Border zone channel mass predicts ventricular arrhythmias independently of LVEF in ICD patients
J Lubian Esplugues, E Silva Garcia, A Del Rio Lechuga, F Camacho Jurado, R Toro Cebada, M Alba Sachez, M J Tey Aguilera, M Urgiles Ortiz, M Garcia Garcia, A Villar Ruiz, M Herruzo Rojas, J Fernandez-ArmentaAbstract
Background
Left ventricular ejection fraction (LVEF) remains the cornerstone for implantable cardioverter-defibrillator (ICD) selection, despite limited arrhythmic specificity. Cardiac magnetic resonance (CMR) enables detailed scar characterization, including border zone (BZ) tissue and conducting channels within dense scar. We evaluated whether BZ and channel mass predict ventricular arrhythmias independently of LVEF and explored mediation and interaction effects.
Methods
We conducted an observational study of 168 ICD recipients undergoing pre-implant CMR with quantitative scar analysis. BZ and channel mass were quantified using standardized post-processing (ADAS3D) (Figure 1). The primary endpoint was appropriate ICD therapy. Cox regression assessed associations between scar metrics and outcomes. LVEF adjustment evaluated mediation, and interaction terms tested effect modification by LVEF.
Results
Among 168 patients (60±12 years; 81% male; 46% ischemic; LVEF 38±17%), 31 (18%) experienced appropriate ICD therapy during a median follow-up of 34 months. BZ mass (HR 1.017, 95% CI 1.000–1.033; p=0.046) and channel mass (HR 1.063, 95% CI 1.011–1.118; p=0.016) were significantly associated with appropriate ICD therapy, whereas LVEF was not (HR 0.997, 95% CI 0.977–1.018; p=0.799). Although both scar metrics correlated inversely with LVEF, adjustment for LVEF did not attenuate their hazard ratios, indicating no evidence of mediation. A significant interaction was observed between channel mass and LVEF (p=0.030) (Table 1). Channel mass was strongly associated with arrhythmic events in patients with LVEF ≤30% (HR 1.16, 95% CI 1.07–1.25; p<0.001), and this association was significantly modified by LVEF (p for interaction=0.019).
Conclusions
Channel mass independently predicts ventricular arrhythmias. LVEF does not mediate this association but modifies its magnitude, underscoring scar architecture as a key arrhythmic risk marker beyond systolic function.