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Purpose: Reflex syncope is a burdensome disease with considerable repercussions on the quality of life. Tilt training is a therapeutic option, but evidence on this topic is scarce and outdated. Hyperventilation is oftentimes associated with reflex syncope. This study aimed to evaluate the effectiveness of tilt training in patients with reflex syncope and study the association between reflex syncope and hyperventilation., Methods: Patients referred for tilt training after a positive tilt test from July 2014 to March 2021 were included in a single-center, retrospective registry. Demographic characteristics and outcomes of the program were collected. The response of tilt training on (pre)syncope recurrence and the association with hyperventilation were studied., Results: A total of 173 patients were included. The median age was 27 [17-48] years. Patients needed 2 [1-3] sessions to reach the first negative tilt training. The tilt training program was successfully completed by 65% of patients. An additional 3% reported no complaints in daily life, despite remaining symptomatic during tilt training. Another therapy was initiated in 10% of patients, while 21% dropped out of the tilt training. Presyncope recurred in 21% of patients during a follow-up period of 21 months [16-23]. Concomitant hyperventilation was suspected in 24%. Among these patients, 74% were referred for a hyperventilation provocation test, which confirmed the diagnosis in 82%., Conclusion: We report a reasonable success of tilt training in a contemporary cohort of patients. In patients completing the tilt training program, presyncope, and syncope recurrence was low. Concomitant hyperventilation seems prevalent in patients with reflex syncope and warrants specific attention and treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Hornikx, Haemers, Stans, Robyns, Garweg, Ector, Vandenberk and Willems.)

Background: The leadless Micra AV pacemaker is designed to provide atrioventricular (AV) synchronous tracking by detecting atrial contraction. Detection of the mechanical atrial signals can become challenging at a fast sinus rate., Objective: The purpose of the study was to evaluate the AV synchronous performance during exercise in outpatients implanted with a Micra AV pacemaker., Methods: Patients were enrolled at least 1 month after Micra AV implantation and underwent a cycle test protocol. Serial device interrogations (each minute) and continuous electrocardiograms were collected to measure AV synchrony and determine maximum achieved sinus and ventricular rates for each patient. In addition, the A1, A2, A3, and A4 accelerometer signal amplitudes were measured at the start and peak of exercise., Results: Thirty-five patients (mean age 75.6 ± 13.4 years; 28 (80%) male) were enrolled in the study; 22 (64%) were predominantly ventricular paced (>90%) during exercise. Mean AV synchrony was 90.4% in the entire cohort and 84.7% in patients with high-degree AV block. The mean amplitude of the accelerometer signals increased significantly from the start to the peak of exercise: A1, 4.1-6.3 m/s 2 ; A2, 2.4-3.8 m/s 2 ; and A4, 4.5-7.6 m/s 2 (P < .01 for all). The time from the ventricular ecvent (VS/VP) to A2 showed a decrease of 25 ms for each 100 ms decrease of the R-R interval., Conclusion: Maintaining AV synchrony during maximal exercise in elderly patients is achievable by adequate detection of atrial contraction at fast sinus rates by the leadless Micra AV pacemaker. All components of the accelerometer signal increased, likely because of increased contractility related to exercise., Competing Interests: Disclosures Drs Garweg and Willems have received consultant/speaker fees and research grants from Abbott, Biotronik, and Medtronic. Mr Sheldon and Ms Anders are employees of Medtronic. Mr Sheldon is a shareholder of Medtronic. Dr Willems is funded as a senior clinical investigator by the Research Foundation – Flanders (FWO Vlaanderen). The rest of the authors report no conflicts of interest., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Advances in leadless pacemaker technology have enabled accelerometer-based atrioventricular (AV) synchronous pacing by sensing atrial mechanical contraction., Objective: The purpose of this study was to report the performance of the Micra AV leadless pacemaker from the worldwide Micra AV post-approval registry (PAR) through 12 months., Methods: The Micra AV PAR is a prospective, single-arm, observational registry designed to assess the safety and effectiveness of Micra AV in a real-world setting. For the present interim analysis, major complications and system revisions through 12 months were summarized and compared to a historical cohort of 2667 patients implanted with a transvenous dual-chamber pacing system., Results: The device was successfully implanted in 796 of 801 patients (99.4%) at 97 centers in 19 countries. Micra AV patients were older (74.1 years vs 71.1 years; P < .0001) with a higher incidence of renal disease (22.3% vs 9.8%; P < .0001) compared with transvenous dual-chamber patients. Through 12 months, the major complication rate was 3.7% in Micra AV patients compared with 8.8% in transvenous dual-chamber patients (hazard ratio 0.42; 95% confidence interval 0.28-0.61; P < .001). The system revision rate was 1.5% in Micra AV patients compared with 5.5% for transvenous dual-chamber patients (hazard ratio 0.25; 95% confidence interval 0.13-0.47; P < .001); this reduction was largely driven by the absence of lead dislodgments requiring revision. The median AV synchrony index was 79.4% (interquartile range 65.2%-86.4%) in patients paced >90%., Conclusion: The Micra AV leadless pacemaker was implanted with a high rate of success in patients with multiple comorbidities, with a significantly lower rate of complications and system revisions through 12 months compared to a historical cohort of patients with transvenous dual-chamber pacemakers., Competing Interests: Disclosures Dr Garweg has received consultant/speaker fees and research grants from Abbott, Biotronik, and Medtronic. Dr Chinitz has received consulting fees from Medtronic, Boston Scientific, and Biosense Webster and speaking/teaching honorarium fees from Boston Scientific and Biotronik. Dr Marijon has received consulting fees from Medtronic, Abbott, and Boston Scientific. Dr Haeberlin has received travel fees/educational grants from Medtronic, Biotronik, Abbott, and Philips/Spectranetics without impact on personal remuneration and works as a proctor for Medtronic. Dr El-Chami serves as a consultant for Medtronic, Boston Scientific, and Biotronik. Dr Roberts has received honoraria from Medtronic, Boston Scientific, and Abbott and research funding from Boston Scientific. Dr Piccini has received clinical research grants from Abbott and Philips and serves as a consultant for Abbott, Boston Scientific, Medtronic, and Philips. Drs Stromberg and Fagan are employees/shareholders of Medtronic. Dr Clementy has received consulting fees from Medtronic. The remaining authors have nothing to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Aims: In cardiac device implantation, having both surgical skills and ability to manipulate catheter/lead/wire is crucial. Few cardiologists, however, receive formal surgical training prior to implanting. Skills are mostly acquired directly on-the-job and surgical technique varies across institutions; suboptimal approaches may increase complications. We investigated how novel