BACKGROUND AND AIMS:Left bundle branch area pacing (LBBAP) promotes physiological synchronous activation of the left ventricle and may be particularly beneficial in patients with atrioventricular block (AVB), but its mortality benefit remains unclear. This study aims to compare long-term survival in AVB patients receiving either LBBAP or right ventricular pacing (RVP) and to analyse predictors of mortality during LBBAP. METHODS:MELOS RELOADED, a multicentre European collaboration, was a registry-based study of pacemaker patients with AVB, left ventricular ejection fraction (LVEF) >40% and ventricular pacing >20%. The primary outcome was all-cause mortality based on national registries. A 1:1 propensity score matching was performed between the RVP and LBBAP groups. Kaplan-Meier curves and multivariable Cox proportional hazards models were used to estimate survival. RESULTS:In total, 3382 patients receiving LBBAP or RVP were matched. At 4-year follow-up, the Kaplan-Meier curve showed an absolute difference in survival of 11.8% in favour of LBBAP (P < .001). LBBAP was a robust predictor of reduced mortality with a hazard ratio (HR) of 0.53 (95% confidence interval 0.42-0.65, P < .001). Within the LBBAP group, the following independent predictors of increased mortality were identified: lack of confirmed left bundle branch capture (HR 1.85, P < .001), lower percentage of ventricular pacing (HR 1.12), and age. CONCLUSIONS:This is the first large study demonstrating the long-term survival benefit of LBBAP. This strengthens the use of LBBAP in AVB patients with preserved/mildly reduced LVEF while awaiting the results of randomized trials. Confirmation of left bundle branch capture seems advisable to achieve optimal results with LBBAP.

AIMS:Patients with first-degree atrioventricular (AV) block and mechanical AV dyssynchrony can present with heart failure (HF)-like symptoms. AV-optimized conduction system pacing (CSP) can improve haemodynamics and symptoms, but selection criteria remain uncertain. We aimed to identify electrocardiographic and echocardiographic predictors of an acute haemodynamic response to AV-optimized CSP in symptomatic first-degree AV block. METHODS AND RESULTS:Nineteen patients (mean age 60.5 ± 21.1 years; 37% female) with symptomatic first-degree AV block underwent baseline electrocardiography and echocardiography followed by AV-optimized conduction system pacing and repeat echocardiographic assessment. Electrocardiographic parameters (PR interval, P wave duration/PR interval ratio) and echocardiographic indices (E/A wave confluence, A-Q interval, and DFT/RR ratio) were tested for association with change in left ventricular stroke volume (LVSV).The mean PR interval was 395 ± 61 ms, the mean A-Q interval 155 ± 65 ms, and the mean DFT/RR ratio 0.34 ± 0.1. E/A wave confluence was present in 15 patients (79%). AV-optimized pacing increased LVSV by 7.8 ± 3.9 ml, corresponding to an 11.8 ± 5.7% relative increase (P < .01). Echocardiographic parameters were associated with LVSV response, including A-Q interval (r = 0.63, P = .004), DFT/RR ratio (r = -0.59, P = .008), and E/A wave confluence (r = 0.57, P = .01). Electrocardiographic parameters were not associated with LVSV change. CONCLUSIONS:Echocardiographically assessed mechanical AV dyssynchrony, rather than electrocardiographic parameters, is associated with an acute haemodynamic response to pacing. Echocardiographic evaluation may help identify patients with prolonged PR interval who could benefit from AV-optimized CSP.

