Beta-blocker discontinuation noninferior to continuation in stable post-MI patients without heart failure

This was a randomized, open-label, noninferiority trial conducted across 25 centers in South Korea. The study enrolled 2540 patients who had experienced a myocardial infarction (MI), had a left ventricular ejection fraction (LVEF) of at least 40%, had no heart failure, and whose condition remained stable after receiving beta-blocker therapy for at least 1 year following their MI. The median follow-up duration was 3.1 years (interquartile range, 2.5 to 3.5).

The intervention was the discontinuation of beta-blocker therapy. The comparator was the continuation of beta-blocker therapy. The specific dosing, titration schedules, or types of beta-blockers used were not reported in the provided data. Patients were randomized to either stop their beta-blockers or to continue taking them as prescribed.

The primary outcome was a composite of death from any cause, recurrent myocardial infarction, or hospitalization for heart failure. The primary end-point event occurred in 58 patients in the discontinuation group (4-year Kaplan-Meier estimate, 7.2%) and in 74 patients in the continuation group (4-year Kaplan-Meier estimate, 9.0%). The hazard ratio was 0.80, with a 95% confidence interval of 0.57 to 1.13. The P-value for noninferiority was 0.001, meeting the prespecified noninferiority margin. This indicates that discontinuing beta-blockers was statistically noninferior to continuing them for this composite endpoint.

No specific data on key secondary outcomes were provided in the input. The study results focused on the primary composite endpoint.

Detailed safety and tolerability findings, including specific adverse event rates and discontinuation rates due to adverse events, were not reported. The input states only that the incidence of serious adverse events was similar in the two groups. Tolerability data were not provided.

These results challenge the traditional paradigm of indefinite beta-blocker therapy for all post-MI patients, which was largely established by landmark trials like the Beta-Blocker Heart Attack Trial (BHAT) and the Norwegian Timolol Trial conducted in the 1980s. Those trials demonstrated mortality benefits of beta-blockers initiated early after MI in broader populations, often including patients with reduced ejection fraction. The current study specifically addresses a modern, stable cohort without systolic dysfunction or heart failure who have already completed at least one year of therapy, a scenario not directly tested in the older landmark studies.

Key methodological limitations include the open-label design, which introduces potential for bias in outcome assessment, though the use of hard clinical endpoints may mitigate this. The noninferiority margin was set at a hazard ratio of 1.4, which is a clinically relevant threshold but should be considered when interpreting the results. The study population was exclusively from South Korea, which may limit generalizability to other ethnic and healthcare demographics. The specific beta-blockers used and their doses were not reported, which could affect the interpretation of the results.

The clinical implications are specific. For stable post-MI patients with preserved LVEF (≥40%) and no heart failure who have tolerated at least one year of beta-blocker therapy, these data provide evidence that discontinuing the medication may be a reasonable consideration without increasing the short-to-medium-term risk of death, recurrent MI, or heart failure hospitalization. This could simplify medication regimens and potentially reduce side effects and costs. However, this decision should be individualized, considering patient preferences, reasons for initial beta-blocker use (e.g., angina, arrhythmia), and the absence of other compelling indications.

Several important questions remain unanswered. The long-term effects (beyond 3-4 years) of beta-blocker discontinuation in this population are unknown. The study did not report outcomes for individual components of the composite endpoint (e.g., mortality alone), nor did it assess patient-reported outcomes like quality of life, symptoms, or reasons for discontinuation in the continuation group. The applicability to patients with other compelling indications for beta-blockers (like atrial fibrillation) or to those with borderline LVEF (e.g., 40-50%) is unclear. Finally, the optimal method for tapering and discontinuing beta-blockers was not described.