Introduction
The risk of sudden cardiac arrest (SCA) in patients with reduced ejection fraction increases after a myocardial infarction (MI).
However, the risk factors for SCA among patients with an ejection fraction (EF) >35% after MI remain poorly understood.
This article summarizes findings from a large, real-world study conducted between January 2008 and March 2017, analyzing adult patients (≥18 years) with a primary diagnosis of incident myocardial infarction and elevated serum troponin levels consistent with MI.
Patient Characteristics
The objective was to identify risk factors for SCA among patients with a post-MI ejection fraction >35% using a large, contemporary cohort.
Sample size: 31,286 patients with incident myocardial infarction and post-MI EF >35%.
Mean age: 64.1 years (range 54.9–74.0).
Women: 39%.
History of coronary heart disease: 94%.
Diabetes mellitus: 35%.
Mean post-infarction EF: 55% (IQR 45%–60%).
EF between 35% and 50%: 32% of patients.
All patients underwent coronary angiography:
Percutaneous coronary intervention (PCI): 19,171 (61%).
Coronary artery bypass graft (CABG): 4,065 (13%).
Medication use:
Beta-blockers: 81%.
ACE inhibitors/ARBs: 62%.
Identified Risk Factors
The following variables were significantly associated with an increased risk of sudden cardiac arrest:
Absence of coronary revascularization at the time of MI.
Revascularization via CABG instead of PCI.
Ejection fraction 35–50% (vs. ≥50%).
Black race.
History of heart failure, COPD, renal failure, or diabetes mellitus.
Use of antiarrhythmic therapy.
Absence of beta-blocker therapy.
Markedly elevated serum troponin (>7.5 ng/mL).
Key Findings
Patients with EF >35% post-MI still had a substantial 1-year SCA risk of approximately 1.8%.
A risk model was developed to identify patients at higher risk, based on:
Lack of coronary revascularization
EF 35–50%
Black race
History of COPD or renal failure
Antiarrhythmic therapy
Absence of beta-blockers
After adjusting for confounders, SCA risk was highest in patients with EF 36–39%, and lower among those with EF ≥45%.
Clinical Implications
Patients with a post-MI EF greater than 35% face a non-negligible risk of sudden cardiac arrest.
Applying a multifactorial risk model that includes coronary revascularization status, EF range, comorbidities, and pharmacologic therapy can help clinicians:
Identify patients at elevated risk.
Implement closer monitoring and targeted preventive strategies.
Optimize beta-blocker use and revascularization decisions post-MI.
This stratification can improve patient outcomes through early intervention and personalized management.
Reference
Selçuk Adabag et al. Predictors of Sudden Cardiac Arrest Among Patients With Post‐Myocardial Infarction Ejection Fraction Greater Than 35%.
Journal of the American Heart Association (JAHA)