Inflammation in Remote Myocardium and Left Ventricular Remodeling After Acute Myocardial Infarction: A Pilot Study Using T2 Mapping.

BACKGROUND The pathophysiological changes in the remote myocardium after acute myocardial infarction (MI) remains less understood. PURPOSE To assess the inflammation in the remote myocardium post-MI and its association with left ventricular (LV) remodeling using T2 mapping. STUDY TYPE Prospective. ANIMAL MODEL AND SUBJECTS Twelve pigs at 3-day post-MI, 6 pigs at 3-month post-MI, 6 healthy pigs; 54 patients at 3-day and 3-month post-MI, 31 healthy volunteers; FIELD STRENGTH/SEQUENCE: A 3 T MRI/ steady-state free-precession sequence for T2 mapping (animals: 0, 30, and 55 msec; human: 0, 25, and 55 msec), phase-sensitive inversion recovery gradient echo for late gadolinium enhancement (LGE), balanced steady free-precession sequence for cine. ASSESSMENT Infarcted myocardium was defined on LGE, remote T2 was measured on T2 maps. LV remodeling was evaluated as LV end-diastolic volume change index between two scans using cine. CD68 staining was conducted to detect monocyte/macrophage. STATISTICAL TESTS Student-t test and one-way ANOVA were used to compare remote T2 with normal controls. The association of remote T2 with LV remodeling was assessed using linear regression. P values of <0.05 were used to denote statistical significance. RESULTS Compared with healthy pigs, remote T2 significantly increased from 3 days to 3 months post-MI (31.43 ± 0.67 vs. 33.53 ± 1.15 vs. 36.43 ± 1.07 msec). CD68 staining demonstrated the inflammation in remote myocardium post-MI but not in healthy pigs. Significant remote myocardial alterations in T2 were also observed in human group (40.51 ± 1.79 vs. 41.94 ± 1.14 vs. 42.52 ± 1.71 msec). In patients, the 3-month remote T2 (β = 0.432) and remote T2 variation between two scans (β = 0.554) were both independently associated with LV remodeling. CONCLUSION T2 mapping could characterize the abnormalities in the remote myocardium post-MI, which was potentially caused by the inflammatory response. Moreover, variations in remote T2 were associated with LV remodeling. EVIDENCE LEVEL 1 TECHNICAL EFFICACY: Stage 3.