Bi-PESA may offer a feasible and potentially preferable alternative for patients with HOCM who decline or are ineligible for surgical myectomy or alcohol septal ablation.

Ambient temperature has been recognized as an environmental trigger for adverse cardiovascular events. However, its association with ventricular arrhythmias (VAs) in patients with implantable cardioverter-defibrillators (ICDs) remains understudied, particularly in China. We conducted a time-stratified case-crossover study among a cohort of patients with ICDs from 2019 to 2024. Conditional logistic regression models, integrated with restricted cubic splines, distributed lag nonlinear models, and distributed lag linear models, were used to estimate the association between ambient temperature and the occurrence of VAs, adjusting for relative humidity and public holidays. A total of 322 VA events were identified among 1053 patients with ICDs. Only extremely high ambient temperatures were significantly associated with increased probabilities of VA events, which increased by 180% (OR = 2.80, 95% CI: 1.08-7.28) over 1 day and 196% (OR = 2.96, 95% CI: 1.06-8.30) over 2 days compared with the incidence at reference temperatures. Subgroup analyses suggested that females, older patients, and those residing in the monsoon climate zone might be more susceptible to high-temperature risks. This investigation into the role of ambient temperature in VAs in patients with ICDs provides insights into its highly complex relationships and emphasizes the need for additional research and public health interventions.

Background For patients with a high risk of sudden cardiac death, despite the benefits of an implantable cardioverter defibrillator (ICD), some patients are still at high risk of death.Aim The purpose of this study was to develop and validate a nomogram predicting all-cause mortality for patients with an ICD.Methods We retrospectively analysed the data of multicentre ICD registration study from 2010 to 2014 in China. A total of 617 ICD patients formed a development cohort. The physical activity monitored by ICD and clinical data was collected. Univariate and multivariate Cox regression analyses were used to screen mortality predictors and construct the nomogram. The performance of the nomogram was evaluated by the consistency index (C-index) and the calibration curve. Additionally, extensive subgroup and sensitivity analyses were conducted to evaluate the model’s robustness. A total of 196 ICD patients formed a validation cohort.Results In the development cohort, physical activity, diabetes and left ventricular end-diastolic diameter were selected as independent prognostic factors. The nomogram was constructed by these three factors. The C-index of the nomogram was 0.80 (95% CI 0.75 to 0.84). The calibration curve showed that the predicted survival probability of the nomogram was in good agreement with the actual survival probability. In the validation cohort, the C-index of the nomogram was 0.74 (95% CI 0.64 to 0.84), and the calibration curve still maintained good consistency. Crucially, the nomogram maintained stable and excellent discriminative capacity across primary and secondary prevention subgroups, as well as for predicting specific cardiac and sudden cardiac death.Conclusions Our study develops and validates a nomogram predicting all-cause mortality for patients with an ICD by integrating the physical activity monitored by ICD and clinical data. The nomogram performs well and can provide personalised death risk assessment for ICD patients.Trial registration number ChiCTR-ONRC-13003695.

Bachmann bundle, which connects the left and right atria, serves as the preferential pathway for interatrial electrical conduction. Conduction disorder within this bundle is an important mechanism of interatrial block and is closely related to the initiation and progression of atrial fibrillation. Bachmann bundle pacing can improve interatrial conduction delay, restore atrial synchrony, and reduce the risk of atrial fibrillation in some observational studies. Although Bachmann bundle pacing has certain clinical application prospects, its identification criteria need to be further clarified. This article reviews the research progress on Bachmann bundle and Bachmann bundle pacing, so as to provide a reference for future studies.

