Leadless Pacemaker Research Articles

Abstract 4118415: Device Dislodgement and Embolization associated with a New Leadless Pacemaker

Background: Leadless pacemakers (LP) avoid the pocket and lead-related complications of transvenous pacing. A potential complication of LPs is dislodgement and/or embolization (D/E) during or after implant. No D/E occurred in the original 725-patient Micra™ VR clinical trial. However, in the 526-patient LEADLESS II-phase 2 trial, the rate of dislodgement for 200 Aveir™ VR LPs was 1.5%. Thus, there appears to be a significant difference in D/E rates between these LPs that have different fixation mechanisms and insertion tools. Aims: We aimed to determine if the Aveir VR LP has continued to exhibit D/E since it was approved by the Food and Drug Administration (FDA) in April 2022. Methods: We queried the FDA's Manufacturers and User Facility Device Experience (MAUDE) database for Aveir D/E that occurred in the U.S. and were reported by the manufacturer from April 2022-December 2023. The number of Aveir VR implants in the U. S. was obtained from the manufacturer's publicly available product performance report. D/E outside the U.S. were excluded. Results: During the 21 months, 55 of 3,139 (1.75%) Aveir VR implants exhibited D/E. More D/E (34;61.8%) occurred during implant, with 18 (52.9%) of these happening after release of the device from the tether mode. Fourteen (41.2%) of the intra-procedural D/E occurred when the device prematurely released from the delivery catheter, and two dislodged during cardiopulmonary resuscitation (CPR). D/E occurred in 21 patients (38.2%) after implant and were signified by loss of pacing or inability to interrogate the device. Four (19%) out of those 21 patients presented with symptomatic bradycardia. The dislodged devices commonly embolized to the pulmonary artery and right atrium/vena cava. LP retrieval was successful in 49 (89%) cases. Thirty-two patients (58.1%) received a new LP, 5 patients were transitioned to a transvenous system, and a replacement device was not specified for 17 (31%) patients. One patient died during implantation due to ventricular fibrillation (VF) not related to D/E. Conclusions: Fixation issues and premature separation of the device from the delivery catheter appear to be responsible for most of these D/E. Studies are needed to determine if impedance or another metric is associated with adequate Aveir fixation. The manufacturer should address the premature separation problem with Aveir. Success of D/E retrieval may be related to tools specific for Aveir. Further studies are needed to compare between the two LPs.

Abstract 4118070: High Output Heart Failure After Leadless Pacemaker Placement In a Heart Transplant Recipient

Introduction: The advent of leadless pacemaker (LP) technology has revolutionized cardiac rhythm management by minimizing risks associated with traditional transvenous pacemakers. LP use is expected to increase as dual-chamber LP systems emerge into clinical practice. The LP requires a large-bore venous sheath (27-Fr) through a femoral vein. One risk of large bore femoral cannulation is creation of an occult arteriovenous fistula (AVF), which can cause high output heart failure (HOHF) over time. In the LEADLESS II trial, the event rate for AVF was 0.2%. HOHF as a complication of LP implant has not been previously reported. We describe the first case of HOHF in a heart transplant (HT) recipient after LP. Case Presentation: An 82-year-old male with a history of HT 26 years earlier underwent leadless pacemaker for recurrent syncope, deemed associated with conduction system disease. He had no history of cardiac allograft rejection, angiographic coronary allograft vasculopathy or left ventricular dysfunction. Six months post-implant he presented with shortness of breath and bilateral lower extremity edema. Management: Evaluation included: 1) Chest X-ray which was suggestive of pulmonary edema 2) natriuretic peptide level of 5,500 pg/ml (6-fold increase from 6 months prior) 3) echocardiogram showing EF of 69%, and 4) bilateral lower extremity Doppler ultrasound where he was found to have a large AVF between the right superficial femoral artery and superficial femoral vein. Subsequent right heart catheterization was notable for a PCWP of 18 mmHg and a cardiac output/index of 11 L/min and 5.8 L/min/m2 respectively, hence confirming HOHF. Treatment with intravenous diuretic was initiated and percutaneous stent placement to correct the AVF was performed with symptomatic relief. Conclusion: This case highlights the rare but serious complication of unrecognized AVF following leadless pacemaker implant. Given that this event occurred in a HT recipient, a more exhaustive work-up was required to rule-out expected causes of congestion. To our knowledge there is only one other case report describing AVF post-LP implant for which no intervention was performed due to absence of symptoms at 6-month follow up and HOHF was not reported. Our case emphasizes that the differential diagnosis of new onset of signs and symptoms of heart failure that develop post LP implant in general and in HT recipients specifically, should include HOHF related to an unrecognized procedural AVF.

Abstract 4138230: Incidence of Worsening Tricuspid Regurgitation Following Implantation of Leadless versus Dual-Chamber Pacemakers

Introduction: Cardiac implantable electronic devices (CIED) may result in or worsen tricuspid regurgitation (TR), which is associated with a higher risk of morbidity and mortality ( Figure 1 ). However, the incidence of TR following implantation of leadless pacemakers versus dual-chamber pacemakers (DC-PPM) is not well described. Hypothesis: Micra leadless pacemakers will have a lower incidence of worsening TR relative to standard DC-PPMs. Aims: To evaluate the incidence of worsening TR after implantation of leadless and DC-PPMs. Methods: We performed a retrospective study of all patients who underwent Micra leadless pacemaker or DC-PPM implantation at the University of California, San Diego from 2/2019-2/2024. The primary outcome was incidence of worsening TR. Results: A total of 476 patients underwent CIED implantation with both pre- and post-echocardiograms completed, of which 26.9% (n=128) had a Micra leadless pacemaker implanted and 73.1% (n=348) had a DC-PPM implanted. The average time to first post-implantation echocardiogram was 359 days in the Micra group and 510 days in the DC-PPM group (p=0.004). Worsening TR post-CIED implantation occurred in 21.9% (n=28) of patients who had a Micra and 25.9% (n=90) of patients who had a DC-PPM (p=0.192). The TR worsened by an average of 0.88 ± 0.32 grades in the Micra group versus 0.98 ± 0.33 grades in the DC-PPM group (p=0.08). Conclusion: In this analysis, leadless pacemaker implantation was associated with a statistically insignificant trend towards less TR. However, the degree of worsening TR following leadless pacemaker or DC-PPM implantation is relatively mild and of unclear clinical significance.