Cardiac implantable electronic devices (CIEDs) are integral to heart failure (HF) management, providing therapies for bradyarrhythmias, cardiac resynchronization therapy (CRT), sudden cardiac death (SCD) prevention, and remote monitoring. This review summarizes current and potential future indications, emerging technologies, and challenges in the implementation of CIEDs in HF. Conventional right ventricular pacing in HF patients is increasingly being replaced by biventricular pacing (BVP) and left bundle branch area pacing (LBBAP), while leadless pacing pacemakers have emerged as an alternative to conventional transvenous systems, offering the potential to reduce lead- and device-related complications. As BVP remains the standard approach for CRT, recent data bestow LBBAP as a promising alternative and integration platform. Newer implantable cardioverter-defibrillator technologies, including subcutaneous and extravascular systems, may reduce lead-related complications while maintaining effective arrhythmia termination and recognition. Advances in atrial fibrillation management, implantable hemodynamic monitoring, and novel pacing indications such as atrioventricular recoupling and personalized pacing in HF with preserved ejection fraction are expanding the therapeutic potential of CIEDs. However, the adoption of these innovations is challenged by limited randomized evidence, procedural complexity, and substantial disparities in access and implementation across healthcare systems. Ongoing clinical trials will help define the role of emerging device technologies and monitoring strategies, while efforts to improve guideline adherence, value-based procurement, and equitable access remain essential to maximize the benefits of CIED therapy in patients with HF. HF – heart failure; LVEF – left ventricular ejection fraction; BVP – biventricular pacing; CSP – conduction system pacing; LP – leadless pacing; LBBAP – left bundle branch area pacing; RCT – randomized clinical trial; HFrEF – heart failure with reduced ejection fraction; CRT – cardiac resynchronization therapy; LOT-CRT – left optimized resynchronization therapy; AF – atrial fibrillation; TV-ICD – transvenous implantable cardiac defibrillator; SCD – sudden cardiac death; HFpEF – heart failure with preserved ejection fraction

Conduction system pacing (CSP) is an emerging new method of cardiac resynchronization therapy (CRT), however, one third of patients with left bundle branch block (LBBB) have distal conduction disease, which is not amenable to correction with CSP. There is an emerging need for tailored analysis of ventricular depolarization patterns for patient selection for CRT pacing modality. We retrospectively analyzed 12 lead hrECGs, equivalent dipole (ED) trajectories and standard transthoracic echocardiograms of 18 heart failure patients fulfilling Strauss criteria for LBBB and indication for CRT randomized to the CSP arm of the ongoing CSP-Sync study (NCT05155865). Based on achievement of left bundle branch capture with shortening of left ventricular activation time, 12 patients had proximal LBBB (pLBBB group), and 6 had intact proximal LBBB conduction (dLBBB group) with similar average baseline QRS durations between the groups (179±14 ms in the pLBBB and 165±20 ms in the dLBBB group, p = 0.1). All patients fulfilled the Strauss criteria with no significant difference in the additional criterion (R wave > 0.1 mV in V1; p = 0.7). In the pLBBB group ED trajectory had an initial leftward direction (six vs. zero patients, p = 0.03) with a uniform (12 vs. one patient, p < 0.001) and slower (0.57 ± 0.12 m/s in the pLBBB vs. 0.75 ± 0.15 m/s in the dLBBB group, p = 0.01) velocity. After 6 months the pLBBB group achieved greater relative QRS duration shortening (26% ± 8% vs. 14% ± 9%; p < 0.02) and relative reductions in end left ventricle systolic volumes (41.3% ± 17.6% vs. 15.8% ± 6.1%; p = 0.004) with better improvement in ejection fraction (17.1% ± 11.0% vs. 5.5% ± 1.0%; p = 0.02). The ED trajectories from 12-lead hrECGs could better differentiate patients with proximal or distal LBBB than standard 12-lead ECG alone.

The use of intracardiac echocardiography (ICE) and 3-D electroanatomical mapping (3-D EAM) systems allows safe fluoroless catheter ablations (CAs) in nearly all types of arrhythmias. Nevertheless, for patients with cardiac implantable electronic devices (CIEDs) there exists a notable paucity of data concerning the rate of leads’ dislocation in fluoroless procedures. The aim of this single-centre retrospective study was to evaluate the rate of leads’ dislocation in fluoroless CA of arrhythmias necessitating left sided approach in patients with CIEDs. We performed a retrospective study in patients with CIED who underwent fluoroless CA with transseptal puncture (TSP) for any arrhythmia between February 2016 and November 2023. All procedures were performed without fluoroscopy, guided by a 3-D EAM system and ICE. The leads were repeatedly visualized with ICE during introduction of catheters, their manipulation, TSP and ablation. The device´s parameters were tested before and after the procedure. Our study included 88 patients. A total of 105 procedures (90 [86.5 %] in males, average age at procedure 65.6 ± 10.6 years) was performed for 119 arrhythmias; there were 41 (39.4 %) CAs of atrial fibrillation or atypical flutter and 13 (12.5%) concomitant ablations of typical flutter, 1 (1.0 %) ablation of focal atrial tachycardia, 59 (56.7 %) of ventricular tachycardia and 5 (4.8 %) of ventricular ectopy. 60 patients (56.7 %) had single-chamber intracardiac defibrillator (ICD VR), 11 patients (10.6 %) had dual-chamber intracardiac defibrillator (ICD DR), 1 patient (1.0 %) had permanent single-chamber pacemaker, 15 patients (14.4 %) had permanent dual-chamber pacemaker, and 11 patients (10.6 %) had cardiac resynchronization devices (CRT-D or CRT-P). For 7 patients (6.7 %) the retrospective data about device’s type is missing. In two procedures (2/106, 1.9 %) we observed ventricular lead dislocation while there were no atrial lead dislocations. One ventricular lead dislocation happened in CA of atypical flutter in a patient with ICD DR during manoeuvring of catheters in the right heart chambers. The other ventricular lead dislocated in a patient with ICD VR who experienced coronary air embolism during CA of ischemic ventricular tachycardia necessitating cardiopulmonary resuscitation with chest compressions. According to ICE imaging the lead dislocation happened after the successful resuscitation, therefore it was not related to fluoroless ablation method. Both lead dislocations required subsequent lead repositioning. There were no lead dislocations related to the TSP and the process of obtaining transseptal approach. In other patients, the device interrogation after completion of procedures showed no change in parameters. Lead dislocations in patients with CIEDs undergoing leftsided fluoroless CAs are rare and appear unrelated to TSP.

