Abstract Body (Do not enter title and authors here): Background: Patients with non-ischemic dilated cardiomyopathy (NIDCM) and ventricular tachycardia (VT) typically have a basal perivalvular substrate with predominant antero-septal or infero-lateral distribution. Isolated apical substrate responsible for VT in NIDCM has not been previously characterized.
Objectives: The purpose of this study is to characterize the prevalence, characteristics and catheter ablation outcomes of NIDCM with isolated apical VT substrate.
Methods: Patients with NIDCM and VT from an isolated apical scar were identified from a prospective registry of consecutive patients with NIDCM undergoing VT ablation between 2018 and 2023. Isolated apical scar was defined as apical abnormal bipolar low voltage area (LVA, <1.5 mV for the endocardium, <1.0 mV for the epicardium with abnormal electrograms) demonstrated to participate in VT with activation, entrainment and/or pace mapping in the absence of abnormal electroanatomic substrate in other LV segments. Patients with hypertrophic cardiomyopathy were excluded.
Results: Out of 208 patients with NIDCM and VT undergoing catheter ablation during the study period, 5 (2.4%; age 52±10 years, LVEF 37±12%) had isolated apical substrate and underwent a total of 8 ablation procedures (2 endocardial, 6 endo-epicardial). One patient had isolated apical scar on pre-procedural cardiac MRI. All patients had both endocardial and epicardial scar identified. At the end of the procedure, non-inducibility of any VTs was achieved in all cases. After a median follow-up of 11 months (range 6-14 months) after the last procedure, there were no deaths and all patients remained free from recurrent VT.
Conclusion: In patients with NIDCM, isolated apical VT substrate is rare. Endo-epicardial catheter ablation is typically needed in these patients and is associated with good VT control over follow-up.