Preoperative β-Blockers as a Coronary Surgery Quality Metric: The Lack of Evidence of Efficacy

Background: Two quality measures used in public reporting and value-based payment programs require β-blockers be administered less than 24 hours before isolated coronary artery bypass graft surgery to prevent atrial fibrillation and mortality. Questions have arisen about continued use of these measures. Methods: We conducted a systematic search for randomized controlled trials (RCTs) examining the impact of preoperative β-blockers on atrial fibrillation or mortality after isolated coronary artery bypass graft surgery to determine what evidence of efficacy supports the measures. Results: We identified 11 RCTs. All continued β-blockers postoperatively, making it unfeasible to separate the benefits of preoperative vs postoperative administration. Meta-analysis was precluded by methodologic variation in β-blocker utilized, timing and dosage, and supplemental and comparison treatments. Of the eight comparisons of β-blockers/β-blocker plus digoxin versus placebo (n = 826 patients), six showed significant reductions in atrial fibrillation/supraventricular arrhythmias. Of the three comparisons (n = 444) of β-blockers versus amiodarone, two found no significant difference in atrial fibrillation; the third showed significantly lower incidence with amiodarone. One RCT compared β-blocker plus amiodarone versus each of those drugs separately; the combination reduced atrial fibrillation significantly better than the β-blocker alone, but not amiodarone alone. Seven RCTs reported short-term mortality, but this outcome was too rare and the sample sizes too small to provide any meaningful comparisons. Conclusions: Existing RCT evidence does not support the structure of quality measures that require β-blocker administration specifically within 24 hours before coronary artery bypass graft surgery to prevent postoperative atrial fibrillation or short-term mortality. Quality measures should be revised to align with the evidence, and further studies conducted to determine optimal timing and method of prophylaxis.