Claudia Herrera Siklódy

Aims: Stereotactic arrhythmia radiotherapy (STAR) is an emerging non-invasive option for refractory ventricular tachycardia (VT); yet, the underlying myocardial effects in humans remain poorly understood. Within the STOPSTORM consortium, we developed the Bio-STAR framework for standardized ex vivo assessment of STAR-treated myocardium and here report its feasibility and initial findings in human samples. Methods and results: Bio-STAR standardizes myocardial sampling into non-irradiated control (NFNI), minimally fibrotic irradiated, and fibrotic irradiated zones, guided by visual inspection, electroanatomical maps, and radiotherapy dose overlays. Recommended analyses span ex vivo MRI, histology, immunohistochemistry/-fluorescence, molecular panels, and live-cell assays. Application to two explanted non-ischaemic cardiomyopathy hearts (transplantation 3–5 months post-STAR) confirmed the protocol’s applicability to end-stage remodelling. In exploratory analyses of irradiated regions, patient-specific patterns emerged, including stress marker upregulation, and altered NaV1.5, SERCA2a, and CaV1.2 when normalized to cardiomyocyte content. Functional analyses in a limited number of viable cardiomyocytes from the respective regions demonstrated heterogeneous excitability, supporting the feasibility of isolating live cells from STAR-treated regions in which Ca2+ signalling can be quantitatively assessed in future studies involving larger patient cohorts. Conclusion: Bio-STAR provides a reproducible framework for multimodal analysis of STAR-treated myocardium, enabling harmonized cross-centre research. Early human data demonstrate that cardiomyocyte viability and isolatability are preserved across all assessed regions and that STAR-exposed areas may exhibit region-specific structural features, while functional data on Ca2+ handling remain exploratory and require validation in larger datasets. Broad adoption will be the key to delineating dose–time–substrate relationships and disentangling radiation effects from underlying cardiomyopathy.

Background and Aims: Stereotactic arrhythmia radioablation (STAR) is increasingly used for refractory ventricular tachycardia (VT), yet prospective multicentre outcome data remain limited. Here, the planned interim analysis of the prospective Standardized Treatment and Outcome Platform for Stereotactic Therapy Of Re-entrant tachycardia by a Multidisciplinary (STOPSTORM) registry is reported. Methods: STOPSTORM is a European prospective, international, multicentre registry of patients treated with STAR. The primary efficacy endpoint was the change in sustained VT episode burden comparing the 6 months before versus the 6 months after STAR. The primary safety endpoint was the occurrence of serious adverse events (SAEs) adjudicated as possibly or probably treatment-related. Overall survival was assessed using time-to-event methods. Results: Across 28 centres, 193 patients were included (mean age 68±9 years; 88% male; 53% non-ischaemic cardiomyopathy). Median follow-up was 19 months. Among 107 evaluable patients with ≥6-month follow-up, the median VT episode burden was reduced by 80% after STAR. Among patients surviving ≥6 months, 72% were free from implantable cardioverter-defibrillator (ICD) shock. In the full cohort, 12 SAEs were adjudicated as possibly or probably treatment-related, including pericardial effusion, coronary events, and early post-treatment ventricular arrhythmia. Overall survival probability was 77% at 12 months. Conclusions: In the largest prospective multicentre cohort reported to date, STAR was associated with a substantial reduction in VT burden and ICD shocks, with a low frequency of possibly or probably treatment-related SAEs.

Introduction: Natriuretic peptides have shown to predict atrial fibrillation (AF) ablation success using thermal energies. Pulsed‐field ablation (PFA) is a novel AF ablation technology. This study investigates the predictive value of NT‐proBNP and clinical parameters for pulmonary vein isolation (PVI) success using PFA, cryoballoon ablation (CBA), and radiofrequency ablation (RFA). Methods: We included all patients undergoing primary PVI between May 2019 and December 2023 from our prospective registry, excluding those in randomized trials or without NT‐proBNP measured ≤1 day before the procedure. Follow‐up included 7‐day Holter‐ECGs at 3, 6, and 12 months. The primary endpoint was atrial arrhythmia recurrence between days 90–365. NT‐proBNP was dichotomized using the age‐ and sex‐adjusted 95th percentile in healthy adults. Results: Among 1,391 patients (median age 67 years; 29% female) undergoing primary PVI with RFA ( n = 302), CBA ( n = 399), or PFA ( n = 690), elevated NT‐proBNP levels were observed in 55%, with no significant differences between ablation modalities. NT‐proBNP correlated with age and left atrial volume and was higher in patients with persistent AF. Overall, 1‐year arrhythmia recurrence rate was 32.1%, without differences between ablation technologies. Elevated NT‐proBNP was associated with recurrence across all subgroups. In multivariate Cox regression, NT‐proBNP and persistent AF were the strongest independent predictors of recurrence. A simplified model including only NT‐proBNP and AF type yielded a concordance index of 0.62. Conclusions: NT‐proBNP is a robust predictor of atrial arrhythmia recurrence after PVI, independent of the ablation technology, and may support shared, evidence‐based decision‐making with patients regarding ablation success probability. Trial registration: The Swiss‐AF‐PVI registry is registered with ClinicalTrials.gov (NCT03718364)