Abstract 4136330: It’s ‘Tachy’ To Be Fooled - Adenosine Use During Leadless Pacemaker Placement to Ensure Reliable Threshold Assessment in the Setting of Tachycardia

Introduction: Accurate assessment of pacing thresholds during permanent pacemaker implantation is critical to ensure device function and longevity. A few reports have described rate-related threshold variability during Micra TM leadless pacemaker (Medtronic Inc, Minneapolis, MN) procedures. Postulated mechanisms for this phenomenon include variable myocardial contact or micro-dislodgment, and inflammation-induced phase IV block. In this case series, we demonstrate the use of adenosine to induce transient heart block for accurate threshold assessment in patients with tachycardia during leadless pacemaker placement. Cases: A 69-year-old male with a history of atrial flutter presented with complete atrioventricular (AV) block requiring emergent transvenous pacing. A Micra placement was performed. During the procedure, the patient was tachycardic in rapid atrial flutter despite multiple doses of metoprolol. It was noted that with rapid pacing from the pacemaker at 120 pulses per minute (ppm) the threshold was ≤1V at 0.24 ms. An adequate “tug-test” was performed and at least 2 of 4 tines were noted to be fixated based on fluoroscopic motion. To confirm the capture threshold before final deployment, 12 mg of adenosine was given to induce heart block. However, at a rate of 60 ppm, there was no ventricular capture at 3V at 0.24ms. The device was repositioned and repeat threshold testing with adenosine at 60 ppm was 0.38V at 0.24ms. Pacing parameters were assessed the next day and remained stable. Similarly, a 75-year-old female with ischemic cardiomyopathy was admitted with new atrial fibrillation (AF). She then developed pauses prompting Micra placement. During initial threshold testing, she was in rapid AF despite receiving multiple doses of metoprolol. Heart block was induced with 12mg adenosine to assess the threshold at a lower pacing rate of 60 ppm. The capture threshold achieved was 0.5V at 0.24ms. Discussion: Nusbickel et al., Yoshiyama et al., and Sano et al. have reported rate dependent discrepancies in capture thresholds after Micra implantation. Our cases highlight the importance of capture threshold assessment at lower pacing rates during implantation. In patients who are tachycardic at the time of the procedure, adenosine may be useful to more reliably assess device capture threshold and determine the need for repositioning.

Abstract 4115543: Safety and Efficacy of a Novel Technique for Extraction of Micra TM Leadless Pacemaker with Aveir TM Retrieval Catheter System: An Eight Case series.

Background: Leadless cardiac pacemakers (LCP) have evolved as an excellent alternative to transvenous pacemaker (TVPM) for bradycardia therapy with excellent safety and efficacy outcomes. Micra TM was the first commercially available LCP. The device attaches to the right ventricular myocardium with four Nitinol FlexFix™tines. Its inherent design poses problems with retrievability. This leads to many devices being turned off and left behind in the right ventricle at the end of its life. The Aveir retrieval catheter was recently launched as part of the Aveir family of LCP and has a tri-loop snare re-docking mechanism, steerability, and protective sleeve. Goals: We aim to show the safety and efficacy of using this novel retrieval catheter for extraction of the Micra™ LCP in lieu of abandoning the LCP in the right ventricle. Results: We present a case series of 8 successful retrievals of Micra™ LCP using the Aveir™ retrieval catheter. Four patients had the LCP removed during upgrade to cardiac resynchronization therapy and the other four had the LCP removed at the time of replacement of the LCP at device end-of-life. The mean age of the cohort was 72.6±9.4 years (62.5% female). The average age of the retrieved LCP was 4 years and 4 months with the oldest device being in place for 7 years and 7 months. Median retrieval time, defined as time from retrieval catheter in to retrieval catheter out, was 4.8±2.4 minutes. In 100% of the cases the LCP was successfully retrieved in its entirety via femoral venous access. There were no intra- or post-procedural complications, including vascular complications, pericardial effusions, right ventricular dysfunction or worsening tricuspid regurgitation. At six months follow up, patients continued to remain free of the above complications. Conclusion: This case series demonstrates the safety and feasibility of using the Aveir™ retrieval catheter for extraction of the Micra™ LCP device in lieu of abandonment. Additional studies should be considered to assess the risk and benefits of abandoning the device in the right ventricle extraction of the LCP with this novel technique. The authors acknowledge the steep learning curve associated with this procedure. Further multicenter analysis of this technique is necessary to determine its generalizability.