proficiency-based progression (PBP) simulation training impacts the surgical quality of implantations, compared to traditional simulation (SIM) training., Methods and Results: In this international prospective study, novice implanters were randomized (blinded) 1:1 to participate in a simulation-based procedure training curriculum, with proficiency demonstration requirements for advancing (PBP approach) or without (SIM). Ultimately, trainees performed the surgical tasks of an implant on a porcine tissue that was video-recorded and then scored by two independent assessors (blinded to group), using previously validated performance metrics. Primary outcomes were the number of procedural Steps Completed, Critical Errors, Errors (non-critical), and All Errors Combined. Thirty novice implanters from 10 countries participated. Baseline experiences were similar between groups. Compared to SIM-trained, the PBP-trained group completed on average 11% more procedural Steps (P < 0.001) and made 61.2% fewer Critical Errors (P < 0.001), 57.1% fewer Errors (P = 0.140), and 60.7% fewer All Errors Combined (P = 0.001); 11/15 (73%) PBP trainees demonstrated the predefined target performance level vs. 3/15 SIM trainees (20%) in the video-recorded performance., Conclusion: Proficiency-based progression training produces superior objectively assessed novice operators' surgical performance in device implantation compared with traditional (simulation) training. Systematic PBP incorporation into formal academic surgical skills training is recommended before in vivo device practice. Future studies will quantify PBP training's effect on surgery-related device complications., Competing Interests: Conflict of interest: J.M. conducted the present research project as part of his PhD studies at KU Leuven, Belgium. J.M. is also an employee of Medtronic. M.S. reports personal fees (honoraria for educational activity) from Medtronic during the conduct of the project and personal fees from Biotronik outside the submitted work; A.P. reports personal fees (honoraria for educational activity) from Medtronic during the conduct of the project; L.M. reports grants and personal fees (support for Fellowship programme, research grants, consulting honoraria) from Medtronic, Abbott, and Boston Scientific during the conduct of the project; A.R. reports teaching honoraria from Medtronic outside the submitted work; H.R. reports personal fees (honoraria for educational activity) from Medtronic during the conduct of the project and outside the submitted work; C.G. reports research funding from Abbott, Biotronik, and Medtronic, and speaker/consultancy fees from Medtronic, Biotronik, and Abbott outside the submitted work; A.G.G. reports personal fees (consulting) from Medtronic during the conduct of the project; T.V. reports personal fees (lectures honoraria) from Medtronic outside the submitted work., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Competing Interests: Disclosures The authors have no conflicts of interest to disclose.

Background and Aims: Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed., Methods: All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models., Results: 1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001)., Conclusions: Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

The second generation of transcatheter pacing systems, called Micra AV, can provide atrioventricular (AV) synchronous pacing via a new pacing algorithm relying on sensing mechanical atrial contraction. Several novel programming parameters were introduced to enable AV synchronous pacing, including an A3 window and A4 window as well as a conduction mode switch and an activity mode switch. In addition to several automated features, manual programming optimization of some of the novel parameters is key to improving AV synchrony. A solid knowledge of the features and their programming is essential for electrophysiologists implanting or following patients with Micra AV devices. Differences in programming optimization might partially explain the high variability of AV synchrony published in real-world data reports. This article reviews the key programming parameters of Micra AV. Subsequently, optimal programming recommendations for defined patient profiles are presented. Those were established by consensus within an expert panel comprised of 11 European electrophysiologists from high-volume Micra AV centres. The patient profiles were (1) high degree AV block and slow sinus rhythm; (2) high degree AV block and fast sinus rhythm; and (3) intermittent AV block. The panel recommended to evaluate the mechanical atrial activity on transthoracic echocardiography prior to implant. It was also agreed that Auto A3 Threshold and Tracking Check should be turned off in all patients, AV conduction mode switch should be turned off in all patients with high degree AV block, and the lower rate should be programmed to 50 bpm with exceptions based on individual clinical assessment. Future studies will be useful to evaluate the strength of those recommendations to improve the AV synchrony., Competing Interests: Conflict of interest: C.G. receives consultant and/or speaker fees and research grants from Abbot, Biotronik, and Medtronic. A.B. has received consultant and/or speaker fees from Abbott, Bayer Healthcare, Biosense Webster, Biotronik, Boston Scientific, Bristol-Myers Squibb, Cook Medical, Daiichi Sankyo, Medtronic, Pfizer, and Spectranetics/Philips. N.C. receives consulting fees from Medtronic. C.D.A. received research grants from Biotronik, Medtronic, Abbott, LivaNova, Boston Scientific, AtriCure, Philips, and Acutus; and received compensation for teaching purposes and proctoring from Medtronic, Abbott, Biotronik, Livanova, Boston Scientific, Atricure, Acutus Medical, and Daiichi Sankyo. J.B.J. receives consulting fees from Medtronic. T.R. receives research grants from the Swiss National Science Foundation, the Swiss Heart Foundation, and the Sitem Insel support fund; speaker/consulting honoraria or travel support from Abbott/SJM, Bayer, Biosense Webster, Biotronik, Boston Scientific, Daiichi Sankyo, Farapulse, Medtronic, and Pfizer-BMS; support for the institution’s fellowship programme from Abbott/SJM, Biosense Webster, Biotronik, Boston Scientific, and Medtronic. All remaining authors have declared no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Left bundle branch pacing (LBBP) has been shown to better maintain electrical synchrony compared with right ventricular pacing (RVP), but little is known about its impact on mechanical synchrony. This study investigates whether LBBP better preserves left ventricular (LV) mechanical synchronicity and function compared with RVP., Methods and Results: Sixty patients with pacing indication for bradycardia were included: LBBP (n = 31) and RVP (n = 29). Echocardiography was performed before and shortly after pacemaker implantation and at 1-year follow-up. The lateral wall-septal wall (LW-SW) work difference was used as a measure of mechanical dyssynchrony. Septal flash, apical rocking, and septal strain patterns were also assessed. At baseline, LW-SW work difference was small and similar in two groups. SW was markedly decreased, while LW work remained mostly unchanged in RVP, resulting in a larger LW-SW work difference compared with LBBP (1253 ± 687 mmHg·% vs. 439 ± 408 mmHg·%, P < 0.01) at last follow-up. In addition, RVP more often induced septal flash or apical rocking and resulted in more advanced strain patterns compared with