Dual-chamber Pacing Research Articles

Traditional dual-chamber right ventricular pacing versus conduction system pacing in the US medicare population

Abstract Introduction Conduction system pacing (CSP) has emerged as an alternative therapy to traditional right ventricular (RV) pacing. However, the majority of CSP studies reflect small cohorts or single-center experience. Purpose This analysis aimed to compare CSP to dual chamber (DC) RV pacing in a large, population-based cohort utilizing data from the Micra Coverage with Evidence Development (CED) study. Methods Medicare administrative claims data were used to identify patients implanted with a DC RV pacemaker. Lead placement data from Medtronic’s device registration system was used to identify patients with treated with CSP (N=6,197) using a 3830 catheter-delivered lead or DC RV (non-3830 lead, non-CSP placement) (N=16,989) at the same centers. CSP patients were stratified into left bundle branch area pacing (LBBAP) (N=4,738) and His-bundle pacing (HBP) (N=1,459). Incident heart failure hospitalizations (iHFH), all-cause mortality, complication rates and reinterventions at 6 months were analyzed. Results CSP (LBBAP and HBP) patients with a 3830 catheter-delivered lead experienced significantly lower rates of iHFH (HR: 0.70, P=0.02) and all-cause mortality at 6 months compared with DC RV patients (HR: 0.66, P<.0001) (figure). There was no difference in complications (HR: 0.89, P=0.06) or need for reintervention (HR: 0.83, P=0.08) with LBBAP compared to DC RV, though HBP patients experienced significantly higher rates of complications (HR: 1.41, P=0.001) compared to LBBAP. Conclusion Patients treated with CSP with a 3830 catheter-delivered lead experienced significant all-cause mortality and HFH benefits compared to DC RV pacing. LBBAP had lower complications compared to HBP. These real-world results in a large cohort of Medicare patients align with findings in small clinical studies demonstrating the benefits of LBBAP. Future research will focus on understanding patient selection for CSP.Figure

Two is Better than One: Aveir DR Leadless Pacemaker System with Dual Chamber Pacing

Two is Better than One: Aveir DR Leadless Pacemaker System with Dual Chamber Pacing

Chronic wireless communication between dual-chamber leadless pacemaker devices

BackgroundAveir DR (Abbott, Abbott Park, IL) is a dual-chamber leadless pacemaker (LP) system with distinct atrial and ventricular LPs (ALP, VLP) that communicate wirelessly to deliver atrioventricular synchronous pacing. Success rates of these implant-to-implant (i2i) transmissions have not been systematically evaluated. ObjectiveThis study aims to evaluate chronic i2i success rates in a clinical setting. MethodsPatients meeting standard dual-chamber pacing indications were enrolled and implanted with dual-chamber LP systems as part of a prospective international clinical trial (Aveir DR i2i Study). The percent of successful i2i transmissions from ALP-to-VLP (A-to-V) and VLP-to-ALP (V-to-A) were interrogated from LPs in de novo patients using the device programmer at implant, discharge, and at 1, 3, and 6 months postimplant (1M, 3M, 6M). ResultsA total of 399 patients completed device implant and i2i diagnostic interrogation (62% male; age 69 years; 65% sinus node dysfunction, 32% atrioventricular [AV] block). Median A-to-V and V-to-A i2i success rates exceeded 90% of beats at all time-points from implant to 6M. The minority of patients with A-to-V or V-to-A i2i success in <70% of beats at implant (A-to-V: 19% of patients, V-to-A: 31% of patients) showed roughly 40% improvement by 1M, with this minority dropping to roughly 5% of patients by 6M. Improvement in i2i communication success may be attributed to reprogramming of i2i setting levels, natural changes in dominant posture, and device stabilization. ConclusionWireless implant-to-implant communication in the new dual-chamber leadless pacemaker system demonstrated successful transmissions in >90% of beats throughout the 6-month evaluation period. Communication success improved significantly over time postimplant for specific subgroups. Clinical Trial RegistrationAveir DR i2i Study, ClinicalTrials.gov ID NCT05252702.

