Transcatheter Pacemaker Research Articles

Impact of age on patient selection in leadless pacemaker implant: experience with the micra transcatheter pacemaker

Abstract Background The safety and efficacy of the Micra AV leadless pacemaker has been demonstrated in the real-world setting. However, whether the patient profile and outcomes differ based upon patient age is not known. Purpose To report age-stratified peri-procedural outcomes and intermediate-term follow-up of patients undergoing Micra implant. Methods Patients (n=801) from the Micra AV Post-Approval Registry were included and divided into age groups: ≤40 (n=40), 41-<65 (n=110), 65-80 (n=332), and >80 (n=319). Baseline characteristics were summarized. A Fine-Gray competing risk model was used to compare risk for major complication through 12 months. Pacing burden and projected longevity were summarized. Results Among 801 included patients, 40 (5.0%) were ≤40 years of age with a mean age of 29.2 ± 6.6 years (range: 16-40) and 60.0% were female. Among patients ≤40, 20.0% had a prior CIED while 27.5% were precluded from transvenous pacing. Patients ≤40 had lower BMI and lower co-morbidity burden compared with older patients. The most common indication for implant was AV block in all age groups, however 35.0% of patients ≤40 had a syncope indication compared to ≤15.5% for older groups. Micra was successfully implanted in 100% of patients ≤40 years. The major complication rate at 12 months was 2.7% in patients ≤40 and did not significantly differ across age groups (P=0.82, Figure). Median pacing percentage was lowest in the ≤40 group (n=17, median= 1.0%) and was highest in the >80 group (n=127, median 88.0%). Median projected longevity across all patients was 10.9 years and was 14.8 years among patients ≤40 with 82.3% having longevity ≥10 years. Conclusion Micra was successfully implanted across a broad range of age groups. Younger patients tended to be healthier and had a low median percentage pacing. The rate of major complications was low and did not differ across age groups.Major complication rate by age subgroup

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<0.0001) and had a significantly higher incidence of renal disease (22.3% vs. 9.8%, P<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<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<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 17552: Pre-Existing Right Ventricular Lead Performance After Transcatheter Tricuspid Valve Replacements (TTVR)?

Introduction: Transcatheter tricuspid regurgitation (TTVR) is an investigational method for nonsurgical candidates with severe tricuspid regurgitation (TV). Many of these patients possess transvenous right ventricular (RV) leads, which can be a cause for TTVR. Outcomes regarding RV lead viability and functionality after TTVR have varied widely. We sought to describe the outcomes and management of RV leads after TTVR at our institution. Hypothesis: We expect transcatheter tricuspid valve replacement to negatively impact the performance of pre-existing right ventricular leads. Methods: This was a retrospective observational analysis of patients who received TTVR at our center independent of other clinical trials. Statistical analysis was performed using SPSS BMI Software. Results: A total of 30 patients underwent TTVR between 2021 and 2023. Nine patients had CIEDs, including one with SICD and one with transcatheter pacemaker. This resulted in 7 (23%) with an RV lead crossing the TV at the time of TTVR (3 Evoque valves, 5 S3 valves). The RV leads were connected to a pacemaker (PM) in five (71%) patients, an implantable cardiac defibrillator (ICD) in one and a CRT-D in another. On average, the patients underwent TTVR 5 years after cardiac implantable electronic device (CIED) implantation. All patients received RV lead testing at least once after TTVR and they were followed up for a median of 7 months after TTVR. 3 patients underwent pre-emptive lead extraction, which let to four (57%) patients with “jailed” RV leads. 3 of the four patients with jailed leads had lead dysfunction requiring system revision or reprogramming - including elevated lead threshold, clinical evidence of transient loss of capture, and non-jailed atrial lead undersensing post TTVR. Conclusions: We report a high incidence of lead malfunction due to RV jailing with TTVR and good outcomes of those undergoing preemptive extraction strategies. Approaches such as leadless systems and coronary sinus systems may be useful in this patient population.

