Characterization of infarcted myocardium by T1-mapping and its association with left ventricular remodeling.

PURPOSE Acutely infarcted native T1 (native T1AI) and extracellular volume (ECVAI) could quantify myocardial injury after acute myocardial infarction (AMI). Therefore, we sought to further explore their association with left ventricular (LV) remodeling during follow-up. METHODS 56 ST-segment-elevation MI patients were prospectively recruited and completed acute and 3-month cardiac magnetic resonance scans. T1 mapping, late gadolinium enhancement and cine imaging were performed to measure native T1AI, ECVAI, infarct size and LV global function, respectively. LV remodeling was evaluated as the change in LV end-diastolic volume index (△EDV) at follow-up scan compared with baseline. RESULTS In acute scan, 37 patients (66.07 %) had microvascular obstruction (MVO). The native T1AI did not significantly differ between patients with or without MVO (1482.0 ± 80.6 ms vs. 1469.0 ± 71.6 ms, P =  0.541). However, ECVAI in patients without MVO was lower than that in patients with MVO (49.60 ± 8.57 % vs. 58.53 ± 8.62 %, P = 0.001). The native T1AI only correlated with △EDV in patients without MVO (rmvo- = 0.495, P = 0.031); while ECVAI was associated with △EDV in all patients (rmvo- = 0.665, P =  0.002; rmvo+ = 0.506, P =  0.001; rall patients = 0.570, P <  0.001). Furthermore, ECVAI was independently associated with LV remodeling in multivariable linear regression analysis (β = 0.490, P =  0.002). CONCLUSION As a promising parameter for early risk stratification after AMI, ECVAI is associated with LV remodeling during follow-up; while native T1AI may be feasible when MVO is absent.