Ventricular tachycardia (VT) is a regular, rapid (faster than 100 beats per minute) abnormal heart rhythm resulting from aberrant electrical conduction in the ventricles of the heart. Coronary heart disease is responsible for the majority of VT cases. Defibrillation and antitachycardia pacing, effective means of terminating a life-threatening acute episode of VT, can be delivered via implantable cardioverter-defibrillator (ICD). ICDs are able to both monitor the heart rhythm continuously and deliver therapy in response to tachycardia that meets pre-programmed detection criteria. For patients with VT refractory to medical management requiring multiple ICD shocks, electrophysiologic mapping may be utilized to localize the arrhythmogenic focus, which can be subsequently ablated with cardiac catheter radiofrequency ablation. The goal of catheter ablation is to identify (through electroanatomical mapping) and then eliminate the channels of surviving myocardium within the substrate. Many patients experience continued episodes of VT refractory to both medication and multiple catheter ablation attempts. ICD shocks are associated with substantially increased risk of hospitalization, quality of life impairment, and death.~Stereotactic body radiotherapy (SBRT) is a technique used most commonly as a cancer treatment, whereby a precise, high dose of radiation is delivered to a target. For patients with VT refractory to medication and catheter ablation, noninvasive targeting of the arrhythmogenic substrate with SBRT (in this case termed cardiac radioablation, CRA) is an emerging technique demonstrating favorable efficacy.~Using a protocol similar to that utilized by the phase I/II ENCORE-VT trial (NCT02919618), this study aims to replicate previously reported favorable results in a multi-institutional setting. Accrued patients will receive CRA to 25 Gy in a single fraction.
The purpose of this study is to evaluate the safety and efficacy of cardiac radioablation (CRA) as a means of noninvasive treatment of ventricular tachycardia (VT) refractory to both medication and catheter ablation.