Abstract 4134340: Title: Comorbidities Associated with One Year Mortality and Hospital Readmission After Leadless Pacemaker Implantation

Introduction: Previous studies have noted racial and ethnic disparities in access to leadless pacemaker implantation (LPI), but none have evaluated the socioeconomic disadvantaged (SED). Additionally, few studies have evaluated outcomes of LPI beyond thirty days on a large scale. This study aimed to determine which comorbidities are associated with one-year readmissions and mortality after LPI, including SED via the Social Deprivation Index (SDI). Methods: Patients ages ≥18 were identified in the Healthcare Cost and Utilization Project State Inpatient Databases in New York and Florida from 2016-2019 with follow-up into 2020. These states were chosen due to availability for linkage of the 2018 SDI (1-100, higher scores representing more disadvantage). International Classification of Diseases 10 codes for LPI were used. The risk of readmission and mortality was assessed using Cox proportional hazards first in an unadjusted fashion for each comorbidity in the Charlson Comorbidity Index. In addition to demographic variables, only significant variables from the unadjusted analysis were included in the final adjusted multivariable models. Results: 3,094 patients met inclusion criteria. The readmission and mortality rates at one, three, and twelve months were 17.2%, 31.3%, 50.2% and 5.7%, 7.1%, 10.7%, respectively. The most common diagnoses for readmission were dyspnea/chest pain (9.4%), heart failure (4%), and sepsis (3.8%). Federal insurance, heart failure (CHF), pulmonary disease, diabetes without complications, and renal disease (CKD) were associated with increased risk for twelve-month readmissions. African American race, myocardial infarction, CHF, CKD, and higher SDI were associated with increased risk for twelve-month mortality. Conclusion: CHF and CKD put patients at high risk of readmission and mortality. Sepsis was among the most common causes of readmission at twelve months. Patients of higher SED are at increased risk of mortality within one year after LPI.

Abstract 4134594: More than One Way to Catch a Fish: Micra Extraction Case Series

Description of Cases: Case 1: A 72 year old male with atrial fibrillation (AF) and tachy-brady syndrome underwent Micra implantation. On post-procedure day 2, pacing thresholds were unacceptably elevated. A new Micra device was deployed; subsequently, a microsnare was placed through the Micra delivery catheter and the docking button of the old Micra was successfully snared (Figure A). The old Micra was then captured over the delivery catheter and removed from the body. Case 2: A 76 year old male underwent Micra implantation and AV node ablation for AF with persistent tachycardia. One month later, he presented with heart failure and interval decrease in ejection fraction from 66% to 33%. After biventricular leads were implanted, an Agilis catheter was advanced towards the Micra. The docking button was successfully snared with a gooseneck snare (Figure B), and the Micra was extracted with gentle traction. Case 3: A 76 year old male with complete heart block and longstanding persistent AF received a Micra. Nine months later, he presented with heart failure and interval decrease in ejection fraction from 55% to 25%. A defibrillator lead was implanted but no suitable CS branch was identified. The Aveir retrieval catheter was advanced and the Micra docking button was captured with the triloop snare (Figure C). The protective sleeve was advanced over the Micra and it was successfully removed. Subsequently, a left bundle area lead was placed. Discussion: Although uncommon, extraction of the tined leadless pacemaker (Micra) may be indicated at times. As rates of implantation continue to increase, establishing uniform procedures for extraction becomes increasingly important. These three cases highlight unique options for Micra extraction, and the feasibility of each approach. However, a dedicated tool and protocol would be ideal for patient safety and consistency. No complications occurred with the above cases.

Two-year outcomes of Micra AV leadless pacemakers in the Micra AV CED study.

Leadless pacing is a safe and effective alternative to transvenous pacing for bradycardia. Micra AV is a leadless, single-device solution that provides atrioventricular synchronous ventricular pacing therapy. Early results from the Micra AV CED study showed reductions in short-term complications associated with the Micra AV leadless pacemaker among US Medicare patients. The objective of this study is to compare chronic complications, re-interventions, and all-cause mortality at 2 years between patients implanted with a Micra AV leadless pacemaker and a traditional dual-chamber transvenous (DC-TV) pacemaker. Patients implanted with a Micra AV leadless pacemaker (n = 7552) or a DC-TV pacemaker (n = 110 558) in 2020 and 2021 were identified using device registration-linked Medicare administrative claims data. Competing risk models compared the unadjusted and propensity score overlap weight-adjusted complication, re-intervention, and all-cause mortality rates of Micra AV and DC-TV patients at 2 years. Micra AV patients had significantly more comorbidities (end-stage renal disease 14.9 vs. 2.0%, P < 0.0001; renal dysfunction 47.9 vs. 34.2%, P < 0.0001; diabetes 46.2 vs. 38.3%, P < 0.001; congestive heart failure 41.4 vs. 30.6%, P < 0.0001). Two years post-implant, Micra AV patients had lower complication rates [adjusted 5.3 vs. 9.6%, hazard ratio (HR): 0.54, 95% confidence interval (CI) 0.49-0.61, P < 0.0001] and lower re-intervention rates (adjusted 3.5 vs. 5.6%, HR: 0.62, 95% CI 0.54-0.72, P < 0.0001) than DC-TV patients. Upgrades to cardiac resynchronization therapy were low in both groups (adjusted 1.6 vs. 1.7%, P = 0.40), as were Micra AV upgrades to a dual-chamber system (adjusted 1.4%). All-cause mortality rates remained higher in Micra AV than in DC-TV patients (unadjusted HR: 2.48, 95% CI 2.35-2.62, P < 0.0001; adjusted HR: 1.53, 95% CI 1.44-1.62, P < 0.0001). Patients implanted with Micra AV had lower complications and re-intervention rates at 2 years than patients implanted with a traditional DC-TV pacemaker. All-cause mortality remained higher in Micra AV patients, likely due to their higher comorbidity burden and other differences in baseline characteristics. ClinicalTrials.gov ID NCT04235491.

