Automated Extracellular Volume Fraction Mapping Provides Insights Into the Pathophysiology of Left Ventricular Remodeling Post–Reperfused ST‐Elevation Myocardial Infarction

BACKGROUND: Whether the remote myocardium of reperfused ST‐segment elevation myocardial infarction (STEMI) patients plays a part in adverse left ventricular (LV) remodeling remains unclear. We aimed to use automated extracellular volume fraction (ECV) mapping to investigate whether changes in the ECV of the remote (ECV(R) (emote)) and infarcted myocardium (ECV(I) (nfarct)) impacted LV remodeling. METHODS AND RESULTS: Forty‐eight of 50 prospectively recruited reperfused STEMI patients completed a cardiovascular magnetic resonance at 4±2 days and 40 had a follow‐up scan at 5±2 months. Twenty healthy volunteers served as controls. Mean segmental values for native T1, T2, and ECV were obtained. Adverse LV remodeling was defined as ≥20% increase in LV end‐diastolic volume. ECV(R) (emote) was higher on the acute scan when compared to control (27.9±2.1% vs 26.4±2.1%; P=0.01). Eight patients developed adverse LV remodeling and had higher ECV(R) (emote) acutely (29.5±1.4% vs 27.4±2.0%; P=0.01) and remained higher at follow‐up (28.6±1.5% vs 26.6±2.1%; P=0.02) compared to those without. Patients with a higher ECV(R) (emote) and a lower myocardial salvage index (MSI) acutely were significantly associated with adverse LV remodeling, independent of T1(Remote), T1(Core) and microvascular obstruction, whereas a higher ECV(I) (nfarct) was significantly associated with worse wall motion recovery. CONCLUSIONS: ECV(R) (emote) was increased acutely in reperfused STEMI patients. Those with adverse LV remodeling had higher ECV(R) (emote) acutely, and this remained higher at follow‐up than those without adverse LV remodeling. A higher ECV(R) (emote) and a lower MSI acutely were significantly associated with adverse LV remodeling whereas segments with higher ECV(I) (nfarct) were less likely to recover wall motion.