Abstract 2026: The Use of Contrast-Enhanced Cardiac Magnetic Resonance Imaging after Acute Myocardial Infarction for Prediction of Future Ventricular Dysfunction and ICD Implantation Qualification
The period immediately following MI is associated with a heightened risk for sudden cardiac death (SCD). However, ICD trials for primary prevention of SCD using LVEF as a selection criterion have shown benefit only when implanted remotely from the index MI.
Methods: A prospective study of 96 patients (84% men, mean age 56 ± 11 yrs) with a ST-elevation MI had infarct size and EF quantified using contrast-enhanced cardiac magnetic resonance (CMR) early (< 1 week) and late (> 3 months) post MI. Patients were divided into 2 groups: Group 1 - late EF > 35%; Group 2 - late EF ≤ 35%.
Results: In the study cohort, the late EF was 41 ± 10%. In Group 1, early infarct size was significantly lower (17.1 ± 8.5% vs. 35.2 ± 8.2%, p < 0.001), and early EF was higher (43.7 ± 8.6% vs. 30.5 ± 6.5%, p < 0.001) compared to Group 2. Multivariate analysis demonstrated that infarct size was the only independent predictor of late EF ≤ 35% after controlling for early EF (OR 1.29 per % change, 95% CI 1.05 to 1.58, p = 0.02). Area under the ROC curve for early infarct size to predict late EF > or ≤ 35% was 0.94 ± 0.03. An infarct size > 34% was found to be 100% specific for the prediction of late EF ≤ 35%. Additionally, a subgroup of 20 patients with an early EF > 35% was identified to evaluate infarct size as a predictor of a long-term decrease in EF. Among these patients, 10 had persistent late EF ≤ 35%. Of the remaining 10 patients with late EF > 35%, none had an infarct size > 34% (Figure⇓).
Conclusion: Infarct size as determined by CMR immediately post-MI is a powerful predictor of late EF. As late EF ≤ 35% is the currently accepted criterion for ICD implantation, it is possible that early infarct size by CMR can identify patients who will benefit from an ICD early post-MI.