Stereotactic arrhythmia radioablation (STAR) is a novel, non-invasive, and promising treatment option for ventricular arrhythmias (VAs). It has been applied in highly selected patients mainly as bailout procedure, when (multiple) catheter ablations, together with anti-arrhythmic drugs, were unable to control the VAs. Despite the increasing clinical use, there is still limited knowledge of the acute and long-term response of normal and diseased myocardium to STAR. Acute toxicity appeared to be reasonably low, but potential late adverse effects may be underreported. Among published studies, the provided methodological information is often limited, and patient selection, target volume definition, methods for determination and transfer of target volume, and techniques for treatment planning and execution differ across studies, hampering the pooling of data and comparison across studies. In addition, STAR requires close and new collaboration between clinical electrophysiologists and radiation oncologists, which is facilitated by shared knowledge in each collaborator's area of expertise and a common language. This clinical consensus statement provides uniform definition of cardiac target volumes. It aims to provide advice in patient selection for STAR including aetiology-specific aspects and advice in optimal cardiac target volume identification based on available evidence. Safety concerns and the advice for acute and long-term monitoring including the importance of standardized reporting and follow-up are covered by this document. Areas of uncertainty are listed, which require high-quality, reliable pre-clinical and clinical evidence before the expansion of STAR beyond clinical scenarios in which proven therapies are ineffective or unavailable.

• Keywords
• Ablation, Radiotherapy, Stereotactic arrhythmia radioablation (STAR), Sudden death, Ventricular tachycardia,
• MeSH
• Action Potentials MeSH
• Cardiology * standards   MeSH
• Tachycardia, Ventricular * physiopathology   surgery   diagnosis   MeSH
• Consensus MeSH
• Humans MeSH
• Radiosurgery * adverse effects   standards   methods   MeSH
• Risk Factors MeSH
• Patient Selection * MeSH
• Treatment Outcome MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Practice Guideline MeSH
• Geographicals
• Europe MeSH

BACKGROUND AND PURPOSE: Stereotactic arrhythmia radioablation (STAR) has been suggested as a promising therapeutic alternative in cases of failed catheter ablation for recurrent ventricular tachycardias in patients with structural heart disease. Cyberknife® robotic radiosurgery system utilizing target tracking technology is one of the available STAR treatment platforms. Tracking using implantable cardioverter-defibrillator lead tip as target surrogate marker is affected by the deformation of marker-target geometry. A simple method to account for the deformation in the target definition process is proposed. METHODS: Radiotherapy planning CT series include scans at expiration and inspiration breath hold, and three free-breathing scans. All secondary series are triple registered to the primary CT: 6D/spine + 3D translation/marker + 3D translation/target surrogate-a heterogeneous structure around the left main coronary artery. The 3D translation difference between the last two registrations reflects the deformation between the marker and the target (surrogate) for the respective respiratory phase. Maximum translation differences in each direction form an anisotropic geometry deformation margin (GDM) to expand the initial single-phase clinical target volume (CTV) to create an internal target volume (ITV) in the dynamic coordinates of the marker. Alternative GDM-based target volumes were created for seven recent STAR patients and compared to the original treated planning target volumes (PTVs) as well as to analogical volumes created using deformable image registration (DIR) by MIM® and Velocity® software. Intra- and inter-observer variabilities of the triple registration process were tested as components of the final ITV to PTV margin. RESULTS: A margin of 2 mm has been found to cover the image registration observer variability. GDM-based target volumes are larger and shifted toward the inspiration phase relative to the original clinical volumes based on a 3-mm isotropic margin without deformation consideration. GDM-based targets are similar (mean DICE similarity coefficient range 0.80-0.87) to their equivalents based on the DIR of the primary target volume delineated by dedicated software. CONCLUSION: The proposed GDM method is a simple way to account for marker-target deformation-related uncertainty for tracking with Cyberknife® and better control of the risk of target underdose. The principle applies to general radiotherapy as well.

• Keywords
• Cyberknife, deformation, motion management, radiotherapy, stereotactic, target definition, tracking,
• Publication type
• Journal Article MeSH

Stereotactic body radiotherapy (SBRT) has been reported as an attractive option for cases of failed catheter ablation of ventricular tachycardia (VT) in structural heart disease. However, even this strategy can fail for various reasons. For the first time, this case series describes three re-do cases of SBRT which were indicated for three different reasons. The purpose in the first case was the inaccuracy of the determination of the treatment volume by indirect comparison of the electroanatomical map and CT scan. A newly developed strategy of co-registration of both images allowed precise targeting of the substrate. In this case, the second treatment volume overlapped by 60% with the first one. The second reason for the re-do of SBRT was an unusual character of the substrate-large cardiac fibroma associated with different morphologies of VT from two locations around the tumor. The planned treatment volumes did not overlap. The third reason for repeated SBRT was the large intramural substrate in the setting of advanced heart failure. The first treatment volume targeted arrhythmias originating in the basal inferoseptal region, while the second SBRT was focused on adjacent basal septum without significant overlapping. Our observations suggested that SBRT for VT could be safely repeated in case of later arrhythmia recurrences (i.e., after at least 6 weeks). No acute toxicity was observed and in two cases, no side effects were observed during 32 and 22 months, respectively. To avoid re-do SBRT due to inaccurate targeting, the precise and reproducible strategy of substrate identification and co-registration with CT image should be used.

