Background/Purpose Implantable loop recorders (ILR) are increasingly used in cardiac rhythm monitoring and diagnostic work-up of unexplained syncope. ILR battery longevity according to manufacturers’ product performance specifications typically ranges between two to four years, but real-world data in this population are lacking. Methods This monocentric, prospective, observational study included consecutive patients with unexplained syncope undergoing ILR implantation between 10/2007 and 10/2019 The main purpose was to determine real-world battery longevity of ILR. Diagnostic yield and relationship between arrhythmogenic diagnosis and duration of ILR-monitoring was explored. Results The study included 309 patients (59 years [38-73], 49% female) with ILR implantation for unexplained syncope. Median battery longevity was 42 [40-45] months. 99.5% of ILR reached prespecified battery longevity. The time to end-of-life varied by up to 33 months among the same ILR models. Overall arrhythmogenic diagnostic yield counted 27% (73% sick sinus syndrome, 20% atrioventricular block and 7% ventricular tachycardia). Median time to diagnosis was 10 [2-25] months, with the latest event at 43 months. The cumulative diagnostic yield for arrhythmogenic event was 15.7%, 22.9%, 34.9% , 54.2%, 72.3% and 100% at 1, 2, 6, 12, 24 and 48 months respectively. In univariate analysis, 1 st degree AV-block and prolonged HV time on EP study were predictors of diagnosis, while QRS duration abnormality borderline missed significance. Conclusions Real-world battery longevity of ILRs matched industry projected longevity in 99.5% of patients implanted with ILR for unexplained syncope. A battery longevity of minimum 3.5 years is recommended to maximize the diagnostic yield in this population.

Introduction Left bundle branch area pacing (LBBAP) aims to achieve physiological pacing by capturing the conduction system in the area of the left bundle branch. LBBAP has exclusively been performed using lumen-less pacing leads (LLL) with fixed helix design. This study explores the feasibility, safety and pacing characteristics of LBBAP using stylet-driven leads (SDL) with an extendable helix design. Methods Patients, in which LBBAP was attempted for bradycardia or heart failure pacing indications, were prospectively enrolled at the Ghent University Hospital. LBBAP was attempted with two different systems: 1/ LLL with fixed helix (SelectSecure 3830, Medtronic, Inc) delivered through a preshaped sheath (C315His Medtronic) and 2/ SDL with extendable helix (SoliaS60, Biotronik, SE & CO) delivered through a new delivery sheath (Selectra 3D, Biotronik). Results The study enrolled 50 patients (mean age 7014 years, 44% female). LBBAP with SDL was successful in 20/23 (87%) patients compared to 24/27 (89%) of patients in the LLL group (p=0.834). Screw attempts, screw implant depth, procedural and fluoroscopy times were comparable among both groups. Acute LBBAP thresholds were low and comparable between SDL and LLL (0.50.15V versus 0.40.17V, p=0.251). Pacing thresholds remained low at 32.1 months of follow up in both groups and no lead revisions were necessary. Post procedural echocardiography revealed a septal coronary artery fistula in one patient with SDL LBBAP. Conclusion LBBAP using stylet-driven pacing leads is feasible and yields comparable implant success to LBBAP with lumen-less pacing leads. LBBAP thresholds are low and comparable with both types of leads.

His bundle pacing (HBP) offers physiologic pacing by placing the pacing lead directly to the His bundle. We present a case in which a HBP lead, implanted at the fragile membranous septum, resulted in a persistent restrictive peri-membranous ventricular septal defect (VSD). This complication of HBP has not been reported before but brings new insights in the discussion regarding the optimal position of a pacing lead in the ventricular septum. The fragility of the membranous septum and low rate of spontaneous closure of membranous VSD, might favor lead placement in the muscular septum when aiming for physiologic pacing.