Para-Hisian accessory pathways (PHAPs) remain among the most challenging substrates for catheter ablation because of their close anatomical relationship to the atrioventricular (AV) conduction system and the consequent risk of iatrogenic AV block. The non-coronary cusp (NCC) has emerged as a valuable alternative when right-sided ablation is ineffective or associated with an unacceptable risk of injury to the His bundle. We report the case of a 23-year-old man who presented with pre-excited atrial fibrillation. Electrophysiological study localized an anteroseptal/para-Hisian accessory pathway. Electroanatomical mapping identified the earliest ventricular activation at the para-Hisian region; however, multiple irrigated radiofrequency applications from the right atrial septum failed to eliminate pre-excitation because of the close proximity to the His bundle. A retrograde aortic approach to the NCC was subsequently undertaken using three-dimensional electroanatomical mapping integrated with intracardiac echocardiography. Mapping within the NCC demonstrated an accessory pathway potential with atrioventricular fusion and ventricular activation preceding delta-wave onset by 20 ms. Radiofrequency delivery at this site resulted in elimination of pre-excitation within 3 s while preserving normal AV conduction. No recurrence of pre-excitation or impairment of AV nodal conduction was observed during post-ablation assessment. This case supports the NCC as a safe and effective alternative target when conventional right-sided ablation is unsuccessful or poses a significant risk of AV conduction injury.

Cardiac radioablation (CRA) for refractory ventricular tachycardia (VT) was introduced in 2017 following the success of the ENCORE-VT trial (1). The current standard of care radiation therapy dose is 25 Gy in 1 fraction, however, the optimal therapeutic dose is being explored. Previous studies have shown fibrosis, reduced bipolar voltage, and scar formation in areas treated with radioablation at doses above 15 Gy. A study suggest that CRA upregulates connexin-43 and sodium channel, NaV1.5, thereby enhancing conduction velocity through cellular reprogramming, even at lower doses (2). In this interim analysis of a single institution, phase 2, dose de-escalation clinical trial, we report the early efficacy in managing refractory ventricular tachycardia. Eligible patients with ischemic or non-ischemic cardiomyopathy experiencing recurrent, monomorphic VT unresponsive to standard medical therapy were offered participation in the study. Patients unable to undergo or contraindicated to invasive electrophysiology study were included if their arrhythmic substrate could be identified non-invasively. Exclusion criteria included prior thoracic radiation therapy, active connective tissue disease, or interstitial pulmonary fibrosis. The CRA workflow is summarised in Figure A. Implantable defibrillators were programmed at the physician’s discretion, with an anti-tachycardia pacing (ATP) zone set, typically set 20 msec slower than the documented arrhythmia. Following treatment, a 6-week blanking period was allowed. During this blanking period, arrhythmia events were tracked but were not included in the efficacy analysis. Follow-ups, including device interrogation, were conducted at 6 weeks, 3 and 6 months. Five patients (4 males [80%], mean age 77 ± 3.2 years) have received CRA of 20 Gy in 1 fraction. The median left ventricular ejection fraction was 25% (range 19%-35%). Four patients had an ischemic substrate, and one had a non-ischemic substrate (valvular disease). The average planning target volume was 187.5 ml (IQR 95.9–209.3 ml). After a median follow-up of 6 months, four patients remained stable, and one patient died (secondary to septic shock). Two patients had recurrent VT, one of which presented as a VT storm within the 6-week blanking period but subsequently stabilised. The total VT burden, defined as any sustained VT episodes requiring ICD therapies (both ATP and/or shocks), decreased significantly from 14 episodes to 1 (p = 0.042; Graph A). Episodes requiring an ICD shock reduced from 6 to 0, while those requiring ATP decreased from 14 to 1. VT storm events decreased from 3 to 0. This interim analysis demonstrates that a 20 Gy dose effectively reduces VT burden. Preliminary efficacy results for a single 20 Gy dose of CRA are promising; however, data remain too limited for definitive conclusions.Figure A:Workflow for CRA Graph A:6-month ventricular arrhythmia

