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Lower dose beta-blocker therapy is associated with increased survival after myocardial infarction

Beta-blocker therapy after acute myocardial infarction ( MI ) improves survival. Beta-blocker doses used in clinical practice are often substantially lower than those used in the randomized trials establishing their efficacy.

This study evaluated the association of beta-blocker dose with survival after acute myocardial infarction, hypothesizing that higher dose beta-blocker therapy will be associated with increased survival.

A multicenter registry enrolled 7,057 consecutive patients with acute myocardial infarction. Discharge beta-blocker dose was indexed to the target beta-blocker doses used in randomized clinical trials, grouped as more than 0% to 12.5%, more than 12.5% to 25%, more than 25% to 50%, and more than 50% of target dose.

Follow-up vital status was assessed, with the primary endpoint of time-to-death right-censored at 2 years.

Of 6,682 patients with follow-up ( median 2.1 years ), 91.5% were discharged on a beta-blocker ( mean dose 38.1% of the target dose ).

Lower mortality was observed with all beta-blocker doses ( p less than 0.0002 ) versus no beta-blocker therapy.

After multivariable adjustment, hazard ratios for 2-year mortality compared with the more than 50% dose were 0.862 ( 95% confidence interval [ CI ]: 0.677 to 1.098 ), 0.799 ( 95% CI: 0.635 to 1.005 ), and 0.963 ( 95% CI: 0.765 to 1.213 ) for the more than 0% to 12.5%, more than 12.5% to 25%, and more than 25% to 50% of target dose groups, respectively.

Multivariable analysis with an extended set of covariates and propensity score analysis also demonstrated that higher doses were not associated with better outcome.

In conclusion, these data do not demonstrate increased survival in patients treated with beta-blocker doses approximating those used in previous randomized clinical trials compared with lower doses.
These findings provide the rationale to re-engage in research to establish appropriate beta-blocker dosing after myocardial infarction to derive optimal benefit from this therapy. ( Xagena )

Goldberger JJ et al, J Am Coll Cardiol 2015;66:1431-1441

XagenaMedicine_2015