Late gadolinium enhancement dispersion mapping predicts major arrhythmic events in patients with prior myocardial infarction.

BACKGROUND

Myocardial scar heterogeneity is a key determinant of ventricular arrhythmias after myocardial infarction (MI). Late gadolinium enhancement dispersion mapping (LGE-DM) quantifies structural complexity, but its prognostic role in ischemic cardiomyopathy remains unevaluated.

METHODS

We retrospectively included 364 consecutive patients with prior MI (>90 days). For each LGE image, a parametric map was generated and each enhanced pixel scored (0-8) based on surrounding signal distribution; the global dispersion score (GDS) was calculated as the mean pixel score, quantifying pixel-to-pixel heterogeneity. The endpoint was a composite of sudden cardiac death (SCD), resuscitated cardiac arrest, sustained ventricular tachycardia, or appropriate ICD therapies.

RESULTS

During a median follow-up of 4 years, 42 arrhythmic events occurred. Patients with events showed significantly higher GDS than event-free patients (0.53 vs 0.32, P < 0.0001). Multivariable Cox regression confirmed GDS as an independent predictor (HR 1.16 per 0.1-unit increase, 95% CI 1.03-1.29), while LVEF and LGE extent were not, and GDS remained independently associated with events when LGE extent was forced into the model (HR 1.12 per 0.1-unit increase, P = 0.005). In patients with LVEF >35%, GDS was the only independent predictor across all multivariable models. Harrell's C-index was 0.682, with an optimism of 0.012 on bootstrap resampling. ROC analysis identified GDS >0.5 as a provisional cut-off derived within the same cohort (apparent AUC 0.74 overall; 0.81 in the LVEF >35% subgroup). Kaplan-Meier analysis confirmed worse prognosis in patients with GDS >0.5 (overall: p = 0.0002; LVEF >35%: p < 0.0001).

CONCLUSIONS

LGE dispersion independently predicts malignant ventricular arrhythmias post-MI, outperforming LGE extent and LVEF. GDS may improve SCD risk stratification particularly in patients with LVEF >35%, a population not adequately targeted by current LVEF-based criteria. External validation is required before the proposed threshold can be used clinically.