Subendocardium-involved late gadolinium enhancement in non-ischemic dilated cardiomyopathy improves risk stratification of sudden cardiac death

The prognostic value of late gadolinium enhancement (LGE) phenotypes-particularly subendocardial involvement-for sudden cardiac death (SCD) remains unclear in dilated cardiomyopathy (DCM). Whether LGE phenotype integrating pattern and location can improve SCD risk stratification is an unmet need.

DCM patients who underwent cardiac MRI were retrospectively enrolled. The endpoint was a composite of SCD and surrogate SCD events. Among 902 patients (mean age 46 ± 14 years, 78.7% men), subendocardium-involved and mid-wall LGE were observed in 129 (14.3%) and 263 (29.1%) patients, predominantly involving the lateral (65.1%) and septal wall (97.7%), respectively. During a median follow-up of 77 months (IQR 40–92 months), 51 (5.7%) patients experienced SCD events. Multivariable analysis identified septal mid-wall LGE (HR 3.59; 95% CI 1.73–7.47; P = 0.001) and lateral subendocardium-involved LGE (HR 3.07; 95% CI 1.39–6.75; P = 0.005) as independent predictors. A three-tier risk stratification model was developed, classifying patients into: lowest risk (neither septal mid-wall nor lateral subendocardium-involved LGE; reference), intermediate risk (either phenotype alone; HR 4.8, 95% CI 2.2–10.46, P < 0.001), and highest risk (both phenotypes; HR 10.71, 95% CI 3.53–32.46, P < 0.001). The model showed the best improvement in model discrimination and reclassification over left ventricular ejection fraction (C-statistic improvement: 0.23; net reclassification improvement = 0.67; integrative discrimination index = 0.27; all P < 0.05).

SCD was predicted by both lateral subendocardium-involved LGE and septal mid-wall LGE in DCM. The novel SCD risk model integrating these phenotypes demonstrated superior prognostic performance compared with conventional prognosticators.