Multimodal fusion workflow for target delineation in cardiac radioablation of ventricular tachycardia.

BACKGROUND: Cardiac radioablation (CR) is an innovative treatment to ablate cardiac arrythmia sources by radiation therapy. CR target delineation is a challenging task requiring the exploitation of highly different imaging modalities, including cardiac electro-anatomical mapping (EAM). PURPOSE: In this work, a data integration process is proposed to alleviate the tediousness of CR target delineation by generating a fused representation of the heart, including all the information of interest resulting from the analysis and registration of electro-anatomical data, PET scan and planning computed tomography (CT) scan. The proposed process was evaluated by cardiologists during delineation trials. METHODS: The data processing pipeline was composed of the following steps. The cardiac structures of interest were segmented from cardiac CT scans using a deep learning method. The EAM data was registered to the cardiac CT scan using a point cloud based registration method. The PET scan was registered using rigid image registration. The EAM and PET information, as well as the myocardium thickness, were projected on the surface of the 3D mesh of the left ventricle. The target was identified by delineating a path on this surface that was further projected to the thickness of the myocardium to create the target volume. This process was evaluated by comparison with a standard slice-by-slice delineation with mental EAM registration. Four cardiologists delineated targets for three patients using both methods. The variability of target volumes, and the ease of use of the proposed method, were evaluated. RESULTS: All cardiologists reported being more confident and efficient using the proposed method. The inter-clinician variability in delineated target volume was systematically lower with the proposed method (average dice score of 0.62 vs. 0.32 with a classical method). Delineation times were also improved. CONCLUSIONS: A data integration process was proposed and evaluated to fuse images of interest for CR target delineation. It effectively reduces the tediousness of CR target delineation, while improving inter-clinician agreement on target volumes. This study is still to be confirmed by including more clinicians and patient data to the experiments.

Heart transplantation as a rescue strategy for patients with refractory electrical storm.

AIMS: Heart transplantation (HT) can be proposed as a therapeutic strategy for patients with severe refractory electrical storm (ES). Data in the literature are scarce and based on case reports. We aimed at determining the characteristics and survival of patients transplanted for refractory ES. METHODS AND RESULTS: Patients registered on HT waiting list during the following days after ES and eventually transplanted, from 2010 to 2021, were retrospectively included in 11 French centres. The primary endpoint was in-hospital mortality. Forty-five patients were included [82% men; 55.0 (47.8-59.3) years old; 42.2% and 26.7% non-ischaemic dilated or ischaemic cardiomyopathies, respectively]. Among them, 42 (93.3%) received amiodarone, 29 received (64.4%) beta blockers, 19 (42.2%) required deep sedation, 22 had (48.9%) mechanical circulatory support, and 9 (20.0%) had radiofrequency catheter ablation. Twenty-two patients (62%) were in cardiogenic shock. Inscription on wait list and transplantation occurred 3.0 (1.0-5.0) days and 9.0 (4.0-14.0) days after ES onset, respectively. After transplantation, 20 patients (44.4%) needed immediate haemodynamic support by extracorporeal membrane oxygenation (ECMO). In-hospital mortality rate was 28.9%. Predictors of in-hospital mortality were serum creatinine/urea levels, need for immediate post-operative ECMO support, post-operative complications, and surgical re-interventions. One-year survival was 68.9%. CONCLUSION: Electrical storm is a rare indication of HT but may be lifesaving in those patients presenting intractable arrhythmias despite usual care. Most patients can be safely discharged from hospital, although post-operative mortality remains substantial in this context of emergency transplantation. Larger studies are warranted to precisely determine those patients at higher risk of in-hospital mortality.