beta-Blocker use following myocardial infarction: low prevalence of evidence-based dosing

Abstract

Background: Quality improvement programs have shown increased use of beta-blockers post-myocardial infarction (MI), but there are no data on whether appropriate doses are administered.

Methods: In a prospective registry that enrolled consecutive patients with MI, we evaluated beta-blocker dosing at discharge after MI and 3 weeks later and assessed clinical predictors for treatment with very low doses. We studied 1,971 patients (70.8% male) with a mean age of 63.9 +/- 13.7 years, of whom 48.2% had an ST-elevation MI.

Results: beta-Blocker utilization rates following MI were 93.2% at discharge: 20.1% received <25% of target dose, 36.5% received 25% of target dose, 26.4% received 26% to 50% of target dose, and 17.0% received >50% of target dose. Between discharge and 3 weeks, 76.4% had no change in beta-blocker dose, with 11.9% and 11.6% having their dose reduced and increased, respectively. Absence of hypertension, acute percutaneous coronary intervention, older age, and no angiotensin-converting enzyme inhibitor therapy were consistent predictors of treatment with very low beta-blocker doses.

Conclusions: Underdosing of beta-blockers is highly prevalent among patients post-MI. This represents an important opportunity in quality improvement for the care of patients who have suffered an MI.

Figure 1

The graph shows the percent of patients taking various doses of beta-blockers at discharge. Doses are shown as the proportion or percent of daily target dose - <25% - n=347; 25% - n=629; 26–50% - n=454; >50% - n=293. Each bar is subdivided to indicate metoprolol dosing and dosing of other beta-blockers.

Figure 2

The graph shows the distribution of beta-blocker dosing (shown as percent of daily target dose – see legend) at 3 weeks stratified by whether the dose was reduced (n=171), remained the same (n=1095), or increased (n=167) since hospital discharge.