Device dislodgement and embolization associated with a new leadless pacemaker.

Currently, there are two approved single chamber leadless pacemakers (LP) in the United States (US), Micra VR™; approved since 2016 and AVEIR VR™; approved in 2022. A potential complication of LPs is dislodgement and/or embolization (D/E) during or after implant. According to the IDE trials, there appears to be a significant difference in D/E rates between the two LPs that have different fixation mechanisms; Micra uses nitinol tines, while AVEIR uses an active screw helix. The aim of this study was to determine if the AVEIR VR LP has continued to exhibit D/E in the United States since it was approved by the Food and Drug Administration (FDA) in April 2022. The FDA Manufacturer and User Facility Device Experience (MAUDE) database was searched for US D/E reports communicated by the manufacturers of both LP devices. For AVEIR VR we reviewed reports from approval till December 2023, and for Micra VR we looked at reports from approval to April 2024. Excluded were reports based on information indirectly obtained from registries, journals, social media, or volunteers. Total number of US implants was acquired from the manufacturers' product performance reports. During a period of 21 months, 5990 AVEIR VR implants had been registered in the United States, of which 53 (0.88%) encountered D/E both during and after the procedure. More D/E (32; 60.4%) occurred during the implantation procedure, with device release problems being the most prominent procedural issue involved with these events. Within a 8-year period, 72 237 Micra VR implants have been registered in the United States, of which 211 (0.29%) showed D/E. The rate of D/E since the US approval of both devices was significantly higher for AVEIR VR compared to Micra VR (0.88% vs 0.29%; p < .0001). AVEIR VR implants may be complicated by dislodgement with or without embolization. Currently, the estimated incidence is about 0.9%, which is significantly higher than Micra VR. Fixation issues and separation problems of the device from the delivery catheter appear to be responsible for most of these D/E events.

Intracardiac leadless pacemaker: long term safety over traditional pacemakers. a systematic review and meta-analysis

Abstract Introduction Leadless pacemaker (LP) is a novel technology designed to reduce lead-related, including pocket infections, associated with traditional pacemakers. LP can be used in patients with high-degree AV block, sinus node dysfunction, and bradycardia with syncope. We conducted a systematic review and meta-analysis to examine the long-term safety of intra-cardiac leadless pacemakers compared with traditional pacemakers. Methods Our protocol was registered in advance on PROSPERO. Studies were eligible if they compared complications, revision, cardiac perforation, infections, and all-cause mortality between patients who received leadless pacemakers versus traditional pacemakers. The systematic search was conducted in five databases (MEDLINE, EMBASE, CENTRAL, Web of Science, Scopus) without restriction. The random-effect model was implemented to calculate pooled odds ratio (OR) with a 95% confidence interval (CI). Also, the Mantel-Haenszel method, Paule-Mandel estimator for tau^2, Q-Profile method for the confidence interval of tau^2 and tau, and Hartung-Knapp adjustment for random effects model methods were used for the prediction of data extracted directly from the curves. ROBINS-I tool was used for the risk of bias assessment, and the certainty of the evidence was evaluated with the GRADE approach. Results Of 6450 studies screened, we identified 21 observational studies of Nanostim and Micra leadless pacemakers. The pooled incidence of complications of leadless versus traditional pacemakers at 1, 6, 12-24 months show the odds are clinically and statistically different (OR=0.66, 95% CI: 0.42–1.02; OR=0.44, 95% CI: 0.22–0.86; OR=0.41, 95% CI: 0.32–0.53 respectively). The pooled incidence of infection rate at 6, 12-24 months is lower in patients with LP (OR=0.37, 95% CI: 0.31–0.44; OR=0.20, 95% CI: 0.00–97.31). The studies comparing all-cause mortality during 6, 12-24 months in leadless versus traditional pacemakers did not show statistically significant differences in these outcomes (OR=1.26, 95% CI: 0.88–1.81; OR=0.86, 95% CI: 0.25–2.92 respectively. Conclusion Our results show that complications and infections occur less frequently in patients with leadless pacemakers than in patients with conventional pacemakers with no difference in all-cause mortality. However, there is a need for high-quality randomized clinical trials and propensity score-matched studies focusing on this clinically relevant question.Complication Forest plotsInfection Forest plots

Extraction of leadless and tranvenous pacemakers: occurrence, causes and complications from a national US database

Abstract Background Leadless pacemakers are usually implanted as second line treatment in patients with increased risk for infection, difficult or obstructed vascular access, and other causes preventing an implantation of a traditional pacemaker. Data regarding the occurrence and need for leadless pacemaker extraction (LLPE) are currently absent and have not been compared to outcomes of transvenous pacemaker extraction (TLE). Moreover, leadless pacemaker implantation during TLE for active infection in being advocated without backing data. We aimed to assess the rate, causes and complications of device extraction in a large US national database. Methods Patients undergoing LLPE and TLE in the USA between 2016 and 2019 were identified from the National Inpatient Sample (NIS) database using ICD-10 codes. Clinical and sociodemographic data, in-hospital complications, outcomes and mortality were collected. Baseline characteristics and outcomes were compared between patients undergoing TLE and LLPE. Multivariate logistic regression identified predictors of in-hospital complications. Results An estimated total of 55,235 patients underwent an extraction procedure during the study period. 54,050 (97.8%) patients underwent TLE and 1,185 (2.1%) underwent LLPE. Patients who underwent LLPE were older, more likely females and had a higher comorbidity rate (Charlson-Deyo-Comorbidity-Index; 46% vs 39%, p&amp;lt;0.001). Etiology for LLPE was identified and reported only in 25.7% of cases, however infection causing extraction occurred in 11.4% of LLPE cases and 8% had LLPE due to device dysfunction. Main etiologies for TLE were infections (40.9%) and lead dysfunction (29.4%). In comparison to TLE, LLPE resulted in higher in-hospital mortality (7.2% vs. 3%, p&amp;lt;0.001) and vascular complications (2.5% vs. 1.0%, p&amp;lt;0.001). Multivariable analysis confirmed that LLPE was associated with more than double the risk of in-hospital mortality. Conclusion Extraction of leadless pacemakers due to infection is not rare. Patients undergoing LLPE have higher prevalence of vascular complications and in-hospital mortality in a US nationwide, all-comer registry.

