Effect of beta-blockers on cardiovascular hospitalisation after myocardial infarction: A substudy of the BETAMI-DANBLOCK trial
H Caglar, T H Holmager, A M D Kristensen, M W Fagerland, S Halvorsen, D Atar, J Munkhaugen, E PrescottAbstract
Background
The role of long-term beta-blocker therapy after myocardial infarction (MI) in patients with LVEF ≥40% remains debated. In the ABYSS trial, patients with a prior MI (≥6 months before enrolment) were randomised to interruption or continuation of long-term beta-blocker therapy. Interruption was associated with an increased risk of a composite of death, MI, stroke, or cardiovascular hospitalisation, primarily driven by cardiovascular hospitalisations. We therefore examined whether our findings in BETAMI-DANBLOCK align with these results.
Purpose
To assess whether continued beta-blocker therapy beyond 6 months after MI is associated with a lower risk of the composite of death, MI, stroke, or cardiovascular hospitalisation.
Methods
This is a post hoc analysis of the open-label, randomised BETAMI-DANBLOCK trial which randomized patients with LVEF ≥40%. to beta-blocker therapy or no beta-blocker therapy within 14 days after MI. To reflect a clinically stable population comparable to that enrolled in ABYSS, only patients who were alive and free from heart failure and recurrent MI at 6 months were included in the analysis. Outcomes were assessed from this 6-month landmark until the end of follow-up. The primary outcome was aligned with ABYSS and defined as a composite of death, nonfatal MI, nonfatal stroke, or hospitalisation for cardiovascular reasons. Cardiovascular hospitalisations were identified through national registries using International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) I-diagnosis codes (diseases of the circulatory system). Hazard ratios were estimated using Cox proportional hazards models adjusted for the randomisation stratification variables (site and LVEF <50%). Risk differences with 95% confidence intervals (CI) were calculated. Patients were censored at emigration
Results
At 6 months after randomisation, the study population comprised 5,431 patients. A primary composite-outcome event occurred in 639 of 2,720 patients (23.5%) assigned to beta-blocker therapy and in 698 of 2,711 patients (25,7%) assigned to no beta-blocker therapy (risk difference, 2.3 percentage points; 95% CI, 0.0 to 4.5) corresponding to a hazard ratio of 1.13 (95% CI, 1.01 to 1.25) (Figure 1),. The individual components of the composite outcome are shown in Figure 2.
Conclusions
In BETAMI-DANBLOCK, long-term beta-blocker therapy among patients with MI and LVEF ≥40% was associated with a lower risk of cardiovascular events, including hospitalisation for cardiovascular reasons, beyond 6 months after randomisation. These findings are consistent with the ABYSS trial and provide additional evidence supporting continued beta-blocker therapy in clinically stable post-MI patients.Cumulative incidence of composite outcomeComposite outcome and its components