Background The Aveir leadless pacemaker employs an active fixation method, enabling real-time monitoring of electrical parameters during implantation. However, comprehensive studies regarding the electrical parameters during this procedure are rare. Objective This study aims to analyze the electrical characteristics to further guide the implantation strategy and improve device stability and safety. Methods This multi-center retrospective study enrolled 119 patients (mean age 70.18 years; 59.58% female) who received the Aveir VR leadless pacemaker from November 2024 to May 2025 across ten centers in China. Intraprocedural variations in commanded electrogram (CEGM), current of injury (COI), impedance, pacing threshold, and sensing parameters were meticulously documented. Results CEGM mapping demonstrated various morphologies (R, RS, QR, QRS, and QS) aiding localization. During fixation, 58.82% of patients exhibited an increased COI from mapping to 0.5 turns, which was associated with reduced short-term pacing thresholds. From 0.5 to 1 turn, 52.94% showed further COI increases. ROC analysis revealed that an impedance increase has predictive value for short-term pacing thresholds, with an AUC of 0.634 and a cut-off value of 230 Ω (sensitivity 0.622, specificity 0.41). Lead stability showed a moderate correlation with impedance increase (ρ=0.44, P<0.001), while the correlation with COI was weak. Conclusion During Aveir implantation, CEGM variations guide site localization. Initial COI increases (0-0.5 turns) are linked to optimal short-term thresholds. Monitoring impedance increase is vital, as a threshold of 230 Ω serves as a key indicator of device stability and fixation quality. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial Not applicable. ### Funding Statement This research was funded by a grant from the Fundamental Research Funds for the Central Universities (Grant No. #3332024039). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All patients provided written informed consent. The present study was approved by the Ethics Committee of Fuwai hospital I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Datasets used or analyzed during the current study are available from the corresponding author on reasonable request.

Background Increasing evidence shows sex-specific differences in the efficacy of cardiac resynchronization therapy (CRT). Without a clear cardiac rationale, relying solely on sex to evaluate resynchronization outcomes is insufficient. Objectives This study sought to assess whether QRS duration (QRSd) normalized to cardiac size (QRSd/left ventricular end-diastolic dimension [QRSd/LVEDD]) could underlie the observed sex-specific differences in resynchronization efficacy and guide CRT implantation. Methods This multicenter retrospective study screened 602 patients with heart failure who underwent biventricular or left bundle branch area pacing for resynchronization therapy. The primary composite outcome included all-cause mortality, heart failure hospitalizations, and ventricular tachyarrhythmic events. Interaction analysis and structural equation modeling were applied to evaluate whether QRSd/LVEDD could independently predict outcomes and elucidate sex-specific differences. Results Compared with male patients, female patients (n = 216) had a higher QRSd/LVEDD ratio (2.66 vs 2.48; P < 0.001). After QRSd/LVEDD adjustment, female patients no longer exhibited greater left ventricular ejection fraction improvement. Sex-specific differences initially observed in clinical outcomes (HR: 1.71; 95% CI: 1.17-2.48; P = 0.005) were eliminated by QRSd/LVEDD (HR: 1.14; 95% CI: 0.76-1.69; P = 0.527), with a significant dose-response relationship (P < 0.001). QRSd/LVEDD also stratified prognosis within each sex group (P < 0.001). No sex-specific differences were found among patients with the same QRSd/LVEDD (QRSd/LVEDD ≥2.55, P = 0.744; QRSd/LVEDD <2.55, P = 0.123). Structural equation modeling revealed that sex did not directly influence clinical outcomes (P = 0.693) but exerted an indirect effect through QRSd/LVEDD (P < 0.001). QRSd/LVEDD exhibited superior ability to predict clinical outcomes compared with QRSd and was integrated into machine learning modeling for individualized CRT risk prediction. Conclusions QRSd/LVEDD effectively eliminated sex-specific differences in CRT efficacy and outperformed QRSd in predicting clinical outcomes. Sex did not directly influence CRT outcomes but mediated its effect indirectly through QRSd/LVEDD.

