Long-Term Beta-Blocker Therapy after Myocardial Infarction in the Reperfusion Era: A Systematic Review.

Beta-blockers are recommended as standard of care for patients who experience a myocardial infarction (MI). However, evidence to support this recommendation is primarily derived from the pre-reperfusion era. In the reperfusion era, short-term (≤ 30 days) beta-blocker therapy has been demonstrated to reduce recurrent MI and angina, but not mortality. The objective of this review was to evaluate the evidence for long-term (≥ 1 yr) beta-blocker therapy in patients post-MI without left ventricular dysfunction in the reperfusion era. A systematic search of MEDLINE, EMBASE, CENTRAL, and Google from inception to September 2017 was performed. Included were randomized controlled trials and observational propensity score cohort studies published within the past 10 years that compared beta-blockers to placebo/no beta-blockers at discharge in patients with an acute MI but without left ventricular dysfunction or heart failure. Outcomes of interest included all-cause and cardiovascular mortality, nonfatal MI, and nonfatal stroke. Eight cohort studies were included. Follow-up ranged from 1 to 5 years. Two smaller studies demonstrated a reduction in all-cause mortality with beta-blockers, whereas there was no difference observed in six studies. One study showed reduced cardiovascular mortality at 1 year, but no difference in sudden cardiac death. One study demonstrated a reduction in cardiac mortality at 3 years, but no difference in MI or stroke. None of the four studies that reported adverse cardiovascular events demonstrated a benefit with beta-blocker therapy. Though these data are limited by observational methodology, the majority of the included studies failed to demonstrate a benefit in survival or cardiovascular events with long-term beta-blockers in post-MI patients with normal left ventricular function. In the absence of a contemporary randomized controlled trial, this evidence imparts uncertainty regarding the current standard of care and suggests that it may be reasonable to discontinue beta-blockers in patients without impaired left ventricular function at 1-year post-MI who do not have another indication for use.