Micra 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

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

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.

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.

5970Morbidity and mortality in patients precluded for transvenous pacemaker implantation: experience with the Micra transcatheter pacemaker

Abstract Background The Micra transcatheter pacemaker has proven to be a safe and effective alternative to transvenous pacemakers (TVPs). However, the safety profile after Micra implantation in patients deemed poor candidates for TVPs is poorly understood. Purpose To evaluate the safety and all-cause mortality outcomes in Micra recipients stratified by whether or not they were precluded for therapy with TVP. Methods Micra patients from the Micra Transcatheter Pacing (IDE) Study, Continued Access (CA) study, and Post-Approval Registry (PAR) were divided into groups based upon whether or not the implanting physician considered the patient to be precluded from receiving a transvenous pacing system. All-cause mortality was compared between the Micra patient groups and patients receiving a single-chamber transvenous pacing system (SC-TVP) since 2010 from the Medtronic product surveillance registry using univariate and multivariate Cox models. Results Among 2,819 patients who underwent a Micra implant attempt, the overall major complication rate through 24 months was 3.5%. In these patients, 548 were deemed precluded from TVP implantation. Prior device infection or bacteremia (38.9%), venous access issues (36.1%) and thrombosis (10.2%) were amongst the most common causes of preclusion for TVP implantation. These patients were younger (71.7 vs. 76.7 years), more frequently on hemodialysis (26.3% vs. 2.5%), and more often had a prior CIED implanted (38.4% vs. 4.4%) than non-precluded patients. Over an average follow-up of 13.5±11.1 months, all-cause mortality was significantly higher in precluded Micra patients compared with SC-TVP patients (HR: 2.16, 95% CI: 1.54–3.2, P&lt;0.001) (Figure 1). However, there was no significant difference in all-cause mortality when comparing non-precluded Micra patients and SC-TVP patients (HR: 1.12, 95% CI: 0.86–1.44, P=0.401). Acute all-cause death (within 1 month) among Micra patients was 2.74% and 1.32% in the precluded and non-precluded TVP groups, respectively. The procedure-related death rate was 0.55% for the TVP precluded group and 0.13% for the not precluded group (P=0.092). The major complication rate through 24-months was similar between the two Micra groups (4.0% vs 3.4%, P=0.630). All-cause mortality for Micra and SC-TVP Conclusion The overall safety profile of Micra remains is in line with previously reported data. All-cause mortality risk (both acute and long term) appears to be higher in patients who were precluded from receiving TVP. Acknowledgement/Funding Supported by Medtronic

Abstract 16812: Clinical Use of Rate Adaptive Pacing With a Leadless Pacemaker: Results From the Micra Transcatheter Pacing System Post-Approval Registry

Introduction: The Micra transcatheter pacemaker has similar functionality and features to existing transvenous VVIR systems despite its small size and intracardiac location. Rate adaptive pacing with Micra is achieved via a programmable 3-axis accelerometer that detects activity in the presence of cardiac motion and has demonstrated to be proportional to workload in the investigational trial. In this analysis, we report the clinical usage of rate adaptive pacing in the Micra Post-Approval Registry (PAR). Methods: The Micra PAR is a prospective, non-randomized, multi-center registry evaluating safety performance of Micra in real-world clinical practice following commercial release. All patients intended to be implanted with a Micra were eligible for enrollment. Micra PAR patients with device data available from an interrogation at least 30-days post-implant were included in this analysis. The clinical usage of VVIR vs. VVI pacing modes was summarized based upon last device interrogation. Results: Among the 713 patients included in this analysis from 117 centers, average age was 75.4 ± 14.4 years and 60.0% were male. Overall 45.3% had rate adaptive pacing enabled. Of 457 patients with a primary pacing indication of bradyarrhythmia with AF, 58.0% were programmed VVIR (figure). The pacing indication distribution for the VVIR patient group was: 82% bradycardia with AF, 4% sinus node dysfunction, 8% AV block, 4% syncope, and 1% other. Among patients with a primary indication of syncope or sinus node dysfunction, the majority were programmed VVI (83.9% and 79.1%, respectively). Of patients with &lt;10% pacing, 2.5% were programmed VVIR vs. 97.5% VVI. Of those with &gt;90% pacing, 88.8% were VVIR vs. 11.2% VVI. Conclusions: In real-world clinical practice, VVIR was programmed in &lt;50% of Micra patients. Patient groups with the highest utilization of VVIR mode include those with &gt;90% ventricular pacing and those with a primary pacing indication of bradyarrhythmia with AF.

P3877Impact of age on patient selection in leadless pacemaker implant: experience with the Micra transcatheter pacemaker

P3877Impact of age on patient selection in leadless pacemaker implant: experience with the Micra transcatheter pacemaker

Rate adaptive pacing in an intracardiac pacemaker

The Micra transcatheter pacemaker was designed to have similar functionality to conventional transvenous VVIR pacing systems. It provides rate adaptive pacing using a programmable 3-axis accelerometer designed to detect patient activity in the presence of cardiac motion. The purpose of this study was to evaluate the system's performance during treadmill tests to maximum exertion in a subset of patients within the Micra Transcatheter Pacing Study. Patients underwent treadmill testing at 3 or 6 months postimplant with algorithm programming at physician discretion. Normalized sensor rate (SenR) relative to the programmed upper sensor rate was modeled as a function of normalized workload in metabolic equivalents (METS) relative to maximum METS achieved during the test. A normalized METS and SenR were determined at the end of each 1-minute treadmill stage. The proportionality of SenR to workload was evaluated by comparing the slope from this relationship to the prospectively defined tolerance margin (0.65-1.35). A total of 69 treadmill tests were attempted by 42 patients at 3 and 6 months postimplant. Thirty tests from 20 patients who completed ≥4 stages with an average slope of 0.86 (90% confidence interval 0.77-0.96) confirmed proportionality to workload. On an individual test basis, 25 of 30 point estimates (83.3%) had a normalized slope within the defined tolerance range (range 0.46-1.08). Accelerometer-based rate adaptive pacing was proportional to workload, thus confirming rate adaptive pacing commensurate to workload is achievable with an entirely intracardiac pacing system.