Leadless versus transvenous single-chamber ventricular pacemakers: 3 year follow-up of the Micra CED study

Chronic kidney disease and transvenous cardiac implantable electronic device infection-is there an impact on healthcare utilization, costs, disease progression, and mortality?

AIMS

Cardiac implantable electronic device (CIED) infections are a burden to hospitals and costly for healthcare systems. Chronic kidney disease (CKD) increases the risk of CIED infections, but its differential impact on healthcare utilization, costs, and outcomes is not known.

METHODS AND RESULTS

This retrospective analysis used de-identified Medicare Fee-for-Service claims to identify patients implanted with a CIED from July 2016 to December 2020. Outcomes were defined as hospital days and costs within 12 months post-implant, post-infection CKD progression, and mortality. Generalized linear models were used to calculate results by CKD and infection status while controlling for other comorbidities, with differences between cohorts representing the incremental effect associated with CKD. A total of 584 543 patients had a CIED implant, of which 26% had CKD and 1.4% had a device infection. The average total days in hospital for infected patients was 23.5 days with CKD vs. 14.5 days (P < 0.001) without. The average cost of infection was $121 756 with CKD vs. $55 366 without (P < 0.001), leading to an incremental cost associated with CKD of $66 390. Infected patients with CKD were more likely to have septicaemia or severe sepsis than those without CKD (11.0 vs. 4.6%, P < 0.001). After infection, CKD patients were more likely to experience CKD progression (hazard ratio 1.26, P < 0.001) and mortality (hazard ratio 1.89, P < 0.001).

CONCLUSION

Cardiac implantable electronic device infection in patients with CKD was associated with more healthcare utilization, higher cost, greater disease progression, and greater mortality compared to patients without CKD.

Evaluating Cardiac Lead Safety Using Observational, Real-World Data: EP PASSION Proof-of-Concept Study

BACKGROUND

Traditional post-approval study (PAS) designs have been accepted by regulatory authorities to fulfill post-marketing requirements for cardiac leads but they have several limitations.

OBJECTIVES

The authors conducted a proof-of-concept study of alternative methods that utilize real-world data (RWD) to evaluate lead safety in large patient populations.

METHODS

Abbott patient device databases were linked with Medicare Fee-For-Service (FFS) claims to identify lead complications among patients implanted with Abbott Optisure™ lead. A 1:1 comparison between the PAS method and RWD method of detecting mechanical lead-related complication events was conducted in 444 PAS subjects who were enrolled in Medicare FFS. Agreement between methods was evaluated using McNemar's test and Cohen's kappa. Survival free from complications at 3 years was compared between the PAS and RWD cohorts using an equivalence acceptance criterion of ±2.5%.

RESULTS

There were 1,171 PAS patients and 5,804 Medicare FFS patients who received an Optisure™ lead between August 27, 2014 - June 14, 2016. Patients were followed through December 31, 2018. Complete agreement was found between PAS-reported and claims-detected complications (McNemar's p-value=1.00, Cohen's Kappa = 1.0). Survival free from complications at 3 years using the RWD method was 98.4% (95% CL: 98.0%-98.7%), which was within the acceptable range of the PAS 98.4% (95% CL: 97.6%-99.0%).

CONCLUSION

These results show a close agreement between RWD-detected and PAS-reported lead complication rates, which highlight the potential benefits of RWD-based methods to enhance the generation of clinical evidence for lead safety.

The Effectiveness and Safety of Leadless Pacemakers: An Updated Meta-Analysis

BACKGROUND

Leadless pacemakers (LPs) are promising alternatives to traditional transvenous pacemakers (TVPs), but their comparative effectiveness and safety in clinical outcomes remain uncertain.

METHODS

We systematically searched PubMed, Embase, Scopus, Cochrane, and ClinicalTrials.gov for studies comparing LPs and TVPs. A restricted maximum likelihood random-effects model was used for all outcomes. Heterogeneity was assessed using I2 statistics. We performed a subgroup analysis with studies with multivariate-adjusted data.

