Clifford Robinson, MD
Washington University in Saint Louis
Washington University in St Louis : Assistant Professor : Employee
Astra Zeneca : Consultant; DFINE : Speaker's Bureau : Travel Expenses; Elekta : Research Grants; EMD Serono : Consultant; Radialogica : Advisory Board; Varian Medical Systems : Research Grants : Speaker's Bureau : Travel Expenses
Radialogica : Stock Options
Materials/Methods: Arrhythmogenic scar regions were targeted by combining noninvasive anatomic and electric cardiac imaging with a standard stereotactic body radiation therapy workflow followed by delivery of a single fraction of 25 Gy to the target. SAEs were defined as CTCAE v4.0 grade 3-5 events that were possibly, probably, or definitely related to treatment. Efficacy was tracked using indwelling implantable cardioverter defibrillators or 24-hour PVC burden (as measured by Holter monitor) comparing the 6 months before treatment to 6-month intervals after treatment.
Results: 19 patients underwent treatment. Median follow-up of living patients is 24.1 months (range, 12.8-28.8). One and 2-year OS was 72% and 58%. Eight deaths have been recorded to date: 1 unrelated (pancreatitis), 3 unlikely (accident, amiodarone toxicity, VT recurrence), and 4 possible (2 heart failure, 2 VT recurrence). Additional probably or definitely related late (>6 month) SAEs included a grade 3 pericardial effusion at 2.2 years and a grade 4 gastropericardial fistula at 2.4 years requiring surgical repair.
The group experienced a median of 119 vs. 3 vs. 2 VT episodes in the 6 months before treatment vs. 0-6 months vs. 6-12 months after treatment. 17/18 evaluable patients had a reduction in VT (mean 94% reduction in total VT burden compared to baseline) in the first 6 months. 16/18 patients had a persistent reduction in VT during the next 6 months (mean 84% reduction in total VT burden compared to baseline).
Conclusion: Noninvasive electrophysiology-guided cardiac radioablation in high risk refractory ventricular arrythmia is associated with markedly reduced burden that largely persisted through the first year. Two SAEs probably or definitely related to treatment were observed > 2 years after treatment. Vigilant long-term follow-up will define the full safety profile of this novel therapy.