Conduction system pacing associated with reduced heart failure hospitalizations and all-cause mortality compared with traditional right ventricular pacing in the Medicare population

BackgroundConduction system pacing (CSP) has emerged as an alternative therapy to traditional right ventricular (RV) pacing. However, most CSP studies reflect small cohorts or single-center experience. ObjectiveThis analysis compared CSP with dual-chamber (DC) RV pacing in a large, population-based cohort using data from the Micra Coverage with Evidence Development study. MethodsMedicare administrative claims data were used to identify patients implanted with a DC RV pacemaker. Lead placement data from Medtronic’s device registration system identified patients treated with CSP (n = 6197) using a 3830 catheter–delivered lead or DC RV (non–3830 lead, non–CSP placement; n = 16,989) at the same centers. CSP patients were stratified into left bundle branch area pacing (LBBAP; n = 4738) and His bundle pacing (HBP; n = 1459). Incident heart failure hospitalizations, all-cause mortality, complication rates, and reinterventions at 6 months were analyzed. ResultsCSP patients with a 3830 catheter–delivered lead experienced significantly lower rates of incident heart failure hospitalization (hazard ratio [HR], 0.70; P = .02) and all-cause mortality at 6 months compared with DC RV patients (HR, 0.66; P < .0001). There was no difference in chronic complications (HR, 0.97; P = .62) or need for reintervention (HR, 0.95; P = .63) with CSP compared with DC RV, although LBBAP patients experienced significantly lower rates of complications (HR, 0.71; P = .001) compared with HBP. ConclusionDC pacemaker patients treated with CSP using a 3830 catheter–delivered lead experienced significant all-cause mortality and heart failure hospitalization benefits compared with DC RV pacing. LBBAP had lower complications compared with HBP. These real-world results align with findings in small clinical studies demonstrating the benefits of CSP.

Systematic review and meta-analysis on the impact on outcomes of device algorithms for minimizing right ventricular pacing.

Physiological activation of the heart using algorithms to minimize right ventricular pacing (RVPm) may be an effective strategy to reduce adverse events in patients requiring anti-bradycardia therapies. This systematic review and meta-analysis aimed to evaluate current evidence on clinical outcomes for patients treated with RVPm algorithms compared to dual-chamber pacing (DDD). We conducted a systematic search of the PubMed database. The predefined endpoints were the occurrence of persistent/permanent atrial fibrillation (PerAF), cardiovascular (CV) hospitalization, all-cause death, and adverse symptoms. We also aimed to explore the differential effects of algorithms in studies enrolling a high percentage of atrioventricular block (AVB) patients. Eight studies (7229 patients) were included in the analysis. Compared to DDD pacing, patients using RVPm algorithms showed a lower risk of PerAF [odds ratio (OR) 0.74, 95% confidence interval (CI) 0.57-0.97] and CV hospitalization (OR 0.77, 95% CI 0.61-0.97). No significant difference was found for all-cause death (OR 1.01, 95% CI 0.78-1.30) or adverse symptoms (OR 1.03, 95% CI 0.81-1.29). No significant interaction was found between the use of the RVPm strategy and studies enrolling a high percentage of AVB patients. The pooled mean RVP percentage for RVPm algorithms was 7.96% (95% CI 3.13-20.25), as compared with 45.11% (95% CI 26.64-76.38) of DDD pacing. Algorithms for RVPm may be effective in reducing the risk of PerAF and CV hospitalization in patients requiring anti-bradycardia therapies, without an increased risk of adverse symptoms. These results are also consistent for studies enrolling a high percentage of AVB patients.

Atrioventricular Synchrony Delivered by a Dual-Chamber Leadless Pacemaker System.