Background: Accurate electroanatomical mapping relies on voltage thresholds to differentiate electrically inactive areas, fibrotic scar, and healthy myocardium. These thresholds have been well established for high-density mapping catheters with small, closely spaced electrodes. However, the optimal voltage thresholds for a novel pulsed-field ablation catheter with integrated mapping capabilities remain unclear. This case series evaluates different voltage thresholds for the variable-loop circular catheter (VLCC, Varipulse, Biosense Webster) compared with a dedicated high-density mapping catheter (Octaray, Biosense Webster). Case summary: Four patients undergoing left atrial catheter ablation—including pulmonary vein isolation (PVI), posterior wall ablation, and ablation for scar-related atrial flutter—were mapped using both the VLCC and Octaray catheter. The key findings include: (i) standard voltage thresholds for high-density catheters overestimate voltage in scarred and ablated tissue when applied to the VLCC, necessitating adjusted voltage settings; (ii) the VLCC effectively identified PVI and reconnections, posterior wall isolation, anterior wall scarring, and atrial flutter circuits; and (iii) while the VLCC identified areas of scar, its representation remained less precise compared with high-density mapping. Discussion: This case series demonstrates that the VLCC provides satisfactory mapping performance in common use cases but requires voltage threshold adjustments for accurate visualization. Despite its ability to detect ablation endpoints, scar characterization remains less accurate. Further quantitative analysis of electrogram differences and a prospective evaluation in a larger patient population are necessary to determine the optimal voltage thresholds for this catheter.

Introduction: Pulmonary vein (PV) isolation is a cornerstone therapy for symptomatic atrial fibrillation (AF). Current 3D-navigation technologies used with radiofrequency (RF) ablation allow drastic reduction of X-ray exposure and better anatomical characterization improving acute and long-term procedural results. Cryoballoon ablation (CA) procedures typically rely on conventional fluoroscopy, resulting in significant X-ray exposure. Although contemporary fluoroscopy technologies allow for potential 3D imaging integration, their specific utility in improving procedural guidance during CA remains undefined. Method: Using semi-automatic segmentation obtained from pre-procedural cardiac computed tomography, 3D segmentations of the left atrium, including PV, spine and primary bronchi walls were fused on the real-time fluoroscopy acquisitions in three standard positions (AP, LAO, RAO), acquired at the beginning of the procedure (Figure1). We compared procedural characteristics of CA performed with 3D-fusion imaging to conventional fluoroscopy-guided procedures. Results: Thirty-six patients (aged 60±13 yo, 85% male) with paroxysmal AF treated with CA were included in the study: 18 in the control group (conventional fluoroscopy) and 18 in the 3D-assisted group. Acute PV isolation was achieved in all patients. The 3D-assisted CA was associated with significantly shorter procedure duration (mean 97.8±15.5 vs 82.1±16.1 min, p=0.0048); left-sided dwelling time (mean 77±15.2 vs 65.1±14.4 min, p=0.0351); and lower X-ray energy delivered to the patient (Dose Area product) with mean 661±373.1 vs 378.1±316.8 cGy*cm2 (p=0.013). Interestingly, we found that 72.2% of 3D guided procedures were done in less than 90min, while 77.8% of conventional cases required more than 90min to be completed (Figure 2D). Conclusion: 3D-fusion imaging integration is feasible and allows for an exact PV anatomy depiction on fluoroscopy. Our data illustrates that it might significantly improve CA efficiency (shorter procedure duration) and safety (lower X-ray exposure and left-sided dwelling time). Our approach could also impact long-term results since it might reduce the likeability of missing intermediate PVs. Further research is needed to evaluate the incremental value of 3D imaging in long term efficacy.Figure 1Figure 2