LBBP. At 1 year follow-up, LV ejection fraction (EF) and global longitudinal strain (GLS) were more decreased in RVP compared with LBBP (ΔLVEF: -7.4 ± 7.0% vs. 0.3 ± 4.1%; ΔLVGLS: -4.8 ± 4.0% vs. -1.4 ± 2.5%, both P < 0.01). In addition, ΔLW-SW work difference was independently correlated with LV adverse remodelling (r = 0.42, P < 0.01) and LV dysfunction (ΔLVEF: r = -0.61, P < 0.01 and ΔLVGLS: r = -0.38, P = 0.02)., Conclusion: LBBP causes less LV mechanical dyssynchrony than RVP as it preserves a more physiologic electrical conduction. As a consequence, LBBP appears to preserve LV function better than RVP., Competing Interests: Conflict of interests: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Leadless pacemakers (PMs) were recently introduced to overcome lead-related complications. They showed high safety and efficacy profiles. Prospective studies assessing long-term safety on cardiac structures are still missing., Objective: The purpose of this study was to compare the mechanical impact of Micra with conventional PM on heart function., Methods: We conducted a non-inferiority trial in patients with an indication for single chamber ventricular pacing. Patients were 1:1 randomized to undergo implantation of either Micra or conventional monochamber ventricular pacemaker (PM). Patients underwent echocardiography at baseline, 6 and 12 months after implantation. Analysis included left ventricular ejection fraction (LVEF), global longitudinal strain (GLS) and valve function. N-terminal-pro hormone B-type natriuretic peptide (NT-pro-BNP) levels were measured at baseline and 12 months., Results: Fifty-one patients (27 in Micra group and 24 in conventional group) were included. Baseline characteristics were similar for both groups. At 12 months, (1) the left ventricular function as assessed by LVEF and GLS worsened similarly in both groups (∆LVEF -10 ± 7.3% and ∆GLS +5.7 ± 6.4 in Micra group vs. -13.4 ± 9.9% and +5.2 ± 3.2 in conventional group) (p = 0.218 and 0.778, respectively), (2) the severity of tricuspid valve regurgitation was significantly lower with Micra than conventional pacing (p = 0.009) and (3) median NT-pro-BNP was lower in Micra group (970 pg/dL in Micra group versus 1394 pg/dL in conventional group, p = 0.041)., Conclusion: Micra is non inferior to conventional PMs concerning the evolution of left ventricular function at 12-month follow-up. Our data suggest that Micra has a comparable mechanical impact on the ventricular systolic function but resulted in less valvular dysfunction., (© 2023 Wiley Periodicals LLC.)

Background: Leadless pacemakers have been developed to avoid some of the complications that are associated transvenous pacemakers. Pericardial effusion is a rare complication of leadless pacemaker implantation, which may result from perforation of the delivery catheter. In this study, we describe preclinical perforation performance of an updated Micra delivery catheter., Methods: To assess preclinical perforation performance of the updated delivery catheter, three analyses were performed. First, Finite Element Analysis (FEA) computational modeling was performed to estimate the target tissue stress during Micra delivery catheter tenting. Second, benchtop perforation forces of ovine tissue were recorded for the original and updated delivery catheters. Finally, a Monte-Carlo simulation combining human cadaveric Micra implant forces and human ventricular tissue perforation properties was performed to estimate clinical perforation performance., Results: FEA modeling demonstrated a 66% reduction in target tissue stress when using the updated Micra delivery catheter (6.2 vs. 2.2 psi, Original vs. Updated Micra delivery catheter). Updated Micra delivery catheters required 20% more force to perforate porcine ventricular tissues in benchtop testing (μ upd  = 26.9N vs. μ org  = 22.4N, p = .01). Monte-Carlo Simulation of catheter performance in human cadaveric tissues predicts 28.5% reduction of catheter-perforated cases with the updated delivery catheter., Conclusions: This study, using computer modelling and benchtop experimentation, has indicated that increased surface area and rounding of the updated Micra catheter tip significantly improves preclinical perforation performance. It will be important to evaluate the impact of these catheter design changes with robust registry data., (© 2023 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Importance: In cardiac device implant training, there is no common system to objectively assess trainees' ability to perform tasks at predetermined performance levels before in vivo practice; therefore, patients are potentially exposed to risks related to operators' early learning curve., Objective: To assess the effect on implant performance quality of novel metrics-based simulation training to proficiency (proficiency-based progression [PBP]) vs traditional simulation-based training (SBT)., Design, Setting, and Participants: In this prospective randomized trial, conducted between March 8, 2022 and November 24, 2022, novice implanters were randomized (blinded) 1:1 to participate in an SBT curriculum (procedural knowledge e-learning and in-person simulation training) at an international skills training center, with proficiency demonstration requirements at each training stage for advancing (PBP approach) or without the requirements. Ultimately, trainees performed a cardiac resynchronization therapy (CRT) implant using virtual reality simulation. The procedure was video-recorded and subsequently scored using previously validated metrics by 2 independent assessors blinded to group. Physicians who had already implanted more than 20 pacemakers or defibrillators and fewer than 200 CRT systems as the first operator were eligible. Thirty-two implanters from 10 countries voluntarily enrolled in the training program and were randomized; 30 (15 per group) started and completed training. Data analysis was performed from November 27 to December 22, 2022., Intervention: Training with PBP vs SBT., Main Outcome and Measures: The primary outcome comprised 4 objectively assessed performance metrics derived from the video-recordings: number of procedural steps completed, errors, critical errors, and all errors combined., Results: Baseline experience of the 30 participants (19 [63%] male; mean [SD] number of years in implant practice, 2.0 [1.8]; median [IQR] number of implanted pacemakers or defibrillators, 47.5 [30.0-115.0]; median [IQR] number of implanted CRT systems, 3.0 [1.25-10.0]) was similar between study groups. Compared with the SBT group, the PBP group completed 27% more procedural steps (median [IQR], 31 [30-32] vs 24 [22-27]; P < .001) and made 73% fewer errors (median [IQR], 2 [1-3] vs 7 [5-8]; P < .001), 84% fewer critical errors (median [IQR], 1 [0-1] vs 3 [3-5]; P < .001), and 77% fewer all errors combined (errors plus critical errors) (median [IQR], 3 [1-3] vs 11 [8-12]; P < .001); 14 of the 15 PBP trainees (93%) demonstrated the predefined target performance level vs 0 of the 15 SBT trainees., Conclusions and Relevance: In this randomized trial, the PBP approach to novice implanter training generated superior objectively assessed performance vs SBT. If implemented broadly and systematically, PBP training may ensure safe and effective performance standards before trainees proceed to (supervised) in vivo practice. Future studies are needed to verify implications on procedure-related patient complications., Trial Registration: ClinicalTrials.gov Identifier: NCT05952908.

