Abstract
Background.
Solid organ transplant recipients (SOTRs) are at heightened risk for cardiovascular implantable electronic device-related complications, particularly infection, because of chronic immunosuppression and comorbidities. Although leadless pacemakers (LPs) reduce infection risk by eliminating transvenous leads and generator pockets, adoption in SOTRs has remained limited, largely because earlier systems were restricted to single-chamber ventricular pacing and lacked physiologic atrioventricular synchrony. The helix-fixation Aveir LP platform enables atrial, ventricular, and dual-chamber leadless pacing, but clinical experience in transplant recipients remains limited.
Methods.
We conducted a retrospective, multisite analysis across an integrated health system, identifying all adult SOTRs who underwent Aveir LP implantation between January 2022 and October 2025. Clinical characteristics, transplant details, pacing indications, device configuration, procedural outcomes, and follow-up data were collected. Primary outcomes included procedural success, complications, and device-related infection. Secondary outcomes included pacing performance, need for system revision or upgrade, and early device durability.
Results.
Thirteen SOTRs (mean age 64 ± 15 y; 15% female) underwent Aveir LP implantation, including atrial (n = 4), ventricular (n = 5), and dual-chamber (n = 4) systems. Transplanted organs included heart (46%), lung (31%), kidney (38%), and liver (15%), with 31% having multiple organ transplants. Over half of patients were critically ill at implantation, and 46% were dialysis-dependent, representing a high-risk cohort. All procedures were acutely successful with no intraprocedural complications. During a median follow-up of 258 d (interquartile range, 216–641 d), no device-related infections occurred. Electrical performance remained stable, with 1 atrial device replacement at 2.5 y for elevated capture thresholds.
Conclusions.
In a high-risk population of SOTRs, atrial and atrioventricular synchronous leadless pacing using the Aveir platform was feasible, achieved high acute procedural success, and demonstrated favorable early safety signals, including absence of device-related infection over available follow-up. Larger studies with longer-term follow-up are needed to define durability and long-term outcomes.
INTRODUCTION
Solid organ transplant recipients (SOTRs) require lifelong immunosuppression and remain at increased risk for systemic infections and complications from cardiovascular implantable electronic devices (CIEDs).1,2 Transvenous pacing systems carry a 1%–5% risk of device-related infection at 1 y, driven by intravascular leads and generator pockets that serve as substrates for bacterial adherence and biofilm formation—risks amplified in immunocompromised patients.3,4 Leadless pacemakers (LPs) obviate these structural vulnerabilities. The first-generation tined-fixation based Micra LP demonstrated favorable outcomes in multiple high-risk cohorts, including critically ill patients, but its restriction to single-chamber ventricular (VR) pacing and lack of atrioventricular (AV) synchrony limited broader physiologic application. Despite nearly a decade of commercial availability, adoption of leadless pacing in SOTRs has remained low. For example, among 568 SOTRs who underwent pacemaker implantation at the Mayo Clinic since 2016, only 39 received a tined-fixation LP (Micra)—despite institutional availability—largely reflecting historical limitations of leadless systems to single-chamber pacing and the inability to provide physiologic AV synchrony.
The helix-fixation Aveir LP system represents an important technological advancement, enabling atrial (AR), VR, and dual-chamber (DR) pacing.5 This capability enables physiologic pacing, including AV synchrony, in SOTRs with sinus node dysfunction or conduction disease. In the present study, we report the first multisite experience demonstrating the feasibility of AR leadless pacing for sinus node dysfunction and AV synchronous (DR) leadless pacing for AV block in SOTRs.
MATERIALS AND METHODS
We performed a retrospective analysis across all Mayo Clinic sites (Arizona, Florida, Minnesota), identifying adult SOTRs who underwent Aveir LP implantation from January 2022 to October 2025. Clinical, transplant, and procedural variables were abstracted, alongside pacing indications, device configuration, and follow-up performance metrics. Outcome measures included procedural success, acute and delayed complications, device-related infection, system upgrade or revision, and pacing stability over time. The study was approved by the Mayo Clinic Institutional Review Board. Considering the retrospective nature of the study, the Institutional Review Board waived the need for consent.
RESULTS
Among 58 SOTRs undergoing LP implantation, 13 received an Aveir LP (mean age 64 ± 15 y; 15% female); 4 received DR, 4 AR, and 5 VR devices (Table 1). Transplanted organs included kidney (n = 5, 38%), liver (n = 2, 15%), heart (n = 6, 46%), and lung (n = 4, 31%). Median time from first transplant to device implant was 10 mo (interquartile range, 1–123 mo), and 5 patients received device implants within 6 mo of transplant (a period of profound immunosuppression).2 Indications included sinus node dysfunction (n = 7, 53%), AV block (n = 2, 15%), tachy-brady syndrome (n = 1, 8%), and AR fibrillation with rapid VR response before AV node ablation (n = 3, 23%; Table 2).