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

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic, inc. Introduction Advances in leadless pacemaker technology have enabled accelerometer based atrioventricular synchronous (AVS) pacing by sensing atrial mechanical contraction. However, acute safety performance of these devices in real-world clinical practice has not been assessed. Objectives To report the acute performance of the Micra AV transcatheter pacemaker from the worldwide Micra AV post-approval registry (PAR). 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), and major complications occurring within 30-days 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 802 patients (99.4%) at 99 centers. Mean age was 74.1±15.1 years and 42.3% were female. The most common pacing indication was AV block (55.7%). Comorbidities included diabetes (29.7%), CAD (22.8%), and heart failure (12.1%), with 31.3% precluded from transvenous device therapy. Micra AV patients were on average older (74.1 vs. 71.1 yrs, P<0.0001) and had a significantly higher incidence of renal disease (22.3% vs. 9.8%, P<0.0001). Major complications occurred in 2.6% of Micra AV patients and in 7.1% TV-DC patients (P<0.001, Figure). The reduction in major complications was largely driven by the absence of pneumothoraces and lead dislodgements among Micra AV patients. Of the 309 patients programmed to VDD mode with at least 30 days of device follow-up, the median AV synchrony index was 86.0% (IQR: 69.2% - 97.2%). Mean A4 amplitude was 2.1±1.6 m/s2 post-implant and 2.2±1.7 m/s2 at follow-up (P=0.57) in 308 patients with paired assessments. 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 acute complications relative 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.

Removal of a leadless pacemaker using a 2.5cc syringe and silk thread during surgical treatment of infective endocarditis

Removal of a leadless pacemaker using a 2.5cc syringe and silk thread during surgical treatment of infective endocarditis

Leadless transcatheter pacemaker: Indications, implantation technique and peri-procedural patient management in the Italian clinical practice

BackgroundSafety and efficacy of leadless pacemakers (L-PM) have been demonstrated in multiple clinical trials, but real-world data on patient selection, implantation technique, and peri-procedural patient management in a clinical practice setting are lacking. MethodsConsecutive patients undergoing L-PM implantation in 14 Italian centers were followed in a prospective, multicentre, observational project. Data on baseline patient characteristics, clinical indications, implantation procedure, and peri-procedural patient management were collected. The rate and nature of device-related complications were also recorded. ResultsA total of 782 L-PM patients (68.4% male, 75.6 ± 12.4 years) were included in the analysis. The main patients-related reason leading to the choice of implanting a L-PM rather than a conventional PM was the high-risk of device infection (29.5% of cases). The implantation success rate was 99.2%. The median duration of the procedure was 46 min. In 90% of patients the device was implanted in the septum. Of patients on oral anticoagulant therapy (OAT) (n = 498) the implantation procedure was performed without interrupting (17.5%) or transiently interrupting OAT without heparin bridging (60.6%). During a median follow-up of 20 months major device-related complications occurred in 7 patients (0.9%): vascular access-site complications in 3 patients, device malfunction in 2 patients, pericardial effusion/cardiac tamponade in one patient, device migration in one patient. ConclusionsIn the real world setting of Italian clinical practice L-PM is often reserved for patients at high-risk of infection. The implantation success rate was very high and the risk of major complications was low. Peri-procedural management of OAT was consistent with available scientific evidence.