Real-world evidence of implanting leadless pacemakers after transcatheter aortic valve implantation procedures

Abstract Background Conduction disturbances can be a complication of Transcatheter Aortic Valve Implantation (TAVI) procedures, for which transvenous pacemakers (TVPs) are recommended. Leadless pacemakers (LPs) are a safe alternative to TVPs in a pacemaker-indicated population, but little is known about their use for TAVI-related conduction disturbances. Purpose To examine rates of pacemaker implantation post-TAVI, compare complications, all-cause mortality, and ventricular pacing rates in LP vs. TVP patients, and assess pacemaker deactivations/upgrades in LP patients. Methods Data from Optum’s de-identified Clinformatics Data Mart Database linked to a device registry between 2016 and 2021 were used to identify patients with TAVI procedures that are subsequently implanted with an LP or a TVP. Claims data were used to assess complications and all-cause mortality; device-reported parameters were used to calculate VP rates and deactivations. Complication rates, all-cause mortality, ventricular pacing rates, and device deactivations were calculated for patients with a pacemaker implant between 7 days before and 90 days after TAVI. Chronic complication rates, defined as complications with the potential to occur outside the acute peri- or post-procedural period, were assessed at 1 year. Regressions were used to compare complications and all-cause mortality, adjusting for patient characteristics. Results In a cohort of 18,073 patients with a TAVI procedure, 11.7% were implanted with a pacemaker at 1 year post-TAVI; 76.7% of implants occurred within 7 days. LPs comprised 7.2% of the total pacemaker implants observed. Of those LPs in the registry, around 25% have VDD capability. LP patients were older (avg. 84 LP, 82 TVP, p=0.02) and were more likely to have atrial fibrillation, end-stage or chronic kidney disease, and ventricular arrhythmias. Of patients implanted with a pacemaker within 90 days post-TAVI (LP N=122, TVP N=1,779), there were no differences in 30-day complication rates (12.3% LP, 15.6% TVP, unadj. p=0.33, adj. p=0.27). LP had fewer chronic complications than TVP (0.8% LP, 9.4% TVP, unadj. p=0.02, adj p=0.02) though the sample size was small. LP patients had higher unadjusted 30-day all-cause mortality (4.1% LP, 1.0% TVP, unadj. p=0.01, adj. p=0.06), reflecting the higher acuity of LP patients. At both 30 days and 1 year post-implant, most patients (85.3% LP, 72.7% TVP) continued to receive pacing support (ventricular pacing &amp;gt;10%). TVP patients were more likely than LP patients to be pacing dependent (ventricular pacing ≥90%) at both 30 days (53.8% vs. 29.4%) and 1 year (44.7% vs. 35.7%) post-implant. There were no observed deactivations/upgrades in LP patients at 1 year. Conclusion LPs, when used concomitantly with TAVI procedures, show similar acute and lower chronic complication rates compared to patients treated with TVPs implanted with TAVI. Most patients who received a pacemaker post-TAVI continue to receive pacing support.Acute and Chronic complicationsVentricular pacing

Leadless pacemaker - lead parameters stability and battery longevity in the mid-term follow-up

Abstract Background A leadless pacemaker (L-PM) has been designed to avoid the need for a pacemaker pocket and transvenous lead. Long-term safety will largely depend on the need for replacements, mainly due to battery depletion (end-of-life). While the mean L-PM battery longevity predicted by the manufacturer is 12 years, real-world longevity data are still scarce. We aimed to describe L-PM parameters’ stability and battery longevity during the mid-term follow-up. Methods Single-center registry of consecutive patients undergoing L-PM implantation from May 2015 to November 2023. Procedural characteristics, lead parameters and battery longevity were collected immediately after implantation and during the most recent follow-up visit. Results Overall, 261 consecutive patients had a transcatheter L-PM implanted through a femoral vein (mean age 78±10 years; 66% male). Mean procedural duration was 44±28min and fluoroscopy time was 4,4±3,9min. The device was successfully implanted in all but one patient. The main indications for permanent pacing were high-degree atrioventricular block [N=130 (50%)], atrial fibrillation with pauses [N=78 (30%)], and sinus node disease [N=28 (11%)]. Immediately after implantation, three cases (1,2%) of pericardial effusion (one with tamponade) were reported. In one case (0,4%), a conventional pacemaker was implanted due to L-PM acute dysfunction. No other procedure-related complications, including dislodgment, were reported at discharge. After a mean follow-up of 2,8±1,7years, the pacing threshold and R-wave amplitude remained stable [0,67mV vs. 0,62mV (p=0,9); and 10,3mV vs. 16,1mV (p&amp;lt;0,001), respectively] and mean ventricular pacing was 54±38%. Expected battery longevity was &amp;gt;8 years (maximum value) in 84% of the patients. In the subgroup of patients with &amp;gt;5 years of follow-up (N=20; mean follow up of 6,3±1,8years), the expected battery longevity was &amp;gt;8 years in 85% (N=17) of the patients. In three cases, the L-PM was upgraded to cardiac resynchronization therapy or left bundle branch area pacing due to pacing-induced left ventricular dysfunction. There was one case of L-PM end-of-life 6 years after implant (pacing threshold 0,5mV; ventricular pacing 100%), in which a second L-PM was successfully implanted. Overall, 78 (31%) patients died, a mean of 2,2±1,9 years after L-PM implantation, none related to the device. Conclusion In this real-world cohort, L-PM maintained stable pacing parameters and, in the mid-term follow-up, only one battery depletion was observed while expected longevity remained above 8 years in the large majority of patients. Longer follow up will allow better understanding of both technical and clinical aspects relevant to manage end-of-life devices.Table 1Figure 1