RESULTS

We included 21 studies involving 47,229 patients, of whom 12,199 (25.8%) underwent LP implantation. Compared with TVPs, LPs were associated with a significantly lower risk of overall complications (OR 0.61; 95% CI 0.45-0.81; p < 0.01), dislodgement (OR 0.34; 95% CI 0.20-0.56; p < 0.01), and pneumothorax (OR 0.27; 95% CI 0.16-0.46; p < 0.01). No significant difference in all-cause mortality was observed in the overall analysis (OR 1.43; 95% CI 0.65-3.15; p = 0.35) and in studies with multivariate-adjusted data (OR 1.34; 95% CI 0.65-2.78; p = 0.43). However, LPs were associated with a higher risk of pericardial effusion (OR 2.47; 95% CI 1.39-4.38; p < 0.01) and cardiac tamponade (OR 3.75; 95% CI 2.41-5.83; p < 0.01). LPs also demonstrated a lower pacing capture threshold (MD -0.19 V; 95% CI [-0.23 V]-[-0.16 V]; p < 0.01), but no significant difference in impedance (MD 32.63 ohms; 95% CI [-22.50 ohms]-[87.76 ohms]; p = 0.25).

CONCLUSIONS

These findings suggest that LPs were associated with lower overall complication rates and similar effectiveness to TVPs. However, randomized controlled trials are warranted to validate these results.

[Treatment with cardiac electronic implantable devices]

Cardiac device therapy provides not only treatment options for bradyarrhythmia but also advanced treatment for heart failure and preventive measures against sudden cardiac death. In heart failure treatment it enables synergistic reverse remodelling and reduces pharmacological side effects. Cardiac resynchronization therapy (CRT) has revolutionized the treatment of reduced left ventricular ejection fraction (LVEF) and left bundle branch block by decreasing the mortality and morbidity with improvement of the quality of life and resilience. Conduction system pacing (CSP) as an alternative method of physiological stimulation can improve heart function and reduce the risk of pacemaker-induced cardiomyopathy. Leadless pacers and subcutaneous/extravascular defibrillators offer less invasive options with lower complication rates. The prevention of infections through preoperative and postoperative strategies enhances the safety of these therapies.

Impact of omitting the intravenous heparin bolus on outcomes of leadless pacemaker implantation

BACKGROUND

Early guidance recommended a bolus of intravenous heparin at the beginning of leadless pacemaker (LP) implantation procedures. However, due to concern about bleeding complications, more recent practice has tended toward omitting the bolus and only running a continuous heparin infusion through the introducer sheath. The impact of omitting the heparin bolus on procedural outcomes is not clear.

METHODS

We reviewed all Medtronic Micra LP implants at our institution from 9/2014 to 9/2022. The decision to bolus with heparin was at operator discretion.

RESULTS

Among 621 LP implants, 326 received an intravenous heparin bolus, 243 did not, and 52 patients were excluded because heparin bolus status could not be confirmed. There was a trend toward more frequent omission of the heparin bolus with more recent implants. Median follow-up after LP implant was 14.3 (interquartile range [IQR]: 8.4-27.9) months. There was no difference between heparin bolus and no bolus groups in the number of device deployments/recaptures (1.42 ± 0.81 vs. 1.31 ± 0.66, p = .15). Implant-related adverse events were also similar between heparin bolus and no bolus groups: access-site hematoma requiring intervention (7 vs. 5, p = .99), pseudoaneurysm (1 vs. 1, p = .99), cardiac perforation (1 vs. 1, p = .99), intraprocedural device thrombus formation (2 vs. 4, p = .41), 30-day rehospitalization (21 vs. 15, p = .98), and 30-day all-cause mortality (16 vs. 14, p = .70). There was one additional nonfatal cardiac perforation in a patient who was excluded due to unknown heparin bolus status. Regarding device electrical parameters between heparin bolus and no bolus groups, there were no significant differences at the time of implant: pacing capture threshold 0.5 ± 0.4 vs. 0.5 ± 0.3, p = .10; pacing impedance 739.9 ± 226.4 vs. 719.1 ± 215.4, p = .52; R wave sensing 11.7 ± 5.7 vs. 12.0 ± 5.4, p = .34). Long-term device performance was also similar between groups.

CONCLUSION

Omission of the systemic heparin bolus at the time of LP implantation appears safe in appropriately selected patients. Heparin bolus may still be considered in long cases requiring multiple device deployments or in patients at high risk for thrombotic complications.