A dual-chamber leadless pacemaker system has been designed for atrioventricular synchronous pacing using wireless, beat-to-beat, implant-to-implant (i2i) communication between distinct atrial and ventricular leadless pacemakers. The atrioventricular synchrony achieved across various ambulatory scenarios has yet to be systematically evaluated. A prospective, single-arm, unblinded, multicenter, international clinical trial of the leadless pacemaker system was conducted in patients with a conventional dual-chamber pacing indication enrolled from February 2022 to March 2023. Leadless pacemaker systems were implanted, and 12-lead Holter electrocardiographic recordings were collected 3 months after implantation over various postures/activities: sitting, supine, left lateral recumbent, right lateral recumbent, standing, normal walk, and fast walk. An independent Holter core laboratory performed a manual adjudication of the percent of atrioventricular synchronous beats using the standard 300-millisecond PR interval limit. Atrium-to-ventricle and ventricle-to-atrium i2i communication success rates were also assessed. Post hoc summary statistics describing the relationships between atrioventricular synchrony and i2i success, posture/activity, implantation indication, atrioventricular event, and heart rate were calculated. In the evaluable population (n=384 of 464 enrolled [83%]; 61% male; age, 70 years; weight, 82 kg; 60% ejection fraction; 95% of beats evaluable), the mean atrioventricular synchrony of 98% of beats observed across all postures using the standard 300-millisecond limit was greater than both atrial-to-ventricular i2i (94%) and ventricular-to-atrial i2i (94%; P<0.001), exceeding both i2i values in 95% of patients. Atrioventricular synchrony was achieved in >95% of evaluable beats across all postures/activities, implantation indications, atrioventricular paced/sensed event combinations, and heart rate ranges (including >100 bpm). This dual-chamber leadless pacemaker system demonstrated atrioventricular synchrony in 98% of evaluable beats at 3 months after implantation. Atrioventricular synchrony was maintained across postures/activities and remained robust for heart rates >100 bpm.

A leadless ventricular pacemaker providing atrioventricular synchronous pacing in the real-world setting: 12-Month results from the Micra AV post-approval registry

BackgroundAdvances in leadless pacemaker technology have enabled accelerometer-based atrioventricular (AV) synchronous pacing by sensing atrial mechanical contraction. ObjectiveThe 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. MethodsThe 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. ResultsThe 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%. ConclusionThe 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.

Therapeutic options for neurocardiogenic syncope: a meta-analysis of randomised trials with and without blinding

BackgroundNeurocardiogenic syncope is a common condition with significant associated psychological and physical morbidity. The effectiveness of therapeutic options for neurocardiogenic syncope beyond placebo remains uncertain.MethodsThe primary endpoint was the risk...

Leadless pacemaker implementation at the right atrial appendage apex: An initial preclinical assessment.

This study evaluates the feasibility and efficacy of implanting a leadless pacemaker at the right atrial appendage (RAA) in a preclinical minipig model, aiming to address the limitations of atrial pacing with current leadless devices like the Medtronic Micra, which is typically used for right ventricular implantation. Four minipigs, each with a median body weight of 45.8±10.0kg, underwent placement of the Micra transcatheter pacing system (TPS) via the right femoral vein into the RAA apex. The pacing performance was assessed over 1-week (short-term) and 3-month (long-term) periods. The initial findings indicated successful implantation, with satisfactory intrinsic R-wave amplitudes and pacing threshold. In the following period, the sensitivity, threshold, and impedance were stable with time. Notably, upon explanation at 3 months, a deep myocardial penetration by the device was observed, necessitating a redesign for safe long-term use in a growing subject's heart. While initial results suggest that RAA apex placement of the Micra TPS is promising for potential inclusion in a dual-chamber pacing system, the issue of myocardial penetration highlights the need for device redesign to ensure safety and effectiveness in long-term applications.

Heart rate is an important predictor of pacing induced cardiomyopathy in a machine learning analysis

Abstract Background 10-20% of patients who have right ventricular pacing develop pacing induced cardiomyopathy (PICM). Home monitoring (HM) could identify patients developing PICM in real-time and facilitate echocardiographic confirmation, medication optimisation and if necessary cardiac resynchronisation therapy (CRT). Purpose To identify predictors of PICM using machine learning models. Methods Consecutive cases of patients who developed PICM (12) after dual chamber pacing were identified from our implant database and matched 4:1 with propensity matched controls who underwent pacing but did not develop PICM (48) (Table 1.) HM data from the 6 months prior to echocardiographic diagnosis of PICM was analysed. PICM was defined as (1) a deterioration in left ventricular (LV) ejection fraction (EF) of &amp;gt;10%, (2) to an EF of &amp;lt;45%, (3) with right ventricular (RV) pacing &amp;gt;20% and (4) the exclusion of alternative causes. Three types of ML models were generated (1) random forest, (2) extreme gradient boosted (XGBoost) (3) K-nearest neighbours algorithm (KNN), with 10-fold cross-validation. Results HM data were available for 12 PICM cases (75 ± 8 years, 72% male). PICM occurred at 2.0 ± 1.2 years. There was no difference between cases and controls in atrial pacing (8±15% vs 18±22% p=0.14), ventricular pacing (81±29% vs 85±24% p=0.62) or base rate (53±5bpm vs 53±5bpm p=0.80). Of the 34 RM features analysed, mean ventricular heart rate was identified as the most important predictor of PICM; area under curve with XG Boost 0.95, KNN 0.95, and random forest 0.86. Other RM features failed to add any more predictive power to the models. Mean ventricular rate was significantly higher in cases than controls (80±6 bpm vs 69±9 bpm p&amp;lt;0.001). Sensitivity analysis was performed to assess whether episodes of atrial fibrillation (AF) were responsible for the higher ventricular rates. After days of AF days were excluded, mean ventricular rate was still significantly higher in cases than controls (79± 6vs 69±9bpm p&amp;lt;0.001) (Figure 1). 10/12 patients had a subsequent CRT upgrade. No consistent pattern emerged in heart rate changes in the first 3 months after CRT upgrade. Conclusion In a group of patients with normal left ventricular function at implant, remotely monitored heart rate can predict early-onset PICM. Further work is required to understand when these heart rate differences emerge, and whether they improve with positive LV remodelling.Table 1.Figure 1.