Background: Atrial fibrillation/flutter (AF/AFl) is commonly diagnosed arrhythmia, associated with increased morbidity and mortality. Therefore, we have to improve our early AF/AFl diagnostics. Several studies indicated association between conduction delay, excessive atrial ectopic beats (AEBs) and AF/AFl onset. Association with some other AEB features is less clear. Objective: To validate the role of early AEBs from Holter-ECG in relation to documented AF/AFl events. Methods and Results: We enrolled 14 consecutive patients (6 female, median 60.5 years) with documented AF/AFl during or within 6 months after Holter-ECG (AF-group). Control group consisted of 10 clinically similar consecutive patients (5 female, median 64.5 years), without any evidence of AF/AFl, but with comparable burden of AEBs. Holter-ECGs were examined with 3-channel Holter system (Schiller, Darwin2 software). 24-hour data were analyzed for number and/or burden (%) of: a) AF/AFl, b) AEBs, c) early-AEBs (coupling interval cut-off <530 ms), d) AEB pairs, triplets, runs, and e) bigeminy. In addition, P-wave duration (cut-off <130 ms), PQ, QRS, and QTc were measured. AF-group had higher burden of early-AEBs (p<0.03) and longer P-waves (p<0.05) than controls. In both groups, non-conducted and aberrantly-conducted early-AEBs, AEBs in bigeminy, pairs, triplets and runs were found, as-well-as no difference for PQ, QRS, and QTc (p=NS). The majority of 243 AF/AFl events started during day-time and in 83% with early-AEBs. Before AF onset, outbursts of early-AEBs were encountered in 58% of patients. Conclusion: A higher burden of early AES in the Holter ECG and a longer P-wave duration predict the occurrence of AF/AU.

Conduction system pacing with left bundle branch area pacing (LBBAP) for cardiac resynchronization therapy (CRT) is an emerging alternative to standard biventricular (BiV) pacing. However, prospective randomized studies comparing both strategies are limited. The study compared left ventricular (LV) reverse remodelling and clinical endpoints between LBBAP and BiV pacing in patients with Class I indication for CRT. The CSP-SYNC study was a prospective, single-centre study, which included 62 patients with Class I indication for CRT and left bundle branch block fulfilling Strauss criteria. Patients were randomly assigned 1:1 to LBBAP or BiV and followed for at least 6 months. Crossovers were allowed if the primary allocation strategy was unsuccessful. The primary endpoint was the difference in improvement of left ventricular ejection fraction (LVEF). Secondary echocardiographic endpoints included reduction of end systolic volume (ESV) and CRT response defined as ESV reduction ≥ 15 %. Non-echocardiographic endpoints were post-procedural QRS duration, reduction of NT-proBNP, improvement of 6-minute walk test (6-MWT) and incidence of heart failure (HF) hospitalizations. Analysis was performed using intention-to-treat principle. Thirty-one patients were randomized to each group. Most patients were males (71%), 32 % had ischemic cardiomyopathy and all were receiving optimal medical treatment. There was one crossover (1.6%) from LBBAP to BiV pacing. At six months, there was a greater improvement of LVEF in the LBBAP group (14.0 ± 10.4%, P < 0.01) than in the BiV group (8.5 ± 7.5 %, P < 0.01) (P = 0.02). Similarly, ESV reduction was more significant in the LBBAP group (-62.5 ± 45.1 ml, P < 0.01) than in the BiV group (-39.6 ± 40.1 ml, P < 0.01) (P = 0.04). (Figure). While the number of patients with ESV reduction ≥15% did not differ between both groups (P = 0.09), significantly more patients in the LBBAP group achieved LVEF ≥50% (P < 0.01). Reduction of QRS duration, level of NT-proBNP, and improvement in 6-MWT distance were significant and comparable in both groups. During a mean follow-up of 22.1 ± 7.5 months, there were 2 HF hospitalizations in the LBBAP group (6.5%) and 7 (22.6%) in the BiV group, however, using time to event analysis statistical significance was not reached (p=0.09). In patients with Class I indication for CRT, LBBAP demonstrated a greater degree of LV reverse remodelling and similar clinical outcomes compared to BiV pacing. Further adequately powered studies to address cardiovascular outcomes are warranted to establish LBBAP as a first-line therapeutic option in CRT patients.Echo at baseline and 6 months follow-up.