Leadless cardiac pacemaker in elderly patients: How old for a new technology?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Leadless transcatheter pacemakers are considered as a safe and effective option for cardiac pacing in patients (pts) at higher risk of complications with conventional transvenous cardiac pacing. Purpose Our aim was to assess the clinical "real-life" feasibility and outcomes of leadless pacing in elderly pts in a high-volume center over a mid-term follow-up (FU) period. Methods Elderly pts (aged ≥ 75 years) who underwent leadless MICRA® system pacemaker implantation with a FU period above 3 months were included in this retrospective monocentric study. Results 130 pts were included (84 ± 5.6 years old, male 66.2%). Indications were: Atrioventricular block (permanent 15.4%; transient 27.7%), atrial fibrillation bradycardia 50% and sinus node dysfunction 6.9%. Leadless system pacing was preferred over conventional pacing in pts with: transvenous pacemaker extractions due to infectious 18.5% or vascular 1.5% complications; active systemic infection and urgent need for cardiac stimulation 20%; complex conventional vascular approach 21.6%; severe tricuspid valve disease 1.5%; deterioration of general condition and clinical frailty 22.3%; shortly after transvalvular aortic valve replacement 8.5%. Among the pts, 6.2% had previous leadless Nanostim® device implantation with dysfunction of the system. Pts had either local anesthesia 13.2% or deep sedation 86.8%. The average fluoroscopy time was 4.3±2.9 minutes and number of device deployments before the final position ranged from 1 to 7 with a mean value of 1.5±1 positions. Pacing threshold during implant was 0.5±0.4 V at 0.24ms, only 4 pts (3%) had an implant threshold of >1.0 V at 0.24 ms. Two postoperative deaths were observed: 1 cardiac arrest related to myocardial dysfunction and consequent pulmonary edema in a patient with advanced heart failure, and 1 death secondary to myocardial perforation with need for surgical repair that occurred among the first implantations with an apical device position and a patient with multiple comorbidities. The total rate of major complications was 2.3% with only 1 vascular complication at the femoral puncture site. The median time from the leadless pacemaker implant procedure to discharge was 5±6.5 days (minimum 1 and maximum 40 days): 55.6% pts were able to leave the cardiology department within the first 72 hours. The mean FU period was 17 months ± 15 months with a mortality rate of 12.3% (cardiovascular impairment 5.4%; non cardiovascular-related deaths 6.9%). Increase in pacing thresholds was noted in 4 pts with subsequent stabilization; 92.2% of pts presented with thresholds lower than 1V at 0.24 ms. All pts remained free of infections during FU with no cases of device dislodgement observed. Conclusion Elderly pts are at higher risk of complications; our experience confirms their clinical frailty and underlines the favorable safety profile of leadless system pacing with a low rate of complications and stable pacing thresholds.

Development and validation of a risk score for predicting pericardial effusion in patients undergoing leadless pacemaker implantation: experience with the Micra transcatheter pacemaker.

AimsThere 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 resultsPatients (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.ConclusionThe 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 registrationThe 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).

Leadless pacemaker implant in patients requiring CIED extraction: outcomes based upon timing of extraction

Abstract Background Previous results from global Micra Transcatheter Pacemaker clinical trials have demonstrated leadless pacing as a safe and attractive option for patients with prior cardiac implantable electronic device (CIED) infection and extraction. Whether outcomes differ based upon the timing of prior device extraction has not been studied. Purpose To describe characteristics and outcomes of patients undergoing CIED extraction during or prior to Micra implantation. Methods Patients who underwent CIED explant and Micra implantation were identified from the Micra Post-Approval Registry and Micra Acute Performance studies. Baseline characteristics were summarized. A Fine-Gray competing risk model was used to compare risk for major complication through 24 months. Results Of the 2739 patients included in the studies, 99 (3.6%) patients had CIED extraction the day of Micra implantation (same day) and 127 (4.6%) patients had CIED extraction within 30 days prior to Micra implantation (prior). Although infection was the primary reason for CIED extraction in both groups, a larger proportion of prior patients underwent extraction for this reason (87.4% vs. 42.4%). In contrast, more same day patients underwent CIED extraction for physician/elective reasons (16.2% vs. 3.1%). Same day patients prior device history included pacemaker (42 dual chamber and 30 single chamber), ICD (1 single chamber and 4 dual chamber), CRT (7 CRT-ICD and 13 CRT-P) while prior patients device history included pacemaker (29 single chamber, 80 dual chamber), ICD (3 dual chamber), CRT (5 CRT-ICD and 7 CRT-P). Overall, patients with extraction were aged 72.8±14.3 years, predominantly male (65.9%), and medical history was similar between groups, with the exception to CHF, which was higher for the same day group (18.2% vs 6.3%, P=0.021). The implant success rate was 98.0% for same day patients and 100% for prior patients. Median procedure duration was not significantly different between the groups (26.0 minutes and 25.0 minutes for same day and prior, respectively). Average follow-up duration was 16.5±13.8 months (range 0–53.4) for same day patients and 18.2±15.2 months (range 0–58.3) for subsequent patients. The rate of acute major complications (&amp;lt;30 days) was 5.1% for same day and 3.2% for prior. Through 24 months, the rate of major complications was 6.4% for same day and 6.0% for prior (HR: 1.19, 95% CI: 0.40 – 3.50, P=0.76, Figure). The rate of major complications related to infection was low and did not differ by group (1.01% vs. 1.57%, P=1.00) Conclusion The Micra leadless pacemaker was implanted with a high success rate following CIED extraction. Outcomes following CIED extraction appear similar, whether the extraction is performed during or prior to Micra implant. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Medtronic, Inc. Risk of major complications

