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Background: Left bundle branch area pacing (LBBAP) has emerged as a physiological alternative pacing strategy to biventricular pacing (BIVP) in cardiac resynchronization therapy (CRT). We aimed to assess the impact of LBBAP vs. BIVP on all-cause mortality and heart failure (HF)-related hospitalization in patients undergoing CRT., Methods: Studies comparing LBBAP and BIVP for CRT in patients with HF with reduced left ventricular ejection fraction (LVEF) were included. The coprimary outcomes were all-cause mortality and HF-related hospitalization. Secondary outcomes included procedural and fluoroscopy time, change in QRS duration, and change in LVEF., Results: Thirteen studies (12 observational and 1 RCT, n = 3239; LBBAP = 1338 and BIVP = 1901) with a mean follow-up duration of 25.8 months were included. Compared to BIVP, LBBAP was associated with a significant absolute risk reduction of 3.2% in all-cause mortality (9.3% vs 12.5%, RR 0.7, 95% CI 0.57-0.86, p < 0.001) and an 8.2% reduction in HF-related hospitalization (11.3% vs 19.5%, RR 0.6, 95% CI 0.5-0.71, p < 0.00001). LBBAP also resulted in reductions in procedural time (mean weighted difference- 23.2 min, 95% CI - 42.9 to - 3.6, p = 0.02) and fluoroscopy time (- 8.6 min, 95% CI - 12.5 to - 4.7, p < 0.001) as well as a significant reduction in QRS duration (mean weighted difference:- 25.3 ms, 95% CI - 30.9 to - 19.8, p < 0.00001) and a greater improvement in LVEF of 5.1% (95% CI 4.4-5.8, p < 0.001) compared to BIVP in the studies that reported these outcomes., Conclusion: In this meta-analysis, LBBAP was associated with a significant reduction in all-cause mortality as well as HF-related hospitalization when compared to BIVP. Additional data from large RCTs is warranted to corroborate these promising findings., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: In vitro models to evaluate cardiac pulsed field ablation (PFA) have not been well established. We sought to create a standardized vegetable model and staining protocol for assessing unipolar PFA using a surface electrode., Methods: We exposed potato slabs to unipolar PFA in a saline bath using a 3.5 mm electrode catheter and grounding pad connected to a custom-built high-voltage generator. Lesions were clearly visualized after staining with 2,3,5-triphenyltetrazolium chloride (TTC) using a timed protocol to reveal a necrotic center and a periphery of electroporated cells with intact mitochondria., Results: Lesion volume increased linearly with increasing voltage and logarithmically with repetitive PFA applications., Conclusion: The findings observed in this vegetable model using a TTC staining protocol are consistent with findings observed with cardiomyocytes., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Purpose: Targets for substrate-based catheter ablation of scar-related ventricular tachycardia (VT) include sites with fractionated and late potentials (LPs). We hypothesized that in patients with cardiac resynchronization therapy (CRT), the pacing mode may influence the timing of abnormal electrograms (EGMs) relative to the surface QRS complex., Methods: We assessed bipolar EGM characteristics in left ventricular low bipolar voltage areas (< 1.5 mV) from 10 patients with coronary disease and a CRT device undergoing catheter ablation for VT. EGMs at 81 sites were analyzed during three different pacing modes (biventricular (BiV), right ventricular (RV)-only, and left ventricular (LV)-only) pacing., Results: Stimulus to end of local electrogram duration (Stim-to-eEGM) depended significantly on the stimulation site (BiV, LV, or RV, p = 0.032). Single-chamber pacing unmasked LPs, not present during BiV pacing, in three patients. In another three patients, a concomitant increase in stimulus to end of surface QRS duration caused by single-site pacing compensated for the increase in Stim-to-eEGM duration, thereby prohibiting LP unmasking., Conclusion: The sequence of ventricular activation, as determined by the pacing site in patients with CRT devices, has a major influence on the detection of late potentials during substrate-guided ablation. Further study is warranted to define the optimal approaches, including the rhythm, for substrate mapping, but our findings suggest that BiV pacing may be most likely to obscure detection of late potentials as compared to single-site pacing.

