Stereotactic arrhythmia radioablation (STAR) appears to be beneficial in selected patients with therapy-refractory ventricular tachycardia (VT). However, high-dose radiotherapy used for STAR-treatment may affect functioning of the patients' implantable cardioverter defibrillator (ICD) by direct effects of radiation on ICD components or cardiac tissue. Currently, the effect of STAR on ICD functioning remains unknown.A retrospective pre-post multicenter study evaluating ICD functioning in the 12-month before and after STAR was performed. Patients with (non)ischemic cardiomyopathies with therapy-refractory VT and ICD who underwent STAR were included and the occurrence of ICD-related adverse events was collected. Evaluated ICD parameters included sensing, capture threshold and impedance. A linear mixed-effects model was used to investigate the association between STAR, radiotherapy dose and changes in lead parameters over time.In total, 43 patients (88% male) were included in this study. All patients had an ICD with an additional right atrial lead in 34 (79%) and a ventricular lead in 17 (40%) patients. Median ICD-generator dose was 0.1 Gy and lead tip dose ranged from 0-32 Gy. In one patient (2%), a reset occurred during treatment, but otherwise, STAR and radiotherapy dose were not associated with clinically relevant alterations in ICD leads parameters.STAR treatment did not result in major ICD malfunction. Only one radiotherapy related adverse event occurred during the study follow-up without patient harm. No clinically relevant alterations in ICD functioning were observed after STAR in any of the leads. With the reported doses STAR appears to be safe.
ABSTRACT Background Stereotactic arrhythmia radioablation (STAR) is emerging as a potential new therapy for patients with refractory ventricular tachycardia (VT). The arrhythmogenic substrate (target) is synthesized from clinical and electro-anatomical information. This study was designed to evaluate the baseline interobserver variability in target delineation for STAR. Methods Delineation software designed for research purposes was used. The study was split into three phases. Firstly, electrophysiologists (observers) delineated a well-defined structure in three patients (spinal canal). Secondly, observers delineated the arrhythmogenic cardiac VT target in three patients previously treated with STAR based on case descriptions. To evaluate baseline performance, a basic workflow approach was used, no advanced techniques were allowed (e.g. image integration). Thirdly, observers delineated three predefined segments from the cardiac 17-segment model. Interobserver variability was evaluated by assessing volumes, variation in distance to the median volume as expressed by the root-mean-square of the observer standard deviation (RMS SD) over the target volume, and the Dice coefficient. Results Ten electrophysiologists completed the study. For the first phase (spinal canal delineation), interobserver variability was low as indicated by low variation in distance to the median volume (RMS SD range: 0.02-0.02cm) and high Dice coefficients (mean: 0.97±0.01). In the second phase (VT-target delineation), distance to the median volume was large (RMS SD range: 0.52-1.02cm) and the Dice coefficients low (mean: 0.40±0.15). In the third phase (segment delineation), similar results were observed (RMS SD range: 0.51-1.55cm, Dice coefficient mean: 0.31±0.21) Conclusions Interobserver variability is high for manual delineation of the VT-target and ventricular segments. Difficulties in cardiac anatomical orientation on traditional radiation oncology CT scans appear to be an important driver of variability. This evaluation of the baseline observer variation shows that there is a need for methods and tools to improve variability and allows for future comparison of interventions aiming to reduce observer variation.
Sudden death and cardiac arrest frequently occur without explanation, even after a thorough clinical evaluation. Calcium release deficiency syndrome (CRDS), a life-threatening genetic arrhythmia syndrome, is undetectable with standard testing and leads to unexplained cardiac arrest.
Abstract Aims Stereotactic arrhythmia radiotherapy (STAR) is suggested as potentially effective and safe treatment for patients with therapy-refractory ventricular tachycardia (VT). However, the current prospective knowledge base and experience with STAR is limited. In this study we aimed to prospectively evaluate the efficacy and safety of STAR. Methods and results The StereoTactic Arrhythmia Radiotherapy in the Netherlands no.1 was a pre-post intervention study to prospectively evaluate efficacy and safety of STAR. In patients with therapy-refractory VT, the pro-arrhythmic region was treated with a 25 Gy single radiotherapy fraction. The main efficacy measure was a reduction in the number of treated VT-episodes by ≥50%, comparing the 12 months before and after treatment (or end of follow-up, excluding a 6-week blanking period). The study was deemed positive when ≥50% of patients would meet this criterion. Safety evaluation included left ventricular ejection fraction, pulmonary function, and adverse events. Six male patients with an ischaemic cardiomyopathy were enrolled, and median age was 73 years (range 54–83). Median left ventricular ejection fraction was 38% (range 24–52). The median planning target volume was 187 mL (range 93–372). Four (67%) patients completed the 12-month follow-up, and two patients died (not STAR related) during follow-up. The main efficacy measure of ≥50% reduction in treated VT-episodes at the end of follow-up was achieved in four patients (67%). The median number of treated VT-episodes was reduced by 87%. No reduction in left ventricular ejection fraction or pulmonary function was observed. No treatment related serious adverse events occurred. Conclusions STAR resulted in a ≥ 50% reduction in treated VT-episodes in 4/6 (67%) patients. No reduction in cardiac and pulmonary function nor treatment-related serious adverse events were observed during follow-up. Clinical trial registration Netherlands Trial Register—NL7510.