AV synchrony maintained by a dual-chamber leadless pacemaker in real-world conditions

Abstract Background/Introduction A dual-chamber leadless pacemaker system has been developed to provide atrial and ventricular pacing and maintain atrioventricular (AV) synchrony. The device demonstrated an ability to maintain consistent AV synchrony in an in-clinic setting when tested through a series of postures and gaits under some programming restrictions. Assessing AV synchrony within real-world conditions is needed to understand the device’s performance under wider variations in activity and over a longer period. Purpose Assess a dual-chamber leadless pacemaker’s ability to maintain AV synchrony in an ambulatory environment of daily living under clinically driven programmed settings. Methods Implanted de novo subjects, who had at least 25% atrial pacing after 3-months post-implant, wore a 12-lead Holter monitor for a minimum of 24 hours during normal daily activities and completed a symptom diary. Devices were programmed to a dual chamber pacing mode and clinically appropriate settings then interrogated pre- and post-assessment. An independent Core Laboratory evaluated AV Synchrony, based on a configurable sampling window approach at repeated intervals, and defined synchronous cycles based on whether PR intervals fell within a 50 ms margin of the programmed Paced AV Delay. Results Among the 50 subjects who were administered the assessment, 48 of their Holters were analyzable (mean age 71.4 ± 10.9 years; 66.7% male), and 47 subjects had paired device interrogation data available. The analyzable population was predominantly indicated for sinus node dysfunction (83.3%) with a minority indicated for AV block (16.7%). The mean ± standard deviation of the programmed paced AV delay was 260.0 ± 47.6 ms, and mean PR interval was 241.4 ± 35.1 ms. An atrial paced beat and ventricular paced beat were each present in 69.5% and 22.5% of the evaluable cardiac cycles in the population, respectively. Mean AV Synchrony was maintained above 97% (95% CI: 95.5, 98.8) in the entire cohort and was sustained at high rates within each sub-population. Device metrics that diagnose the rate of directional implant-to-implant (i2i) communication also confirmed device data average throughput rates above 90% (Picture 1). There were no reported episodes of oversensing, undersensing, loss of capture, or pauses. Conclusion Among subjects with standard pacemaker indications, the dual-chamber leadless pacemaker system maintains very high rates of AV synchrony, exceeding i2i throughput, within real-world conditions utilizing clinically appropriate programmed settings.AV Synchrony and i2i by Indication

When the dual-chamber pacing system is the optimal choice for Brugada patients in need of implantable cardiac defibrillator.

Abstract This letter discusses key points from Esposito et al.'s case report on a Brugada Syndrome (BrS) patient treated with S-ICD and later TV-ICD due to recurrent syncope. It highlights the significance of asystole in BrS-related. Additionally, it recommends dual-chamber TV-ICD systems with CLS algorithms for optimal management, citing their efficacy in reducing syncopal recurrences. Finally, it underscores the importance of considering reflex bradyarrhythmias in device selection for BrS patients at increased sudden cardiac death risk.