Background:Cardioneuroablation (CNA) is an ablation technique that targets epicardial ganglionic plexi to reduce syncope burden and avoid pacemaker implantation in patients with cardioinhibitory vasovagal syncope (VVS). This study aims to demonstrate feasibility and safety of CNA in high-risk refractory VVS patients using continuous monitoring with an implantable loop recorder (ILR).Methods:Data was collected prospectively for patients undergoing CNA. Patients were required to have recurrent syncope with documented asystole, refractory to conservative measures. Ganglionic plexi (GPs) were identified by fragmented signals and high frequency stimulation (HFS). Ablation was performed until loss of positive response to HFS, Wenckebach cycle shortening was achieved, or an increase in sinus rate of > 20 bpm. Follow-up was performed through remote and clinic follow-up of their ILRs.Results:Between December 2020 and July 2023 six patients (mean age 29 ± 3, 67 % female)underwent CNA. The baseline heart rate and Wenckebach cycle length was 63.2 ± 15 bpm and 582 ms before and 91 ± 5 bpm and 358 ms after ablation respectively. During a median follow-up of 13.4 months, 3/5 patients had no further syncopal episodes, 1 had a recurrence, underwent repeat CNA with no further episodes at 1 year, and 1 had 5 syncopal events, which was a dramatic reduction from nearly daily episodes pre-CNA. There were no procedure related complications.Conclusions:A dramatic reduction in documented pauses and syncope burden was noted post CNA. Appropriate patient selection with rigorous objective follow-up in an experienced center is necessary. Larger studies are required to confirm these findings.

Modern implantable devices capable of pacing are armed with a multitude of programmable and automated features. Although some features represent important advances in device safety and performance, many also can mimic device malfunction and cause clinical manifestations and unnecessary hospital admission. We report a case of "pseudo-malfunction" of a pacemaker due to hysteresis programming that caused symptomatic bradycardia after atrioventricular (AV) node ablation.

BackgroundCardiac radioablation (CRA) is a new and promising treatment modality for patients with ventricular tachycardia refractory to standard-of-care treatment. Electroanatomic maps are used to define radiation target volumes; however, there is currently no native method to import electroanatomic maps into the treatment planning system (TPS).PurposeTo develop Edico, a semi-automated tool to enable electroanatomic map import into a TPS, by converting electroanatomic maps to a Digital Imaging and COmmunications in Medicine (DICOM) standard. The overall aim is to facilitate target volume delineation and improve workflow efficiency in treating patients.MethodsEdico imports voltage and spatial data from electroanatomic maps and sorts these into voxels to be exported in a DICOM format, with each voxel containing the average voltage value of the data that falls within it. Three different rectangular electroanatomic maps were created and processed using Edico to ensure that expected features are maintained through processing. A sensitivity analysis of voxel size was completed using 19 different electroanatomic maps processed at five different sets of voxel dimensions, for a total of 95 resulting voxelized datasets. The coefficient of variation in each populated voxel in the datasets was analyzed to determine which voxel sizes are necessary to ensure that data loss is kept to a minimum throughout processing, despite averaging. Five electroanatomic maps were used to re-contour clinical target volumes and planning target volumes for previously-treated patients with their electroanatomic maps now directly registered to their planning computed tomography (CT) scans.ResultsAll three rectangular test electroanatomic maps were processed as expected. All tested voxel sizes resulted in low coefficients of variation overall, with the exception of the largest voxel size of 1.8 x 1.8 x 8 mm. When using Edico, a user should choose voxel dimensions similar to or smaller than those of a planning CT. Of five pairs of clinical and planning target volumes from previously treated patients, adjustments were made to four (80%), retrospectively, using the electroanatomic maps generated using Edico, registered to the patients' planning CTs.ConclusionsEdico provides a reliable solution for electroanatomic map import into a TPS and facilitates clinical and planning target volume identification in CRA.

