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Predicting Sudden Cardiac Death After Acute MI
Study Questions:
Does use of left ventricular ejection fraction (LVEF) and/or other variables identify patients who benefit from defibrillator implantation to prevent sudden death after acute myocardial infarction (MI)?
Methods:
The analysis pooled 20 data sets with 140,204 post-MI patients containing information on demographics, medical history, clinical characteristics, biomarkers, electrocardiography, echocardiography, and cardiac magnetic resonance imaging. Separate analyses were performed in patients 1) carrying a primary prevention cardioverter-defibrillator with LVEF ≤35% (implantable cardioverter-defibrillator [ICD] patients), 2) without cardioverter-defibrillator with LVEF ≤35% (non-ICD patients ≤35%), and 3) without cardioverter-defibrillator with LVEF >35% (non-ICD patients >35%). The primary outcome was sudden cardiac death or, in defibrillator carriers, appropriate defibrillator therapy. Using a competing risk framework and systematic internal–external cross-validation, a model using LVEF only, a multivariable flexible parametric survival model, and a multivariable random forest survival model were developed and externally validated. Predictive performance was assessed by random-effect meta-analysis.
Results:
There were 1,326 primary outcomes in 7,543 ICD patients, 1,193 in 25,058 non-ICD patients ≤35%, and 1,567 in 107,603 non-ICD patients >35% during mean follow-up of 30.0, 46.5, and 57.6 months, respectively. In these three subgroups, LVEF poorly predicted sudden cardiac death (c-statistics between 0.50 and 0.56), considering additional parameters did not improve calibration and discrimination, and model generalizability was poor.
Conclusions:
More accurate risk stratification for sudden cardiac death and identification of low-risk individuals with severely reduced LVEF or of high-risk individuals with preserved LVEF was not feasible, neither using LVEF nor using other predictors.
Perspective:
The PROFID study assessed the use of LVEF and other clinical criteria to identify patients who benefit from defibrillator implantation after acute MI. Current guidelines recommend implantation of a defibrillator for primary prevention of sudden death among patients post-acute MI and LVEF <35%. Based on the findings from this large, pooled cohort, LVEF was a poor predictor of sudden death. No other clinical variables were reliably able to identify low-risk patients with severely reduced LVEF who would not benefit from a defibrillator or high-risk patients with mildly reduced or preserved LVEF who may have benefitted from defibrillator implantation. Though the findings of the current analysis are limited by study design, they do add to existing doubts about using LVEF <35% as a sole criterion to identify patients at risk for sudden death. There remains a need for further study to refine criteria for patients truly at high risk for sudden cardiac death after acute MI.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Implantable Devices, SCD/Ventricular Arrhythmias, Prevention
Keywords: Defibrillators, Implantable, Acute Coronary Syndrome, Myocardial Infarction, Death, Sudden, Cardiac
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