ETD

• cardiac magnetic resonance
• ischemic cardiomyopathy
• late gadolinium enhancement
• ventricular arrhythmias

BACKGROUND: Myocardial fibrosis is the pathological substrate of arrhythmic events in cardiomyopathy. Cardiac Magnetic Resonance (CMR), particularly Late Gadolinium Enhancement (LGE), is the standard for cardiac scar characterization. A novel post-processing tool, LGE Dispersion Mapping (LGE-DM), quantifies scar heterogeneity through the Global Dispersion Score (GDS).
METHODS: We evaluated 364 patients with prior myocardial infarction (>90 days): 153 with left ventricle ejection fraction (LVEF) ≤35% and 211 with LVEF >35%. For each LGE image, a parametric map was generated, and each enhancing pixel was scored (0–8) based on the surrounding signal distribution; the GDS was calculated as the mean score of all pixels.
RESULTS: During a median follow-up of 4 years (range 2–6), 42 patients experienced major arrhythmic events. The median LGE extent was 15% of LV mass (IQR 7–28%). Kaplan–Meier analysis showed that patients with GDS >0.5 had significantly worse outcomes both in the total cohort and in the LVEF >35% subgroup (Log-Rank P<0.001). In multivariate analysis, GDS >0.5 independently predicted arrhythmic events in both the total cohort (HR 14.7, 95% CI 1.6–134, P=0.001) and the LVEF >35% subgroup (HR 70, 95% CI 2.3–213, P=0.01).
CONCLUSIONS: GDS is a quantitative marker of ischemic scar heterogeneity that identifies patients at higher risk of malignant arrhythmic events, independently of LVEF and LGE extent.