Description of multiparametric targeting techniques for stereotactic arrhythmia radioablation in refractory ventricular tachycardia: A quaternary medical center experience

Abstract

Background: Ventricular tachycardia (VT) is a potentially life-threatening arrhythmia which remains a major contributor to cardiac morbidity and mortality worldwide. Recently the use of stereotactic radiation has demonstrated efficacy, although standardization of methodology is lacking and variations in technique exist. In this paper, we discuss our outcomes as well as the various options available and the proposed indications for each.
Methods: 12-lead EKGs and device-obtained tracings were used to approximately localize the arrhythmogenic origin and to define the arrhythmic mechanism. When feasible, electrophysiology studies (EPS) with 3-D electroanatomic (EA) mapping during which a 3-D electroanatomic substrate map was created to delineate cardiac structures, identify areas of low voltage scar and confirm arrhythmic circuits. A 4-D cardiac magnetic resonance imaging (cMRI) or cardiac computed tomography (cCT) was performed to delineate cardiac geometry and structures. The Stereotactic arrhythmia radioablation (STAR) treatment plans delivered a total dose of 25 Gy in a single treatment fraction covering the entire arrhythmogenic target.
Results: Six of the nine patients showed a reduction in VT events at 6 weeks post STAR. One patient underwent cardiac transplantation two weeks following STAR. Excluding this patient from the analysis, all but one patient had a dramatic diminution in VT events (to 0) at 6 months post-procedure, including both patients with an LVAD. Six of the nine patients survived at least 4 months post procedure event free and 6 patients survive to date. The lone patient who did not respond died 13 months post procedure, however he had no further defibrillator discharges. Another patient died two months post procedure from uncontrolled multiple myeloma. One patient developed an asymptomatic pleural effusion, but no serious STAR-induced postoperative complications occurred.
Conclusions: STAR appears to be an effective therapy for refractory ventricular tachycardia, although long term data are still developing. Additional clinical trials and techniques are in development and STAR programs should be encouraged for additional well-equipped centers with experienced multidisciplinary clinicians.