Quantification of artifacts during cardiac magnetic resonance in patients with leadless Micra pacemakers.

When cardiac magnetic resonance (MR) is performed after previous leadless transcatheter pacemaker implantation, an image distortion has to be expected in the heart region and evaluation of myocardial tissue can be affected. In this clinical prospective study, we aim to assess the extent and impact of this artifact on individual ventricular segments and compare it to conventional pacing devices. Total of 20 patients with leadless pacemaker placed in the right ventricle underwent cardiac MR imaging in a 1.5 Tesla scanner. A multiplanar segmentation was used to demarcate the left and right ventricular myocardium as well as the pacemaker-caused image artifact in systolic and diastolic time frames. Artifact size and its relative influence on myocardial segments were quantitatively assessed and expressed in AHA-17 model. Implanted leadless pacemaker caused an image artifact with a volume of 48 ± 5 ml. Most distorted were the apical septal (53 ± 23%), apical inferior (30 ± 18%), and midventricular inferoseptal (30 ± 20%) segments. The artifact intersection with basal and lateral segments was none or negligible (up to 2%). The portion of left ventricular (LV) myocardium affected by the artifact was significantly higher in systole (8 ± 4%) compared to diastole (10 ± 3%; p < .001). Implantation of leadless pacemaker represents no obstacle for cardiac MR imaging but causes an image artifact located mostly in septal, inferoseptal, and anteroseptal segments of apical and midventricular LV myocardium. With the exception of the apex, diastolic timing reduces the image distortion of all segments and improves global ventricular assessment.

Major adverse clinical events associated with implantation of a leadless intracardiac pacemaker

Leadless intracardiac pacemakers were developed to avoid the complications of transvenous pacing systems. The Medtronic Micra™ transcatheter pacemaker is one such system. We found an unexpected number of major adverse clinical events (MACE) in the Food and Drug Administration's Manufacturers and User Facility Device Experience (MAUDE) database associated with Micra implantation. The purpose of this study was to describe these MACE and compare them to implant procedure MACE in MAUDE for Medtronic CapSureFix™ active-fixation transvenous pacing leads. During January 2021, we queried the MAUDE database for reports of MACE for Micra pacemakers and CapSureFix leads using the simple search terms "death," "tamponade," and "perforation." Reports from 2016-2020 were included. The search identified 363 MACE for Micra and 960 MACE for CapSureFix leads, including 96 Micra deaths (26.4%) vs 23 CapSureFix deaths (2.4%) (P <.001); 287 Micra tamponades (79.1%) vs 225 tamponades for CapSureFix (23.4%) (P <.001); and 99 rescue thoracotomies for Micra (27.3%) vs 50 rescue thoracotomies for CapSureFix (5.2%) (P <.001). More Micra patients required cardiopulmonary resuscitation (21.8% vs 1.1%) and suffered hypotension or shock (22.0% vs 5.8%) than CapSureFix recipients (P <.001). Micra patients were more likely to survive a myocardial perforation or tear if they had surgical repair (P = .014). Micra leadless pacemaker implantation may be complicated by myocardial and vascular perforations and tears that result in cardiac tamponade and death. We estimate the incidence is low (<1%). Rescue surgery to repair perforations may be lifesaving. MACE are significantly less for implantation of CapSureFix transvenous ventricular pacing leads.

Conventional single-chamber pacemakers versus transcatheter pacing systems in a "real world" cohort of patients: A comparative prospective single-center study.