• Keywords
• electroanatomical mapping, failed catheter ablation, safety, stereotactic body radiotherapy, ventricular tachycardia,
• Publication type
• Journal Article MeSH
• Case Reports MeSH

The electrophysiology-guided noninvasive cardiac radioablation, also known as STAR (stereotactic arrhythmia radioablation) is an emerging treatment method for persistent ventricular tachycardia. Since its first application in 2012 in Stanford Cancer Institute, and a year later in University Hospital Ostrava, Czech Republic, the authors from all around the world have published case reports and case series, and several prospective trials were established. In this article, we would like to discuss the available clinical evidence, analyze the potentially clinically relevant differences in methodology, and address some of the unique challenges that come with this treatment method.

• Keywords
• ablation, noninvasive, radiosurgery, stereotactic body radiation therapy, substrate ablation, ventricular tachycardia,
• Publication type
• Journal Article MeSH
• Review MeSH

BACKGROUND: Here we aimed to evaluate the respiratory and cardiac-induced motion of a ICD lead used as surrogate in the heart during stereotactic body radiotherapy (SBRT) of ventricular tachycardia (VT). Data provides insight regarding motion and motion variations during treatment. MATERIALS AND METHODS: We analyzed the log files of surrogate motion during SBRT of ventricular tachycardia performed in 20 patients. Evaluated parameters included the ICD lead motion amplitudes; intrafraction amplitude variability; correlation error between the ICD lead and external markers; and margin expansion in the superior-inferior (SI), latero-lateral (LL), and anterior-posterior (AP) directions to cover 90% or 95% of all amplitudes. RESULTS: In the SI, LL, and AP directions, respectively, the mean motion amplitudes were 5.0 ± 2.6, 3.4. ± 1.9, and 3.1 ± 1.6 mm. The mean intrafraction amplitude variability was 2.6 ± 0.9, 1.9 ± 1.3, and 1.6 ± 0.8 mm in the SI, LL, and AP directions, respectively. The margins required to cover 95% of ICD lead motion amplitudes were 9.5, 6.7, and 5.5 mm in the SI, LL, and AP directions, respectively. The mean correlation error was 2.2 ± 0.9 mm. CONCLUSIONS: Data from online tracking indicated motion irregularities and correlation errors, necessitating an increased CTV-PTV margin of 3 mm. In 35% of cases, the motion variability exceeded 3 mm in one or more directions. We recommend verifying the correlation between CTV and surrogate individually for every patient, especially for targets with posterobasal localization where we observed the highest difference between the lead and CTV motion.

• Keywords
• stereotactic body radiotherapy, ventricular tachycardia,
• Publication type
• Journal Article MeSH

BACKGROUND: Stereotactic body radiotherapy (SBRT) has emerged recently as a novel therapeutic alternative for patients with ventricular tachycardias (VTs) resistant to convetional treatment. Nevertheless, many aspects related to SBRT are currently unknown. CASE SUMMARY: A 66-year-old man with ischaemic heart disease, a history of coronary artery bypass graft surgery and left ventricular dysfunction was referred for recurrent symptomatic episodes of slow VT (108 b.p.m.). The arrhythmia was resistant to antiarrhythmic drug therapy with amiodarone and repeated catheter ablation. The patient was scheduled to SBRT, however, the first session failed to suppress VT recurrences. After 20 months, the patient underwent re-do ablation procedure that revealed a newly developed scar with its core adjacent to the presumed critical part of the VT substrate. Catheter ablation again failed to eliminate VT and the second session of SBRT was scheduled. To improve targeting of the VT substrate for SBRT, we applied our recently developed original method for integration of data from the electroanatomical mapping system with computer tomography images. The second session of SBRT with precise targeting using the novel strategy led within 3 months to the successful elimination of VT. DISCUSSION: This case report describes a patient in whom the recurrent VT was abolished only by properly targeted SBRT. Above all, the case highlights the importance of precise identification and targeting for SBRT. Our case also documents in vivo, by electroanatomical voltage mapping, the development of SBRT-related myocardial lesion. This represents an important mechanistic proof of the concept of SBRT.

• Keywords
• Case report, Catheter ablation, Stereotactic radiotherapy, Ventricular tachycardia,
• Publication type
• Journal Article MeSH