Purpose: Cardiomyopathies frequently lead to conduction system disease and/or arrhythmias necessitating device therapy, catheter ablation, or both. Endomyocardial biopsy (EMB) is avoided with recent right ventricle (RV) lead implants and optimal timing is uncertain. We determined outcomes of EMB at the time of ablation or device implantation procedures., Methods: We retrospectively analyzed patients undergoing EMB during their electrophysiological procedure between January 2014 and July 2016. EMB was obtained using cephalic/subclavian access prior to device implants or femoral venous/arterial access after ablation procedures. Sites of electrogram (EGM) abnormality and/or scar on imaging were targeted when possible., Results: Twenty-five patients (23 male, 59.7 ± 15.1 years) were included. Sixteen had reduced ejection fraction. EMB was performed during device implants in 9, during ablation in 13, and during combined procedures in 3 patients. RV and left ventricle (LV) EMB were obtained in 19 and 6 patients, respectively. 3.9 ± 1.8 samples/patient (median 4) were obtained. EMB yielded a diagnosis in 7 (28%, all RV) patients (4 cardiac implantable electronic device implantation, 2 ablation, and 1 both): cardiac amyloid in 4, lymphocytic myocarditis in 2, and cardiac sarcoid in 1. All 7 patients had imaging or voltage abnormalities in the chamber biopsied. Abnormal but non-diagnostic findings, most commonly fibrotic change, were found in 14 patients. At mean follow-up of 1.1 ± 0.9 years, 5 other patients received a clinical diagnosis (3 cardiac sarcoid, 1 arrhythmogenic cardiomyopathy, and 1 Brugada syndrome/arrhythmogenic cardiomyopathy overlap syndrome). Two patients developed minor device pocket hematomas and one developed pericardial effusion (underwent concomitant epicardial mapping and ablation for VT)., Conclusions: RV or LV EMB can be performed safely during EP procedures and can assist with diagnosis, influencing management. EGM-guided EMB in patients presenting with scar-related VT was low yield for specific pathologies.

Background: Atrial fibrillation (AF) and cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) are two separate entities that coexist in a significant percentage of patients. We sought to investigate whether AF inducibility during CTI AFL ablation predicted the occurrence of AF at follow-up after successful AFL ablation., Methods: A systemic review of Medline, Cochrane, and Embase was done for all the clinical studies in which assessment of AF inducibility in patients undergoing ablation for CTI AFL was performed. Given the low heterogeneity (i.e., I 2 <25), we used a fixed effect model for our analysis., Results: A total of 10 studies (4 prospective and 6 retrospective) with a total of 1299 patients (male, 73%; mean age 59 ± 11 years) fulfilled the inclusion criteria. During a mean follow-up period of 23 ± 7.6 months, 407 patients (31%) developed AF during AFL ablation. The overall incidence for new-onset AF during follow-up was 29% (47% in the group with inducible AF vs. 21% in the non-inducible group). The odds ratio (OR) for developing AF after AFL ablation in patients with AF inducibility for all studies combined was 3.72, 95% CI 2.83-4.89 [prospective studies (OR 5.52, 95% CI 3.23-9.41) vs. retrospective studies (OR 3.23, 95% CI 2.35-4.45)]., Conclusions: Although ablation for CTI AFL is highly effective, AF continues to be a long-term risk for individuals undergoing this procedure. AF induced by pacing protocols in patients undergoing CTI AFL predicts for future AF. Inducible AF is a clinically relevant finding that may help guide decisions for long-term anticoagulation after successful typical AFL ablation especially in patients with elevated CHADS-VASc scores (≥2) and in considering prophylactic PVI during CTI AFL ablation.