PurposeDespite the developments in conventional transvenous pacemakers (VVI-PM), the procedure is still associated with significant complications. Although there are no prospective clinical trials that compared VVI-PM with transcatheter pacemaker systems (TPS).MethodsThis is a prospective, observational, single-center study that included all patients with an indication for a single-chamber pacemaker implant within a 4-year period. All clinical, ECG and echocardiographic characteristics at implant, electrical parameters, associated complications and mortality were analyzed. A Cox survival model and a Bayesian cohort analysis were performed for differences in complication rates between groups.ResultsThere were 443 patients included (198 TPS and 245 VVI-PM). The mean age was 81.5 years (TPS group, 79.2 ± 6.6 years; VVI-PM group, 83.5 ± 8.9 years). There was a male predominance in TPS group (123, 62.1% vs. 67, 27.3%; p < 0.001). The presence of systolic dysfunction and renal insufficiency were more frequent in VVI-PM group than in TPS patients. Mean follow-up was 22.3 ± 15.9 months. In a multivariable paired data the TPS group presented fewer complications than VVI-PM group (HR = 0.39 [0.15–0.98], p-value 0.013), but major complications were not different (6, 3% vs 14, 5.6% respectively, p = 0.1761). There was no difference in the mortality rate between the groups. The TPS group had less risk than VVI-PM group to have a complication, with a 96% of probability.ConclusionsTPS patients had a lower overall complication rate than VVI-PM patients including matched-pair samples using a Bayesian analysis. These results confirm the safety profile of TPS in clinical practice.

A prospective, multicenter, single-arm study of performance of the micra transcatheter pacemaker in chinese patients: A comparison to the global experience

Background: We have compared the patient characteristics and safety and efficacy results of the Micra transcatheter pacemaker from the China Micra Transcatheter Pacing Study with those from the global trials. Subjects and Methods: In this prospective, multicenter, single-arm study, patients with a class I or II guideline recommendation for single-chamber pacemaker therapy were enrolled from seven centers in China between July 30, 2018, and December 12, 2018. The primary outcome measure of this study was freedom from system- or procedure-related major complications through 6 months postimplantation (prespecified performance goal 83%). Patient baseline characteristics and major complications were compared with data from the global trials. Performance after medically indicated magnetic resonance imaging (MRI) scans was characterized. The study was approved by the ethics committee at each participating center and registered with ClinicalTrials.gov (Identifier: NCT03624504). Results: Implantation was successful in 81 of 82 (98.8%) patients with a mean follow-up of 8.7 ± 1.5 months. Chinese patients who had lower body mass index were more often female, and less frequently had a pacing indication associated with atrial fibrillation (AF) compared with global patients. Through 6 months postimplantation, two major complications occurred, with a major complication-free rate of 97.6% (95% confidence interval: 90.6–99.4%), exceeding the primary endpoint performance goal (P = 0.002). The major complication rate was in line with rates from the Micra investigational trial and Post-Approval Registry (2.4% vs. 3.7% and 2.9%, respectively, P = 0.50). Among 14 patients who underwent 3T MRI scans, electrical performance was stable with mean pre- and post-MRI pacing thresholds of <0.5 V. No MRI-related device performance issues were observed. Conclusion: In the hands of new operators in China, the Micra pacemaker was implanted successfully with a very low complication rate. Although Chinese Micra patients were on average of smaller stature and the majority had a pacing indication not associated with AF, Micra performance was excellent and in line with the global trial experience.

A Predictive Model for the Long-Term Electrical Performance of a Leadless Transcatheter Pacemaker

This study sought to formulate a predictive model for describing the long-term electrical performance of Micra (Medtronic, Mounds View, Minnesota). 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. 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≥12months post-implantation, defined as≥2.0V at 0.24ms or an increase of≥1.5V from implantation or need for system revision due to elevated thresholds at≤12months post-implantation. We evaluated for univariate and multivariate associations between patient and device characteristics at implantation and for elevated thresholds at 12months. Among the total cohort, 75 patients (4.1%) had elevated thresholds at 12months; 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 12months (all p<0.05). A history of diabetes, male sex, elevated PCT, and low impedance at implantation were independentpredictors of elevated thresholds at 12months. These metrics represent the foundation of a simple tooltoaid in procedural decision making.