Safety and efficacy of leadless pacemaker extraction using a novel retrieval tool: a multicenter analysis

Abstract Background Leadless pacemakers (LP) have emerged as a safe and effective alternative for cardiac pacing, increasingly adopted by the medical community. While rare, complications such as pacemaker syndrome or device dislodgment can occur. In such instances, the extraction of the leadless pacemaker and its replacement with a new device should be considered. Purpose This multicenter study aimed to describe the use of the Aveir retrieval sheath during Micra extraction procedure and to assess the success rates and potential complications associated with the procedure. Methods In this observational study, we analyzed prospectively collected data from 14 patients that underwent leadless pacemaker using Abbott retrieval catheter at three high volume centers for pacemaker extraction and leadless implant in United States. Thought femoral vein the Aveir steerable retrieval catheter is advanced to the right atrium and then across the tricuspid valve. Under TEE and fluoroscopy guidance the snare is advanced over the Micra, and the button is secured. A protective sleeve is advanced over the LP. With application of traction to snare and countertraction with the sleeve against the endocardium, the LP is free from the myocardium and removed via the sheath. (Fig. 1) The procedural duration should be intended as the combined total of the time taken for the extraction of the existing pacemaker and the implantation time of the new device. Extractions performed during the first year were described as early and thereafter as late. Procedural success was described as complete extraction of LP without procedural complication. Results The reason for early explant was LP dislodgment and for late explant was pacemaker syndrome. Median time to extraction was 4±2 months in early explant and 35±9 months in late explant. Procedural time in early and late groups was 68.7 and 72.3 min respectively (P=0.32). Fluoroscopy time in early and late groups was 12.2 and 16.4 respectively (P= 0.18). LP was then replaced with a transvenous pacemaker. Success was 100% in both groups. No complication occurred in both groups. Conclusion Micra pacemaker using Aveir retrieval catheter is an effective tool irrespective of dwell time.

Safety profile, electrical performances and clinical outcomes of a novel leadless pacemaker; first results from real-world clinical practice in Saudi Arabia

Abstract Introduction Leadless pacemakers (LP) are emerging as an effective and safe alternative to transvenous pacemakers to reduce lead-related and pocket-related complications and to improve patient experience. A new LP system, the Aveir VR, has been approved in 2022 for US and other countries, and in 2023 for Europe, and features innovative characteristics such as the active fixation helix mechanism and the possibility to measure sensing/pacing parameters before LP deployment. Purpose Evaluate safety, electrical performances and clinical outcomes associated with the first Aveir VR LP implants in 2 Hospitals in Saudi Arabia. Methods We performed a prospective evaluation of all-comer patients who received Aveir VR LP. Decision for LP implant was based on conditions such as cardiac pacing indication, lack of upper extremity venous access, risk of device infection, and life expectancy, and using shared decision-making. Clinical and electrical data were collected at implant and at 1st and 6th month visits. Results A total of 54 patients (25 female, mean age 69 years) were included between December 2022 and October 2023. Pacemaker implant indication was AV block in 25 (46%) patients, sinus node disease in 19 (35%) patients, atrial fibrillation and slow ventricular response in 9 (17%) patients and left bundle branch block in 1 (2%) patient. Implant was successful in all attempted cases. Final device position was lower septum in 51/54 (94.4%) patients and mid-septum in 3/54 (5.6%) patients. Mean procedure time was 48±22 minutes and showed a decreasing trend as a function of operator experience with a mean of 55, 50 and 36 minutes in the first, second and third group of consecutive implants, respectively. Mean fluoroscopic time was 11±8 minutes and showed a decreasing trend as a function of operator experience with a mean of 13, 13 and 6 minutes in the first, second and third group of consecutive implants, respectively. Final device position was achieved at first attempt in 42/54 (77.8%) cases and at first or second attempt in 51/54 (94.4%) cases. At implant mean R wave sensing was 7.6±3.7 mV, mean impedance was 724±335 Ohm, mean threshold was 1.0±0.6 V at 0.4 ms. During implant there was one patient with pericardial effusion treated with pericardiocentesis. In a mean follow-up of 73 days there were no procedure-related or device-related complications, electrical parameters showed acceptable values, and all implanted devices performed as expected. Median longevity, estimated at last follow-up visit, was 19 years (interquartile range: 12-20 years). Conclusion First real-world cases of use of a novel leadless pacemaker in Saudi Arabia show optimal feasibility and good safety profile and electrical performances. Procedure and fluoroscopic times were acceptable and decreased as a function of operator experience. Longevity estimations predict very long service life-times.