Aim: To provide a detailed description of the workflow at our telecardiology centre and to analyse the workload of real-world remote monitoring with the aim to assess the feasibility to outsource this service., Methods: A retrospective analysis was conducted on the telecardiology service provided at the University Hospitals of Leuven by extracting patient demographic data, general time usage and detailed information about the type of remote contacts. 10,869 contacts in 948 patients have been included. A 2-week prospective study was conducted on the same service by documenting and monitoring every action performed by specialised nurses when analysing and solving remote monitoring transmissions. 337 contacts in 262 patients were collected during this period., Results: Both analyses indicated similar numbers of events and interventions. Unplanned transmissions were more challenging and required more interventions than planned transmissions. Relatively little time (retrospective median: 1.83 min; prospective median: 1.56 min, per event) was spent on incoming non-actionable 'normal' transmissions (retrospective: 46%; prospective: 40% of all events). Retrospectively 54% and prospectively 60% of transmissions showed abnormalities and were responsible for most of the time expended. Disease-related issues were the most frequent cause for these 'abnormal' alerts. Contacting patients and physicians were key interventions undertaken. Interaction initiated by patients mainly involved the installation process (42%) and bedside monitoring problems (32%)., Conclusion: External data centres could deal with 40% of the transmissions, but the decline in workload would be negligible for the in-hospital remote monitoring team, because very little time is spent dealing with the many 'non-event' transmissions whereas most of the time is spent solving clinical problems. Providing sufficient resources and optimising communication protocols is necessary to aid in managing the workload of the remote monitoring team., Implications for practiceContacting patients and physicians are key interventions for specialist nurses in remote monitoring centres.Detailed timing confirmed that most time was spent on relevant disease-related clinical problems.Despite dealing with ∼40% of transmissions, outsourcing to external data centres would decrease the workload only by 15-25%.Patient initiated contacts with questions concerning remote monitoring form a high burden and should be countered by scaling the service and creating communication protocols.

Aims: Diagnosis of Long QT syndrome (LQTS) is based on prolongation of the QT interval corrected for heart rate (QTc) on surface ECG and genotyping. However, up to 25% of genotype positive patients have a normal QTc interval. We recently showed that individualized QT interval (QTi) derived from 24 h holter data and defined as the QT value at the intersection of an RR interval of 1,000 ms with the linear regression line fitted through QT-RR data points of each individual patient was superior over QTc to predict mutation status in LQTS families. This study aimed to confirm the diagnostic value of QTi, fine-tune its cut-off value and evaluate intra-individual variability in patients with LQTS., Methods: From the Telemetric and Holter ECG Warehouse, 201 recordings from control individuals and 393 recordings from 254 LQTS patients were analysed. Cut-off values were obtained from ROC curves and validated against an in house LQTS and control cohort., Results: ROC curves indicated very good discrimination between controls and LQTS patients with QTi, both in females (AUC 0.96) and males (AUC 0.97). Using a gender dependent cut-off of 445 ms in females and 430 ms in males, a sensitivity of 88% and specificity of 96% were achieved, which was confirmed in the validation cohort. No significant intra-individual variability in QTi was observed in 76 LQTS patients for whom at least two holter recordings were available (483 ± 36 ms vs. 489 ± 42 ms, p  = 0.11)., Conclusions: This study confirms our initial findings and supports the use of QTi in the evaluation of LQTS families. Using the novel gender dependent cut-off values, a high diagnostic accuracy was achieved., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The handling editor JE is currently organizing a Research Topic with the author BV., (© 2023 Robyns, Nuyens, Vandenberk, Haemers, Breckpot, Garweg, Ector and Willems.)

Background: While prior Micra trials demonstrated a high implant success rate and favorable safety and efficacy results, changes in implant populations and safety over time is not well studied. The objective of this analysis was to report the performance of Micra in European and Middle Eastern patients and compare to the Micra Investigational Device Exemption (IDE) and Micra Post Approval Registry (PAR) studies., Methods: The prospective, single-arm Micra Acute Performance European and Middle Eastern (MAP EMEA) registry was designed to further study the performance of Micra in patients from EMEA. The primary endpoint was to characterize acute (30-day) major complications. Electrical performance was analyzed. The major complication rate through 12 months was compared with the IDE and PAR studies., Results: The MAP EMEA cohort ( n  = 928 patients) had an implant success rate of 99.9% and were followed for an average of 9.7 ± 6.5 months. Compared to prior studies, MAP EMEA patients were more likely to have undergone dialysis and have a condition which precluded the use of a transvenous pacemaker ( p  < .001). Within 30 days of implantation, the MAP EMEA cohort had a major complication rate of 2.59%. Mean pacing thresholds were low and stable through 12 months (0.61 ± 0.40 V at 0.24 ms at implant and 12 months). Through 12 months post-implantation, the major complication rate for MAP EMEA was not significantly different from IDE ( p  = .56) or PAR ( p  = .79)., Conclusion: Despite patient differences over time, the Micra leadless pacemaker was implanted with a high success rate and low complication rate, in-line with prior reports., Competing Interests: Dr. Roberts reports having received honoraria from Medtronic, Inc and Boston Scientific. Dr. Clémenty reports having received consulting fees from Medtronic, Inc; Dr. Winter reports having received lecture fees from ZOLL‐CMS Germany, Medtronic, Inc. and Biotronik. Mr. Anderson, Mrs. Pol and Dr. Butler report being employees and shareholders of Medtronic, Inc. Dr. Garweg reports receiving consultant fees from Medtronic, Inc. The remaining authors have nothing to disclose., (© 2023 The Authors. Journal of Arrhythmia published by John Wiley & Sons Australia, Ltd on behalf of Japanese Heart Rhythm Society.)