Background:Endocardial catheter ablation for ventricular tachycardia (VT) may fail because of the inability to deliver transmural lesions. Ultra-low-temperature cryoablation (ULTC) uses near-critical nitrogen and can generate temperatures as low as -196 °C. We report a series of 18 patients who underwent ULTC at the McGill University Health Centre (MUHC), representing the largest single-centre experience to date. Methods:Eighteen patients with monomorphic drug-refractory VT underwent VT ablation with ULTC at our institution as part of the first-in-human CryoCure-VT trial (NCT04893317). After voltage map, the mapping catheter was replaced with the ULTC catheter, and lesions were applied over a fixed duration of time (60-180 seconds), followed by a 60-second thaw and another application at the original duration (freeze-thaw-freeze). Duration of ablation time was selected depending on the wall thickness of the left ventricle monitored with intracardiac echo to achieve tissue depths of 4.5 to 7.5 mm. Results:Baseline left ventricular ejection fraction was 32%, mean age 71 years, 94% were male. A total of 32 sustained VTs were induced in 16 of 18 patients. A total of 177 cryoablation lesions were delivered (9.8 lesions per patient). Of the 16 patients with inducible VT, 15 (94%) were rendered noninducible postablation, and 1 was inducible only for a nonclinical VT. Complications included 1 pericardial effusion that required drainage. From 18 patients, 16 (89%) were discharged within the first 24 hours postablation. Conclusions:ULTC is feasible and permits acute control of monomorphic VT during VT ablation procedures in drug-refractory patients.

The rapid identification of cardiac implanted electronic devices (CIEDs) is important in several clinical settings. Computer vision applications based on convolutional neural networks (CNNs) have been applied widely in cardiac imaging, and these methods have also been used to identify CIEDs on chest radiographs (CXRs). 1 Chudow J.J. Jones D. Weinreich M. et al. A head-to head comparison of machine learning algorithms for identification of implanted cardiac devices. Am J Cardiol. 2021; 144: 77-82 Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar , 2 Howard J.P. Fisher L. Shun-Shin M.J. et al. Cardiac rhythm device identification using neural networks. JACC Clin Electrophysiol. 2019; 5: 576-586 Crossref PubMed Scopus (36) Google Scholar , 3 Kim U.-H. Kim M.Y. Park E.-A. et al. Deep learning-based algorithm for the detection and characterization of MRI safety of cardiac implantable electronic devices on chest radiographs. Korean J Radiol. 2021; 22: 1918 Crossref PubMed Scopus (2) Google Scholar , 4 Weinreich M. Chudow J.J. Weinreich B. et al. Development of an artificially intelligent mobile phone application to identify cardiac devices on chest radiography. JACC Clin Electrophysiol. 2019; 5: 1094-1095 Crossref PubMed Scopus (9) Google Scholar However, previously published studies are limited by the small scale of data sets.

Background: Pulmonary vein isolations (PVI) are being performed using a high-power, short duration (HPSD) strategy. The purpose of this study was to compare the clinical efficacy and safety outcomes of a HPSD vs low-power long duration (LPLD) approach to PVI in patients with paroxysmal atrial fibrillation (AF). Methods: Patients were grouped according to a HPSD ([≥]40 W) or LPLD ([≤] 35 W) strategy. The primary endpoint was the one-year recurrence of any atrial arrhythmia lasting [≥] 30 seconds, detected using three 14-day ambulatory continuous ECG monitoring. Procedural and safety endpoints were also evaluated. The primary analysis were regression models incorporating propensity scores yielding adjusted relative risk (RRa) and mean difference (MDa) estimates. Results: Of the 398 patients included in the AWARE Trial, 173 (43%) underwent HPSD and 225 (57%) LPLD ablation. The distribution of power was 50 W in 75%, 45 W in 20% and 40 W in 5% in the HPSD group, and 35W with 25W on the posterior wall in the LPLD group. The primary outcome was not statistically significant at 30.1% vs 22.2% in HPSD and LPLD group with RRa 0.77 (95% confidence interval [CI]) 0.55-1.10; p=0.165). The secondary outcome of repeat catheter ablation was not statistically significant at 6.9% and 9.8% (RRa 1.59 [95% CI 0.77-3.30]; p=0.208) respectively. The incidence of any ECG documented AF during the blanking period was numerically lower in the HPSD group: 1.7% vs 8.0% (RRa 3.95 [95% CI 1.00-15.61; p=0.049). The total procedure time was significantly shorter in the HPSD group (MDa 97.5 minutes [95% CI 84.8-110.4)]; p<0.0001) with no difference in adjudicated serious adverse events. Conclusions: A HPSD strategy was associated with significantly shorter procedural times with similar efficacy in terms of clinical arrhythmia recurrence. Importantly, there was no signal for increased harm with a HPSD strategy.

