PO-04-231 THERAPIES DELIVERED BEFORE AND AFTER NONINVASIVE CARDIAC RADIOABLATION: A SECONDARY ANALYSIS OF THE ENCORE-VT TRIAL

Noninvasive Cardiac RadioAblation (CRA) is a new therapy for refractory ventricular tachycardia (VT) that delivers focused radiation to VT-related myocardial scar. Because CRA reduced VT events, we hypothesize therapies will be reduced. To compare type and number of therapies delivered before and after cardiac radioablation in patients with scar-based VT. This was a retrospective analysis of ICD interrogations from the ENCORE-VT trial (NCT02919618), where patients with high-burden of VT were treated with 25 Gray/1 fraction to myocardial scar nearest the VT exit site. For each patient, all device-identified VT episodes which required therapy were reviewed for the 6-month period prior to CRA and 6-month period after (excluding 6-week blanking period). Episodes of non-sustained VT, non-treated VT, or VF were excluded. Type and number of therapies derived from device review were used for primary comparison. Of the 19 patients enrolled into the trial, 16 were included for analysis (excluded 2 patients treated for PVCs, 1 patient death in first 6 months). Cohort analysis (Top Figure) using Student’s t-test showed statistically significant reduction in VT episodes (P 0.0006) and antitachycardia pacing (ATP) therapies (P 0.0004) post therapy and a greater than 78% reduction in shocks. Compared to pre-treatment (Bottom Figure), by percentage, ATP terminated VT more often post-treatment with two or fewer sequences. Three of more ATP sequences were seen, by percentage, more often pre-treatment as compared to post-treatment. Compared to before cardiac radioablation, episodes of VT and number of therapies for VT were significantly reduced. In addition, when VT did recur post-treatment, it was more susceptible to termination by two or fewer ATP sequences.