In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

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AimsPermanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker.Methods and resultsPatients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and <2 V 3-month mean pacing capture threshold at 0.24 ms pulse width (efficacy). Patients were implanted (n = 140) from 23 centres in 11 countries (61% male, age 77.0 ± 10.2 years) for atrioventricular block (66%) or sinus node dysfunction (29%) indications. During mean follow-up of 1.9 ± 1.8 months, the safety endpoint was met with no unanticipated serious adverse device events. Thirty adverse events related to the system or procedure occurred, mostly due to transient dysrhythmias or femoral access complications. One pericardial effusion without tamponade occurred after 18 device deployments. In 60 patients followed to 3 months, mean pacing threshold was 0.51 ± 0.22 V, and no threshold was ≥2 V, meeting the efficacy endpoint (P < 0.001). Average R-wave was 16.1 ± 5.2 mV and impedance was 650.7 ± 130 ohms.ConclusionEarly assessment shows the transcatheter pacemaker can safely and effectively be applied. Long-term safety and benefit of the pacemaker will further be evaluated in the trial.Clinical Trial RegistrationClinicalTrials.gov ID NCT02004873.

Accelerometer-based atrial sensing is feasible and significantly improves AVS in patients with AV block and a single-chamber leadless pacemaker implanted in the right ventricle.

IntroductionLeadless pacemakers may provide a safe and attractive pacing option to patients with cardiac implantable electronic device (CIED) infection. We describe the characteristics and outcomes of patients with a recent CIED infection undergoing Micra implant attempt.Methods and ResultsPatients with prior CIED infection and device explant with Micra implant within 30 days, were identified from the Micra post approval registry. Procedure characteristics and outcomes were summarized. A total of 105 patients with prior CIED infection underwent Micra implant attempt ≤30 days from prior system explant (84 [80%] pacemakers and 13 [12%] ICD/CRT‐D). All system components were explanted in 93% of patients and explant occurred a median of 6 days before Micra implant, with 37% occurring on the day of Micra implant. Micra was successfully implanted in 99% patients, mean follow‐up duration was 8.5 ± 7.1 months (range 0‐28.5). The majority of patients (91%) received IV antibiotics preimplant, while 42% of patients received IV antibiotics postprocedure. The median length of hospitalization following Micra implant was 2 days (IQR, 1‐7). During follow‐up, two patients died from sepsis and four patients required system upgrade, of which two patients received Micra to provide temporary pacing support. There were no Micra devices explanted due to infection.ConclusionImplantation of the Micra transcatheter pacemaker is safe and feasible in patients with a recent CIED infection. No recurrent infections that required Micra device removal were seen. Leadless pacemakers appear to be a safe pacing alternative for patients with CIED infection who undergo extraction.

Aims  Clinical trials have demonstrated the safety and efficacy of the Micra leadless VVI pacemaker; however, longer-term outcomes in a large, real-world population with a contemporaneous comparison to transvenous VVI pacemakers have not been examined. We compared reinterventions, chronic complications, and all-cause mortality at 2 years between leadless VVI and transvenous VVI implanted patients. Methods and results  The Micra Coverage with Evidence Development study is a continuously enrolling, observational, cohort study of leadless VVI pacemakers in the US Medicare fee-for-service population. Patients implanted with a leadless VVI pacemaker between March 9, 2017, and December 31, 2018, were identified using Medicare claims data linked to manufacturer device registration data (n = 6219). All transvenous VVI patients from facilities with leadless VVI implants during the study period were obtained directly from Medicare claims (n = 10 212). Cox models were used to compare 2-year outcomes between groups. Compared to transvenous VVI, patients with leadless VVI had more end-stage renal disease (12.0% vs. 2.3%) and a higher Charlson comorbidity index (5.1 vs. 4.6). Leadless VVI patients had significantly fewer reinterventions [adjusted hazard ratio (HR) 0.62, 95% confidence interval (CI) 0.45–0.85, P = 0.003] and chronic complications (adjusted HR 0.69, 95% CI 0.60–0.81, P &lt; 0.0001) compared with transvenous VVI patients. Adjusted all-cause mortality at 2 years was not different between the two groups (adjusted HR 0.97, 95% CI 0.91–1.04, P = 0.37). Conclusion  In a real-world study of US Medicare patients, the Micra leadless VVI pacemaker was associated with a 38% lower adjusted rate of reinterventions and a 31% lower adjusted rate of chronic complications compared with transvenous VVI pacing. There was no difference in adjusted all-cause mortality at 2 years.