Introduction: Micra atrioventricular (AV) provides leadless atrioventricular synchronous pacing by sensing atrial contraction (A4 signal). Real-world operation and reliability of AV synchrony (AVS) assessment using device data have not been described. The purposes of this study were to (1) assess the correlation between AVS and atrial mechanical sensed-ventricular pacing (AM-VP) percentages in patients with permanent high-degree AV block and (2) report on the real-world effectiveness of Micra AV., Methods: The correlation between ECG-determined AVS in-clinic and device-collected %AM-VP was assessed using data from 40 patients with high-degree AV block enrolled in the Micra Atrial tRacking using a Ventricular AccELerometer (MARVEL) 2 study. A retrospective analysis to assess continuously-sampled %AM-VP since last session, device programming, and electrical parameters was performed using Micra AV transmissions from the Medtronic CareLink database. Patients with transmissions ≥180 days postimplant were included., Results: Among the 40 MARVEL 2 AV block patients with a median %VP of 99.7%, AVS was highly correlated with AM-VP (median AVS 87.1%, median AM-VP 79.1%; R 2  = 0.764, p < .001). The CareLink cohort included 4384 patients programmed to VDD mode. The mean A4 amplitude was 2.3 ± 1.8 m/s 2 at implant and 2.3 ± 1.6 m/s 2 at 28 weeks. In patients with %VP >90% (n = 1662), the median %AM-VP was 74.7%. For the full cohort, median %VP was 65.6% and median projected battery longevity was 10.5 years., Conclusion: In patients with a high pacing burden, %AM-VP provides a reasonable estimation of AVS. The first large real-world analysis of Micra AV patients with >90% VP showed stable atrial sensing over time with a median %AM-VP, a correlate of AVS, of 74.7%., (© 2022 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Aims: There is limited information on what clinical factors are associated with the development of pericardial effusion after leadless pacemaker implantation. We sought to determine predictors of and to develop a risk score for pericardial effusion in patients undergoing Micra leadless pacemaker implantation attempt., Methods and Results: Patients (n = 2817) undergoing implant attempt from the Micra global trials were analysed. Characteristics were compared between patients with and without pericardial effusion (including cardiac perforation and tamponade). A risk score for pericardial effusion was developed from 18 pre-procedural clinical variables using lasso logistic regression. Internal validation and future prediction performance were estimated using bootstrap resampling. The scoring system was also externally validated using data from the Micra Acute Performance European and Middle East (MAP EMEA) registry. There were 32 patients with a pericardial effusion [1.1%, 95% confidence interval (CI): 0.8-1.6%]. Following lasso logistic regression, 11 of 18 variables remained in the model from which point values were assigned. The C-index was 0.79 (95% CI: 0.71-0.88). Patient risk score profile ranged from -4 (lowest risk) to 5 (highest risk) with 71.8% patients considered low risk (risk score ≤0), 16.6% considered medium risk (risk score = 1), and 11.7% considered high risk (risk score ≥2) for effusion. The median C-index following bootstrap validation was 0.73 (interquartile range: 0.70-0.75). The C-index based on 9 pericardial effusions from the 928 patients in the MAP EMEA registry was 0.68 (95% CI: 0.52-0.83). The pericardial effusion rate increased significantly with additional Micra deployments in medium-risk (P = 0.034) and high-risk (P < 0.001) patients., Conclusion: The overall rate of pericardial effusion following Micra implantation attempt is 1.1% and has decreased over time. The risk of pericardial effusion after Micra implant attempt can be predicted using pre-procedural clinical characteristics with reasonable discrimination., Clinical Trial Registration: The Micra Post-Approval Registry (ClinicalTrials.gov identifier: NCT02536118), Micra Continued Access Study (ClinicalTrials.gov identifier: NCT02488681), and Micra Transcatheter Pacing Study (ClinicalTrials.gov identifier: NCT02004873)., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Early results from the Micra investigational trial and Micra Post-Approval Registry (PAR) demonstrated excellent safety and device performance; however, outcomes based on anticoagulation (AC) status at implant have not been evaluated., Objective: The purpose of this study was to report implant characteristics, perforation rate, and vascular-related events based on perioperative oral AC strategy in patients undergoing Micra implant., Methods: We compared procedure characteristics, major complications, and vascular events, including pericardial effusion, stratified by any adverse event (including major complications, minor complications, and observations) or major complication only according to AC status in the Micra PAR., Results: Among 1795 patients with AC status available, 585 were not on AC, 795 had AC interrupted, and 415 had AC continued during Micra implant. Non-AC patients tended to be younger, with less history of atrial fibrillation and chronic obstructive pulmonary disease, and more history of dialysis than interrupted and continued patients. The implant success rate was similar for all groups (99.1%-99.8%). Through 30 days postimplant, the overall major complication rate was 3.1% for the non-AC group, 2.6% for the interrupted group, and 1.5% for the continued group. The combined rate for any vascular or pericardial effusion adverse event did not differ significantly among AC strategies (6.5%, 4.8%, and 3.6%, respectively)., Conclusion: Implant of Micra seems to be safe and feasible regardless of an interrupted or continued periprocedural oral AC strategy, with no increased risk of perforation or vascular complications., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Cryoballoon ablation (CRYO) for pulmonary vein isolation (PVI) in atrial fibrillation (AF) has become an established treatment option as alternative for radiofrequency catheter ablation (RFCA). As symptom relief is still the main indication for PVI, quality of life (QoL) is a key outcome parameter. This review summarizes the evidence about the evolution of QoL after CRYO., Methods: A search for clinical studies reporting QoL outcomes after CRYO was performed on PUBMED and COCHRANE. A total of 506 publications were screened and 10 studies met the in- and exclusion criteria., Results: All studies considered QoL as a secondary endpoint and reported significant improvement in QoL between baseline and 12 months follow-up, independent of the QoL instruments used. The effect size of CRYO on QoL was comparable between studies and present in both paroxysmal and persistent AF. Direct comparison between CRYO and RFCA was limited to two studies, there was no difference between ablation modalities after 12 months FU. Two studies in paroxysmal AF reported outcome beyond 12 months follow-up and QoL improvement was maintained up to 36 months after ablation. There were no long-term data available for persistent AF., Conclusion: CRYO of AF significantly improves QoL. The scarce amount of data with direct comparison between subgroups limits further exploration. Assessment of QoL should be considered a primary outcome parameter in future trials with long-term follow-up., (© 2021 Wiley Periodicals LLC.)