Implantation of the Micra transcatheter pacing system: A single center North India experience.

BackgroundThe leadless pacemaking transcatheter system, Micra, is a miniaturized, single-chamber pacemaker system. We report herein our experience with implantation of the Micra TPS system.ObjectiveThe current study was conducted to evaluate the safety and efficacy of the leadless Micra Transcatheter Pacemaker System (Medtronic).Research design and methodsThis was a prospective single centre nonrandomized study without controls. A transcatheter pacemaker was implanted in patients who had guideline based indications for ventricular pacing. 28 subjects were screened based on the selection criteria. Mica TPS was implanted. Parameters assessed were: duration of procedure (from femoral vein puncture to venous access closure), fluoroscopy time, number of device repositions, periprocedural electrical measurements (sensing, threshold and impedance) and in-hospital, intermediate to long term adverse events related to procedure.Result and conclusions: The device was successfully implanted in 28 subjects. The mean intraoperative sensing value was 9.04 ± 1.5 mV and the impedance was 766.89 ± 213.9 Ω. At discharge from hospital, those values were 13.2 ± 15.83 mV and 855 ± 111.7, respectively. The recommended pacing threshold value as achieved in all subjects was 0.78 V, i.e. ≤ 1 V at 0.24 ms. There was no adverse event or complications reported for any of the subjects. Mean time from hospitalization to discharge was 1.5 days. Implantation of leadless pacemakers is feasible, safe and provides advantages over the conventional system.

Leadless pacemaker implant in patients with a history of open heart surgery: experience with the Micra transcatheter pacemaker

Abstract Background The Micra transcatheter pacemaker has demonstrated a favorable safety and efficacy profile relative to transvenous pacing. Patients with a history of open heart surgery have a higher risk of complications with transvenous pacemakers during follow-up. The experience with leadless pacemakers among a large cohort of patients with a history of open heart surgery has not been reported. Objective To report outcomes in patients with a history of open heart surgery undergoing Micra implant. Methods Patients undergoing Micra implant from the Micra Transcatheter Pacing Post-Approval Registry (PAR) were included in the analysis. Baseline and procedural characteristics, major complications, and electrical performance were compared among patients with vs. without history of cardiac surgery. Results A total of 331 out of 1815 (18.2%) patients had a history of open heart surgery, underwent Micra implant, and were followed for 19.4±10.4 months. The mean age was 74.6±13.5 years, 40% were female. The most common cardiac surgery was aortic valve surgery (71%) followed by mitral valve surgery (39%). Patients with prior open-heart surgery were more likely to have contraindications to transvenous pacing, were more likely to be on oral anticoagulants, and had more co-morbidities including atrial fibrillation, heart failure, and coronary artery disease (all p&amp;lt;0.005). Implantation was successful in 327 of 331 patients (98.8%) with a median procedure time of 29 minutes. Mean pacing capture thresholds (PCTs) at implant were 0.66±0.51V and remained stable through follow-up. There were 11 major complications in 10 cardiac surgery patients, with no device or procedure-related infections reported. The major complication rate was 3.1% (Figure) and was not significantly different than that of patients without a history of open heart surgery (HR: 0.85, P=0.640). There was 1 cardiac perforation (with no intervention required) in the open heart surgery group (0.3%) and there were 14 cardiac perforations (0.94%, P=0.332) in the non-open heart surgery group of which 10 required intervention. Conclusion The Micra transcatheter pacemaker can be safely implanted in patients with a history of open heart surgery, with a similar long-term safety profile to patients without a history of open heart surgery. Importantly, there were no device-related infections reported in either group. Risk of Major Complication Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Medtronic, Inc.

