Discharge Beta Blockers, RASi Cut Late Risk in MI, Mid-Range EF

The study covered in this summary was published in medRxiv.org as a preprint and has not yet been peer reviewed.

Key Takeaways

  • Beta-blocker therapy at discharge in patients with mildly reduced left ventricular ejection fraction (LVEF, 40% – 49%) after acute myocardial infarction (MI) was associated with lower 2-year rates of major adverse cardiac events (MACE).

  • Renin-angiotensin-system (RAS) inhibitor therapy at discharge after acute MI with heart failure with mildly reduced EF (HFmrEF) was associated with lower rates of rehospitalization due to heart failure.

  • Patients with mildly reduced LVEF after acute MI had better 2-year clinical outcomes if they were on beta blockers or RAS inhibitors at discharge.

Why This Matters

  • Evidence supporting beta blockers and RAS inhibitors after acute MI has previously been in patients with LVEF less than 40%.

  • This study suggests clinical benefits from these therapies in patients with LVEF of 40% to 49%, a group for which outcomes on these drugs have not been well characterized.

  • The findings suggest that beta blockers and RAS inhibitors can be considered in patients with mildly reduced LVEF after an acute MI in the era of early coronary reperfusion therapy and contemporary optimal medical therapies.

Study Design

  • The analysis featured 2607 patients with LVEF of 40% to 49% who were enrolled in the Korea Acute Myocardial Infarction Registry–National Institute of Health (KAMIR-NIH) from 2011 to 2015. Patients unable to undergo echocardiography at their initial hospitalization were excluded.

  • The cohort for the beta-blocker analysis consisted of 685 patients prescribed the drugs at discharge who were propensity matched to 363 patients not on beta blockers. Similarly, 1003 patients who were discharged on RAS inhibitors were propensity matched to 556 not on RAS inhibitors.

  • The primary endpoint of 2-year MACE included cardiac death, MI, coronary revascularization, and rehospitalization due to heart failure. Secondary endpoints included the individual MACE components, death from any cause, stroke, major adverse cardiac and cerebrovascular events, and MACE or noncardiac death.

  • Beta blockers and RAS inhibitors were prescribed before discharge at the discretion of attending physicians.

Key Results

  • Patients on beta blockers at discharge benefited with a significantly lower 2-year rate of MACE (fully adjusted hazard ratio [HR], 0.68; P = .015). The difference was driven primarily by reduced rates of MI (HR, 0.50; P = .035) and revascularization (HR, 0.62; P = .030) and was consistent across subgroups.

  • The only observed association between RAS inhibitors at discharge for clinical endpoints at 2 years was for rehospitalization due to heart failure (fully adjusted HR, 0.53; P = .010), which was consistent across subgroups. 

  • No significant interaction was observed between an EF below 45% and an EF above 45% with respect to 2-year clinical endpoints.

  • Both beta blockers and RAS inhibitors had been used at lower-than-recommended dosages.

Limitations

  • Treatment at discharge was not randomized.

  • Propensity matching could not control for all potential confounders.

  • Patient compliance with the prescribed medications could not be determined.

  • Of those not on beta blockers or RAS inhibitors at discharge, 41% and 46%, respectively, crossed over during follow-up to receive the drug in their respective propensity-matched groups.

  • Beta blockers and RAS inhibitors were prescribed at only one-fourth to one-half of maximal guideline-recommended dosages, and dosages at the time of clinical events was not available.

Disclosures

The study received no commercial funding. The authors had no relevant disclosures.

This is a summary of a preprint research study, Association of the Medical Therapy with Beta-Blockers or Inhibitors of Renin-Angiotensin System with Clinical Outcomes in Patients with Mildly Reduced Left Ventricular Ejection Fraction after Acute Myocardial Infarction, written by researchers at the Jeju National University College of Medicine, Department of Internal Medicine, Republic of Korea, on medRxiv provided to you by Medscape. The study has not yet been peer reviewed. The full text of the study can be found on medRxiv.org.

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