TABLE 1.
Baseline characteristics of transplant recipients undergoing Aveir leadless pacemaker implantation
| Characteristic | N = 13 |
|---|---|
| Age at implant, y, mean ± SD | 64 ± 15 |
| Female, n (%) | 2 (15) |
| Transplant type, n (%) | |
| Heart | 6 (46) |
| Lung | 4 (31) |
| Liver | 2 (15) |
| Kidney | 5 (46) |
| Multiple organ transplant | 4 (31) |
| Months since first transplant, median (IQR) | 10 (1–123) |
| Indication for pacing, n (%) | |
| Sinus node dysfunction | 7 (54) |
| Atrioventricular block | 2 (15) |
| Tachy-brady syndrome | 1 (8) |
| Atrial fibrillation with RVR | 3 (23) |
| Implant type, n (%) | |
| DR | 4 (31) |
| AR | 4 (31) |
| VR | 5 (46) |
| ESRD on dialysis, n (%) | 6 (46) |
| Critically ill at time of implant, n (%) | 7 (54) |
| Diabetes, n (%) | 7 (54) |
AR, atrial device; DR, dual-chamber system; ESRD, end-stage renal disease; IQR, interquartile range; RVR, rapid ventricular rate (pacemaker implanted before atrioventricular node ablation); VR, ventricular device.
TABLE 2.
Indications and outcomes with Aveir implant in transplant recipients
| Patient number | Transplant type | Indication for pacing | Device type | Immunosuppressive medications | Pacemaker and transplant during same hospitalization | Postprocedure events |
|---|---|---|---|---|---|---|
| 1 | Kidney | AF/RVR | VR | Mycophenolate, tacrolimus, prednisone | No | No |
| 2 | Heart Kidney |
SND | AR | Mycophenolate, tacrolimus, prednisone | Yes | No |
| 3 | Heart Kidney |
SND | AR | Mycophenolate, tacrolimus, prednisone | Yes | Device removal and reimplant at 2.5 y |
| 4 | Lung Heart |
SND | DR | Mycophenolate, cyclosporin | No | No |
| 5 | Lung | AF/RVR | VR | Azathioprine, methotrexate, prednisone | No | No |
| 6 | Kidney | AVB | DR | Mycophenolate, tacrolimus, prednisone | No | No |
| 7 | Heart | SND | DR | Mycophenolate, tacrolimus, prednisone | No | MSSA bacteremia |
| 8 | Liver | Tachy-brady | VR | Mycophenolate, tacrolimus, prednisone | No | No |
| 9 | Lung | SND | VR | Mycophenolate, tacrolimus, prednisone | Yes | No |
| 10 | Lung | AF/RVR | VR | Mycophenolate, tacrolimus, prednisone | Yes | Biventricular pacemaker upgrade |
| 11 | Heart | SND | AR | Mycophenolate, tacrolimus, prednisone | No | No |
| 12 | Heart | SND | AR | Mycophenolate, tacrolimus, prednisone | No | No |
| 13 | Kidney Liver |
AVB | DR | Mycophenolate, tacrolimus, prednisone | Yes | No |
Immunosuppressive medications at time of pacemaker implant are listed.
AF/RVR, atrial fibrillation with rapid ventricular rate (before atrioventricular node ablation); AR, atrial device; AVB, atrioventricular block; DR, dual-chamber device; MSSA, methicillin-sensitive Staphylococcus aureus; SND, sinus node dysfunction; VR, ventricular device.
Seven patients (53%) were critically ill at implantation—3 with cardiogenic shock due to right ventricular dysfunction and bradycardia (postorthotopic heart transplant), 1 with cardiogenic shock in the setting of bradycardia, 1 with cardiogenic shock in the setting of atrial fibrillation and rapid ventricular rates, and 2 with shock from multiple causes. More than half had diabetes (54%), and 6 (46%) were dialysis-dependent, reflecting profound infectious vulnerability and elevated CIED-related risk. This cohort therefore represents a high-risk “stress test” for leadless pacing, rather than a low-risk or elective population.
Procedural was successful in all patients with no intraprocedural complications. At a median follow-up of 258 d (interquartile range, 216–641 d), no device-related bloodstream infections were observed (Figure 1). Electrical performance remained stable, with favorable sensing and thresholds and projected battery longevity of approximately 5 y (AR) and 10 y (VR) at 6-mo evaluation. In orthotopic heart transplantation (OHT) recipients (n = 6), serial endomyocardial biopsies were performed without interference from the device.
FIGURE 1.
Outcomes in solid organ transplant recipients undergoing Aveir pacemaker implantation. AR, atrial device; DR, dual-chamber system; IQR, interquartile range; MSSA, methicillin-sensitive Staphylococcus aureus; VR, ventricular device.