Impact on preoperative estimation of atrial mechanical amplitudes with vdd leadless pacemaker

Abstract Background It would be useful to determine whether the device can sense the mechanical atrial amplitude (A4) before the implantation of a VDD leadless pacemaker (Micra AV^RT, Medtronic, US). Purpose To evaluate whether identifiable A4 is associated with preoperative echocardiographic parameters. Methods Echocardiographic measurements were performed to quantify atrial motion of the interventricular septum in patients who received a leadless pacemaker implantation. We visually divided the septum into five segments from the base to the apex. As shown in Figure 1, the myocardial velocity of each segment measured on tissue doppler imaging (TDI) was defined as EV1, EV2, EV3, EV4, and EV5 (m/s), respectively. After the implantation, amplitude of A4 was compared to the local EV. Results We retrospectively analyzed 30 patients who had Micra AV implanted into the right ventricular septum by imaging examination and had measurable EV for each segment. The mean age was 82.3±7.8 years, 15 (50%) patients were female, 11 (37%) patients had organic heart disease, and 23 (77%) patients had atrial ventricular block. The mean LVEF and A4 amplitude were 60.4 ± 8.9% and 2.7 ± 1.8 m/s^2, respectively, and the mean atrial mechanical sensing rate (AMSR) was 79.9±24.0%. The A4 amplitude was positively correlated to the AMSR (r=0.48), while the AMSR was significantly better in patients with A4 amplitude over 1.0 m/s^2 (88.0 ± 10.4% vs. 41.0 ± 33.6%, p=0.04). The A4 amplitude was correlated to the EV of the implantation site estimated from fluoroscopy and echocardiography (r=0.62) in Figure 2. 24 patients had local EV over 3.0 cm/s, and among them, 22 (92%) patients had A4 amplitude over 1.0 m/s^2. Conclusion Local EV over 3.0 cm/s, as determined by preoperative echocardiography, might predict high-frequency AMSR.

Predictor of A4-amplitude using preprocedural electrocardiography in patients with leadless pacemakers

Abstract Background Based on the historical studies of leadless pacemakers (LP), high atrio-ventricular synchrony (AVS) with mechanical sensing-based VDD pacing is largely influenced by A4-amplitude. A limited study investigated the predictors of A4-amplitude using clinical and echocardiographic parameters. Objective This study aimed to investigate the predictors of A4-amplitude preoperatively to select patients who could benefit the most from AVS among patients with VDD LPs. Methods Data from patients who received VDD LP implantations from November 2021 to August 2023 at our institution were analyzed. Twelve-lead electrocardiography and transthoracic echocardiography were performed before VDD LP implantations. To assess the electrical indices associated with the A4-signal, the electrocardiographic morphological P-wave parameters were analyzed including the P-wave duration, P-wave amplitude, maximum deflection index (MDI), and P-wave dispersion. Results A total of 50 patients who underwent VDD LP implantations (median age, 84 years; 64% male) were included and divided into two groups based on the median value of A4-amplitude, the high-A4 group (A4-amplitude &amp;gt;2.5m/s2, n=26) and low-A4 group (A4-amplitude ≤2.5m/s2, n=24). There was a significant difference between the high-A4 and low-A4 groups in the LVEF (P=0.01), P-wave dispersion (P=0.01), and MDI (P&amp;lt;0.001). A multivariate logistic analysis revealed that a lower MDI was an independent predictor of a high A4-amplitude (odds ratio: 0.78, 95% confidence interval: 0.67 to 0.92; P=0.003). Conclusion Preoperative electrocardiographic evaluations of the P-wave morphology may be useful for predicting A4-amplitude. The MDI was the only independent A4-amplitude predictor that seemed promising for selecting VDD LP patients.abstract figure

The influence of prolonged antibiotic treatment before lead extraction procedures on the outcomes of device reimplantation in cardiac implantable electronic device infections

Abstract Background Cardiac implantable electronic devices (CIED) related infections have a considerable clinical and economic burden in the cohort of CIED-implanted patients and require a complex and thoughtful approach of the "heart team". Complete CIED removal is recommended for all patients with confirmed CIED infection, but the optimal duration of antibiotic therapy (AT) before lead extraction (LE) and its impact on the time of reimplantation are still debatable [1-2]. This study was aimed to evaluate the impact of prolonged AT before LE on the outcomes of device reimplantation. Methods Consecutive cases of LE due to CIED infection at our centre from 2013 to 2022 were reviewed. Our approach assumed the duration of AT for a minimum of 2 weeks for patients with pocket infection (PI), and at least 4 weeks for endocarditis with the exception of non-response to the AT. The target time for reimplantation was 2-3 days after LE with the exception of uncontrolled infection, positive blood culture, logistical reasons or reevaluation of pacing indications during follow-up. Results From a total of 256 LE, 202 (in 198 patients) were due to CIED infection (pacemaker-67,8%, CRT-19,8%, ICD-12,4%). In 62,4% of the cases there was only PI, in 24,7% only endocarditis and in 12,9% it was concomitant. Systemic infection was found in 43,1% of the cases. The mean dwell time of the leads was 92.2±5.0 months (n=201, median 84, IQR 29.0-132.0). In cases of PI, the mean time of AT before LE was 21,7±1,0 days (n=124, median 21, IQR 14.0-28.0), whereas it was 31,6±1,7 days (n=76, median 28, IQR 21.0-42.0) in cases of endocarditis (p&amp;lt;0.05). The duration of AT after LE was 17.7±0.8 days (n=121, median 14, IQR 14.0-21.0) in cases of PI and 22.7±1.4 days (n=76, median 21, IQR 14.0-28.0) in cases of endocarditis (p&amp;lt;0.05). Procedural success was achieved in 98,5% and the procedural failure rate was 1,5%. Major complication rate was 2,5% and minor complication rate was 8,9%. There was no intraprocedural death. Device reimplantation after LE was performed in 68,8% (139) of all patients. The majority of reimplantations (57,6%) occurred within 7 days after LE (figure 1). The mean reimplantation time was 43.6±12.1 days (n=135, median 6, IQR 4.0-15.0), without statistically significant difference in time to reimplantation between PI and endocarditis (p=0.78). 9 patients were reimplanted with epicardial ventricular lead and 1 with leadless pacemaker. Total reinfection rate was 2% (4), all the cases were due to contralateral PI with reimplantation after LE in 11, 12, 38 and 596 days, respectively. One of the patients was also diagnosed with an allergy to silicone, nickel and palladium. Mortality rate during the first 30 days was 5%. Uneventful 12-month follow-up was achieved by 80,2%. Conclusions Appropriate prolonged AT before LE led to feasibility of early device reimplantation with a low rate of reinfection.Time to preimplantation

