Stereotactic Radiosurgery as Second-line Therapy for Ventricular Tachycardia

"Radiotherapy Implementation: During treatment on a TrueBeam™ linear accelerator (Varian Medical Systems, Palo Alto, CA, USA), a planned radiation dose of 25 Gy will be delivered to the defined planning target volume (PTV) using highly conformal stereotactic techniques. Image-guided radiotherapy (IGRT), respiratory gating, and Triggered Tracking will be utilized, targeting the previously delineated defibrillation lead of the implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D), with position verification every 15 degrees of gantry rotation.~Patient positioning will be performed using kV-kV imaging, based on pre-determined fiducial markers on the ICD/CRT-D defibrillation lead, followed by verification using gated cone-beam computed tomography (CBCT). Continuous ECG monitoring will be conducted throughout the treatment, and the patient will remain under cardiologist supervision."

CA will be conducted in an electrophysiology laboratory and will routinely follow diagnostic procedures, including an electrophysiological study (EPS) and three-dimensional electroanatomical mapping (3D-EAM). Once sufficient data on the nature and location of the arrhythmic substrate have been obtained from the three primary mapping modules-voltage, activation, and propagation-spatial 3D-EAM maps will be integrated with a 3D left ventricular reconstruction from multislice computed tomography (MSCT) or cardiac magnetic resonance (CMR). Subsequently, ablation will be performed by delivering energy to predefined target sites identified as the arrhythmia source to close the sVT isthmus or eliminate late potentials (LPs) and/or low-amplitude ventricular activities (LAVAs). Following CA, a repeat induction attempt of sVT using programmed ventricular pacing (VP) will be conducted to verify procedural efficacy.