Ablation of ventricular tachycardia by stereotactic radiation therapy – Non invasive ablation of VT!
Non invasive ablation of VT: Till date, ablation of ventricular tachycardia is done by invasive catheter based mapping of arrhythmia focus within the ventricles. In a potentially path breaking report published in the New England Journal of Medicine, non invasive cardiac radiation for ablation of ventricular tachycardia in 5 patients has been described . Ventricular tachycardia was induced by the already implanted cardioverter-defibrillator (ICD) and noninvasive electrocardiographic imaging of the tachycardia obtained. Stereotactic body radiation therapy (SBRT) was done after standard simulation, planning and treatment protocols. Treatment efficacy was assessed by counting the episodes of ventricular tachycardia recorded by the ICD. Assessment of safety of the procedure was done by serial imaging of the heart and thorax for any potential collateral damage. The mean non invasive ablation time in the five patients was 14 minutes (range 11-18 minutes). Single fraction of 25 Gy radiation was delivered in the awake state. Patients had a total of 6577 episodes of ventricular tachycardia (VT) in the 3 months prior to treatment. 680 episodes of VT were recorded during the 6 week blanking period, which could be attributed to the inflammatory process after ablation and consequent ventricular irritability. After the blanking period, only 4 episodes of VT over the next 46 patient-months, indicating a 99.96% reduction, which electrophysiologists say, is seldom attained after conventional ablation! Mild opacities were noted in the adjacent lung at 3 months, which resolved at one year. Though it is too early to think of non invasive ablation for VT on a large scale as the procedure of choice, this study is definitely a call for action, to conduct larger scale studies of this technique.
- Cuculich PS, Schill MR, Kashani R, Mutic S, Lang A, Cooper D, Faddis M, Gleva M, Noheria A, Smith TW, Hallahan D, Rudy Y, Robinson CG. Noninvasive Cardiac Radiation for Ablation of Ventricular Tachycardia. N Engl J Med 2017; 377:2325-2336.