PO-687-03 TRANSIENT DYSFUNCTION OF CARDIAC RESYNCHRONIZATION THERAPY DEFIBRILLATOR SYSTEM FOLLOWING CARDIAC RADIATION ABLATION

Abstract

Cardiac Radiation Ablation (CRA) for reducing recurrent Ventricular Tachycardia (VT) that is refractory to conventional treatment is an emerging therapy. There is little data regarding effects of CRA on cardiac implanted electronic devices (CIED). Established guidelines related to CIEDs in radiation therapy may not be appropriate for CRA. To report incidence of transient CIED dysfunction during and after CRA despite adherence to established radiation therapy guidelines. N/A A 72 year old man with history of ischemic cardiomyopathy, CRT-D, and recurrent, symptomatic ventricular tachycardia refractory to multiple catheter ablation procedures presented for CRA. Multimodality evaluation for determination of CRA target volume included electranamatomic mapping from catheter ablation procedures, non-invasive programmed stimulation with noninvasive ECGi mapping (CardioInsight, Medtronic, Inc.), cardiac MRI, and 4DCT. A radiation treatment plan delivering 2500 cGy to a basal, inferior left ventricular target. The minimum field edge to CIED was ∼5 cm. The patient underwent CRA with arms raised over his head, a magnet and dosimeter which measured 8.5 cGy during CRA (200 cGy recommended limit) over his CRT-D, and abdominal compression. During the final minutes of CRA, the heart rate elevated from 60bpm to 70bpm, and the patient developed palpitations that were determined to be new phrenic nerve stimulation with LV lead position stability confirmed on CXR. Pacing rate change was determined on interrogation of Biotronik CRT-D be due to device reset, and new phrenic nerve capture, and elevated myocardial pacing threshold were noted at the two basal electrodes on the quadripolar LV lead. Both phrenic capture and threshold elevation were resolved on post-CRA day #1. To our knowledge, this is the first known occurrence of CIED reset and acute changes in pacing parameters related to CRA. The CIED soft reset was most likely due to a neutron interaction from CRA. The etiology of acute changes in pacing parameters remains unclear. Close monitoring of CIEDs during and after CRA is advisable.