Initial implantation experience and short-term follow-up results of implanting leadless intracardiac transcatheter pacing system

Objective: To explore the utility and safety of leadless intracardiac transcatheter pacing system. Methods: The study was a prospective observational study. Patients underwent Micra transcatheter pacing system in Beijing Anzhen hospital from December 2019 to January 2020 were enrolled. The baseline characteristics, platelet count, hemoglobin, anticoagulation and/or antiplatelet therapy, mean procedural time, average fluoroscopy time, number of deployment and electrical parameters (threshold, R-wave amplitude, impedance) were recorded. Ultrasonography of bilateral femoral and iliac veins was performed in all patients. Patients were followed including access site complication, adverse event and device evaluation at implant, hospital discharge, 1 and 3 months post-implant. R-wave≥5 mV, impedance between 400 and 1 500 Ω and threshold increase≤1.5 V than implant is considered a stable parameter. Femoral access site complications included hematoma, hemorrhage, pseudoaneurysm, and arteriovenous fistula. Adverse events included dislodgement, cardiac effusion/perforation and infection. Left ventricular end diastolic diameter and ejection fraction before and at 1 month after implant were reported. Results: Five patients were enrolled and pacemaker implantation was successful in all 5 patients. Patients were all males and the average age was (78.4±8.4) years. 2 patients received aspirin and clopidogrel therapy, 1 patient suffered from anemia and thrombocytopenia occurred in 1 patient. No stenosis, occlusion and vascular malformation of bilateral femoral and iliac veins was observed. The mean implant time was (39.6±1.7) minutes. The average fluoroscopy time was (9.2±1.3) minutes and the number of deployment was (1.40±0.55). Electrical parameters(threshold, R-Wave amplitude and impedance) were as follows: (0.40±0.10) V/0.24 ms, (10.80±3.72) mV and (822.00±162.23) Ω at implant; (0.45±0.07) V/0.24 ms, (13.04±2.41) mV, and (748.0±91.5) Ω at discharge, (0.40±0.06) V/0.24 ms, (14.26±4.11) mV, and (700.0±91.7) Ω at 1 month post-implant and (0.39±0.05) V/0.24 ms, 14.40±3.97 mV, and (682.0±96.0) Ω at 3 months post-implant, respectively. Threshold increase was ≤1.5 V compared to that during implantation, electrical parameters were acceptable and stable. There was no difference in LVEDD [(44.00±5.24) mm vs. (44.00±5.34) mm,P=1.000] and EF [(62.00±3.39)% vs. (62.20±3.56)%, P=0.861] before and 1 month post-implant. No incidence of access site complications, cardiac effusion/perforation, dislodgment or infections occurred during the 3 months. Conclusions: The leadless transcatheter pacemaker implantation performed in our study archived a high implant success rate and favorable safety profile as well as associated with low and stable pacing thresholds. The long-term safety and benefit of leadless pacemaker need to be evaluated in future clinical studies.

Morbidity and mortality in patients precluded for transvenous pacemaker implantation: Experience with a leadless pacemaker

The Micra transcatheter pacemaker is a safe and effective alternative to transvenous permanent pacemakers (TV-PPMs). However, the safety profile and mortality outcomes of Micra implantation in patients deemed poor candidates for TV-PPM are incompletely understood. The purpose of this study was to evaluate safety and all-cause mortality in patients undergoing Micra implantation stratified by whether they were precluded for therapy with a TV-PPM. Patients from the Micra clinical trials were divided into groups on the basis of whether the implanter considered the patient to be precluded from receiving a TV-PPM. Micra groups were compared with one another as well as with a historical cohort of patients who received a single-chamber TV-PPM. A total of 2817 patients underwent a Micra implantation attempt, of whom 546 (19%) patients deemed ineligible for TV-PPM implantation for reasons such as venous access issues or prior device infections. Both acute mortality (2.75% vs 1.32%; P=.022) and total mortality at 36 months (38.1% vs 20.6%; P<.001) were significantly higher in the precluded group than in the nonprecluded group. Mortality was similar among nonprecluded patients and patients implanted with a TV-PPM. The major complication rate through 36 months was similar between the 2 Micra groups (3.81% vs 4.30%; P=.40). All-cause mortality is higher in Micra patients deemed ineligible for TV-PPM implantation than in nonprecluded Micra patients and those who received a TV-PPM, in part related to a higher incidence of chronic comorbidities in these patients. The overall major complication rate was low and did not differ by preclusion status. Micra Post-Approval Registry ClinicalTrials.gov identifier: NCT02536118; Micra Continued Access Study ClinicalTrials.gov identifier: NCT02488681; Micra Transcatheter Pacing Study ClinicalTrials.gov identifier: NCT02004873; Medtronic Product Surveillance Registry ClinicalTrials.gov identifier: NCT01524276.

