PROGNOSTIC VALUE OF NON-INDUCIBILITY ON OUTCOMES OF VENTRICULAR TACHYCARDIA ABLATION: A VENTRICULAR TACHYCARDIA ABLATION VS. ENHANCED DRUG THERAPY IN STRUCTURAL HEART DISEASE (VANISH) SUBSTUDY

Abstract

The traditional endpoint of VT ablation is non-inducibility of VT by programmed electrical stimulation (PES); however, the definition of inducibility remains variable and its prognostic value has been muddied by alterations in peri-ablation antiarrhythmic drug (AAD) therapy or non-standardized ICD programming in prior observational studies. The VANISH trial randomized ischemic VT patients to VT ablation (with endpoint of non-inducibility of VT >=300ms after ablation) vs. AAD escalation. We proposed to determine the predictive value of non-inducibility on long-term clinical outcomes, adjusting for other clinical and procedural characteristics. The relationship of inducibility on the primary composite endpoint of death, VT storm > 30 days, or appropriate ICD shock > 30 days, was assessed using a time-to-event analysis. Survival rates were summarized between inducibility groups using Kaplan-Meier product-limit estimates. Results were analyzed according to presence of inducible VT (defined as inducibility post ablation of any VT – including those < 300ms) vs. non-inducible or inducibility not performed. Polymorphic VT or VF were not considered to be inducible. 129 patients from the ablation arm were included in the primary analysis of which 51 were non-inducible post ablation as compared to 78 who were inducible or where inducibility was not performed. At baseline, there was no significant characteristic or procedural differences between the non-inducible vs inducible/not performed cohorts except for an increased number of ICD shocks within 3 months observed in the latter group. There were no baseline characteristics that were shown to be significantly predictive of inducibility. In multivariate analysis, inducibility was associated with an increase in the primary endpoint of death, appropriate shock or VT storm after 30 days (HR 1.87, 95% CI 1.12, 3.11, P = 0.017). Inducibility of any VT post ablation was associated with an increased risk of the composite outcome in the VANISH Trial. No patient or procedural characteristics were shown to be significantly predictive of inducibility. A randomized trial targeting faster induced VTs may determine whether a more aggressive strategy can improve outcomes.