Leadless Pacemaker Therapy in Symptomatic Complete Heart Block: A Case Report

INTRODUCTION

Cardiac implantable electronic devices (CIEDs), including permanent pacemakers, have revolutionized the management of bradyarrhythmias, high-grade atrioventricular (AV) block, and conduction abnormalities, significantly improving survival and quality of life.^[1] Conventional transvenous systems consist of a pulse generator implanted in a subcutaneous or submuscular pocket, with leads traversing the venous system into the cardiac chambers. Despite their efficacy, these systems are associated with important short- and long-term complications, among which infection is one of the most feared.^[2]

CIED infections may involve the device pocket, leads, or endocardial structures, and though the overall incidence is relatively low (1–2% in most registries), the clinical burden is considerable. The risk is magnified in elderly patients, those with diabetes, renal impairment, immunosuppression, or repeated device revisions.^[3,4] Importantly, device-related infections are associated with increased mortality, prolonged hospitalizations, and a high likelihood of requiring complete device removal, a procedure that itself carries procedural risk.^[5,6] Recurrence after extraction and reimplantation, as observed in some high-risk patients, remains a critical management challenge.

To overcome these limitations, leadless pacemakers were developed. Unlike traditional devices, leadless systems are entirely self-contained, small devices implanted directly into the right ventricle (RV) through a femoral venous catheter-based approach.^[7] By removing subcutaneous pockets and transvenous leads, which are the most common sources of infection, leadless pacemakers markedly reduce infection risk.^[8] In addition, their minimally invasive implantation avoids surgical dissection, making them particularly suitable for weak or comorbid patients.

Emerging evidence strongly supports their safety and efficacy. Real-world data confirm these findings, showing that even patients with significant comorbidities or prior device infections can be successfully managed with leadless pacemakers.^[9] Recent registry analyses and Medicare claims studies suggest that compared with dual-chamber transvenous pacemakers, leadless devices are associated with lower 2-year complication and reintervention rates, despite being used in higher-risk populations.^[10]

International guidelines and health policy bodies have begun to recognize this advantage. The American Heart Association’s 2023 consensus update highlights leadless pacemakers as an infection prevention strategy, particularly in patients with recurrent infections or those at elevated risk. In early 2025, the UK’s National Institute for Health and Care Excellence provisionally recommended the use of leadless pacemakers within the National Health Service (NHS) for selected patients with bradyarrhythmias, citing their superior safety profile and quality of life benefit.

Here, we describe the effective management of a 73-year-old with intermittent complete heart block and recurrent pacemaker pocket infections after several interventions using a leadless device. This case illustrates the clinical decision-making process and reinforces the role of leadless pacing systems in infection-prone patients.

CASE REPORT

A 73-year-old female who is a known case of systemic hypertension presented to cardiology department with symptomatic high grade - AV Block [Figure 1] in October 2024, 2D Echo revealed no regional wall motion abnormality with normal left ventricular systolic function (left ventricular ejection fraction-60%) and for which patient was immediately put on temporary pacemaker implantation (TPI) supports (October 07, 2024) and coronary angiogram was done which showed normal epicardial coronaries [Figure 2] (October 06, 2024) followed by permanent pacemaker insertion (dual-chamber permanent pacemaker) was done successfully.

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Figure 1:

Electrocardiogram at presentation showing intermittent complete heart block with ventricular pauses, necessitating permanent pacing.

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Figure 2:

Coronary angiogram demonstrating normal epicardial coronary arteries. (a) Right coronary artery angiographic view showing a dominant vessel with normal proximal, mid, and distal segments without luminal irregularities. (b) Left coronary angiogram demonstrating normal left anterior descending artery with well-opacified diagonal branches and no evidence of obstructive coronary disease. (c) Left circumflex artery angiographic view showing a nondiseased vessel with normal obtuse marginal branches.

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Two months later (in December 2024) patient presented to the outpatient department with a history of erythema, tenderness, and serous discharge at the pacemaker (pulse generator) pocket site infection [Figure 3]. Laboratory evaluation showed: Hemoglobin 11.9 g/dL, total leukocyte count (TLC) 18,640/µL, erythrocyte sedimentation rate (ESR) 62 mm/h, and C-reactive protein (CRP) 94 mg/L, consistent with active infection. Due to the elevated inflammatory marker, such as CRP, would samples were sent for culture studies. Wound culture showed positive for bacterial infection (Staphylococcus aureus). Further, she underwent wound debridement and relocation of the pulse generator to the left retromammary region on 3rd December 2024.

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Figure 3:

Pocket Site infection of the patient. Clinical photograph demonstrating erosion of the pacemaker lead through the skin at the pocket site, consistent with advanced device infection. Black arrow indicates the site of infection.

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In August 2025, despite appropriate treatment, there was again a recurrence of pacemaker site (left retro mammary site) infection for which again wound debridement was done, and the pulse generator was removed. In view of recurrent pacemaker pocket site infection, patient’s attenders were given an option of abandoning of left-sided implantation and newer pacemaker (dual chamber) transvenous can be implanted in the right infra clavicular region or leadless pacemaker and as the patient had repeated infection over the left side mammary area, patient attenders opted for a leadless pacemaker rather than a right sided transvenous pacemaker.

After getting consent, a temporary pacemaker was put on the transjugular area, and leads were implanted into the RV through internal jugular vein and the patient was observed for a short duration of 7–10 days meanwhile allowing the retromammary wound infection to heal, followed by which the patient was planned for micra atrioventricular (AV2) leadless pacemaker implantation.

