Association of septal late gadolinium enhancement on cardiac magnetic resonance with ventricular tachycardia ablation targets in nonischemic cardiomyopathy

BACKGROUND Ablation of septal substrate-associated ventricular tachycardia (VT) in patients with nonischemic cardiomyopathy (NICM) is challenging. We sought to standardize the characterization of septal substrates on late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) and to examine the association of that substrate with VT exit and isthmus sites on invasive mapping. METHODS LGE-CMR was performed before electroanatomic mapping and ablation for VT in 20 NICM patients. LGE extent and distribution were quantified using myocardial signal-intensity Z scores (SI-Z). The SI-Z thresholds correlating to previously validated voltage thresholds, for abnormal tissue and dense scar were defined. RESULTS Bipolar and unipolar (electrogram) voltage amplitude measurements from the LV and RV were negatively associated with SI-Z from LGE-CMR imaging (p