Six-month electrical performance of the first dual-chamber leadless pacemaker

BackgroundThe first dual-chamber leadless pacemaker (DC-LP) system consists of 2 separate atrial and ventricular devices that communicate to maintain synchronous atrioventricular pacing and sensing. The initial safety and efficacy were previously reported. ObjectiveThe purpose of this study was to evaluate the chronic electrical performance of the DC-LP system. MethodsPatients meeting standard dual-chamber pacing indications were enrolled and implanted with the DC-LP system (Aveir DR, Abbott), including right atrial and ventricular helix-fixation LPs (atrial leadless pacemaker [ALP], ventricular leadless pacemaker [VLP]). Pacing capture threshold, sensed amplitude, and pacing impedance were collected using the device programmer at prespecified timepoints from 0–6 months postimplant. ResultsDe novo devices were successfully implanted in 381 patients with complete 6-month data (62% male; age 69 ± 14 years; weight 82 ± 20 kg; 65% sinus nodal dysfunction, 30% atrioventricular block). ALPs were implanted predominantly in the right atrial appendage anterior base and VLPs primarily at the mid-to-apical right ventricular septum. From implant to 1 month, pacing capture thresholds (0.4-ms pulse width) improved in both ALPs (2.4 ± 1.5 V to 0.8 ± 0.8 V; P <.001) and VLPs (0.8 ± 0.6 V to 0.6 ± 0.4 V; P <.001). Sensed amplitudes improved in both ALPs (1.8 ± 1.3 mV to 3.4 ± 1.9 mV; P <.001) and VLPs (8.8 ± 4.0 mV to 11.7 ± 4.2 mV; P <.001). Impedances were stable in ALPs (334 ± 68 Ω to 329 ± 52 Ω; P = .17) and reduced in VLPs (789 ± 351 Ω to 646 ± 190 Ω; P <.001). Electrical measurements remained relatively stable from 1–6 months postimplant. No differences in electrical metrics were observed among ALP or VLP implant locations. ConclusionThis first in-human evaluation of the new dual-chamber leadless pacemaker system demonstrated reliable electrical performance throughout the initial 6-month evaluation period.

Helix-fixed leadless pacemaker implantation through a valve-in-valve tricuspid prosthesis via the femoral approach.

Leadless pacemakers offer the opportunity to avoid transvenous hardware among patients with tricuspid valve prostheses. We present the first case of a helix-based fixation leadless pacemaker implanted through valve-in-valve tricuspid prostheses in a 43-year-old female with extensive prior cardiac history. At the time of presentation, epicardial pacing was no longer a viable option in the setting of pacemaker dependence. Placement of a helix-fixed, leadless right ventricular pacemaker was performed as a bridge to dual-chamber leadless pacing. This was safely and effectively performed and highlighted favorable procedural characteristics that included RV cavity dimensions and prosthesis type.

Incidence, Risk Factors, and Outcomes of Left Atrial Enlargement in Patients Requiring Right Ventricular Pacing: A Retrospective Study of 461 Cases from 2012 to 2020.

BACKGROUND Long-term right ventricular (RV) pacing has been linked to left atrial enlargement (LAE). The incidence and risk factors associated with significant LAE after RV pacing remain unknown. This retrospective study included 461 patients requiring RV pacing at 2 centers between 2012 and 2020 and aimed to evaluate the incidence, risk factors, outcomes, and complications of LAE. MATERIAL AND METHODS A total of 461 patients with normal-sized pre-implant left atrial dimension and dual-chamber pacing pacemaker implantation for complete atrioventricular block were enrolled. Patients were grouped based on a ≥20% increase from their baseline left atrial dimension by echocardiography, indicating significant LAE, and initial characteristics, echocardiographic data, and outcomes were compared. RESULTS During a mean 7.0±4.9 years follow-up period, 96 patients (20.8%) developed significant LAE, whereas 365 patients did not. In multivariate logistic regression analysis, smaller pre-implant left atrial dimension (OR, 0.776; 95% CI, 0.728-0.828; P<0.001), lower post-implant left ventricular ejection fraction (OR, 0.976; 95% CI, 0.957-0.995; P=0.014), post-implant development of moderate to severe mitral regurgitation (OR, 2.357; 95% CI, 1.172-4.740; P=0.016), and RV pacing duration ≥3.3 years (OR, 1.576; 95% CI, 1.039-2.646; P=0.045) were independent predictors of significant LAE after RV-dependent pacing. There was a significant difference in the incident stroke events between patients without and with significant LAE (9.9% vs 17.7%; log-rank P=0.047). CONCLUSIONS Long-term RV pacing was linked to significant LAE in 20.8% of patients with complete atrioventricular block, with those affected experiencing a higher stroke rate during follow-up.