Introduction: Stereotactic arrhythmia radioablation (STAR) is used as a rescue treatment for refractory ventricular tachycardia (VT). However, the planning phase to accurately delineate the clinical target volume (CTV) still suffers from limitations due to the incompatibility of data formats between 3D electro-anatomical mapping systems (EAM) used for VT ablation and STAR planning software. The concordance between the CTVs as defined by the planning software (CTVSTAR) and the CTV based on EAM data (CTVEAM) remains unknown. Purpose: Within the STOPSTORM European consortium, we compared the concordance between CTVSTAR and CTVEAM in our series of 13 patients (pts) treated by STAR for refractory VT. We also evaluated need for redo ablation of VT after STAR. Method: Using the software Slicer3D, two protocols were retrospectively compared: Protocol 1 comprised the manual contouring of the CTVSTAR based on 4D-CT SCAN drawn side-by-side using EAM (Carto3, Biosense Webster) screenshots and diagnostic reports. Protocol 2 comprised semiautomatic segmentation of CTVEAM based on 4D-CT SCAN using imported EAMs annotated with landmarks for VT substrate delimitation. The delineation of CTVEAM included 3 steps: (1) semiautomatic segmentation of ventricular myocardium (VM), the blood-pool of the concerned ventricle and at least 2 additional cardiac cavities; (2) 3D-alignment of EAM with the segmented cavities; and (3), 3D-delineation of CTVSTAR identified as the transmural section of VM segment surrounding the EAM’s VT substrate delimited by STAR tags (Figure 1). Volume overlap (Dice coefficient, 100% meaning complete overlap) and volume absolute difference (VAD, 0% meaning similar volumes) between CTVs were compared. The following cumulative averages were computed over time: redo ablation (RedoA) and CTV. Results: Figure 1 illustrates the last treated patient (#13) in whom the delineated volumes, CTVSTAR (red) and CTVEAM (blue), displayed good matching (Dice 72% and VAD 4. Figure 2 shows the comparison between CTVSTAR and CTVEAM for the 13 pts (65±7 yo) treated with STAR, resulting in a mean Dice of 47±17% and mean VAD of 40±51%. Figure 3 shows the cumulative RedoA and the cumulative averaged CTVSTAR and CTVEAM over time. Interestingly, the need for redo ablation decreased with increasing CTVs. Conclusion: Our study demonstrates the efficacy of STAR treatment for refractory VT. Our confidence in STAR led to higher CTVs and lower RedoA over time. The high variability of CTV delineation using two different protocols suggests that STAR planning phase can be optimised by appointing intraprocedural anatomical landmarks to the VT substrate.

Aims: The left atrial posterior wall is a potential ablation target in patients with recurrent atrial fibrillation despite durable pulmonary vein isolation or in patients with roof-dependent atrial tachycardia (AT). Pulsed-field ablation (PFA) offers efficient and safe posterior wall ablation (PWA), but available data are scarce. Methods and results: Consecutive patients undergoing PWA using PFA were included. Posterior wall ablation was performed using a pentaspline PFA catheter and verified by 3D-electroanatomical mapping. Follow-up was performed using 7-day Holter ECGs 3, 6, and 12 months after ablation. Recurrence of any atrial arrhythmia lasting more than 30 s was defined as failure. Lesion durability was assessed during redo procedures. Posterior wall ablation was performed in 215 patients (70% males, median age 70 [IQR 61–75] years, 67% redo procedures) and was successful in all patients (100%) by applying a median of 36 (IQR 32–44) PFA lesions. Severe adverse events were cardiac tamponade and vascular access complication in one patient each (0.9%). Median follow-up was 7.3 (IQR 5.0–11.8) months. One-year arrhythmia-free outcome in Kaplan–Meier analysis was 53%. A redo procedure was performed in 26 patients (12%) after a median of 6.9 (IQR 2.4–11) months and showed durable PWA in 22 patients (85%) with only minor lesion regression. Among four patients with posterior wall reconnection, three (75%) presented with roof-dependent AT. Conclusion: Posterior wall ablation with this pentaspline PFA catheter can be safely and efficiently performed with a high durability observed during redo procedures. The added value of durable PWA for the treatment of atrial fibrillation remains to be evaluated.

Aims: Stereotactic arrhythmia radioablation (STAR) has been recently introduced for the management of therapy-refractory ventricular tachycardia (VT). VT recurrences have been reported after STAR but the mechanisms remain largely unknown. We analysed recurrences in our patients after STAR. Methods and results: From 09.2017 to 01.2020, 20 patients (68 ± 8 y, LVEF 37 ± 15%) suffering from refractory VT were enrolled, 16/20 with a history of at least one electrical storm. Before STAR, an invasive electroanatomical mapping (Carto3) of the VT substrate was performed. A mean dose of 23 ± 2 Gy was delivered to the planning target volume (PTV). The median ablation volume was 26 mL (range 14–115) and involved the interventricular septum in 75% of patients. During the first 6 months after STAR, VT burden decreased by 92% (median value, from 108 to 10 VT/semester). After a median follow-up of 25 months, 12/20 (60%) developed a recurrence and underwent a redo ablation. VT recurrence was located in the proximity of the treated substrate in nine cases, remote from the PTV in three cases and involved a larger substrate over ≥3 LV segments in two cases. No recurrences occurred inside the PTV. Voltage measurements showed a significant decrease in both bipolar and unipolar signal amplitude after STAR. Conclusion: STAR is a new tool available for the treatment of VT, allowing for a significant reduction of VT burden. VT recurrences are common during follow-up, but no recurrences were observed inside the PTV. Local efficacy was supported by a significant decrease in both bipolar and unipolar signal amplitude.