Beta-Blockers After Acute MI
What is the association of beta-blocker dose with survival after acute myocardial infarction (MI), hypothesizing that higher-dose beta-blocker therapy will be associated with increased survival?
A multicenter registry enrolled 7,057 consecutive patients with acute MI. Discharge beta-blocker dose was indexed to the target beta-blocker doses used in randomized clinical trials, grouped as >0% to 12.5%, >12.5% to 25%, >25% to 50%, and >50% of target dose. Follow-up vital status was assessed, with the primary endpoint of time-to-death right-censored at 2 years. Multivariable and propensity score analyses were used to account for group differences.
0f 6,682 with follow-up (median 2.1 years), 91.5% were discharged on beta-blocker (mean dose 38.1%). Lower mortality was observed with all beta-blocker doses (p < 0.0002) versus no beta-blocker therapy. After multivariable adjustment, hazard ratios (HRs) for 2-year mortality compared with the >50% dose were 0.862 (95% confidence interval [CI], 0.677-1.098), 0.799 (95% CI, 0.635-1.005), and 0.963 (95% CI, 0.765-1.213) for the >0% to 12.5%, >12.5% to 25%, and >25% to 50% of target dose, respectively. Multivariable analysis with an extended set of covariates and propensity score analysis also demonstrated that higher doses were not associated with better outcome.
The authors concluded that data do not demonstrate increased survival in patients treated with beta-blocker doses approximating those used in prior randomized clinical trials compared with lower doses.
This registry study reports no improvement in outcomes with higher-dose beta-blocker therapy, more specifically the target beta-blocker doses used in prior randomized clinical trials. While baseline differences in the treatment groups prevent a definitive determination of the dose-response relationship between beta-blocker dose and mortality post-MI, the lowest observed mortality was at 25% of the target dose used in randomized trials (i.e., metoprolol 50 mg/day). These findings suggest the need to re-engage in research to establish appropriate beta-blocker dosing following MI to derive optimal benefit.
Keywords: Acute Coronary Syndrome, Adrenergic beta-Antagonists, Metoprolol, Myocardial Infarction, Primary Prevention, Survival
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