Aims: Mitral valve prolapse (MVP) causes left ventricular (LV) remodelling even in the absence of significant mitral regurgitation. To evaluate whether apical insertion of the papillary muscle (PM) influences the pattern and severity of MVP-related LV remodelling., Methods and Results: All MVP patients who underwent CMR at our institution between December 2008 and December 2019 were included, thoroughly reviewed and grouped according to apical/non-apical PM insertion. Apical PM insertion was found in 53/92 patients (58%) and associated with mitral leaflet thickening (P < 0.01) and a trend towards higher prevalence of mitral annular disjunction (P = 0.05). Whereas no differences in ventricular volumes or ejection fraction were found, patients with apical PM insertion showed more lateral wall remodelling with mid lateral wall thinning [2.1 (1.8-2.5) vs. 4.0 (3.5-5.0) mm, P < 0.01], increased LV eccentricity and a lower GCS at this level (15 ± 3% vs. 20 ± 3%, P < 0.01). In long-axis direction, increased end-diastolic mid lateral wall angulation was found (i.e. angle <155° measured in the thinnest point of the mid lateral wall in four-chamber view) with a higher angle variation during systole (25 ± 11° vs. 17 ± 8°, P < 0.01). Remarkably, PM fibrosis was significantly more frequent in patients with apical PM insertion (i.e. 66% vs. 28%, P < 0.01). Finally, a higher burden of premature ventricular complexes (>5%) and non-sustained ventricular tachyarrhythmias was found in patients with apical PM insertion: 53% vs. 25% (P = 0.04) and 38% vs. 18% (P = 0.04), respectively., Conclusion: Apical PM insertion is part of the phenotypic spectrum of MVP, impacts significantly LV remodelling, and potentially may be related to increased ventricular arrhythmogenicity., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Introduction: MARVEL 2 assessed the efficacy of mechanical atrial sensing by a ventricular leadless pacemaker, enabling a VDD pacing mode. The behavior of the enhanced MARVEL 2 algorithm during variable atrio-ventricular conduction (AVC) and/or arrhythmias has not been characterized and is the focus of this study., Methods: Of the 75 patients enrolled in the MARVEL 2 study, 73 had a rhythm assessment and were included in the analysis. The enhanced MARVEL 2 algorithm included a mode-switching algorithm that automatically switches between VDD and ventricular only antibradycardia pacing (VVI)-40 depending upon AVC status., Results: Forty-two patients (58%) had persistent third degree AV block (AVB), 18 (25%) had 1:1 AVC, 5 (7%) had variable AVC status, and 8 (11%) had atrial arrhythmias. Among the 42 patients with persistent third degree AVB, the median ventricular pacing (VP) percentage was 99.9% compared to 0.2% among those with 1:1 AVC. As AVC status changed, the algorithm switched to VDD when the ventricular rate dropped less than 40 bpm. During atrial fibrillation (AF) with ventricular response greater than 40 bpm, VVI-40 mode was maintained. No pauses longer than 1500 ms were observed. Frequent ventricular premature beats reduced the percentage of AV synchrony. During AF, the atrial signal was of low amplitude and there was infrequent sensing., Conclusion: The mode switching algorithm reduced VP in patients with 1:1 AVC and appropriately switched to VDD during AV block. No pacing safety issues were observed during arrhythmias., (© 2021 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Objectives: This study sought to formulate a predictive model for describing the long-term electrical performance of Micra (Medtronic, Mounds View, Minnesota)., Background: The Micra leadless pacemaker is an alternative ventricular pacing option that avoids the pitfalls of transvenous leads. However, well-defined metrics to predict the long-term electrical performance of the device are lacking., Methods: We identified all patients who underwent successful Micra implantation enrolled in the investigational device exemption study, continued access study, or post-approval registry with complete 1-year post-implantation data or system revision due to elevated thresholds (N = 1,843). The analysis endpoint was an elevated pacing capture threshold (PCT) at ≥12 months post-implantation, defined as ≥2.0 V at 0.24 ms or an increase of ≥1.5 V from implantation or need for system revision due to elevated thresholds at ≤12 months post-implantation. We evaluated for univariate and multivariate associations between patient and device characteristics at implantation and for elevated thresholds at 12 months., Results: Among the total cohort, 75 patients (4.1%) had elevated thresholds at 12 months; of these, 13 required system revisions. Predictors associated with elevated thresholds in univariate analysis included the total number of deployments (excluded from the multivariable model), impedance and PCT at implantation, male sex, history of diabetes, and ischemic cardiomyopathy. Multivariable regression modeling found that male sex, history of diabetes, implantation PCT of ≥2 V, and impedance of <800 Ω were independent predictors of elevated PCT at 12 months (all p < 0.05)., Conclusion: A history of diabetes, male sex, elevated PCT, and low impedance at implantation were independent predictors of elevated thresholds at 12 months. These metrics represent the foundation of a simple tool to aid in procedural decision making., Competing Interests: Funding Support and Author Disclosures Ms. Wallace is an employee and shareholder of Medtronic. Mr. Stromberg is an employee and shareholder of Medtronic. Dr. Piccini is supported by R01HL128595 from the National Heart, Lung, and Blood Institute; receives grants for clinical research from Abbott, the American Heart Association, Association for the Advancement of Medical Instrumentation, Bayer, Boston Scientific, and Philips; and serves as a consultant to Abbott, Allergan, ARCA Biopharma, Biotronik, Boston Scientific, LivaNova, Medtronic, Milestone, Myokardia, Sanofi, Philips, and UpToDate. Dr. Roberts has received honoraria from Medtronic. Dr. El-Chami has served as a consultant for Medtronic and Boston Scientific. Dr. Soejima has received honoraria for lecturing with Medtronic, Japan and Abbott, Japan. Dr. Garweg has received research funding from Biotronik, Boston Scientific, and Medtronic; and has received speaker fees and consultancy fees from Medtronic; Boston Scientific, and Biotronik. Dr. Fagan is an employee and shareholder of Medtronic. Dr. Lloyd has provided consulting and research support to Medtronic; and has provided research support to Boston Scientific. Dr. Kiani has reported that he has no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: The feasibility and outcomes of concomitant atrioventricular node ablation (AVNA) and leadless pacemaker implant are not well studied. We report outcomes in patients undergoing Micra implant with concomitant AVNA., Methods: Patients undergoing AVNA at the time of Micra implant from the Micra Transcatheter Pacing (IDE) Study, Continued Access (CA) study, and Post-Approval Registry (PAR) were included in the analysis and compared to Micra patients without AVNA. Baseline