Leadless pacemaker: State of the art and incoming developments to broaden indications

Theleadless pacemaker (LLPM) therapy has been developed in recent years to overcome the transvenous lead and device pocket-related complications. The LLPMs now available are self-contained right ventricular pacemakers and are limited to single-chamber ventricular pacing modality. This literature review deals with the current status of LLPM technology and current areas of clinical applicability. The safety and efficacy outcomes published from randomized clinical trials and real world registries are analyzed and compared with historical conventional transvenous pacemaker data. Furthermore, new pacing modalities and future perspectives to broaden the clinical use and cover most of pacing indications are discussed. Due to the overall safe and effective profile in the short term and intermediate term, also in fragile patients, the LLPM use is constantly growing in daily clinical practice. Actually, it can be considered a landmark innovation, through which a new era of cardiac pacing has begun.     

Rendimiento del marcapasos cardiaco Micra en nonagenarios

Introduction and objectivesThe Micra transcatheter pacing system has shown high effectiveness and a lower complication rate than conventional transvenous pacemakers. However, the benefit of the device is unknown in the very old population (≥ 90 years). The aim of this study was to evaluate the safety and effectiveness of Micra in patients ≥ 90 years.MethodsWe present a prospective observational study with consecutive patients aged > 70 years who underwent implantation of a Micra pacemaker system. Patients were divided into 2 groups: ≥ 90 and < 90 years.ResultsThe Micra system was implanted in 129 patients, of whom 41 were aged ≥ 90 years and 88 < 90 years. The device was successfully implanted in 40 (97.6%) patients ≥ 90 years and in 87 (98.9%) patients < 90 years (P = .58). An adequate position was achieved with need for ≤ 2 repositions in 97.5% and 91.9% of patients, respectively (P = .32). Procedure time (26.1 ± 11.6 vs 30.3 ± 14.2 minutes; P = .11) and fluoroscopy time (6.4 ± 4.7 vs 7.2 ± 4.9 minutes; P = 0.41) were similar in the 2 groups. There were 3 major complications (2.3%), all in the group aged < 90 years: 1 cardiac perforation, 1 femoral hematoma, and 1 femoral pseudoaneurysm. Thirteen patients aged ≥ 90 years (31.7%) and 16 patients aged < 90 years (18.2%) died during a mean follow-up of 230 ± 233 days and 394 ± 285 days, respectively. There were no device-related deaths. No infection, dislocation or migration of Micra were observed. The electrical performance was optimal at follow-up.ConclusionsThe Micra leadless pacing system seems to be safe and effective in patients older than 90 years. It may be considered a reasonable alternative to conventional transvenous pacing in this population.Full English text available from: www.revespcardiol.org/en     

Correlation between AV synchrony and device collected AM-VP sequence counter in atrioventricular synchronous leadless pacemakers: A real-world assessment

Introduction

Micra atrioventricular (AV) provides leadless atrioventricular synchronous pacing by sensing atrial contraction (A4 signal). Real-world operation and reliability of AV synchrony (AVS) assessment using device data have not been described. The purposes of this study were to (1) assess the correlation between AVS and atrial mechanical sensed-ventricular pacing (AM-VP) percentages in patients with permanent high-degree AV block and (2) report on the real-world effectiveness of Micra AV.

Methods

The correlation between ECG-determined AVS in-clinic and device-collected %AM-VP was assessed using data from 40 patients with high-degree AV block enrolled in the Micra Atrial tRacking using a Ventricular AccELerometer (MARVEL) 2 study. A retrospective analysis to assess continuously-sampled %AM-VP since last session, device programming, and electrical parameters was performed using Micra AV transmissions from the Medtronic CareLink database. Patients with transmissions ≥180 days postimplant were included.

Results

Among the 40 MARVEL 2 AV block patients with a median %VP of 99.7%, AVS was highly correlated with AM-VP (median AVS 87.1%, median AM-VP 79.1%; R² = 0.764, p < .001). The CareLink cohort included 4384 patients programmed to VDD mode. The mean A4 amplitude was 2.3 ± 1.8 m/s² at implant and 2.3 ± 1.6 m/s² at 28 weeks. In patients with %VP >90% (n = 1662), the median %AM-VP was 74.7%. For the full cohort, median %VP was 65.6% and median projected battery longevity was 10.5 years.

Conclusion

In patients with a high pacing burden, %AM-VP provides a reasonable estimation of AVS. The first large real-world analysis of Micra AV patients with >90% VP showed stable atrial sensing over time with a median %AM-VP, a correlate of AVS, of 74.7%.