Beta Blockers Reduce Cardiovascular Events by 25% in Post-Myocardial Infarction Patients with Mildly Reduced LVEF: Key Findings from a Meta-Analysis

Impact of Long-term Oral β-blocker Therapy on Patients with Myocardial Infarction

Study Overview

A recent meta-analysis published in The Lancet has demonstrated that long-term oral β-blocker therapy, including medications such as bisoprolol, metoprolol, and carvedilol, results in a 25% reduction in the composite endpoint of all-cause mortality, new myocardial infarction (MI), or heart failure in patients with myocardial infarction (MI) and mildly reduced left ventricular ejection fraction (LVEF 40-49%). The analysis included data from four randomized controlled trials: REBOOT, BETAMI, DANBLOCK, and CAPITAL-RCT, encompassing 1,885 patients hospitalized for acute MI with mildly reduced LVEF.

Patient Distribution

Out of the total participants, 991 were assigned to receive β-blockers, while 894 were placed in a control group without β-blocker treatment. The distribution of specific medications included bisoprolol in 430 patients (44%), metoprolol in 485 patients (49%), and carvedilol in 46 patients (5%).

Key Findings

The study’s key findings indicate significant benefits associated with β-blocker therapy:

– **Reduction in Composite Endpoint**: The therapy decreased the composite endpoint of all-cause death, new MI, or heart failure by 25%, with event occurrences at 11% in the β-blocker group compared to 14% in the control group. The rates translated to 32.6 events per 1,000 patient-years in the β-blocker group versus 43.0 events per 1,000 patient-years in the control group (HR 0.75, 95% CI 0.58-0.97; p=0.031).

– **Decrease in All-cause Mortality**: All-cause mortality was reduced by 22%, with a mortality rate of 6% in the β-blocker group versus 8% in the control group (HR 0.78, 95% CI 0.55-1.11; p=0.169).

– **Reduction in Cardiac Death**: Cardiac death occurrences were reduced by 45%, noted in 2% of patients receiving β-blockers compared to 3% in the control group (HR 0.55, 95% CI 0.28-1.06; p=0.076).

– **Lower Incidence of New Myocardial Infarction**: New MI rates decreased by 23%, occurring in 4% of the β-blocker group against 5% in the control group (HR 0.77, 95% CI 0.50-1.18; p=0.230).

– **Heart Failure Occurrence**: The incidence of heart failure was reduced by 29%, seen in 3% of the β-blocker group versus 4% in the control group (HR 0.71, 95% CI 0.44-1.14; p=0.152).

Timeframe for Therapeutic Benefits

The analysis indicated that the therapeutic benefits of β-blocker therapy began to manifest around three months after initiation and continued to improve throughout the study’s median follow-up of 3.5 years (IQR 2.3-4.5). This consistent separation of survival curves suggests that prolonged continuous therapy is key to achieving these clinical benefits.

Consistency Across Trials

Results showed remarkable consistency across the four trials (REBOOT, BETAMI, DANBLOCK, and CAPITAL-RCT), with no evidence of heterogeneity (Cochran’s Q test p=0.95, I²=0%). Furthermore, the treatment effects were uniform across various factors, including sex, type of MI, LVEF category, β-blocker dosage, and geographical locations (Spain, Italy, Norway, Denmark, and Japan) (p interaction=0.98), underscoring the widespread applicability of these findings.

Safety Profile

The safety analysis revealed no significant increase in adverse events associated with β-blocker therapy.

Clinical Implications

Considerations for Healthcare Professionals

Healthcare professionals may consider the following questions based on the findings of this meta-analysis:

1. Given the therapeutic grey zone for post-MI patients with mildly reduced LVEF (40–49%), do these findings support a shift towards treating this group similarly to HFrEF patients regarding long-term β-blocker therapy?

2. With 30% of MI patients falling into the LVEF 40-49% category, are β-blockers routinely prescribed in practice, or are they primarily reserved for those with reduced EF? What clinical outcomes have been observed in this intermediate ejection fraction group?

3. Considering the median follow-up of 3.5 years highlighting ongoing benefits, how long is β-blocker therapy typically continued in post-MI patients with mildly reduced EF? Is LVEF reassessed periodically to determine the need for continued therapy?

4. The study noted a 29% reduction in new heart failure cases. Should β-blockers be viewed more as a preventive strategy against heart failure in post-MI patients with LVEF 40-49%, and how can this perspective influence discussions about long-term adherence with patients?

5. Given that bisoprolol was used in 44% of patients, metoprolol in 49%, and carvedilol in 5%, how does the choice of β-blocker, particularly bisoprolol’s cardio-selectivity and metabolic profile, affect treatment decisions for patients with comorbidities like diabetes or mild bronchial reactivity?

Conclusion

This meta-analysis provides compelling evidence that β-blocker therapy significantly decreases major adverse cardiovascular events (MACE) by 25% in post-myocardial infarction patients with mildly reduced LVEF (40-49%), a demographic representing up to 30% of all MI patients.

References

Rossello X, Prescott EIB, Kristensen AMD, et al. β blockers after myocardial infarction with mildly reduced ejection fraction: an individual patient data meta-analysis of randomised controlled trials. Lancet. 2025 Sep 13;406(10508):1128-1137. doi: 10.1016/S0140-6736(25)01592-2.