AIMS:There is a lack of data from randomized clinical trials comparing treatment outcomes between conduction system pacing (CSP) modalities and biventricular pacing (BVP) in symptomatic patients with refractory atrial fibrillation (AF) scheduled for atrioventricular node ablation (AVNA). The CONDUCT-AF investigates whether CSP is non-inferior to BVP in improving left ventricular ejection fraction (LVEF) and clinical outcomes in heart failure (HF) patients with symptomatic AF undergoing AVNA. METHODS:This study is an investigator-initiated, prospective, randomized, multicentre clinical trial conducted across 10 European centres, enrolling 82 patients with symptomatic AF, HF with reduced LVEF, and narrow QRS. Participants will be randomized 1:1 to CSP or BVP with subsequent AVNA and followed for at least 24 months. The primary endpoint is the change in LVEF after 6 months. Secondary endpoints will include time to the first occurrence of worsening HF or cardiovascular death and its individual components, total number of HF hospitalizations, change in quality of life, N-terminal pro-B-type natriuretic peptide, 6-min walk test distance, and safety outcomes. CONCLUSIONS:The CONDUCT-AF trial will provide critical insights into the optimal pacing modality for patients with HF and refractory AF undergoing AVNA. Recruitment is expected to conclude in 2025, with the first study results anticipated in 2026.

Brugada syndrome is an inherited cardiac channelopathy with pathognomonic early repolarization alteration (Brugada sign) and is associated with a high risk for sudden death from ventricular fibrillation (VF). Documented ventricular arrhythmic events, sudden unexpected death in family members, accurate evaluation of Brugada signs and arrhythmic syncope, and genotyping of SCN5A for cardiac fast sodium channel Nav1.5, are the most important steps in diagnostic and prognostic evaluation. Treatment with quinidine and the recently introduced catheter ablation procedure are important methods for reducing the high burden of ventricular arrhythmias. However, the decision of whether to implant a cardioverter defibrillator to prevent sudden cardiac death is essential. We present a case of a patient and his family with a novel heterozygotic variant in exon 15 of the gene SCN5A(NM_000335.5):c.2271del, p.(Ile759PhefsTer6), associated with cardiac arrest because of VF during intensive physical effort, with mild structural heart disease, and a short QT. We discuss current guidelines for optimal management of patients with suspected Brugada syndrome.

AIMS:There are limited prospective randomized studies comparing left bundle branch area pacing (LBBAP) and biventricular (BiV) pacing for cardiac resynchronization therapy (CRT). The study tested whether LBBAP is non-inferior to BiV pacing in patients with Class I indication for CRT. METHODS AND RESULTS:The CSP-SYNC study is an investigator-initiated, randomized, single-centre study. Sixty-two patients were randomized 1:1 to LBBAP or BiV. The primary study endpoint was the change in left ventricular ejection fraction (LVEF) at 6 months. Secondary endpoints included changes in echo and clinical parameters after 6 months and 12 months. Thirty-one patients were randomized to each arm. Most patients were males (71%), and 32% had ischaemic cardiomyopathy. At 6 months, similar improvement of LVEF was observed in the LBBAP group compared to the BiV group [14.0% (95% confidence interval (CI): 11.2-16.8) in LBBAP vs. 8.5% (95% CI: 5.6-11.2) in BiV] with a mean intergroup difference of 5.6% (95% CI: 1.6-9.5; P < 0.001 for non-inferiority). Both groups showed comparable decrease in LVESV [-64 mL (95% CI: -78 to -50) vs. -40 mL (95% CI: -54 to -25) respectively, mean difference -24 mL (CI 95%: -44 to -4); P < 0.001 for non-inferiority] and changes in 6-min walk test (P < 0.001 for non-inferiority) and NYHA class (P = 0.011 for non-inferiority). Temporal trends of LV remodelling and heart failure hospitalization rates were also comparable. CONCLUSION:In patients with a Class I indication for CRT, LBBAP was non-inferior to BiV pacing in improving LVEF and provided similar structural and electrical remodelling.