Under local anesthesia and ultrasound-guided right femoral venous access, an 8 Fr sheath was introduced and serially dilated with 12 Fr and 18 Fr dilators. A 27 Fr delivery sheath was advanced to the right atrium. The Micra™ AV2 MC2AVR1 device (Medtronic) was navigated into the RV and positioned and deployed at the mid-septum as shown in Figure 4.

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Figure 4:

Fluoroscopic images demonstrating leadless pacemaker implantation. (a) Delivery catheter with the leadless pacemaker advanced into the right ventricular cavity. (b) Deployment of the leadless pacemaker within the right ventricle under fluoroscopic guidance. (c) Final position of the leadless pacemaker after successful release from the delivery system.

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The four distinct accelerometer signals, such as A1, occur at the beginning of ventricular systole and signify the closing of the mitral and tricuspid valves; A2 occurs during the completion of ventricular systole and signifies the closing of the aortic and pulmonary valves; A3 occurs during ventricular diastole and signifies the passive filling of blood from the atrium to the ventricle; and the A4 signal occurs when the atrium contracts and pushes blood into the ventricle. The first-generation Micra AV has a fixed post-ventricular atrial blanking (PVAB), which limits the highest achievable upper tracking rate. Even though in a Micra AV patient, the A2 signal is properly blanked at 110 bpm by 450 ms PVAB. Yet, the A2 signal timing occurs later, when the heart rate slows to 70 bpm, implicating that the same PVAB setting does not properly blank the A2 signal, and thus the A2 signal is oversensed in the A3 window. To prevent this inappropriate oversensing, auto PVAB was included in Micra AV2 to automatically switch to a shorter PVAB at higher rates^[8] [Figure 5].

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Figure 5:

Leadless Micra AV2 pacemaker and atrioventricular synchrony mechanisms (Figure adapted from Medtronic site^[12]). (a) The Medtronic Micra AV2 leadless pacemaker, designed for atrioventricular (AV) synchronous pacing. (b) Signal acquisition from the device: accelerometer-derived mechanical atrial contraction (A4) marker aligned with ventricular events. Key timing markers (A1-A4) correspond to cardiac cycle phases, validated against Doppler flow. (c) Atrial mechanical marker detection algorithm: illustrates A3 and A4 thresholds, post-ventricular atrial blanking period, and A3 detection window, ensuring accurate identification of atrial contraction while minimizing noise. (d) Integrated electrogram and accelerometer signals: highlights QRS, T, and P waves with corresponding atrial mechanical markers (A1-A4). Signal thresholds and filtering strategies to optimize atrial sensing and maintain AV synchrony.

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Position of the deployed MC2AVRI device was confirmed fluoroscopically and angiographically. Device parameters were checked and good: sensing R-wave amplitude 11 mV, pacing threshold 0.38 V at 0.24 ms, impedance 820 ohms, output 2.5 V at 0.24 ms. After confirmation, the tether was cut, and then the device was released. The semi-permanent lead previously placed through the right internal jugular vein was then removed.

The procedure was uneventful without periprocedural complications. Post-procedure, the patient was shifted to the coronary care unit and monitored there, hemodynamically stable.

The patient recovered well with complete wound healing. At 3-month follow-up, she remained asymptomatic with stable pacing parameters. Inflammatory markers normalized (TLC 8,420/µL, ESR 4 mm/h, CRP 12 mg/L), and there were no signs of reinfection.

DISCUSSION

CIED infections are a serious complication, with an incidence estimated at 1.5–2.4% in pacemaker recipients.^[2,3] Risk factors include advanced age, multiple device revisions, comorbidities such as diabetes or renal disease, and immunosuppression. The patient had advanced age, hypertension, dyslipidemia, and underwent multiple reinterventions, which increased her risk profile.

Although bacterial infection is the commonest cause, a localized foreign body inflammatory reaction to the generator or leads can occasionally contribute to recurrent pocket site inflammation even in the absence of active infection. Histopathological studies have shown chronic inflammatory changes around generator capsules in such cases, suggesting a component of immune-mediated or hypersensitivity reaction to device material.^[11] However, the patient showed a bacterial infection which was confirmed by the wound culture studies (S. aureus).

Pocket site infections typically present with local erythema, swelling, discharge, and systemic features in advanced cases.^[3] The management involves the complete removal of the infected device system along with prolonged antibiotic therapy, as partial extraction is associated with high recurrence.^[5,6] In our patient, despite wound debridement and relocation, infections recurred, necessitating alternative strategies.

Leadless pacemakers signify a transformative advancement. By removing the need for subcutaneous pockets and transvenous leads, the major sources of infection are avoided.^[6] Clinical trials such as the Micra Transcatheter Pacing Study and the Micra Post-Approval Registry demonstrated low infection rates (<0.5%) and durable performance.^[7] Importantly, in patients with prior device infections, leadless pacemakers offer an effective reimplantation strategy with minimal risk of reinfection.

In our case, the implantation was technically successful through femoral venous access, with optimal pacing parameters and no complications. The patient remained stable and symptom-free at discharge. This outcome aligns with prior evidence showing favorable safety and efficacy of leadless devices in elderly patients and those with comorbidities.^[8,9] Thus, in selected patients with recurrent CIED infections, leadless pacemakers should be considered as a viable and safer alternative to traditional pacing systems.

CONCLUSION

This case highlights the successful use of a leadless pacemaker in an elderly patient with recurrent pacemaker pocket infections and comorbid conditions. Leadless pacemakers offer an effective solution for patients with high infection risk, providing reliable pacing while avoiding the morbidity of repeated device relocations.