Background: The triglyceride-to-high-density lipoprotein cholesterol ratio (TG/HDL-c) has been linked to cardiovascular risk. However, its association with device-detected atrial high-rate episodes (AHRE) remains unclear. This study aimed to explore the relationships of TG/HDL-c with incident AHRE and mortality. Methods: This retrospective cohort study included patients implanted with pacemakers equipped with home-monitoring capability and without previous atrial fibrillation, atrial flutter, or atrial tachycardia. AHRE were defined as episodes with a burden exceeding 15 minutes during follow-up. The primary endpoint was AHRE, and the secondary endpoints were all-cause mortality and cardiovascular mortality. Findings: During a mean follow-up of 75.8±16.8 months, AHRE occurred in 303 of 1,463 patients (21.1%). Restricted cubic spline analysis revealed a significant U-shaped nonlinear association of TG/HDL-c ratio with AHRE, all-cause mortality and cardiovascular mortality (all P<0.001 for overall, all P<0.05 for nonlinearity). Multivariable Cox analysis showed that TG/HDL-c was independently and inversely associated with AHRE (hazard ratio [HR] 0.878, 95% confidence interval [CI] 0.771–0.999, P=0.049). As a category variable, compared with the low TG/HDL-c group, the moderate (HR 0.654, 95% CI 0.486–0.881, P=0.005) and high (HR 0.726, 95% CI 0.542–0.973, P=0.032) groups had significantly lower AHRE risk. Notably, the moderate group exhibited the lowest risk for all-cause and cardiovascular mortality. Interpretation: In pacemaker patients undergoing continuous home monitoring, lower TG/HDL-c was independently associated with a higher long-term risk of incident AHRE, and the association was non-linear. TG/HDL-c may serve as an accessible metabolic marker for AHRE risk stratification in this population. Further prospective studies are required to validate these findings and clarify the observed associations with mortality.

Background Recurrent atrial tachyarrhythmia (AT) remains a major challenge following catheter ablation for atrial fibrillation (AF). While pulmonary vein (PV) reconnection is a well-recognized mechanism, the contribution of lesion heterogeneity to iatrogenic AT is not clearly defined.Objective To analyze the clinical characteristics of recurrent AT caused by ablation-induced focal potentials.Methods We retrospectively analyzed 113 patients who underwent repeat ablation for recurrent AT. Mechanisms of AT recurrence were identified using high-resolution electroanatomic mapping and categorized into five types. Nonuniform ablation-related AT-considered iatrogenic-was defined as focal or localized reentrant ATs arising from regions of prior ablation.Results Gap conduction was the most common mechanism of recurrence (51.3%), followed by other mechanisms (27.4%) and nonuniform ablation-related AT (14.2%). The number of reconnected PVs was not significantly associated with the timing of all-mechanism recurrence. Nonuniform ablation-related ATs frequently presented as a combination of AF and atrial flutter (AFL), whereas gap-related recurrence typically manifested as AF.Conclusion Lesion homogeneity plays a critical role in minimizing iatrogenic ATs, highlighting the importance of ablation strategies that optimize both electrical isolation and lesion quality. These findings offer insights for the refinement of ablation techniques and the development of improved catheter technologies.

Background:Sudden cardiac death (SCD) is associated with severe electrocardiogram (ECG) abnormalities. Current prediction relies heavily on static ECG parameters, limiting accuracy. This study aimed to explore dynamic ECG parameters, particularly the S-wave area and its circadian variations, as novel markers for SCD risk prediction. Methods:All participants were divided into three different SCD risk groups based on their disease status at the time of enrollment. Dynamic single-lead ECG data was collected continuously for 24 hours and segmented into 1,440 one-minute intervals with time information tags from 0:00 to 24:00. Forty-two ECG parameters, including the S-wave area, were analyzed. Randomly selected 70% of the samples from Sun Yat-sen Memorial Hospital to construct training set and remaining samples to construct independent test set. Student's t-test was used to compare the expression differences of ECG parameters in different SCD risks patients at different time points within a day. Repeatedly attempted to establish multivariate logistics regression models combining different time points and ECG parameters and performed five-fold cross validation sequentially. Selected time point-ECG parameter combined model with the highest AUC to conduct further univariate logistic regression and calculate odds ratio (OR) of each time point-ECG parameter combination. Results:From September 2017 to December 2020, 289 participants were enrolled: 43 at high risk of SCD (SCDHR), 138 with heart failure (HF), and 108 healthy controls (HC). Significant circadian variations in ECG parameters were observed. In the SCDHR group, key parameters significantly increased during 16:00-22:00, while the HF group showed distinct changes from 21:00-06:00. Logistic regression achieved robust performance in distinguishing groups: SCDHR vs. HC (AUC =0.887 training; AUC =0.747, accuracy =0.755, precision =0.800 test), SCDHR vs. HF (AUC =0.857 training; AUC =0.714, accuracy =0.681, precision =0.280 test) and HF vs. HC (AUC =0.965 training; AUC =0.842, accuracy =0.704, precision =0.867 test). Decision curve analysis and calibration curve showed good clinical performance of three logistics models for each comparison pair. Conclusions:Dynamic ECG parameters, especially time-dependent variations in the S-wave area, were strongly associated with the SCD risk. They may develop into promising markers enhancing predictive accuracy for SCD stratification after further large-scale and prospective validation.