BACKGROUND:Despite technical progress and novel ablation strategies, pulmonary vein (PV) reconnection still occurs in a substantial proportion of patients. The aim of the study was to determine the impact of the elimination of antral low-voltage, fragmented electrograms (LFEGMs) identified by high-density (HD) mapping on the rate of pulmonary vein isolation (PVI) durability. METHODS:Sixty patients with paroxysmal atrial fibrillation (PAF) were randomly assigned to a verification of PV entrance block and presence of LFEGMs on antral isolation lines with an HD mapping catheter (HD group) or to a verification of PV entrance block with a circumferential mapping catheter alone (CM group). In the HD group, LFEGMs were additionally ablated. Mandatory reassessment procedure to assess PVI durability and the presence of LFEGMs was performed 12 months after the index procedure or earlier in case of arrhythmia recurrence. RESULTS:A total of 107 out of 116 (92.2%) PVs were found durably isolated in the HD group, and 97 out of 120 (80.8%) PVs in the CM group (p = 0.02). At the reassessment procedure, a total of 7 [3, 12] and 34 [24, 44] LFEGMs were found in the HD and CM groups, respectively (p = 0.00002). Elimination of LFEGMs at the index procedure reduced the likelihood of antral conduction gaps in the same segments at the reassessment. Arrhythmia recurrence rate was similar between the HD and the CM group (7/29, 24.1% vs. 10/30, 33.3%), p = 0.62, respectively. CONCLUSION:Additional elimination of LFEGMs identified by HD mapping of antral isolation lines after PVI resulted in a significantly higher rate of PVI durability. TRIAL REGISTRATION:ClinicalTrials.gov identifier: (NCT04466358).

Recent advances in electroanatomic mapping (EAM) and invasive imaging with intracardiac echocardiography (ICE) have led to reduction of radiation exposure in electrophysiological procedures. Recent studies have shown that similar approach could be utilized in conduction system pacing (CSP). However, data for performing CSP in pregnant patients is scarce. The aim of this case series study was to examine feasibility and safety of performing left bundle branch area pacing (LBBAP) with near zero-fluoroscopy approach in pregnant patients with the indication for permanent pacemaker implantation. To reduce fluoroscopy 3-dimensional EAM and intracardiac echocardiography system (ICE) was used for relevant anatomy visualisation and lead implantation. Initial mapping and tagging of relevant sites for LBBAP (His bundle area cloud, right ventricular (RV) mid-septum area, and RV apex) on the 3D map was performed from the right femoral vein approach using a 10-polar deflectable diagnostic catheter. The ventricular lead was then connected to the EAM system and navigated to the right ventricular mid-septal area with the aid of ICE. Transseptal lead progression to reach LBBAP was monitored with ICE and confirmed with 12-lead ECG recording system. Atrial lead positioning mainly relied on ICE. Fluoroscopy was only used to determine adequate LBBAP lead slack after sheath removal and after atrial lead positioning, respectively. Two pregnant patients aged 32 and 34 years with third-degree atrioventricular block were included in this case series. One patient had a structurally normal heart, and the other had a congenitally corrected transposition of the great arteries (CCTGA). Dual-chamber pacemaker implantation with LBBAP was successfully performed in both cases. Average time of fluoroscopy was 30 seconds and radiation dose was 0,62 mGy. Average procedure duration was 85 minutes. There were no periprocedural complications and pacing parameters were stable. However, atrial lead dislocation was recorded in one patient during follow-up, which was repositioned after the patient gave birth. Near zero-fluoroscopy approach to LBBAP can be safely performed in pregnant patients with or without congenital heart disease. The clinical adoption of this approach requires further validation in larger studies.