characteristics, acute and follow-up outcomes, and electrical performance were compared between patients with and without AVNA during the follow-up period., Results: A total of 192 patients (mean age 77.4 ± 8.9 years, 72% female) underwent AVNA at the time of Micra implant and were followed for 20.4 ± 15.6 months. AVNA patients were older, more frequently female, and tended to have more co-morbid conditions compared with non-AVNA patients (N = 2616). Implant was successful in 191 of 192 patients (99.5%). The mean pacing threshold at implant was 0.58 ± 0.35 V and remained stable during follow-up. Major complications within 30 days occurred more frequently in AVNA patients than non-AVNA patients (7.3% vs. 2.0%, p < .001). The risk of major complications through 36-months was higher in AVNA patients (hazard ratio: 3.81, 95% confidence interval: 2.33-6.23, p < .001). Intermittent loss of capture occurred in three AVNA patients (1.6%), all were within 30 days of implant and required system revision. There were no device macrodislodgements or unexpected device malfunctions., Conclusion: Concomitant AVN ablation and leadless pacemaker implant is feasible. Pacing thresholds are stable over time. However, patient comorbidities and the risk of major complications are higher in patients undergoing AVNA., (© 2021 The Authors. Journal of Cardiovascular Electrophysiology Published by Wiley Periodicals LLC.)

Background: The MARVEL (Micra Atrial TRacking Using a Ventricular AccELerometer) 2 study assessed the efficacy of atrioventricular (AV) synchronous pacing with a Micra leadless pacemaker. Average atrioventricular synchrony (AVS) was 89.2%. Previously, low amplitude of the Micra-sensed atrial signal (A4) was observed to be a factor of low AVS., Objective: The purpose of this study was to identify predictors of A4 amplitude and high AVS., Methods: We analyzed 64 patients enrolled in MARVEL 2 who had visible P waves on electrocardiogram for assessing A4 amplitude and 40 patients with third-degree AV block for assessing AVS at rest. High AVS was defined as >90% correct atrial-triggered ventricular pacing. The association between clinical factors and echocardiographic parameters with A4 amplitude was investigated using a multivariable model with lasso variable selection. Variables associated with A4 amplitude together with premature ventricular contraction burden, sinus rate, and sinus rate variability (standard deviation of successive differences of P-P intervals [SDSD]) were assessed for association with AVS., Results: In univariate analysis, low A4 amplitude was inversely related to atrial function assessed by E/A ratio and e'/a' ratio, and was directly related to atrial contraction excursion (ACE) and atrial strain (Ɛa) on echocardiography (all P ≤.05). The multivariable lasso regression model found coronary artery bypass graft history, E/A ratio, ACE, and Ɛa were associated with low A4 amplitude. E/A ratio and SDSD were multivariable predictors of high AVS, with >90% probability if E/A <0.94 and SDSD <5 bpm., Conclusion: Clinical parameters and echocardiographic markers of atrial function are associated with A4 signal amplitude. High AVS can be predicted by E/A ratio <0.94 and low sinus rate variability at rest., (Copyright © 2020 The Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Permanent pacing is common after valve intervention. The presence of a conventional pacemaker in this population is recognized as a risk factor for infectious events. Therefore, a leadless pacing system could be the preferred strategy when permanent pacing is required after valve intervention., Aim: To report periprocedural outcomes and follow-up of patients undergoing implantation of a leadless pacing system after valve intervention., Methods: Patients with previous valve intervention at the time of attempted implantation of a leadless pacemaker (Micra™, Medtronic, Minneapolis, MN, USA) were included, and were compared with a control group (patients also implanted with Micra™ without valve intervention)., Results: Among a total of 170 Micra™ implantation procedures, 54 patients (31.8%) had a history of valve intervention: 28 after aortic valve replacement; 10 after mitral valve replacement; one after single tricuspid valvuloplasty; and 15 after multiple valve surgery. Median age of the patients was 82.5 (77.0-86.0) years and 53.7% were male. Patients with previous valve intervention had a higher incidence of arterial hypertension (P=0.014) and ischaemic heart disease (P=0.040). The primary indications for permanent pacing after valve intervention were high-degree atrioventricular block (59.3%) and atrial fibrillation with bradycardia (27.8%). Micra™ was successfully implanted in all patients (n=170) without any procedure-related major complications. During a median follow-up of 12 months, electrical performance was excellent and similar in both groups. Also, a similar reduction in left ventricular ejection fraction was observed at 12 months in both groups, which was correlated with the percentage of right ventricular pacing., Conclusion: A leadless pacemaker is safe and efficient after valve intervention, and therefore represents an effective pacing option in patients after valve intervention., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Background: With increasing cardiovascular implantable electronic device (CIED) implantations, growing number of extractions of leads and devices are noted, mainly for complications such as infection and lead dysfunction. The optimal timing for re-implantation remains uncertain. We  investigated the time to eventual re-implantation of CIEDs in the University Hospitals Leuven, Belgium. Methods: All consecutive patients, referred for extraction between January 2005 and December 2016, were analysed for the timing of eventual re-implantation. Results: Two-hundred and forty-three patients were included. Mean follow-up was 77 ± 37 months. Global re-implantation rate was 89.3%: 100% for lead dysfunctions versus 80.7% following infections. Median time to re-implantation (TTR) was 0 [0-111] days and 8.5 [0-3025] days, respectively ( p  < .001). Globally 0 [0-3025] days. Re-implantation was performed in 83.2% of pacemaker patients, compared to 95.8% of defibrillator patients ( p  < .001). Median TTR was 4 [0-3025] days and 0 [0-345] days, respectively ( p  < .001). In AV-block related pacemaker indications, 90% were re-implanted, compared to 78% for symptomatic indications ( p  = .09). Median TTR was 2 [0-3025] and 6 [0-2047] days, respectively ( p  = .02). Re-implantation was performed in 96.7% of defibrillator patients with a secondary prevention indication, compared to 94.7% with primary prevention indication ( p  = .59). Median TTR was 0 [0-164] and 0 [0-345] days, respectively ( p  = .472). Conclusions: Ten percent of CIEDs is not re-implanted after extraction. CIEDs are re-implanted more often and earlier after extraction for lead dysfunction than after extraction for infectious reasons. Pacemakers are re-implanted less and later than defibrillators. Re-implantation is performed faster in stronger clinical CIED indications.