Long-term follow-up of single-chamber atrial pacing - system upgrade and wenckebach block point behavior: potential implications for leadless AAI pacing?

Abstract Introduction Until recently leadless pacemakers (PM) did not support atrial pacing. A novel dual chamber leadless PM system now provides treatment option for a wide range of indications. Single-chamber atrial stimulation (AAI) for the treatment of symptomatic sick sinus syndrome (SSS) is scarcely used due to concerns about the potential development of atrioventricular block (AVB) and development of paroxysmal atrial fibrillation (AF). Long-term follow-up data of AAI-PM is however scarce. Little is known about the role of serial Wenckebach block point (WBP) measurements in AAI-PM patients for risk stratification. Purpose To assess the incidence of dual chamber upgrade of patients treated with AAI-PM for SSS during long-term follow-up and to investigate the role of serial WBP measurements for risk stratification. Methods Prospectively enrolled patients undergoing implantation of an AAI-PM between October 2002 and December 2023. WBP was measured at implantation and serially during follow up. Results We included a total of 178 patients, of which 58% were female and the median age at implantation was 78 [IQR 71 – 83] years. The median follow-up duration was 6.5 [IQR 2.0 – 9.7] years. 24 patients (13.5%) received a system upgrade to DDD including 3 patients (1.7%) with a mode change to ventricular pacing only (VVI). Adjusted for years of follow-up the upgrade rate was 2.1% per year. Median time to system upgrade was 5.2 [IQR 1.6 – 8.7] years. Reasons for system upgrade were high-degree AVB (38%), low WBP (17%), atrial arrhythmias (33%), unclear syncope (8%) and infection (4%). Median WBP at implantation was 130 [120 – 140] bpm, showing a significant decline over time in the upgrade-group with 105 [95 – 130] bpm compared to the rest of the cohort with 130 [120-130] bpm (p = 0.009). A decline in WBP &amp;gt;20 bpm was found in 17.9% patients and a decline of 10-20 bpm in 33.7% of patients. New-onset atrial arrythmias were found in 36 patients (20%), 29% in the upgrade group and 19% in the rest of the cohort (p = 0.3). Neither age at implantation, sex, WBP at implantation, nor atrial arrhythmia prior to implantation were predictive for the need of a future system upgrade. Conclusion In this cohort of patients undergoing AAI-PM implantation for SSS, a system upgrade was required in 2% per year. The WBP remained stable in 48% of patients. Therefore, AAI-PM due to SSS emerges as a judicious and secure therapeutic modality, warranting increased consideration in the light of new treatment options for leadless pacing.

Comparative safety outcomes of leadless versus transvenous cardiac pacemaker: a systematic review and meta-analysis

Abstract Introduction Leadless Cardiac Pacemakers (LCP) have emerged as a promising alternative to Transvenous Pacemakers (TVP) for managing bradyarrhythmias, especially in cases where TVP options are limited, such as venous access issues in haemodialysis patients or high infection risk individuals. However, long-term safety data, including mortality and hospitalisation rates, are lacking, hindering informed clinical adoption decisions. Purpose This systematic review and meta-analysis compares safety endpoints of LCP with TVP. Methods A systematic search of PubMed, Medline, Embase, Scopus, Web of Sciences, and gray literature was conducted following PRISMA guidelines from release of the Micra LCP to market until May 15, 2023. Meta-analysis was performed using RevMan 5.4. Results Twenty-four studies including data from 33,450 patients (12,802 LCP, 20,648 TVP) were evaluated. The mean age of the population was 77.5 ± 10.6 years, with a mean left ventricular ejection fraction (LVEF) of 58.6 % ± 6.7. Follow-up durations ranged from 6 to 36 months. Compared to TVP, the LCP was associated with significantly fewer overall complications, major complications, acute, mid-term complications, hospitalisations, re-interventions, and device dislodgements (p&amp;lt;0.05). Mortality, tricuspid regurgitation, pacemaker-induced cardiomyopathy, and heart failure hospitalisation rates did not significantly differ. Although LCP showed higher cardiac injury risk, no significant difference in cardiac tamponade rates was observed (Figure 2). LCP exhibited increased vascular-related complications but decreased lung injury, endocarditis, device, and pocket-related issues. Conclusion In the largest review of LCPs, we report that LCP is associated with significantly lower rates of overall complications compared to conventional TVP. This knowledge is critically important as more LCPs enter clinical practice and serves as a baseline against which future data can be evaluated. Nevertheless, proper skill training may help to mitigate the risk of vascular and cardiac injury. These findings underscore the importance of conducting randomized controlled trials to comprehensively evaluate the safety of LCP compared to TVP.Cardiac complication