B-PO02-124 NONISCHEMIC LEFT VENTRICULAR CARDIOMYOPATHY WITH PRESERVED LEFT VENTRICULAR FUNCTION: A TYPE OF ARRHYTHMOGENIC CARDIOMYOPATHY

Abstract

Ventricular tachycardia (VT) may occur in nonischemic cardiomyopathy (NICM) even when left ventricular (LV) systolic function is relatively preserved. The underlying substrate and response to ablation for these subjects are not well characterized. Describe ventricular substrate and ablation outcomes in NICM patients with sustained VT and relatively preserved LV function. Consecutive NICM patients undergoing ablation of LV VTs were reviewed. Those with arrhythmogenic right ventricular cardiomyopathy, cardiac sarcoidosis or only right ventricular VTs were excluded. Of 82 patients (63±14 years, LV ejection fraction [LVEF] 35±14%) , 20 (24%) had LVEF >45%. Of these, pathogenic gene mutations were identified in 7 (LMNA [3], TTN [1], DSP [2], CRYAB [1]). Low bipolar or unipolar was observed in relatively small areas (median 19 cm2) with a predilection for the basal septum and inferolateral epicardial regions (Figure). Ablation was acutely successful in 80% of patients, though 6 (30%) required advanced ablation techniques (needle ablation in 4, simultaneous unipolar ablation in 2) for presumed deep intramural substrate. VT storm was eliminated in 5 of 6 patients. At a median follow-up of 7.4 months, 7 (35%) patients had VT recurrence. The VT recurrence rate was similar to NICM patients with LVEF≤45% (log-rank p = 0.70). LV VT in patients with NICM and LVEF >45% is associated with small areas of scar and can have a genetic cause. The VT substrate is often intramural and difficult to ablate, with recurrence rates comparable to patients with LVEF < 45%.