Sudden cardiac death risk after myocardial infarction across the spectrum of left ventricular ejection fraction: a meta-analysis.
meta_analysis · Level I
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- Record sourced from PubMed, PMID 42571650.
- Also identified by DOI 10.1136/heartjnl-2026-327792.
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Abstract
Implantable cardioverter defibrillator (ICD) therapy is indicated following a myocardial infarction (MI) to curtail the risk of sudden cardiac death (SCD) in patients who are classified as high-risk, defined by a left ventricular ejection fraction (LVEF) ≤35%. The understanding of risk in patients with ischaemic injury who do not meet these criteria is limited. This study aims to assess the burden of SCD in patients' post-MI with LVEF 36-50%. Articles reporting mortality and SCD outcomes for participants with LVEF 36-50% post-MI without additional risk stratification or intervention were included. Medline, Embase and Cochrane databases were searched from index entries until the present. Data were synthesised using a random-effects model. Competing risk adjusted number needed to treat (NNT) for ICD implantation was calculated. This study adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. 7435 records were identified, five studies with 9345 patients were included. The pooled annual rate of SCD in patients with LVEF 36-50% post-MI was 1.74% (95% CI 1.02 to 2.95); a higher annual rate of 6.34% was observed for LVEF≤35% (p=0.03) while a lower yearly rate of 0.55% was observed for LVEF >50% (p=0.02). The proportion of mortality due to SCD was similar across all LVEF strata (p=0.79). Very high between-study heterogeneity was observed (I<sup>2</sup>=89.9% for SCD and I<sup>2</sup>=96.8% for all-cause mortality). During exploratory modelling, the primary prevention ICD NNT for patients with LVEF 36-50% was 19 when applying the MADIT-II ICD treatment effect (HR 0.33, 95% CI 0.20 to 0.53) and extrapolation to a 5-year device lifespan. This is the first meta-analysis reviewing post-MI patients with LVEF 36-50%. These findings highlight a clinically relevant unmet need for patients who carry a substantial burden of SCD despite being outside current ICD eligibility criteria. Further study is needed to improve risk stratification within this population and determine whether suitable intervention is beneficial. CRD42024551830.