BACKGROUND: Left bundle branch area pacing (LBBAP) may be associated with greater improvement in left ventricular ejection fraction and reduction in death or heart failure hospitalization compared with biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy. We sought to compare the occurrence of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and new-onset atrial fibrillation (AF) in patients undergoing BVP and LBBAP. METHODS: The I-CLAS study (International Collaborative LBBAP Study) included patients with left ventricular ejection fraction ≤35% who underwent BVP or LBBAP for cardiac resynchronization therapy between January 2018 and June 2022 at 15 centers. We performed propensity score–matched analysis of LBBAP and BVP in a 1:1 ratio. We assessed the incidence of VT/VF and new-onset AF among patients with no history of AF. Time to sustained VT/VF and time to new-onset AF was analyzed using the Cox proportional hazards survival model. RESULTS: Among 1778 patients undergoing cardiac resynchronization therapy (BVP, 981; LBBAP, 797), there were 1414 propensity score–matched patients (propensity score–matched BVP, 707; propensity score–matched LBBAP, 707). The occurrence of VT/VF was significantly lower with LBBAP compared with BVP (4.2% versus 9.3%; hazard ratio, 0.46 [95% CI, 0.29–0.74]; P 3 episodes in 24 hours) was also significantly lower with LBBAP compared with BVP (0.8% versus 2.5%; P =0.013). Among 299 patients with cardiac resynchronization therapy pacemakers (BVP, 111; LBBAP, 188), VT/VF occurred in 8 patients in the BVP group versus none in the LBBAP group (7.2% versus 0%; P 30 s was significantly lower with LBBAP than with BVP (2.8% versus 6.6%; hazard ratio, 0.34 [95% CI, 0.16–0.73]; P =0.008). The incidence of AF lasting >24 hours was also significantly lower with LBBAP than with BVP (0.7% versus 2.9%; P =0.015). CONCLUSIONS: LBBAP was associated with a lower incidence of sustained VT/VF and new-onset AF compared with BVP. This difference remained significant after adjustment for differences in baseline characteristics between patients with BVP and LBBAP. Physiological resynchronization by LBBAP may be associated with lower risk of arrhythmias compared with BVP.

Aims: Prolonged right ventricular pacing (RVP) increases the risk of cardiomyopathy, atrial fibrillation, heart failure (HF), and mortality. This registry-based trial compared left bundle branch area pacing (LBBAP) with RVP in patients younger than 65 years. Methods and results: Using the ConTempoRary Cardiac Stimulation in Clinical practicE: lEft, BivEntriculAr, Right, and conDuction System Pacing (TREEBEARD) registry (NCT06324682), patients were randomized 1:1 to LBBAP or RVP. The primary endpoint was a composite of cardiovascular (CV) death and HF hospitalization (HFH); secondary endpoints included individual components and all-cause mortality. A total of 344 patients (mean age 58.5 years, 215 males, 172 per arm) were included. At 2 years, the primary composite endpoint occurred in 6.3% of LBBAP vs. 12.7% of RVP patients (HR, 0.78; 95% CI, 0.59–0.87), representing a 22% risk reduction. Subgroup analyses aligned with primary findings. Left bundle branch area pacing significantly reduced HFH risk (HR, 0.79; 95% CI, 0.63–0.86) but showed no difference in CV mortality (HR, 1.02; 95% CI, 0.79–1.32) or all-cause mortality (HR, 1.00; 95% CI, 0.72–1.38). Conclusion: Left bundle branch area pacing significantly lowered the 2-year composite of CV death and HFH compared to RVP in patients aged <65 years old. However, it did not reduce CV or all-cause mortality individually compared to RVP. Clinical Trial Registration: TREEBEARD (NCT06324682)

Background: Sudden cardiac arrest (SCA) may be caused by an acute and reversible myocardial injury, a chronic and irreversible myocardial damage, or a primary ventricular arrhythmia. Cardiac magnetic resonance imaging may identify myocardial edema (ME), which denotes acute and reversible myocardial damage. We evaluated the arrhythmic outcome of SCA survivors during follow‐up and tested the prognostic role of ME. Methods and Results: We included a consecutive series of 101 (71% men, median age 47 years) SCA survivors from 9 collaborative centers who underwent early (<1 month) cardiac magnetic resonance imaging and received an implantable cardioverter‐defibrillator (ICD). On T2‐weighted sequences, ME was found in 18 of 101 (18%) patients. According to cardiac magnetic resonance imaging findings, the arrhythmic SCA was ascribed to acute myocardial injury (either ischemic [n=10] or inflammatory [n=8]), to chronic structural heart diseases (ischemic heart disease [n=11], cardiomyopathy [n=20], or other [n=23]), or to primarily arrhythmic syndrome (n=29). During a follow‐up of 47 months (28 to 67 months), 24 of 101 (24%) patients received an appropriate ICD intervention. ME was associated with a significantly higher survival free from both any ICD interventions (log‐rank=0.04) and ICD shocks (log‐rank=0.03) and remained an independent predictor of better arrhythmic outcome after adjustment for left ventricular ejection fraction and late gadolinium enhancement. The risk of appropriate ICD intervention was unrelated to the type of underlying heart disease. Conclusions: ME on early cardiac magnetic resonance imaging, which denotes an acute and transient arrhythmogenic substrate, predicted a favorable long‐term arrhythmic outcome of SCA survivors. These findings may have a substantial impact on future guidelines on the management of SCA survivors.

Aims: Reliable vascular access and haemostasis techniques are important to the safety of electrophysiology (EP) procedures. This European Heart Rhythm Association (EHRA) survey aimed to evaluate contemporary vascular access site management practices across international EP centres. Methods and results: A 30-question survey was disseminated via the EHRA between March and April 2025, with 401 responses from professionals across 51 countries. Most respondents were cardiology consultants/attendings (82.0%), with 57.3% performing over 150 EP procedures annually. Ultrasound guidance for vascular access was usually or always used by 71.7%, though 21.4% used it rarely or never, and only 17.3% had received formal ultrasound training. Institutional protocols for haemostasis were lacking in around half (46.8%) of centres. Suture-mediated closure was the most common method for haemostasis (60.4%), followed by manual compression (33.0%) and vascular closure devices (VCDs, 5.8%). The figure-of-eight suture with a hand-tied knot was the most frequently used suture technique (79.7%). Just over a third (36.0%) had experience with VCDs, typically reserved for high-risk cases. For procedures requiring transeptal access, 38.1% administered heparin before transeptal puncture, while protamine was rarely or never used by 62.1%. Anticoagulation was partially interrupted in 52.1% and continued uninterrupted in 41.1% of routine atrial fibrillation (AF) ablations. The median bed rest duration post-procedure ranged from 4 h (right-sided EP procedures) to 6 h (AF or left-sided EP procedures). The average quoted vascular complication risk during consent was 3% (inter-quartile range 1–5%). Conclusion: This survey highlights marked variation in vascular access site management during and following EP procedures, emphasizing the need for further clinical trials to inform best practice and guide future standardization efforts.