LAUSR

BACKGROUND Predicting sudden cardiac death risk in the first months after ST-segment elevation myocardial infarction (STEMI) remains challenging. OBJECTIVE The purpose of this study was to investigate the ability of late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) to identify the potentially arrhythmogenic substrate and its temporal evolution after STEMI. METHODS One hundred consecutive patients with a first STEMI were included. Three-dimensional high-resolution LGE-CMR was obtained at 3 T on days 7 and 180. Left ventricular wall was segmented and characterized by pixel signal intensity algorithm in 5 layers from endocardium to epicardium. A 3-dimensional color-coded shell map was obtained for each layer, depicting scar core and border zone (BZ) distribution. Presence and characteristics of BZ channels were registered for each layer. RESULTS At 180 days, left ventricular ejection fraction had improved significantly (from 46.7% ± 10% to 51.5% ± 10%; P <.001) and scar mass was reduced (from 22.6 ± 20 g to 13.8 ± 12 g; P <.001). Most BZ channels (89%) were identified in the same myocardial layer and American Heart Association (AHA) segment, with the same orientation and morphology in both studies. Early LGE-CMR had 96% sensitivity and 90% specificity for predicting presence of BZ channels at 180 days. Greater presence was observed in patients with no-reflow phenomenon at baseline (P = .01). CONCLUSION Most BZ channels can be identified by LGE-CMR at day 7 post-STEMI and, despite scar mass reduction, remain unaltered at 6 months, suggesting that the potentially arrhythmogenic substrate is established within the first week post-STEMI.