Comparison of Global Longitudinal Strain in Dual-chamber versus Ventricular Pacemaker in Complete Heart Block.

Bradycardia caused by total atrioventricular block (TAVB) is treated by implantation of permanent pacemakers (PPMs) in either dual-chamber (DDD) versus ventricular (VVI) pacing modes. DDD is considered a more physiological pacing mode than VVI as it avoids atrioventricular dyssynchrony. However, previous trials have failed to demonstrate the superiority of DDD in improving quality of life and morbidity. This study aims to provide postpacemaker function of the left ventricle (LV) measured with global longitudinal strain (GLS), in TAVB patients. This is a comparative study; samples included in the study are adult TAVB patients undergoing PPM implantation, without significant heart function, and structural abnormality. Echocardiographic parameters are obtained before, after 1 month, and after 3 months post-PPM. A total of 98 TAVB patients undergoes PPM implantation during the study period, 55 patients were excluded, and in the end, only 43 patients fulfill the inclusion criteria. Baseline data between DDD and VVI are compared using unpaired t-test. Statistical significance 1 month post-PPM and 3 months post-PPM is analyzed using paired t-test. There were no significant differences between both groups at baseline. However, significant GLS changes are observed 1 month after PPM in the VVI group (P = 0.002), but no significant change was observed in the DDD group even after 3 months (P = 0.055). In our study, we conclude that DDD is superior in maintaining LV function in the short term in TAVB patients after PPM implantation.

Emergency pacemaker implantation in nonagenarians with CHB: single- versus dual-chamber pacing

Emergency pacemaker implantation in nonagenarians with CHB: single- versus dual-chamber pacing

A leadless ventricular pacemaker providing atrioventricular synchronous pacing in the real-world setting: results from the Micra AV post-approval registry

Abstract Introduction Advances in leadless pacemaker technology have enabled accelerometer based atrioventricular synchronous (AVS) pacing by sensing atrial mechanical contraction. However, longer-term performance of these devices in real-world clinical practice has not been assessed. Objectives To report the performance of the Micra AV transcatheter pacemaker from the worldwide Micra AV post-approval registry (PAR) through 1-year post-implant. Methods The Micra AV PAR is an ongoing prospective single-arm observational study designed to assess the safety and effectiveness of the Micra AV system in the real-world setting. Patients enrolled in the Micra AV PAR will be followed for 3 years. For the present interim analysis, baseline characteristics, total AV synchrony index (sum of %AM-VP, %AM-VS, and AV conduction mode switch percentage), major complications, and system revisions through 12-months of implant were summarized and compared to a historical cohort of 2,667 transvenous dual chamber (TV-DC) pacing patients. Results The device was successfully implanted in 797 of 801 patients (99.4%) at 98 centers in 19 countries between February 2020 and April 2022. Mean age was 74.1±15.1 years, 42.2% were female, and 31.3% were precluded from transvenous device therapy. Micra AV patients were on average older (74.1 vs. 71.1 yrs, P&amp;lt;0.0001) and had a significantly higher incidence of renal disease (22.3% vs. 9.8%, P&amp;lt;0.0001) compared with TV-DC patients. Mean follow-up was 7.7±6.4 months. Through 12-months, the major complication rate was 4.2% in Micra AV patients compared to 8.8% TV-DC patients (HR: 0.48, P&amp;lt;0.001, Figure). At 12-months, the system revision rate was 1.9% in Micra AV patients compared to 5.5% for TV-DC patients (HR: 0.28, P&amp;lt;0.001). The reduction in system revisions was largely driven by the absence of lead dislodgements requiring revision. Of the 397 patients with device interrogation files available for analysis, 315 (79.4%) were programmed to VDD mode at last follow-up and had a median AV synchrony index of 86.4% (IQR: 68.8% - 97.4%). Conclusions The Micra AV leadless pacemaker was implanted with a high rate of success in patients with a high co-morbidity burden, with a significantly lower rate of complications and system revisions through 12-months compared to dual-chamber transvenous pacemakers despite patients being older and having a higher incidence of renal disease. Longer-term performance will continue to be assessed in this ongoing trial.Major Complications Through 12-months

