Long-Term Follow-Up After Acute Myocardial Infarction According to Beta-Blocker Dose

Objective: Our purpose was to examine the association between beta-blocker dose and mortality following acute myocardial infarction.

Methods: This nationwide cohort study enrolled all patients admitted for first-time acute myocardial infarction in Denmark between July 1, 2004 and December 31, 2014, using the Danish National Patient Registry. Patients alive 15 days after admission were followed until death, emigration, or December 31, 2014. Patients were categorized according to daily beta-blocker consumption (0%, >0%-12.5%, >12.5%-25%, >25%-50%, >50%-100%, or >100% of the currently recommended target dose) based on prescriptions registered in the Danish National Database of Reimbursed Prescriptions. Doses were continuously updated during follow-up. Mortality rate ratios (MRRs) were computed and adjusted for confounders using Cox proportional hazard regression.

Results: Among 65,125 patients followed, any beta-blocker dose was associated with significant mortality reduction compared with no treatment (adjusted MRR ≤ 0.92 [95% confidence interval {CI}: 0.86-0.98]). The largest reduction was observed within the first year for beta-blocker doses >25%-50% (adjusted MRR = 0.55 [95% CI: 0.50-0.60]). After 1 year, doses >50%-100% were associated with the largest mortality reduction (adjusted MRR = 0.58 [95% CI: 0.50-0.67]), but it did not differ significantly from that associated with doses >25%-50% (adjusted MRR = 0.68 [95% CI: 0.61-0.77]).

Conclusions: Any beta-blocker dose was associated with significant mortality reduction following acute myocardial infarction compared with no treatment. Doses >25%-50% of the currently recommended target dose were associated with maximal mortality reduction within the first year after acute myocardial infarction, suggesting that higher doses are unnecessary.