Leadless cardiac pacing in resource limited settings: A Groote Schuur hospital experience with the Micra leadless pacemaker

Background: Cardiac pacemakers improve survival and quality of life in patients with atrioventricular (AV) block. However, conventional pacemakers carry a small risk of both acute and chronic lead and pacemaker generator complications. Leadless pacemakers negate these risks by not having a pacing lead and a subcutaneous generator. We report our Groote Schuur Hospital experience with the Medtronic Micra transcatheter pacing system (TPS). Methods: We report a consecutive case series of patients that received the Micra leadless pacemaker. The Micra transcatheter pacemaker, a single chamber ventricular pacemaker, is inserted using a TPS via the femoral vein into the right ventricle. Implantation data were obtained, and medical records were reviewed for the 6 weeks and 1-year follow-up visits. Results: A total of 5 patients were implanted with a Micra leadless pacemaker from 11 March 2015 - 2 November 2016. Four patients were male and 1 female, with an average age of 64 years. Four patients received the pacemaker for a second- or third-degree AV block and 1 patient received the pacemaker for unexplained syncope and right bundle branch block. The Micra leadless pacemaker was successfully implanted in all patients with no acute implantationrelated complications. One-year follow-up was available for 4 patients with good pacing thresholds, sensitivity and impedance. One patient demised after 9 months post Micra implantation due to unrelated causes (acute myeloid leukaemia). Conclusion: The Micra leadless pacing system is safe and effective and shows good short-term results in a real-world, resource-limited setting. This form of pacing offers a viable option for patients who require pacing for AV block, especially in patients with vascular access problems or who are at high risk of lead or pacemaker generator complications.

Very high pacing thresholds during long-term follow-up predicted by a combination of implant pacing threshold and impedance in leadless transcatheter pacemakers.

Micra transcatheter pacemaker system (TPS) usually achieves low implant pacing threshold (IPT). However, IPT may increase in some patientsduring follow-up. To apply implant parameters in predicting long-term occurrence of very high pacing threshold (VHPT) in patients with Micra-TPS. A cohort of 110 consecutive patients implanted with a Micra-TPS from 2014 to 2018 was evaluated at discharge and at 1, 12, 24, 36, and 48 months follow-up. VHPT was defined as greater than 2 V/0.24 ms. VHPT predictors were identified. Micra-TPS was implanted successfully in 108 patients (98.2%). During a mean follow-up of 24 ± 16 months, 18 patients (16.7%) died of causes nonpacemaker-related, and 4 (3.8%) developed VHPT. Patients with VHPT had higher IPT and lower implant impedance than patients with non-VHPT: 1 ± 0.31 vs 0.55 ± 0.29 V/0.24 ms (P = .003) and 580 ± 59 vs 837 ± 232 Ω (P = .03), respectively. IPT and impedance had excellent discriminative power to predict VHPT (area under the curve: 0.85 ± 0.07 and 0.91 ± 0.05, respectively). Negative predictive value (NPV) of IPT ≤ 0.5 V/0.24 ms was 100%; positive predictive value (PPV) was 8% throughout follow-up. Implant impedance ≤ 600 Ω had NPV of 99% throughout follow-up, whereas PPV varied: 16%, 21%, 16%, and 28% at 1, 12, 24, and 36 months, respectively. Sequential combination of IPT greater than 0.5 V/0.24 ms and impedance ≤ 600 Ω improved PPV to 25%, 35%, 27%, and 44%, respectively, whereas NPV remained 99% throughout follow-up. Despite favorable long-term electrical performance of Micra-TPS, a small percent of patients developed VHPT during follow-up. A sequential combination of IPT and impedance could allow the implanter to identify patients who will develop VHPT during long-term follow-up.