Dr. Murat Demirci

Beta-Blocker Interruption or Continuation after Myocardial Infarction (ABYSS trial)

Published in Congress: ESC 2024

Link :
https://www.nejm.org/doi/full/10.1056/NEJMoa2404204

Backround:
Beta-blockers reduce the risk of heart failure and mortality after myocardial infarction (MI). The ESC Acute Coronary Syndromes Guidelines recommend the use of beta-blockers with a class 2 indication after acute myocardial infarction (MI), regardless of left ventricular ejection fraction (LVEF). However, the long-term benefits of this therapy in patients with preserved left ventricular ejection fraction (EF > 40%) and no other primary indication remain uncertain. This study evaluated the safety and efficacy of discontinuing or continuing beta-blocker therapy in patients who have experienced an MI.

Objective:
The aim of this study is to compare the effects of discontinuing long-term beta-blocker therapy versus continuing it on outcomes such as mortality, recurrent MI, stroke, or hospitalization due to cardiovascular causes in patients with a left ventricular ejection fraction above 40% who have experienced a myocardial infarction but have not had a cardiovascular event in the past six months.

Methods:
Patients who had experienced an MI more than six months prior and were on beta-blocker therapy were included in the study. Patients with heart failure with reduced left ventricular ejection fraction (EF < 40%), those who had a cardiac event within the last six months, or those taking beta-blockers for arrhythmia, uncontrolled hypertension, or migraine were excluded from the study. Patients were randomized in a 1:1 ratio to either discontinue beta-blocker therapy or continue it at the same dosage. The primary endpoint was defined as a composite of death, non-fatal myocardial infarction, non-fatal stroke, or hospitalization for another cardiovascular cause.

Results:
In the study, 3,698 patients were randomly divided into two groups. The patients were divided into a beta-blocker discontinuation group (1,846 patients) and a continuation group (1,852 patients). The average follow-up period was set at 3 years. Primary endpoint events occurred in 23.8% of the beta-blocker discontinuation group and 21.1% of the continuation group. The primary endpoint events were 2.8% more frequent in the group that discontinued beta-blockers (HR: 1.16, 95% CI 1.01-1.33, P=0.44).

Conclusion:
Discontinuing beta-blocker therapy did not significantly increase the risk of death, MI, stroke, or hospitalization due to cardiovascular causes; however, the findings did not result in a non-inferior outcome.

Interpretations:
Discontinuation of beta-blockers after 6 months may be considered in patients with an ejection fraction above 40% who have experienced an MI. Rates of death, MI, and stroke appear similar between the groups. The difference in composite primary endpoint events is primarily due to a higher rate of cardiovascular-related hospitalizations in the group that discontinued beta-blockers (18.9% vs 16.6%). The higher hospitalization rates in the discontinuation group suggest that continuing beta-blocker therapy may be advisable. However, further research is needed to determine the long-term benefits of this treatment.