IMPORTANCEThe safety and efficacy of leadless VVI pacemakers have been demonstrated in multiple clinical trials, but the comparative performance of the device in a large, real-world population has not been examined. OBJECTIVE To compare patient characteristics and complications among patients implanted with leadless VVI and transvenous VVI pacemakers. DESIGN, SETTING, PARTICIPANTS The Longitudinal Coverage With Evidence Development Study on Micra Leadless Pacemakers (Micra CED) is a continuously enrolling observational cohort study evaluating complications, utilization, and outcomes of leadless VVI pacemakers in the US Medicare fee-for-service population. Patients implanted between March 9, 2017, and December 1, 2018, were identified and included. All Medicare patients implanted with leadless VVI and transvenous VVI pacemakers during the study period were enrolled. Patients with less than 12 months of continuous enrollment in Medicare prior to leadless VVI or transvenous VVI implant and with evidence of a prior cardiovascular implantable electronic device were excluded, leaving 5746 patients with leadless VVI pacemakers and 9662 patients with transvenous VVI pacemakers. Data were analyzed from May 2018 to April 2021. EXPOSURES Medicare patients implanted with leadless VVI pacemakers or transvenous VVI pacemakers. MAIN OUTCOMES AND MEASURESThe main outcomes were acute (30-day) complications and 6-month complications. RESULTSOf 15 408 patients, 6701 (43.5%) were female, and the mean (SD) age was 81.0 (8.7) years. Compared with patients with transvenous VVI pacemakers, patients with leadless VVI pacemakers were more likely to have end-stage kidney disease (690 [12.0%] vs 226 [2.3%]; P < .001) and a higher mean (SD) Charlson Comorbidity Index score (5.1 [3.4] vs 4.6 [3.0]; P < .001). The unadjusted acute complication rate was higher in patients with leadless VVI pacemakers relative to transvenous VVI pacemakers (484 of 5746 [8.4%] vs 707 of 9662 [7.3%]; P = .02). However, there was no significant difference in overall acute complication rates following adjustment for patient characteristics (7.7% vs 7.4%; risk difference, 0.3; 95% CI, −0.6 to 1.3; P = .49). Pericardial effusion and/or perforation within 30 days was significantly higher among patients with leadless VVI pacemakers compared with patients with transvenous VVI pacemakers in both unadjusted and adjusted models (unadjusted, 47 of 5746 [0.8%] vs 38 of 9662 [0.4%]; P < .001; adjusted, 0.8% vs 0.4%; risk difference, 0.4; 95% CI, 0.1 to 0.7; P = .004). Patients implanted with leadless VVI pacemakers had a lower rate of 6-month complications compared with patients implanted with transvenous VVI pacemakers (unadjusted hazard ratio, 0.84; 95% CI, 0.68-1.03; P = .10; adjusted hazard ratio, 0.77; 95% CI, 0.62-0.96; P = .02). CONCLUSIONS AND RELEVANCEIn this study, despite significant differences in patient characteristics, patients in whom a leadless pacemaker was implanted were observed to have higher rates of pericardial effusion and/or perforation but lower rates...

Original ArticleBackground-The Lead Integrity Alert (LIA) was developed for Medtronic implantable cardioverter defibrillators to reduce inappropriate shocks for rapid oversensing caused by conductor fractures and reported for Medtronic Fidelis conductor fractures. The goal of this study was to compare the performance of LIA with conventional impedance monitoring for identifying lead system events (LSEs) and lead failures (LFs) in lead families that differ from Fidelis. Methods and Results-We analyzed data from 12 793 LIA enabled implantable cardioverter-defibrillator and lead combinations including 6123 St. Jude Riata or Durata, 5114 Boston Scientific Endotak, and 1556 Fidelis combinations followed in the CareLink remote monitoring network for LSEs and LFs. Each alert was adjudicated based on implantable cardioverterdefibrillator stored electrograms/diagnostics and clinical data as an LSE or non-lead system event by 2 physicians after reviewing the electrograms and clinical data. During 13 562 patient-years of LIA follow-up, there were 179 adjudicated alerts, of which 84 were LSEs (including 65 LFs) and 95 were non-lead system events. LIA identified >66% more LSE and >67% more LF compared with conventional impedance monitoring and did not differ by lead family for LSE (P=0.573) or LF (P=0.332). Isolated spikes on electrogram were associated more often with LF in St. Jude leads (71%) compared with Endotak (9%; P<0.001) and Fidelis leads (11%; P<0.001). The non-lead system event detection rate was different among lead families (P<0.001) ranging from 1 in every 78.5 years (Endotak), 228.9 years (St. Jude leads), and 627.6 years (Fidelis). Conclusions-LIA markedly increased the detection rate of LSE compared with conventional impedance monitoring. 1561, 1570, 1571, 1572, 1580, 1581, 1582, 1590, 1591, 1592, 1940, 7000, 7001, 7002, 7010, 7020, 7021, 7022, 7040, 7041, 7042, 7052, 7070, 7071, 7120, 7121, 7122, 7130) or a Boston Scientific Endotak ICD lead (0061, 0064, 0072, 0074, 0075, 0095, 0115, 0125, 0127, 0128, 0134, 0135, 0137, 0138, 0144, 0145, 0147, 0148, 0149, 0154, 0155, 0157, 0158, 0159, 0171, 0174, 0175, 0180, 0181, 0182, 0184, 0185, 0186, 0187) with a CareLink remote monitoring transmission between August 28, 2008, and October 4, 2011, were included in the analysis. Patients with Fidelis leads (models 6930, 6931, 6948, 6949) from a separate prospectively defined cohort were included as controls. Device diagnostic data associated with LIA triggers or any pace-sense impedances that triggered conventional impedance alerts (>2000 or <200 ohms) were reviewed. Follow-up time was calculated in years from the date the LIA algorithm was programmed on to the date of the last LIA enabled transmission. Lead Integrity AlertThe present LIA requires 2 of 3 of components to be satisfied within 60 days: abrupt pace-sense impedance change, frequent extremely short R-R intervals, and rapid nonsustained ventricular tachycardia episodes. 7,11 The abrupt impedance change requires an increase >75% or decrease to <50% of th...