Preoperative beta-blocker use may not help with CABG

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 - Question Direction

The latest study to examine the preoperative use of beta-blockers in CABG found no mortality benefit combined with an uptick in postoperative atrial fibrillation. Still, it probably is not time to take an eraser to related quality metrics or guidelines.  

William Brinkman, MD, of the Cardiopulmonary Research Science and Technology Institute in Dallas, and colleagues previously had shown no benefit with beta-blockers in a similar study based on 12,855 CABG patients. Their single-institution study evaluated data from the Society of Thoracic Surgeons National Adult Cardiac (STS-NCD) database.

The current analysis, published online June 16 in JAMA Internal Medicine, expanded the sample to include all patients who underwent isolated CAGB surgery at hospitals participating in STS-NCD from 2008 to 2012. They excluded patients with a previous MI within 21 days or other high-risk groups, for a total of 506,110 patients from 1,107 facilities.

Their outcomes of interest were perioperative death (during the operative period and within 30 days of surgery), stroke, prolonged ventilation, reoperation, renal failure, deep sternal wound infection and atrial fibrillation.

Patients who did not receive beta-blockers were less likely to have had a prior MI, revascularization, an urgent status and operation after 2010, while the beta-blocker group was more likely to have risk factors such as dyslipidemia, hypertension, diabetes and congestive heart failure.

They found similar operative mortality rates, with a rate of 1.22 percent in the treated group and 1.17 percent in the untreated group. But the beta-blocker group had a higher rate of new-onset postoperative atrial fibrillation (21.38 percent vs. 20.10 percent, adjusted for patient factors). They noted similar results after propensity matching and subgroup analyses.

“On the surface, these observational study data stand in contrast to the endorsed National Quality Forum standards that mandate preoperative beta-blocker use before CABG procedures,” they proposed.

They pointed out that guidelines for atrial fibrillation also call for preoperative beta-blocker treatment. “However, a closer analysis of the studies used to generate this recommendation shows that the timing of initiation of beta-blocker therapy varied widely. Essentially, the data used to generate these guidelines were a mix of preoperative, intraoperative, and postoperative administration of beta-blockers.”

Their study could not assess the type of beta-blocker used, dose or response, a limitation underscored by the authors and by editorialist David M. Shahian, MD, of the Center for Quality and Safety and surgery department at Massachusetts General Hospital in Boston. Shahian emphasized that the study excluded 28 percent of patients in the database who had a recent MI, a group likely to benefit from preoperative beta-blocker treatment. The treatment cohort had a higher prevalence of risk factors, too, and even with propensity matching there were potential shortcomings.

Shahian called the results hypothesis generating and advised sticking with guidelines and good medical judgment. Brinkman et al recommended a prospective randomized clinical trial, a step supported by Shahian.