Substrate Modification Using Stereotactic Radioablation to Treat Refractory Ventricular Tachycardia in Patients With Ischemic Cardiomyopathy.

Abstract

This study aimed to determine the feasibility of using radioablation for arrhythmogenic a substrate modification. Stereotactic body radiation therapy (SBRT) is a promising therapy for ventricular tachycardia (VT) refractory to catheter ablation. A total of 6 male patients (median age 72 years) with ischemic cardiomyopathy (left ventricular ejection fraction 20% [interquartile range (IQR): 16%-25%]) and VT refractory to antiarrhythmic medications and catheter ablations underwent SBRT to extensive scar substrate. In addition to electroanatomical mapping, 5 of 6 patients had computed tomography segmentation using MUSIC (IHU Liryc, Univ. Bordeaux and Inria Sophia Antipolis, France). Regions of wall thinning<5mm, calcification, and intramyocardial fat were targeted for radioablation at 25 Gy. The median planning target volume was 319 (IQR: 280-330) mL. Device-treated or sustained VT episodes were not significantly reduced by radioablation (median 42 [IQR: 19-269] to 29 [IQR: 0-81]; P=0.438). However, a reduction in device shocks was observed from 12 (IQR: 3-19) to 0 (IQR: 0-1) (P=0.046). Over a follow-up period of 231 (IQR: 212-311) days, 3 patients died of end-stage heart failure and 3 of 6 patients had possible adverse events (heart failure exacerbation, pneumonia, and an asymptomatic pericardial effusion). Substrate modification using SBRT assisted by computed tomography segmentation is feasible for treatment of VT in patients with ischemic cardiomyopathy. Although a significant reduction in device shocks was observed, suboptimal VT burden reduction and significant mortality rate in this cohort of patients with advanced cardiomyopathy underscore the need to improve mechanistic understanding for antiarrhythmic effects to guide dosing and targeting of scar substrates.