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

Acutely infarcted native T1 (native T1_AI) and extracellular volume (ECV_AI) 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.

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 T1_AI, ECV_AI, 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.

In acute scan, 37 patients (66.07 %) had microvascular obstruction (MVO). The native T1_AI 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, ECV_AI 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 T1_AI only correlated with △EDV in patients without MVO (r_mvo- = 0.495, P = 0.031); while ECV_AI was associated with △EDV in all patients (r_mvo- = 0.665, P =  0.002; r_mvo+ = 0.506, P =  0.001; r_{all patients} = 0.570, P <  0.001). Furthermore, ECV_AI was independently associated with LV remodeling in multivariable linear regression analysis (β = 0.490, P =  0.002).

As a promising parameter for early risk stratification after AMI, ECV_AI is associated with LV remodeling during follow-up; while native T1_AI may be feasible when MVO is absent.