To investigate the relationship between abdominal obesity and long-term prognosis in patients with a pacemaker. In the SUMMIT Study, patients were categorized by baseline waist circumference into obesity, normal, and lean groups. WC was measured at the midpoint between the last rib and hip bone after exhalation. Regular follow-ups were conducted, with all-cause mortality as the primary endpoint and cardiac death as the secondary endpoint. In total, 492 patients were included in the analysis. The average baseline waist circumference was 84.2 ± 12.7 cm, and abdominal obesity was observed in 37.6

INTRODUCTION:Left bundle branch area pacing (LBBAP) is an emerging strategy for cardiac resynchronization therapy (CRT), but its implementation in heart failure patients remains challenging. This study aimed to assess whether the initial V6 R-wave peak time (V6RWPT) during right ventricular septal pacing (RVSP) for lead localization can predict successful LBBAP implantation. METHODS AND RESULTS:Consecutive patients with left bundle branch block (LBBB) and left ventricular ejection fraction (LVEF) < 50% who met CRT indications were included. Clinical, echocardiographic, and electrocardiographic variables were collected. Among 99 patients enrolled in the study, the success rates for LBBAP and LBBP were 73.7% and 63.6%, respectively. Multivariate regression analysis revealed that baseline Strauss LBBB (OR:5.04, 95% CI:1.45-17.54, p = 0.011) and shorter RVSP V6RWPT (per 10 ms, OR:0.42, 95% CI:0.29-0.59, p < 0.001) had a greater likelihood of successful LBBAP. RVSP V6RWPT (cutoff: 145 ms) yielded the highest area under the curve (AUC:0.888), significantly outperforming LVEDD (AUC:0.721), LAD (AUC:0.709), baseline Strauss LBBB (AUC:0.694), and baseline QRSd (AUC:0.629) (all p < 0.01). Among 56 patients who underwent cardiac magnetic resonance imaging, RVSP V6RWPT correlated significantly with both global (r = 0.592, p < 0.001) and septal scar percentages (r = 0.598, p < 0.001). CONCLUSION:V6RWPT during RVSP is a novel predictor of successful LBBAP implantation in heart failure patients with LBBB. This marker demonstrates strong predictive value and correlates with cardiac scar burden. The RVSP V6RWPT assessment dynamically guides CRT strategy optimization during implantation.

OBJECTIVE:Percutaneous endocardial septal radiofrequency ablation (PESA) shows promise as a treatment for hypertrophic obstructive cardiomyopathy (HOCM). We aimed to explore the efficacy and safety of PESA require further study during a long-term follow-up. METHODS:We enrolled 25 patients HOCM who underwent PESA. The combination of a three-dimensional electrophysiological mapping system and intracardiac echocardiography (ICE) was employed to guide PESA. The patients were followed for 37 months (25-47.5 months), with transthoracic echocardiography performed 22 months (8-29 months) after the procedure. RESULTS:The mean age of patients was 55.3 ± 13.5 years (range: 23 to 79), and 11 (44%) of them were female. PESA led to a significant reduction in the left ventricular outflow tract gradient (LVOTG) from 79.0 ± 37.6 mmHg to 55.6 ± 34.8 mmHg (p = 0.002), as well as syncope episodes (60% vs. 19%, p = 0.0039) in patients with HOCM. The New York Heart Association (NYHA) functional class of the patients was improved from 2.14 ± 0.57 to 1.76 ± 0.54 (p = 0.002). In 10 patients undergoing cardiovascular magnetic resonance imaging (CMRI) both before PESA and at a follow-up of 3-6 months, the maximum left ventricular outflow tract velocity was ameliorated from 232.6 ± 56.8 m/s to 159.4 ± 46.9 m/s (p = 0.024). Besides, the minimum systolic diameter of left ventricular outflow tract was increased from 3.84 ± 2.6 mm to 6.3 ± 2.3 mm (p = 0.0006). There were no instances of cardiac tamponade, lethal arrhythmia, or death. Four patients underwent surgical septal myectomy during the follow-up. CONCLUSIONS:PESA could attenuate LVOT obstruction and improve heart function in patients with HOCM during a long-term follow-up. PESA may be an effective and safe treatment for HOCM.