Leadless pacemakers at 5-year follow-up: the Micra transcatheter pacing system post-approval registry

BACKGROUND AND AIMS

Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed.

METHODS

All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models.

RESULTS

1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001).

CONCLUSIONS

Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection.

Leadless pacemakers: Where are we?

Pacemakers have been the cornerstone of brady-arrhythmia management since the mid-20th century. Despite the widespread use and success of traditional transvenous pacemakers, they are associated with an estimated 15 % complication rate at three years. Driven by the advantages over traditional transvenous pacemakers including a lack of transvenous leads, resistance to infection, and ease of implantation, the number of leadless pacemakers placed annually in the United States has dramatically increased since their initial approval. While current iterations of leadless pacemakers lack the versatility offered by transvenous devices, recent advances in leadless pacing offer an increasingly diverse range of therapeutic options. This review will discuss the past, present, and future emerging technologies, and strategies in leadless pacing.

Transvenous Compared With Leadless Pacemakers: A meta-analysis comparing TP versus LP

This study aims to compare the effectiveness of leadless pacemakers (LPs) and transvenous pacemakers and to examine the safety of both methods. We included patients undergoing single-chamber pacemaker implantation, either LP or TVP. Our outcomes were successful implantation rate, major complication, vascular injury, tamponade, and pneumothorax. We performed a double-arm analysis comparing LP versus TVP, with risk ratio (RR) and 95% confidence interval. A total of 10 studies were included in this meta-analysis. Regarding efficacy endpoints, RR revealed no significant difference between the LP and transvenous pacemaker groups in terms of successful rate of implantation (RR = 1.00; P = 0.77). Regarding safety outcomes, LP experienced lower incidence of major complications (RR = 0.47; P = 0.01), infection (RR = 0.24; P = 0.001), and tamponade (RR = 0.36; P = 0.01). There was no significant difference between both groups regarding pneumothorax (RR = 0.35; P = 0.22) and vascular injury (RR = 1.55; P = 0.25). The study findings suggest that both LPs and TVPs have similar effectiveness. Moreover, the incidences of pneumothorax, vascular injuries, and major complications were found to be comparable between the 2 methods. However, LPs were found to have lower rates of infection and tamponade.

Left atrial strain is a good predictor of atrio-ventricular synchrony in leadless pacemaker pacing

INTRODUCTION

The importance of atrio-ventricular synchrony pacing in sinus rhythm patients is known. To identify patients in whom leadless pacemakers are able to guarantee this atrio-ventricular synchrony, we explored correlations among echocardiographic measures of left atrial (LA) size and function (doppler parameter and strain) with A4 amplitude in patients implanted with new generation Micra-AV device.

METHODS

After implantation with Micra-AV system, patients underwent device interrogation to evaluate AV synchrony based on the sensing of atrial mechanics and echocardiographic exam to assess LA morphology and LA function.

RESULTS

In the 21 studied patients (14 males, 72 ± 13 years), the A4 wave amplitude values inversely correlated with LA antero-posterior diameter, LA volume, LA contraction strain and LA conduit strain, while they were positively related with LA reservoir strain.

DISCUSSION

Our results indicate a statistically significant relationship between morphological echocardiographic LA parameters and atrial contraction signal (A4), detected by leadless pacemakers and used to synchronize ventricular pacing with the atrium. Instantaneous LA function assessment obtained with LA strain provides incremental information over morphological parameters. LA strain evaluates atrial myocardial deformation during the whole cardiac cycle. We found higher value of A4 in patients that have grater absolute value of LAsr, LAscd and LAsct, that are simple and measurable parameters of LA functional capacity.

CONCLUSION

Preimplant echocardiographic evaluation of the atrial contractility may be useful in predicting adequate A4 sensing and consequently a good atrio-ventricular synchrony pacing. Echocardiography LA strain study seems promising in Micra-AV patient selection.

Outcomes of leadless pacemaker implantation after cardiac surgery and transcatheter structural valve interventions

INTRODUCTION

Permanent pacing indications are common after cardiac surgery and transcatheter structural valve interventions. Leadless pacemakers (LPs) have emerged as a useful alternative to transvenous pacemakers. However, current commercially available LPs are unable to provide atrial pacing or cardiac resynchronization and relatively little is known about LP outcomes after cardiac surgery and transcatheter valve interventions.