Abstract 14011: Micra AV Leadless vs. Dual-Chamber Transvenous Pacing Outcomes Among Patients With End-Stage Renal Disease in the Medicare Population

Introduction: Leadless pacing is often considered a useful alternative for patients with end-stage renal disease (ESRD) due to their limited vascular access and high infection risk. However, there is limited evidence on the comparative outcomes of leadless pacing vs. transvenous pacing in this population. Hypothesis: The reduction in complications and reinterventions associated with leadless pacing in the broader population extends to patients with ESRD. Aims: To compare complications and reinterventions between ESRD patients implanted with a Micra AV leadless pacemaker vs. a dual-chamber transvenous pacemaker. Methods: Data from the Micra Coverage with Evidence Development (CED) Study were used to identify ESRD patients implanted with a Micra AV leadless pacemaker (N=1,116), or a dual-chamber transvenous pacemaker (N=2,163) between February 5, 2020 and December 1, 2021 in the Medicare population. Logistic regression was used to compare unadjusted and propensity score overlap weight-adjusted 30-day acute complication rates. Cox models were used to compare 6-month chronic complications and reinterventions between groups. Results: ESRD patients implanted with Micra AV had a higher overall comorbidity burden (mean Charlson Comorbidity Index 7.9 vs. 7.6, P=0.001) and higher rates of emergency admission (18.6% vs. 14.0%, P=0.001). Despite these differences, there was no difference in the rate of complications at 30 days (unadj. 13.9% vs. 13.8%, P=0.92; adj. 12.9% vs. 14.6%, P=0.20). At 6 months, Micra AV patients had significantly lower rates of chronic complications (unadj. HR 0.72, 95% CI: 0.54-0.96, P=0.02; adj. HR 0.64, 95% CI: 0.48-0.87, P=0.004) and reinterventions (unadj. HR 0.50, 95% CI: 0.29-0.86, P=0.01; adj. HR 0.53, 95% CI: 0.30-0.91, P=0.02) (figure) . Conclusion: In patients with ESRD, AV synchronous leadless pacing is associated with lower rates of complications and need for reintervention compared to dual-chamber transvenous pacing.

The Pacemaker and Implantable Cardioverter-Defibrillator Registry of the Italian Association of Arrhythmology and Cardiac Pacing - Report 2022

The Pacemaker (PM) and Implantable Cardioverter-Defibrillator (ICD) Registry of the Italian Association of Arrhythmology and Cardiac Pacing (AIAC) collects information about demographics, clinical characteristics, main indications for PM/ICD therapy and device types from the voluntary Italian collaborating centers. For the year 2022 main data about national PM and ICD implantation activity were obtained on the basis of European Cards and subsequently analyzed to create a standard report. PM Registry: data about 17 800 PM implantations were collected (14 191 first implants and 3609 replacements). The number of collaborating centers was 152. Median age of treated patients was 81 years (75 quartile I; 86 quartile III). Main ECG indications included atrioventricular conduction disorders in 46.0% of first PM implants, sick sinus syndrome in 17.7%, atrial fibrillation plus bradycardia in 7.7%, other unspecified ECG and electrophysiological abnormalities in 43.0%. For first PM implants, pacing in DDDR mode was reported in 42.2%, followed by DDD mode (20.6%), VVIR mode (25.1%), VVI mode (11.1%) and finally VDD-VDDR (5.1%). Median value of longevity of explanted PMs was 8.3 years. ICD Registry: data about 5210 ICD implantations were obtained (3656 first implants and 1554 replacements). The number of collaborating centers was 301. Median age of treated patients was 72 years (63 quartile I; 79 quartile III). Primary prevention indication was reported in 72.4% of first implants, secondary prevention in 27.6% (cardiac arrest in 4.6% of records). A single-chamber ICD was used in 30.3% of first implants, dual-chamber ICD in 30.0% and biventricular ICD in 39.7%. Median value of longevity of explanted ICDs was 7.0 years. In the calendar year 2022, the Italian PM Registry showed stable electrocardiographic and symptom indications, with an important prevalence of dual-chamber pacing. The ICD Registry documented a large use of prophylactic and biventricular ICDs, reflecting a favorable adherence in clinical practice to trials and guidelines. The ICD longevity and the number of recalls demonstrated a favorable trend.