Prognostic Impact of β-Blocker Dose After Acute Myocardial Infarction

BACKGROUND: The differential prognostic impact of β-blocker dose after acute myocardial infarction (AMI) has been under debate. The current study sought to compare clinical outcome after AMI according to β-blocker dose using the Korea Acute Myocardial Infarction Registry-National Institutes of Health (KAMIR-NIH). METHODS AND RESULTS: Of the total population of 13,104 consecutive AMI patients enrolled in the KAMIR-NIH, the current study analyzed 11,909 patients. These patients were classified into 3 groups (no β-blocker; low-dose [<25% of target dose]; and high-dose [≥25% of target dose]). The primary outcome was cardiac death at 1 year. Compared with the no β-blocker group, both the low-dose and high-dose groups had significantly lower risk of cardiac death (HR, 0.435; 95% CI: 0.363-0.521, P<0.001; HR, 0.519; 95% CI: 0.350-0.772, P=0.001, respectively). The risk of cardiac death, however, was similar between the high- and low-dose groups (HR, 1.194; 95% CI: 0.789-1.808, P=0.402). On multivariable adjustment and inverse probability weighted analysis, the result was the same. CONCLUSIONS: The use of β-blockers in post-AMI patients had significant survival benefit compared with no use of β-blockers. There was no significant additional benefit of high-dose β-blockers compared with low-dose β-blockers, however, in terms of 1-year risk of cardiac death.