Efficacy of Long-Term β-Blocker Therapy for Secondary Prevention of Long-Term Outcomes After Coronary Artery Bypass Grafting Surgery

Abstract

Background: Conflicting results from recent observational studies have raised questions concerning the benefit of β-blockers for patients undergoing coronary artery bypass grafting (CABG). Furthermore, the efficacy of long-term β-blocker therapy in CABG patients after hospital discharge is uncertain.

Methods and results: The study included 5926 consecutive patients who underwent CABG and were discharged alive. The prevalence and consistency of β-blocker use were determined in patients with and without a history of myocardial infarction (MI). β-Blockers were always used in 1280 patients (50.9%) with and 1642 patients (48.1%) without previous MI after CABG. Compared with always users (n=2922, 49.3%), the risk of all-cause death was significantly higher among inconsistent β-blocker users (hazard ratio [HR], 1.96; 95% confidence interval [CI], 1.50-2.57), and never using β-blockers was associated with increased risk of both all-cause death (HR, 1.42; 95% CI, 1.01-2.00) and the composite of adverse cardiovascular events (HR, 1.29; 95% CI, 1.10-1.50). In the cohort without MI, the HR for all-cause death was 1.70 (95% CI, 1.17-2.48) in inconsistent users and 1.23 (95% CI, 0.76-1.99) in never users. In the MI cohort, mortality was higher for inconsistent users (HR, 2.14; 95% CI, 1.43-3.20) and for never users (HR, 1.59; 95% CI, 1.07-2.63). Consistent results were obtained in equivalent sensitivity analyses.

Conclusions: In patients with or without previous MI undergoing CABG, the consistent use of β-blockers was associated with a lower risk of long-term mortality and adverse cardiovascular events. Strategies should be developed to understand and improve discharge prescription of β-blockers and long-term patient adherence.

Keywords: adrenergic beta-antagonists; coronary artery bypass; coronary artery disease; myocardial infarction.

Figure 1.

Kaplan–Meier curves of outcomes associated with β-blocker use after coronary artery bypass graft surgery. Shown are rates of all-cause death and major adverse cardiac and cerebrovascular events (MACCEs) in the overall population (A), patients without pervious myocardial infarction (MI; B), and patients with pervious MI (C). The P values were calculated with the log-rank test on the basis of all available follow-up data with always users as reference.

Figure 2.

Hazard ratios (HRs) associated with β-blockers in prespecified subgroups of patients. Subgroup analyses were performed with the use of Cox proportional hazards regression with the always user group as reference and with adjustment for all patient-level variables in Table I in the online-only Data Supplement. The HRs were reported for inconsistent users or never users with always users as reference. CI indicates confidence interval; COPD, chronic obstructive pulmonary disease; LVEF, left ventricular ejection fraction; and MACCE, major adverse cardiac and cerebrovascular events.