Importance:Recurrent atrial fibrillation (AF) commonly occurs after catheter ablation and is associated with patient morbidity and health care costs. Objective:To evaluate the superiority of an augmented double wide-area circumferential ablation (WACA) compared with a standard single WACA in preventing recurrent atrial arrhythmias (AA) (atrial tachycardia, atrial flutter, or atrial fibrillation [AF]) in patients with paroxysmal AF. Design, Setting, and Participants:This was a pragmatic, multicenter, prospective, randomized, open, blinded end point superiority clinical trial conducted at 10 university-affiliated centers in Canada. The trial enrolled patients 18 years and older with symptomatic paroxysmal AF from March 2015 to May 2017. Analysis took place between January and April 2022. Analyses were intention to treat. Interventions:Patients were randomized (1:1) to receive radiofrequency catheter ablation for pulmonary vein isolation with either a standard single WACA or an augmented double WACA. Main Outcomes and Measures:The primary outcome was AA recurrence between 91 and 365 days postablation. Patients underwent 42 days of ambulatory electrocardiography monitoring after ablation. Secondary outcomes included need for repeated catheter ablation and procedural and safety variables. Results:Of 398 patients, 195 were randomized to the single WACA (control) arm (mean [SD] age, 60.6 [9.3] years; 65 [33.3%] female) and 203 to the double WACA (experimental) arm (mean [SD] age, 61.5 [9.3] years; 66 [32.5%] female). Overall, 52 patients (26.7%) in the single WACA arm and 50 patients (24.6%) in the double WACA arm had recurrent AA at 1 year (relative risk, 0.92; 95% CI, 0.66-1.29; P = .64). Twenty patients (10.3%) in the single WACA arm and 15 patients (7.4%) in the double WACA arm underwent repeated catheter ablation (relative risk, 0.72; 95% CI, 0.38-1.36). Adjudicated serious adverse events occurred in 13 patients (6.7%) in the single WACA arm and 14 patients (6.9%) in the double WACA arm. Conclusions and Relevance:In this randomized clinical trial of patients with paroxysmal AF, additional ablation by performing a double ablation lesion set did not result in improved freedom from recurrent AA compared with a standard single ablation set. Trial Registration:ClinicalTrials.gov Identifier: NCT02150902.

Background Recurrence of atrial fibrillation (AF) after a pulmonary vein isolation procedure is often due to electrical reconnection of the pulmonary veins. Repeat ablation procedures may improve freedom from AF but are associated with increased risks and health care costs. A novel ablation strategy in which patients receive "augmented" ablation lesions has the potential to reduce the risk of AF recurrence. Objective The Augmented Wide Area Circumferential Catheter Ablation for Reduction of Atrial Fibrillation Recurrence (AWARE) Trial was designed to evaluate whether an augmented wide-area circumferential antral (WACA) ablation strategy will result in fewer atrial arrhythmia recurrences in patients with symptomatic paroxysmal AF, compared with a conventional WACA strategy. Methods/Design The AWARE trial was a multicenter, prospective, randomized, open, blinded endpoint trial that has completed recruitment (ClinicalTrials.gov NCT02150902). Patients were randomly assigned (1:1) to either the control arm (single WACAlesion set) or the interventional arm (augmented- double WACA lesion set performed after the initial WACA). The primary outcome was atrial tachyarrhythmia (AA; atrial tachycardia [AT], atrial flutter [AFl] or AF) recurrence between days 91 and 365 post catheter ablation. Patient follow-up included 14-day continuous ambulatory ECG monitoring at 3, 6, and 12 months after catheter ablation. Three questionnaires were administered during the trial- the EuroQuol-5D (EQ-5D) quality of life scale, the Canadian Cardiovascular Society Severity of Atrial Fibrillation scale, and a patient satisfaction scale. Discussion The AWARE trial was designed to evaluate whether a novel approach to catheter ablation reduced the risk of AA recurrence in patients with symptomatic paroxysmal AF.