Background: Transvenous 3 permanent pacemaker-related infection is a severe condition associated with significant morbidity and mortality. Leadless pacemakers may be more resistant to bacterial seeding during bloodstream infection because of its small surface area and encapsulation in the right ventricle. This study reports the incidence and outcomes of bacteraemia in patients implanted with a Micra leadless pacemaker. We present 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) findings obtained in a subgroup of patients., Methods: We report a retrospective cohort study of 155 patients who underwent a Micra TPS implant procedure at the University Hospitals of Leuven between July 2015 and July 2019. We identified the patients who developed an episode of bacteraemia, proved by ≥2 positive blood cultures., Results: Of the 155 patients, 15 patients presented an episode of bacteraemia at a median of 226 days (range: 3-1129) days after the implant procedure. Gram-positive species accounted for 73.3% (n = 11) of the bacteraemia including Staphylococcus (n = 5), Enterococcus (n = 3), and Streptococcus (n = 3). The source of infection was identified in nine patients (60%) including endocarditis in four patients, urinary tract in three patients, and skin in two patients. 18 F-FDG PET/CT imaging performed in six patients did not show sign of infection around the leadless pacemaker. Bacteraemia was resolved in all patients after adequate antibiotherapy. Four patients died early during follow up. For all other patients, there were no recurrence of systemic infection during a median follow up of 263 days (range: 15-1134)., Conclusion: In our small cohort, no leadless pacemaker endocarditis was observed among patients with bacteraemia., (© 2020 Wiley Periodicals LLC.)

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is a common supraventricular arrhythmia that is frequently encountered in an otherwise healthy patient population. Recent guidelines of the European Society of Cardiology underline the role of catheter ablation in the long-term management of these patients., Case Summary: This case describes the clinical presentation and treatment options in a patient with typical slow/fast AVNRT, the most common subform of AVNRT, where antegrade conduction occurs over the slow pathway and retrograde conduction over the fast pathway. The ablation strategy in these patients is illustrated based on intracardiac recordings in combination with per-procedural three-dimensional imaging., Discussion: Atrioventricular nodal reentrant tachycardia is a common arrhythmia with good prognosis but significant impact on quality of life of affected patients. Catheter ablation should be considered early as it can be performed safely and with a very high success rate., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: The Micra Transcatheter Pacing System is implanted directly in the right ventricle (RV) through the femoral vein using a steerable transcatheter delivery system. The present study was done to identify determinants of difficult leadless pacemaker implant procedures including operator, patient, and RV anatomical characteristics., Methods: All patients who underwent a Micra implant from July 2015 to December 2018 at our center were analyzed. From an RV angiogram acquired during implantation, RV geometry including systolic and diastolic volumes and ejection fraction was characterized. The presence of septomarginal trabeculation was noted., Results: One hundred twenty-six patients (mean age: 79 ± 11 years old, mostly male: 77%) were enrolled. Mean Micra RV implant procedure time was 24 ± 23 min, with 1.7 ± 1.3 deployments of the device. No significant change in implant procedure time was observed after the first 30 implants. Eleven patients had a prominent septal component of the septomarginal trabeculation in the RV. Univariate analysis showed that the procedure time was positively correlated with the presence of a prominent septal component of the septomarginal trabeculation (P < .001) or an episode of heart failure (P = .02) and negatively correlated with the number of procedures performed by the operator (P < .001). After multivariable analysis, only the presence of a prominent septal component of the septomarginal trabeculation (P < .001) and the number of procedures performed by the operator (P < .001) were associated with the implant procedure time., Conclusions: In our experience, implant procedure time of a Micra leadless pacemaker depended on the presence of a prominent septal component of the septomarginal trabeculation and operator experience., (© 2020 Wiley Periodicals LLC.)

Objectives: This study reports on the performance of a leadless ventricular pacemaker with automated, enhanced accelerometer-based algorithms that provide atrioventricular (AV) synchronous pacing., Background: Despite many advantages, leadless pacemakers are currently only capable of single-chamber ventricular pacing., Methods: The prospective MARVEL 2 (Micra Atrial tRacking using a Ventricular accELerometer 2) study assessed the performance of an automated, enhanced accelerometer-based algorithm downloaded to the Micra leadless pacemaker for up to 5 h in patients with AV block. The primary efficacy objective was to demonstrate the superiority of the algorithm to provide AV synchronous (VDD) pacing versus VVI-50 pacing in patients with sinus rhythm and complete AV block. The primary safety objective was to demonstrate that the algorithm did not result in pauses or heart rates of >100 beats/min., Results: Overall, 75 patients from 12 centers were enrolled; an accelerometer-based algorithm was downloaded to their leadless pacemakers. Among the 40 patients with sinus rhythm and complete AV block included in the primary efficacy objective analysis, the proportion of patients with ≥70% AV synchrony at rest was significantly greater with VDD pacing than with VVI pacing (95% vs. 0%; p < 0.001). The mean percentage of AV synchrony increased from 26.8% (median: 26.9%) during VVI pacing to 89.2% (median: 94.3%) during VDD pacing. There were no pauses or episodes of oversensing-induced tachycardia reported during VDD pacing in all 75 patients., Conclusions: Accelerometer-based atrial sensing with an automated, enhanced algorithm significantly improved AV synchrony in patients with sinus rhythm and AV block who were implanted with a leadless ventricular pacemaker. (Micra Atrial Tracking Using a Ventricular Accelerometer 2 [MARVEL 2]; NCT03752151)., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)