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B-PO02-129 AN EFFICIENT WORKFLOW TO INCREASE THE PRECISION OF NONINVASIVE RADIO-ABLATION OF VENTRICULAR TACHYCARDIA USING COMPUTERIZED ECG MAPPING AND RESPIRATORY GATING

      Background

      Non-invasive stereotactic radiotherapy (SAbR) is an emerging therapy for refractory ventricular tachycardia. However, the precision of SAbR may be limited by respiratory motion, and the current workflow is time intensive.

      Objective

      We hypothesized that a strategy combining computerized 12-lead ECG mapping and respiratory-gated therapy may improve the efficiency and precision of SAbR and increase safety in inferior wall targets near the stomach.

      Methods

      Patients with refractory VT were retrospectively studied at 2 hospitals. VT exit sites were localized in 3D using a simulation-based computational ECG algorithm. Respiratory gated therapy was performed at end-expiration when respiratory motion ≥0.6 cm.

      Results

      In 6 patients (EF 29±13%), 4.2±2.3 VT morphologies/patient were mapped non-invasively; 100% of ECG-mapped sites colocalized to the same cardiac segment when compared with prior invasive mapping when available, requiring less time (33±12 vs 392±107 min, p<0.01). Respiratory gating correlated with smaller planning target volumes compared to non-gated patients (71±7 vs 153±35 cc, p<0.01). 2 patients had inferior wall targets close to the stomach (within 6mm) and had large respiratory motion (spanning 22mm), but no GI complications occurred with respiratory gating. ICD shocks decreased from 23±12 shocks/patient to 0.67±1.0 post-SAbR at 6±5 months follow-up (p<0.001, 97% relative reduction).

      Conclusion

      A novel non-invasive mapping and gating strategy improved workflow efficiency and significantly reduced ICD shocks. Protocol-guided use of respiratory gating delivered precise and safe therapy in patients with targets close to the stomach.
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