Purpose/Objective(s) Ventricular tachycardia (VT) is characterized by electrical re-entry within patches of heterogeneous myocardial fibrosis leading to sustained consecutive ventricular beats at a rate > 100 per minute. Catheter ablation is the standard of care adjunctive therapy for patients who are refractory to medical therapy to destroy the pathways responsible for these arrhythmias. Recently, a novel treatment approach using ablative radiation with stereotactic body radiation therapy (SBRT) to the arrhythmogenic scar regions defined by noninvasive cardiac mapping has been described for patients refractory to standard-of-care therapies. We describe our experience with 6 patients treated with this technique in our institution. Materials/Methods All 6 patients had refractory VT with previously failed ablations and at least one anti-arrhythmic drug. Patients were simulated with 4D computed tomography (4D-CT) and targets were defined using the combined information from cardiac mapping, diagnostic and simulation imaging with cardiologists, medical physicists, and radiation oncologists for each patient. An internal target volume was created based on the cardiac and respiratory motion. An isotropic margin of 3 mm was added to create the planning target volume (PTV). The PTVs were prescribed 25 Gy in 1 fraction normalized so 95% of the PTV was covered by the 25 Gy isodose. Radiation was delivered using volumetric modulated arc therapy. Patients were evaluated immediately following treatment for acute side effects, and then at 6 weeks, 3 months, 6 months, and then yearly. Implantable cardioverter defibrillator (ICD) interrogation was performed regularly by the treating cardiologist to assess the number of VT and ICD events. Results All 6 patients tolerated treatment with no immediate acute side effects. One patient experienced mild esophagitis in the first 3 weeks following treatment which resolved. 4 of 6 patients had immediate significant reduction in the number of VT and ICD events in the first 6 months after treatment (>90%), however, one patient did not respond and required an extracorporeal membrane oxygenation assisted ablation 3 months later. The first two patients treated have had longer follow-up and one remains VT-free and has stopped anti-arrhythmic drugs, however, another has relapsed 2 years following radiotherapy in an area of the arrhythmogenic substrate that was intentionally not irradiated due to organ at risk safety concerns. Conclusion Despite increasing reports in the literature, there are no established criteria to predict success for this treatment, making it difficult to identify optimal patients. Current limited evidence suggests that this technique may be a relatively safe approach that provides an acute reduction in VT burden for those that have run out of conventional treatment options.

