5209Stereotactic radioablation of ventricular tachycardia guided by direct integration of 3D electroanatomic mapping: development and validation of a new method

Abstract

Abstract Background Stereotactic body radiotherapy (SBRT) has emerged as a promising bailout therapy for recurrent ventricular tachycardia (VT) in patients with failed radiofrequency catheter ablation. However, SBRT can function only if the ablation target is precisely identified. Purpose We sought to develop a novel method for direct integration of electroanatomic mapping (EAM) data to an SBRT work station for radioablation of VT. Methods Candidates for SBRT were patients with recurrent, drug-resistant VT who underwent ≥2 previous radiofrequency catheter ablations (CARTO 3, Biosense-Webster, Diamond Barr, CA) and continued to have inducible clinical VT or clinical recurrences of VT. At the end of the last catheter ablation, the operators performed additional EAM to obtain landmarks for image registration: aorta with the ostium of the left main coronary artery or left atrium with ostia of pulmonary veins. Correct position of the catheter at the landmark was verified by intra-cardiac echocardiography. VT substrate–defined by a combination of voltage mapping, pace mapping, and detection of local abnormal ventricular activity and/or late potentials was marked by custom tags as a target for SBRT. The CARTO maps were exported and converted to 3D shells with encoded EAM properties (VTK format). On the following day, the patients underwent contrast-enhanced computer tomography (CT) of the heart. Using 3D Slicer software 4.10 (slicer.org), the EAM-derived anatomical structures with the marked ablation target were projected onto CT images by landmark registration with manual correction. The CT study with the projected contours of the EAM-detected ablation target was imported as a DICOM-RT format into a stereotactic radiotherapy planning work station (Multiplan 3.5, Accuray, Sunnyvale, CA). SBRT was performed using a contemporary radiosurgery system with real-time motion tracking of the ablation target (CyberKnife 8.5, Accuray). The prescribed (X-ray) dose was 25 Gy during a single session. Results The proposed work-flow was verified in four patients with structural heart disease and drug-resistant VT who had 2–3 unsuccessful radiofrequency catheter ablations (all males; age: 68–78 years; left ventricular ejection fraction: 20–25%; ischemic/non-ischemic cardiomyopathy: 2/2). Integration of EAM data with CT was achieved in all patients. None of them experienced acute radiotoxicity after SBRT. At a follow-up checkup at one month, three of the patients remained arrhythmia-free. One patient experienced VT recurrence one day after SBRT, but no VTs recurred during the following month of follow-up. Figure 1 Conclusions This is the first report demonstrating the feasibility of SBRT of VT guided by direct integration of EAM. The proposed method is best suited as a bailout procedure for patients with previously failed catheter ablation. Acknowledgement/Funding M.S. was supported by ESC Research Fellowship 2018