Short- Versus Long-Term Recurrence of Ventricular Tachycardia in Non-Ischemic Cardiomyopathy: is It Due to Incomplete Ablation During the Index Procedure or Progression of the Disease? Results from a Single-Center Study

Background: Non-ischemic cardiomyopathies (NICM) occur in the absence of contributory coronary artery disease or significant valvular heart disease. This study examined if VT recurrence post-scar-homogenization in NICM patients was due to progression of the disease after successful ablation or incomplete ablation during the index procedure. Methods: Consecutive NICM patients receiving redo procedure after their 1st VT ablation were included. All patients underwent bipolar substrate mapping with standard scar settings of normal tissue >1.5 mV and severe scar <0.5 mV. Endocardial scar homogenization was followed by heparin reversal with protamine and subsequent epicardial ablation. Disease progression was defined as extension of index scar area or appearance of new scar and decline in the baseline left ventricular ejection fraction (LVEF). Incomplete ablation was described as ablation within the index scar area that was ablated in the earlier procedure. Recurrence within 12 months was considered as early recurrence . Results: A total of 310 NICM patients (age: 60±13.5 years; male: 231 (74%); LVEF: 37±11%) undergoing their first VT ablation procedure were followed up for 7 years, of which 38 (12.2%) experienced recurrence and underwent re-ablation. Of the 38, 13 received repeat ablation at 5.07±2.56 months ( early recurrence ) and the remaining 25 patients had the redo at 40±21.78 months ( late recurrence ). In these 38 patients, mean LVEF was significantly lower at redo (pre-index: 35.3±10.6; pre-redo: 30.2± 7.07%, p=0.015). In the early-recurrence group , 10 (77%) had ablation sites located within the index scar (incomplete ablation) and 3 (33%) had extension of the index scar area (disease progression) detected. Index scars were mostly mid-myocardial (11, 84.6%). In the late-recurrence cohort , extension of the index scar area was detected in 12 (48%) and new scar were mapped in 19 (76%); none of these patients had incomplete ablation noted. Conclusion: In NICM patients, VT recurrence within 1-year of index procedure was mostly associated with incomplete ablation of mid-myocardial scars, whereas disease progression evidenced by detection of new scar, extension of preexisting scar and decline in LVEF was prevalent in patients with very late recurrence.