Purpose/Objective(s)Ventricular tachycardia (VT) is characterized by electrical re-entry within patches of heterogeneous myocardial fibrosis leading to sustained consecutive ventricular beats at a rate > 100 per minute. Implantable cardioverter-defibrillators (ICD) are the main intervention for reducing mortality, however, they are exclusively a symptom-control therapy. Catheter ablation is the standard of care adjunctive therapy for patients who are refractory to medical therapy. Recently, a treatment approach with a stereotactic body radiation therapy (SBRT) to arrhythmogenic scar regions has been described. Initial results, using a single 25 Gy fraction, suggest this technique may improve morbidity for patient's refractory to standard of care therapy. The optimal dose for this therapy remains unclear and major adverse events with 25 Gy have been reported. This clinical trial hypothesizes that refractory VT treated with SBRT in a single fraction of 20 Gy is non-inferior to 25 Gy.Materials/MethodsInclusion criteria are age > 18 years, cardiomyopathy, recurrent episodes of monomorphic VT failing standard treatment with at least 1 antiarrhythmic drug and previous electrophysiologic ablation. Exclusion criteria are participants with previous thoracic radiation, connective tissue disease, interstitial pulmonary fibrosis, and pregnancy. Participants with contraindications to electrophysiology studies may be eligible for the study, provided the arrhythmic substrate can be defined through other non-invasive methods. We anticipate an incidence rate of approximately 5 VT events per person-year in participants treated with 25 Gy as a historical comparator based on a previous phase I/II trial. Based on a Poisson distribution, and using a non-inferiority margin of 8.5 events per-year (incident rate ratio of 1.70), recruiting 9 participants will provide 80% power when using a one-sided type I error, set at 0.05. Non-inferiority of 20 Gy relative to 25 Gy will be determined if the upper bound of the one-sided 95% confidence interval for the incidence rate ratio is below the pre-specified non-inferiority margin (incidence rate ratio=1.70). The primary efficacy endpoint is the reduction in arrhythmia burden measured by the total number of VT events and ICD treatments for VT comparing the 6 and 12-month periods after a single fraction of 20 Gy SBRT with a single fraction of 25 Gy in the published literature. Our primary safety endpoint is defined as the rate of severe treatment-related adverse events at ≤ 90 days as defined by the CTCAE v5.0. Secondary endpoints include overall survival, late adverse events, antiarrhythmic drug use, and quality of life.ResultsThe Research Ethics Board at the institution has approved this research study and will provide ongoing ethical oversight.ConclusionThis study is currently recruiting participants. This trial is registered at ClinicalTrials.gov, NCT05258422.

Purpose: Patients with right bundle branch block (RBBB) are less likely to respond to cardiac resynchronization therapy (CRT). We aimed to assess whether patients with RBBB respond to CRT with biventricular fusion pacing. Methods: Consecutive patients with RBBB at a single tertiary care center, who were implanted with a CRT device capable of biventricular fusion pacing using SyncAV programming, were assessed and compared to a historical cohort of CRT patients with RBBB. QRSd was measured and compared during intrinsic conduction, nominal CRT pacing and manual electrocardiogram-based optimized SyncAV programming. Left ventricular ejection fraction (LVEF) was also compared before and 6 months after CRT. Results: We included 8 consecutive patients with RBBB (group 1) who were able to undergo SyncAV programming and 16 patients with RBBB (group 2) from a historical cohort. In group 1, compared to mean intrinsic conduction QRSd (155 +/- 13 ms), mean nominally-paced QRSd was 156 +/- 15 ms (Delta QRSd 1.3 +/- 11.6; p = 0.77) and SyncAV-optimized paced QRSd was 135 +/- 14 ms (Delta QRSd -20.0 +/- 20.4; p = 0.03 and Delta QRSd -21.3 +/- 16.3; p = 0.008; compared to intrinsic conduction and nominal pacing respectively). In group 2, mean QRSd with nominal pacing was 160 +/- 24 ms (Delta QRSd 3.8 +/- 33.4; p = 0.66 compared to intrinsic conduction). In group 1, baseline LVEF was 22.1 +/- 11.5 and after 6 months of follow-up was 27.8 +/- 8.6 (p = 0.047). In group 2, the baseline LVEF was 27.2 +/- 10.6 and after 6 months of follow-up was 25.0 +/- 10.0 (p = 0.45). Conclusions: CRT programed to allow biventricular fusion pacing significantly improved electrical synchrony and LVEF in patients with RBBB. Larger studies are required to confirm these findings. (C) 2020 Elsevier Inc. All rights reserved.

Pulmonary vein (PV) isolation for the treatment of atrial fibrillation (AF) is a safe and effective intervention. Most recurrences post ablation are due to reconnection of a PV, highlighting the importance of a robust assessment of PV isolation.