METHODS

This retrospective study included patients who received a Micra VR (MicraTM MC1VR01) or Micra AV (MicraTM MC1AVR1) (Medtronic) leadless pacemaker following cardiac surgery or transcatheter structural valve intervention between September 2014 and September 2022. Device performance and clinical outcomes, including ventricular pacing burden, ejection fraction, and need for conversion to transvenous pacing systems, were evaluated during follow-up.

RESULTS

A total of 78 patients were included, of whom 40 received a Micra VR LP implant, and 38 received a Micra AV LP implant. The mean age of the cohort was 65.9 ± 17.9 years, and 48.1% were females. The follow-up duration for the entire cohort was 1.3 ± 1.1 years: 1.6 ± 1.3 years for the Micra VR group and 0.8 ± 0.5 years for the Micra AV group. Among the cohort, 50 patients had undergone cardiac surgery and 28 underwent transcatheter structural valve interventions. Device electrical performance was excellent during follow-up, with a small but clinically insignificant increase in ventricular pacing threshold and a slight decrease in pacing impedance. The mean right ventricle pacing (RVP) burden significantly decreased over time in the entire cohort (74.3% ± 37.2% postprocedure vs. 47.7% ± 40.6% at last follow-up, p < .001), and left ventricle ejection fraction (LVEF) showed a modest but significant downward trend during follow-up (55.0% ± 10.6% vs. 51.5% ± 11.2% p < .001). Patients with Micra VR implants had significantly reduced LVEF during follow-up (54.1% ± 11.9% vs. 48.8% ± 11.9%, p = .003), whereas LVEF appeared stable in the Micra AV group during follow-up (56.1% ± 9.0% vs. 54.6% ± 9.7%, p = .06). Six patients (7.7%) required conversion to transvenous pacing systems, four who required cardiac resynchronization for drop in LVEF with high RVP burden and two who required dual-chamber pacemakers for symptomatic sinus node dysfunction.

CONCLUSION

Leadless pacemakers provide a useful alternative to transvenous pacemakers in appropriately selected patients after cardiac surgery and transcatheter structural valve interventions. Device performance is excellent over medium-term follow-up. However, a significant minority of patients require conversion to transvenous pacing systems for cardiac resynchronization or atrial pacing support, demonstrating the need for close electrophysiologic follow-up in this cohort.

Atrial mechanical contraction and ambulatory atrioventricular synchrony: Predictors from the OPTIVALL study

INTRODUCTION

The role that preprocedural factors have on atrioventricular synchrony (AVS) provided by leadless pacemakers requires investigation.

METHODS AND RESULTS

We aimed to assess the correlation between mitral inflow echocardiographic parameters and p-wave morphology with the accelerometer A4 signal amplitude. We also sought to identify clinical and echocardiographic predictors of optimal ambulatory AVS (≥85% of cardiac cycles). Forty-three patients undergoing Micra AV implant from June 2020 to March 2023 were prospectively enrolled. Baseline echocardiogram and 12-lead resting ECG were performed. Device follow-up was scheduled at 24 h, 1, 3, and 6 months and yearly after the implant. Ambulatory AVS was studied with a 24 h Holter monitor performed at 3 months follow-up in 35 patients who remained in VDD mode. A4 signal amplitude at 1 month correlated to peak A wave velocity (r = .376; p = .024) at echocardiogram, but no relationship was found with peak A' wave velocity, E/A, or E'/A' ratio. P-wave amplitude in lead I and aVF correlated to A4 signal amplitude at 1- and 3-months follow-up, respectively. Median AVS during 24 h of daily activities was 85.6 ± 7.6% and remained stable up to 100 bpm. Twenty-three out of 35 patients (65.7%) reached optimal ambulatory AVS. There was no association between mitral inflow echocardiographic parameters and optimal AVS. Diabetes (OR: 0.05, 95% CI: 0.01-0.47; p = .009) and chronic obstructive pulmonary disease (COPD) (OR: 0.06, 95% CI: 0.01-0.63; p = .019) strongly predicted ambulatory AVS <85%.

CONCLUSIONS

Diabetes and COPD should be considered when selecting candidates for Micra AV. Measurements of pulsed wave Doppler mitral inflow do not systematically reflect the behavior of the A4 signal amplitude.