Abstract 4088: Isolated Potentials and Pace-Mapping to Guide Ablation for Ventricular Tachycardia in Patients with Non-Ischemic Cardiomyopathy
Background: Isolated potentials (IPs) during sinus rhythm are indicators of fixed scar in patients with prior infarcts. IPs in conjunction with pace-mapping (PM) have been helpful to guide ablation of post-infarction ventricular tachycardia (VT). The purpose of this study was to determine the value of IPs in conjunction with PM to guide VT ablation in patients with non-ischemic cardiomyopathy.
Methods: 32 consecutive patients (23 male, age 56±13 years, ejection fraction 0.30±0.14) with VT and non-ischemic cardiomyopathy were analyzed. Thirty/32 patients had an implanted cardioverter defibrillator (ICD). Electroanatomic maps of the left (n=21) and right ventricle (n=13), the coronary sinus (n=3), and the epicardium (n=4) were obtained during baseline rhythm. PM was performed at sites with low voltage (<1.5mV). Radiofrequency energy was delivered at sites with concealed entrainment or matching pace-maps. Mean follow-up time was 10±9 months.
Results: 173 VTs (cycle length 359±86 ms) were induced. Appropriate ablation sites with IPs during sinus rhythm were recorded in 19/32 patients (59%) (group A). In these patients, a total of 195 appropriate target sites were identified for 56/100 induced VTs (56%); 136/195 sites (70%) displayed IPs. In the remaining 13 patients, no target sites with IPs were identified (group B) despite combined endocardial and transcutaneous epicardial mapping in 3/13 patients. In these 13 patients, a total of 96 appropriate target sites were identified for 25/73 induced VTs (34%). Fifteen/19 patients (79%) in group A were non-inducible at the end of the procedure compared to 2/13 patients (15%) in group B. During a mean follow-up of 10±9 months, 15/19 patients (79%) in group A compared to 1/13 patients (8%) in group B remained arrhythmia free (p=0.0002).
Conclusion: IPs in conjunction with PM are helpful in identifying critical isthmus areas for ablation of VT in patients with non-ischemic cardiomyopathy. Differences in the extent of fixed scar tissue may be the reason for differences in the prevalence of IPs, and this might explain better ablation results in some patients with non-ischemic cardiomyopathy.