BACKGROUND:Severe first-degree atrioventricular (AV) block may produce symptoms similar to heart failure due to AV dyssynchrony, a syndrome termed AV dromotropathy. According to guidelines, it should be considered for permanent pacemaker implantation, yet evidence supporting this treatment is scarce. OBJECTIVES:This study aimed to determine the impact of AV-optimized conduction system pacing (CSP) in patients with symptomatic severe first-degree AV block and echocardiographic signs of AV dyssynchrony. METHODS:Patients with symptomatic first-degree AV block (PR > 250 ms), preserved left ventricular ejection fraction, narrow QRS, and AV dyssynchrony were included in the study. In a single-blind cross-over design, patients were randomized to AV sequential CSP or backup VVI pacing with a base rate of 40 bpm. We compared exercise capacity, echocardiographic parameters, and symptom occurrence at the end of 3 months of each period. RESULTS:Fourteen patients completed the study. During the AV-optimized CSP compared to the backup pacing period, patients achieved a higher workload on exercise test (147.2 ± 50.9 vs. 140.7 ± 55.8 W; p = .032), with a trend towards higher peak VO2 (23.3 ± 7.1 vs. 22.8 ± 7.1 mL/min/kg; p = .224), and higher left ventricular stroke volume (LVSV 74.5 ± 13.8 vs. 66.4 ± 12.5 mL; p < .001). Symptomatic improvement was recorded, with fewer patients reporting general tiredness and 71% of patients preferring the AV-optimized CSP (p = .008). CONCLUSIONS:AV-optimized CSP could improve symptoms, exercise capacity and LVSV in patients with severe first-degree AV block.

Atrial fibrillation and heart failure with preserved ejection fraction (HFpEF) are frequent concomitant diseases sharing several pathophysiological mechanisms leading to structural remodelling of both atria and ventricles. We present a case of an HFpEF patient with rapid atrial fibrillation who remained symptomatic even after successful cardioversion, initiation of antiarrhythmic therapy, and treatment of comorbidities. Due to asymmetric septal hypertrophy, the stress test was performed to exclude outflow tract obstruction and revealed a low basal heart rate with significant chronotropic insufficiency. In addition to SGLT2 initiation, the beta-blocker dose was reduced, and amiodarone was discontinued. This therapy modification led to a marked improvement in exercise capacity, significant reduction of palpitations, reduction of NT-proBNP, and signs of a decreased left ventricular filling pressure with reverse remodelling of LA. This case shows the importance of both individual tailoring of medical therapy and chronotropic insufficiency in HFpEF patients.

AIMS:Primary prevention patients with ischaemic cardiomyopathy and chronic total occlusion of an infarct-related coronary artery (CTO) are at a particularly high risk of implantable cardioverter-defibrillator (ICD) therapy occurrence. The trial was designed to evaluate the efficacy of preventive CTO-related substrate ablation strategy in ischaemic cardiomyopathy patients undergoing primary prevention ICD implantation. METHODS AND RESULTS:The PREVENTIVE VT study was a prospective, multicentre, randomized trial including ischaemic patients with ejection fraction ≤40%, no documented ventricular arrhythmias (VAs), and evidence of scar related to the coronary CTO. Patients were randomly assigned 1:1 to a preventive substrate ablation before ICD implantation or standard therapy with ICD implantation only. The primary outcome was a composite of appropriate ICD therapy or unplanned hospitalization for VAs. Secondary outcomes included the primary outcome's components, the incidence of appropriate ICD therapies, cardiac hospitalization, electrical storm, and cardiovascular (CV) mortality. Sixty patients were included in the study. During the mean follow-up of 44.7 ± 20.7 months, the primary outcome occurred in 5 (16.7%) patients undergoing preventive substrate ablation and in 13 (43.3%) patients receiving only ICD [hazard ratio (HR): 0.33; 95% confidence interval (CI): 0.12-0.94; P = 0.037]. Patients in the preventive ablation group also had fewer appropriate ICD therapies (P = 0.039) and the electrical storms (Log-rank: P = 0.01). While preventive ablation also reduced cardiac hospitalizations (P = 0.006), it had no significant impact on CV mortality (P = 0.151). CONCLUSION:Preventive ablation of the coronary CTO-related substrate in patients undergoing primary ICD implantation is associated with the reduced risk of appropriate ICD therapy or unplanned hospitalization due to VAs.

