Revised Cardiac Risk Index. In the matched cohort, the overall stroke incidence was not significantly different (exposed, 0.35%; 95% CI, 0.29%-0.41% vs. unexposed, 0.32%; 95% CI, 0.26%-0.38%).
Perioperative beta-blocker exposure is associated with lower rates of 30-day mortality and cardiac morbidity in patients with two or more Revised Cardiac Risk Index factors undergoing noncardiac, nonvascular surgery in the VA health care system.
The limitations of this retrospective analysis aside, the current findings would lend support to a strategy of continuation of perioperative beta-blockade in patients undergoing nonvascular surgery with two or more Revised Cardiac Risk Index factors. The results from this analysis should be explored and validated. The inability to detect significant associations between beta-blocker exposure and outcome in patients undergoing vascular surgery warrants further investigation and may have been, as acknowledged by the authors, partly related to the smaller sample size relative to the nonvascular cohort. A multicenter randomized trial, as suggested by the authors, would be of interest to clarify the controversies surrounding effectiveness of perioperative beta-blockade in patients undergoing noncardiac surgery, but would need to avoid withdrawal of pre-existing beta-blockade (which was associated with a two-fold increased mortality risk in the present analysis).
Keywords: Myocardial Infarction, Stroke, Propensity Score, Perioperative Care, Morbidity, Hu Paraneoplastic Encephalomyelitis Antigens, London, Heart Arrest, Vascular Surgical Procedures, Postoperative Period
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