Cardiac magnetic resonance-based prediction of ventricular arrhythmias events in non-ischemic cardiomyopathy: the international, multicenter IMPROVE-NICM study
A C Latini, G Falasconi, C Panico, S Figliozzi, J Acosta, J Armenta, M Ciabatti, E Bertella, M Merlo, F Ricci, M Tritto, A Berruezo, D PenelaAbstract
Background
Risk stratification for sudden cardiac death (SCD) in non-ischemic cardiomyopathy (NICM) remains challenging. Current guidelines recommend a prophylactic implantable cardioverter-defibrillator (ICD) for patients with LVEF <35% (NYHA II–III) (1), but this criterion inadequately predicts arrhythmic risk, since only a minority of ICD carriers receive appropriate therapy (2), while a subset of patients with LVEF >35% experience VAs while unprotected (3). Cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) assessment has gained as a key role in SCD risk stratification, with LGE presence, extent, and location showing adjunctive prognostic value (4-6). LGE-CMR post-processing further enables fibrosis characterization by identifying scar components such as border zone (BZ), core, and BZ channels.
Purpose
To evaluate scar composition as a predictor of VAs beyond traditional risk factors. We hypothesize that the composite arrhythmic outcome of SCD, sustained VAs or appropriate ICD therapy will be higher in those patients with higher number of BZ channels and greater BZ channel mass.
Methods
We conducted a retrospective analysis of a prospectively collected and followed-up cohort of patients with NICM who underwent LGE-CMR, independently of baseline LVEF. First LGE-CMR date accounted for inclusion date. Patients were followed up until occurrence of the composite arrhythmic outcome, death or end of the study, whichever came first. NICM patients with dilated cardiomyopathy, non-dilated left ventricle cardiomyopathy or myocarditis diagnosis were included. Exclusion criteria comprised: i) VAs occurrence before study enrolment; ii) presence of a concomitant or alternative diagnosis of structural heart disease; iii) LGE-CMR not suitable for post-processing due to insufficient image quality.
Results
495 patients (aged 55.8 ± 15.12 years, 67.8% males) were referred to LGE-CMR between February 2016 and September 2025 at 8 centres. During follow-up (25.66 (IQR 9.22-56.20) months) 37 (7.47%) patients experienced the primary outcome. Total scar, core scar, BZ scar and BZ channel scar mass were significantly higher as compared to patients without VAs occurrence (p<0.001). Among scar characteristics, BZ channel mass presence (with a cut-off of 0.81 g) best predicted sustained VAs (AUC 0.83, 95% CI 0.76-0.90), outperforming symptomatic LV disfunction (AUC 0.54 95% CI 45-0.62) and septal LGE presence (AUC 0.69 95% CI 0-60-0.78) in arrhythmic risk stratification accuracy. Patients with BZ channel mass presence as defined above had significantly increased risk of experiencing the outcome (HR 19.11, 95% CI 7.38-49.46, p-value <0.0001).
Conclusions
Among patients with NICM, scar composition, particularly BZ channel mass presence, shows significant, independent prognostic value for sustained VAs occurrence, outperforming existing risk stratification tools.Time-to-event comparisonROC curve comparison