Abstract Introduction Despite technical progress and numerous approaches in ablation strategies, long-term success in paroxysmal atrial fibrillation (PAF) treatment is still suboptimal. Non-transmural ablation lesions in antral isolation lines, causing late electrical reconnection between pulmonary veins (PVs) and left atrium (LA) could present one of the potenital issues for reduced effectiveness of radiofrequency cathether ablation (RFCA). Potentially, these lesions can be identified with high-density (HD) mapping as low voltage, fragmented electrocardiograms (LFEGMs) representing gaps in antral isolation lines. Purpose To compare the long-term pulmonary vein isolation (PVI) durability of two PVI verification methods (circumferential vs high-density mapping catheter) after catheter ablation of PAF. Methods Thirty-three patients with PAF were prospectively randomized to PVI verification by either circumferential mapping catheter (CM group) or HD mapping catheter (HD group). Patients in both groups underwent PVI according to the CLOSE protocol with PVI verification after a 30 minute waiting period. Additionally, in the HD group antral ablation lines were mapped to search for LFEGMs that were defined as fragmented signals (at least 3 deflections) and/or conduction to the LA during stimulation on the ablation line (10 mA at 1 msec) and/or voltage amplitude above 0.1 mV. If LFEGMs were found, additional ablations were performed until electrical inactivity was confirmed with the HD catheter. To monitor AF reccurence 6-day continuous holter ECG was performed after 3, 6, and 12 months after the initial procedure. Arrhythmia recurrence was defined as any atrial tachyarrhythmia lasting more than 30 seconds. Patients also underwent a mandatory second procedure 12 months after the initial PVI, during which HD re-mapping was performed to test durability of PVI and absence of conducting gaps in antral isolation lines. Results There were 16 patients in the CM group and 17 patients in the HD group. Baseline characteristics (gender, age, body mass index, LA volume index, left ventricular ejection fraction, CHA2DS2VASc score) did not significantly differ between the groups. Procedural characteristic are summarized in Table 1. There were significantly more isolated PVs at the remapping procedure in the HD group compared to the CM group (91.2% (62/68) vs 75.0% (48/64); P=0.021). There were also significantly more patients with all PVs durably isolated in the HD group (82.4% (14/17) vs 37.5% (6/16); P=0.008). However, arrhythmia recurrence rate was similiar between the CM and HD group (43.8% (7/16) vs 35.3% (6/17); P=0.640). Conclusion HD mapping improved PVI durability after 12 months compared to standard CM verification. However, lower number of isolated PVs in the HD group did not have an impact on arrhythmia reccurence.

Background Left bundle branch area pacing (LBBAP) has gained increased adoption globally with the use of both lumenless leads (LLLs) and stylet-driven leads (SDLs). As these leads have been developed for conventional endocardial pacing sites, concerns remain regarding the lead integrity with LBBAP. Objectives This study evaluates lead integrity of pacing leads used for LBBAP in a large, real-world cohort of patients with LBBAP. Methods Patients with successful LBBAP from 17 international centers were enrolled in this observational study. Data on overall lead integrity, fracture rates, and locations of fractures were collected. Result The study enrolled 8,255 patients with LBBAP (age 73 ± 13 years, 42% female, 68% LLLs, and 32% SDLs). Overall lead survival rate was 99.7% with median follow-up of 16.4 (Q1-Q3: 6.4-28.8) months. Lead fracture occurred in 12 of 8,255 (0.15%) patients. Lead fracture rates of LLLs occurred in 2 of 5,609 (0.04%) vs 10 of 2,646 (0.4%) patients for SDLs, during a follow-up of 19.5 (Q1-Q3: 9.7-33) and 10.3 (Q1-Q3: 2.9-19.7) months, respectively (P < 0.001). SDL fractures occurred at 13.9 (Q1-Q3: 6.1-17.7) months after implant, whereas 2 LLL fractures occurred at 21 and 31.4 months. SDL and LLL conductor fractures were observed in 7 of 17 and 2 of 17 centers, respectively. Confirmed fractures of the SDL lead originated within the interelectrode lead segment, whereas LLL fractures occurred proximal to the ring. Conclusions LBBAP lead performance of LLLs and SDLs is high at midterm follow-up. SDLs exhibit higher rates of fracture compared to LLLs. Hot spots for conductor fracture are the distal interelectrode segment in SDLs and the segment proximal to the ring electrode in LLLs.