Background Many patients with drug-refractory hypertrophic obstructive cardiomyopathy (HOCM) decline or are ineligible for surgical myectomy or alcohol septal ablation. Although conventional unipolar percutaneous endocardial septal radiofrequency ablation is a minimally invasive alternative, its limited lesion depth yields only modest left ventricular outflow tract gradient (LVOTG) relief. Bipolar radiofrequency catheter ablation creates deeper lesions in the treatment of ventricular arrhythmias; however, its role in HOCM remains unreported. First-In-Human/Early Reports Summary We present the first in-human case of combined bipolar ablation and percutaneous endocardial septal radiofrequency ablation (Bi-PESA) in an older patient with drug-refractory HOCM. Ultimately, the patient experienced significant reduction in the LVOTG, translating to significant symptomatic improvement. Discussion This case suggests Bi-PESA could be a novel, effective, and safe septal reduction option for patients with drug-refractory HOCM. Novelty To our knowledge, this is the first-in-human report of Bi-PESA for HOCM to reduce LVOTG and improve symptoms. Take-Home Message Bi-PESA may offer a feasible and potentially preferable alternative for patients with HOCM who decline or are ineligible for surgical myectomy or alcohol septal ablation.

OBJECTIVES:To evaluate the efficacy and safety of adding Superior Vena Cava Isolation (SVCI) to Pulmonary Vein Isolation (PVI) in patients with drug-refractory paroxysmal atrial fibrillation (PAF). DESIGN:Systematic review and meta-analysis of randomised controlled trials (RCTs) using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach, supplemented with Trial Sequential Analysis (TSA) to assess evidence sufficiency. DATA SOURCES:We searched PubMed, EMBASE, the Cochrane Library (CENTRAL) and Web of Science for relevant studies published up to 13 July 2025. ELIGIBILITY CRITERIA:We included prospective RCTs comparing SVCI+PVI versus PVI alone in adults with drug-refractory PAF, with at least 3 months of follow-up and reporting on atrial fibrillation (AF) recurrence and procedural complications. Case reports, reviews, observational studies, editorials, expert opinions and non-RCT studies were excluded. DATA EXTRACTION AND SYNTHESIS:Two independent reviewers used standardised methods to search, screen and code included studies. Risk of bias was assessed using the Cochrane Collaboration and Evidence Project tools. A meta-analysis was conducted using random effects models, and TSA was conducted to evaluate the conclusiveness of evidence. Findings were summarised in GRADE evidence profiles and synthesised qualitatively. RESULTS:Three RCTs involving 332 patients were included. The addition of SVCI to PVI significantly reduced AF recurrence compared with PVI alone (Risk Ratio 0.54, 95% CI 0.32 to 0.91, p=0.02; I² = 0%, P_heterogeneity=0.79) at a mean 12-month follow-up. TSA confirmed that the current evidence is sufficient. There were no significant differences in procedural complications between groups (Risk Difference 0.00, 95% CI -0.04 to 0.03, p=0.99; I² = 0%, P_heterogeneity=0.96). CONCLUSIONS:Adding SVCI to PVI for PAF ablation significantly reduces AF recurrence without increasing procedural risks. TSA confirms the robustness of the findings, supporting the potential integration of SVCI into routine clinical practice for PAF.

The correlation between sarcopenia and diabetes mellitus (DM) holds considerable importance. The prognosis of ventricular arrhythmias in individuals with type 2 diabetes mellitus complicated by sarcopenia remains uncertain. A retrospective analysis was conducted on patients with DM who underwent implantable cardioverter defibrillator (ICD) implantation at Fuwai Hospital. Sarcopenia status was assessed using the biomarker sarcopenia index(SI). Patients were divided into low SI (less than 81.33, n = 74) and high SI (greater than 81.33, n = 158) groups according to the best cut-off value. The primary endpoint was the occurrence of ventricular arrhythmias. Secondary endpoint was appropriate shock therapy. A total of 232 patients who met the inclusion criteria were included. The average follow-up period was 25.85 ± 16.13 months. During the follow-up, a total of 69 cases (29.7 Sarcopenia is a prevalent comorbidity of diabetes mellitus that has a substantial impact on prognosis. Does sarcopenia contribute to an elevated risk of ventricular arrhythmia and sudden cardiac death in patients diagnosed with type 2 diabetes? We found that patients with T2DM and lower sarcopenia index values had a significantly increased risk of ventricular arrhythmia, indicating the index’s strong predictive ability in this population. Patients with type 2 diabetes and low sarcopenia index should be screened for potential risk of sudden cardiac death and considered for implantable cardioverter defibrillators.

