Stereotactic management of arrhythmia – radiosurgery in treatment of ventricular tachycardia (SMART-VT) – clinical trial protocol and study rationale

Abstract

Patients with vetricular tachycardia are usually treated with antiarrhythmic drugs and ablation if the arrhythmia substrate is available for invasive treatment. Despite high efficiency of this treatment there is a significant group of patients who do not benefit from available treatment methods, either because they cannot be applied or do not allow for durable control of the disease. For that reason a novel treatment method, STereotactic Arrhythmia Radioablation (STAR) has been proposed and its safety and efficiency is extensively studied throughout the world. The method is based on irradiation of the arrhythmia substrate identified with electrophysiological examination with high-precision image-guided radiosurgical methods usually used for ablation of malignant tumors. Here we present the protocol of the first Polish study on STAR in patients with intractable ventricular tachycardia (STARVT, NCT04642963), designed to test the safety of the method. Secondary endpoints include measures of the treatment efficiency.

Histopathological Examination of an Explanted Heart in a Long-Term Responder to Cardiac Stereotactic Body Radiotherapy (STereotactic Arrhythmia Radioablation)

“…STereotactic Arrhythmia Radioablation is challenged by significant conceptual variability between centers. The target delineation can be based on non-invasive cardiac mapping ( 4 ), invasive EAM ( 8 ), or even primarily on 12-lead ECG and medical imaging ( 18 ). The transfer process of the EAM data to radiotherapy planning systems ranges from indirect comparison to software-based transformations ( 9 ), and the median volume of the final structures varies almost sevenfold between centers ( 1 ).…”

“…The trial is ongoing and registered under the ClinicalTrials.gov identifier of NCT04642963. A thorough description of the trial protocol can be found in a previously published article ( 8 ).…”

Radiosurgery in Treatment of Ventricular Tachycardia – Initial Experience Within the Polish SMART-VT Trial

“…The target volume contouring was performed on the spot, using a remote access workstation, through indirect comparison of EAM data and contrast-enhanced CT fused with Deep Inspiration Breath Hold (DIBH) treatment planning CT. The organs-at-risk (OARs) and derivative structures were prepared according to the study protocol ( 10 ). Using Volumetric Modulated Arc Therapy (VMAT) technique, three 6 MeV flattening filter-free photon beam fields, DIBH respiratory motion management, a dose of 25 Gy was delivered to the planning target volume (PTV) ( Figure 3A ).…”

“…Dose constraints for OARs and dose to target are presented in table below ( Table 1 ). Most of them are based on values for thoracic stereotactic radiotherapy, however, dose constraints for coronary arteries have been extrapolated form available data with principle of maximum safety ( 10 ). Each RT fraction is supervised by a cardiologist.…”

“…One of them is the Polish trial SMART-VT ( ClinicalTrials.gov Identifier: NCT04642963) ( 9 ). It was launched on September 11, 2020, and aims to evaluate treatment safety, as described in detail in the trial protocol ( 10 ). Briefly, the inclusion criteria are: structural heart disease and implanted cardioverter-defibrillator (ICD), clinically significant arrhythmia with at least 3 VT episodes per month despite adequate pharmacological treatment, at least one episode of monomorphic VT registered during the electrophysiological study, recurrent VT despite at least one prior catheter ablation and adequate pharmacotherapy or contraindications to catheter ablation and/or pharmacotherapy, ability to understand and will to sign a written informed consent document.…”