Targeting the atrioventricular nodal slow pathway (AVNsp) is the standard treatment in catheter ablation procedures for atrioventricular nodal reentrant tachycardia (AVNRT). However, significant anatomical variability in Koch's triangle poses challenges for precise ablation and increases the risk of atrioventricular block (AVB). Previous studies have reported that the AVNsp visualization strategy reduces the incidence of AVB, however, these studies were conducted in pediatric patients or with the energy of cryoablation. However, the safety and effectiveness of this strategy in adults undergoing radiofrequency ablation (RFA) remains unclear. This study aimed to evaluate the safety and effectiveness of high-density mapping (HDM)-guided AVNsp visualization strategy for AVNRT ablation compared to the conventional approach. We retrospectively analyzed data from 149 AVNRT patients across 3 hospitals in China. Patients were divided into 2 groups: experimental group (i.e. treated with the HDM-guided AVNsp visualization strategy, n = 88) and control group (i.e. treated with the traditional mapping and ablation strategy, n = 61). Procedural parameters, complication rates, and long-term outcomes were compared. The experimental group required fewer ablation points (4.8 ± 3.6 vs 8.5 ± 7.7, p = 0.003), shorter total ablation time (284 ± 178 s vs 408 ± 345 s, p = 0.028), and reduced procedure time (41.4 ± 14.2 min vs 51.5 ± 27.2 min, p = 0.009) compared with the control group. No cases of AVB occurred in the experimental group, while the control group reported 5 (8.2%) transient AVB and 1 (1.6%) persistent first-degree AVB after procedure. After a mean follow-up of 488 ± 246 days, no recurrences of AVNRT were observed in either group. In conclusion, for adult patients with AVNRT, the AVNsp visualization strategy enhances the safety and effectiveness of RFA by reducing procedure time and minimizing the risk of AVB.

BACKGROUND:Left bundle branch (LBB) pacing (LBBP) has been an emerging pacing modality that preserves physiological activation. However, data on the long-term durability of conduction system capture remain limited. In this study we aimed to assess the long-term stability of LBBP capture and identify predictors of capture loss. METHODS:We analyzed data from the multicentre, prospective Image Location and Performance of Left Bundle Branch Pacing (IMAGE-LBBP) cohort. Of 50 patients with bradycardia who underwent mid-term cardiac computed tomography imaging after left bundle branch area pacing implantation, 34 with confirmed LBBP and analyzable imaging at mid-term were included in the long-term analysis. Data on lead-related complications and pacing parameters were prospectively collected. The main outcome was new-onset loss of LBB capture after the mid-term assessment. RESULTS:During a mean follow-up of 60.1 ± 7.9 months, new-onset LBB capture loss occurred in 20.6% (7/34) of patients. Multivariate Cox regression identified mid-term lead tip to left ventricular cavity (Tip-LV) distance as an independent predictor of long-term capture loss (hazard ratio, 2.26; 95% confidence interval [CI], 1.17-4.35; P = 0.015). A cutoff of 2.0 mm yielded high predictive accuracy (area under the receiver operating characteristic curve, 0.881; 95% CI, 0.756-1.0), with 85.7% sensitivity and 77.8% specificity. Kaplan-Meier analysis showed a significantly greater risk of capture loss in patients with a Tip-LV distance > 2 mm compared with those with ≤ 2 mm (hazard ratio, 7.4; 95% CI, 1.6-34.8; log rank P = 0.012). CONCLUSIONS:LBB capture loss is progressive and occurs in approximately 20% of patients during long-term follow-up. A Tip-LV distance > 2 mm at mid-term is strongly associated with subsequent capture loss, highlighting the importance of optimal lead implantation and mid-term anatomical assessment to ensure durable conduction system pacing. CLINICAL TRIAL REGISTRATION:NCT04119323.