One lung transplant recipient underwent biventricular pacemaker upgrade for mitral regurgitation and borderline VR systolic dysfunction; the LP was deactivated and left in situ without sequelae. One patient with history of OHT who was hemodialysis-dependent developed Staphylococcus aureus bacteremia from a skin/soft tissue source, with multimodality imaging demonstrating no LP involvement; antimicrobial therapy alone was effective. Another patient with OHT required AR LP extraction at 2.5 y (recommended replacement time) because of high capture thresholds; the device demonstrated minimal encapsulation, and replacement with a new AR system resulted in excellent subsequent thresholds.
DISCUSSION
This multisite evaluation demonstrates that helix-fixation Aveir LPs can be implanted safely in SOTRs—a population uniquely predisposed to infection and procedural risk. Importantly, more than half of patients in this series had additional infection-predisposing conditions beyond posttransplant immunosuppression, including dialysis dependence, diabetes, prolonged hospitalization, and critical illness at implantation. Despite this, we observed no device-related infections over available follow-up, representing an early but clinically meaningful safety signal in a population where device infection carries disproportionate morbidity. These findings align with emerging data across LP platforms suggesting a lower infection risk than transvenous systems (1%–5% at 1 y).4 Our results also parallel prior observations of reduced device revision rates with LPs compared with transvenous systems (1.5% for Micra versus 5.5% at 1 y).5,6 Selection of the Aveir system over the tined-fixation Micra LP was primarily indication-driven: patients requiring AR or DR physiologic pacing—those with sinus node dysfunction or AV block—were directed toward the Aveir platform, while patients with permanent AR fibrillation or those undergoing AV node ablation, in whom VR rate-responsive pacing was sufficient, were candidates for the Micra system. However, as reflected by the 5 VR Aveir implants in our series, operator preference also contributed to device selection in a subset of patients. This likely reflects an institutional learning curve, whereby operators gained familiarity with the helix-fixation delivery system through initial VR implants before proceeding to the more technically demanding AR and DR configurations. This indication- and preference-based allocation, rather than differential risk stratification, accounts for the difference in device selection within our cohort and represents an inherent limitation of this retrospective series.
Mechanistic explanations for reduced infection susceptibility are increasingly well defined. LPs eliminate the transvenous lead—a major nidus for biofilm formation—and the generator pocket, which is prone to erosion and contamination.3 Experimental and human autopsy studies demonstrate rapid endothelialization and partial encapsulation, reducing the degree of device-blood interaction and the likelihood of hematogenous seeding.7 These features plausibly explain the exceedingly low incidence of LP-associated endocarditis, even during high-grade bacteremia.8
Our findings further inform the evolving perspective on device management during S. aureus bacteremia. Updated societal guidelines recognize that, unlike transvenous CIEDs, LP extraction is not routinely required when clinical and imaging evaluation shows no device involvement.9 This study adds transplant-specific evidence supporting this approach. Importantly, over half of patients received AR or DR devices, and the absence of infection mitigates theoretical concerns regarding AR LP susceptibility related to lower flow states or delayed encapsulation.3
The Aveir platform uniquely enables AR and DR pacing, which is hemodynamically important in many transplant recipients. Stable AR and DR performance observed here parallels results from the Aveir DR Investigational Device Exemption study demonstrating reliable interdevice communication and durable sensing and pacing.5 The ability to deliver physiologic pacing in a fully leadless format represents a meaningful advance for SOTRs, who often experience conduction disturbances or sinus node dysfunction. Notably, the primary barrier to broader Micra adoption in this population is the fundamental limitation to single-chamber VR pacing—precluding AR pacing for sinus node dysfunction and AV synchronous pacing for conduction disease, which represent the predominant pacing indications in SOTRs. The 39 SOTRs who received the Micra LP at our institution since 2016 represent an important comparative cohort; however, transplant-specific Micra outcomes have not been previously reported in the literature. A formal comparative analysis between the Aveir and Micra platforms in SOTRs—including infection rates, procedural outcomes, and device longevity—is planned as a subsequent dedicated analysis and is beyond the scope of this initial report. Notably, our experience with the Aveir DR in 6 OHT recipients expands upon prior published case reports of DR leadless pacing in this population.10,11
Device retrievability is also clinically relevant. The successful explantation of AR device at 2.5 y—with minimal encapsulation—and subsequent successful reimplantation support the feasibility of long-term system management and align with prior reports from VR leadless systems. In contrast, transvenous lead extraction carries up to a 2.3% risk of major complications, particularly in patients with prior venous interventions, common among transplant recipients.12
This study is limited by its retrospective single-arm design, small sample size, absence of a comparator group and variability in follow-up duration. However, the consistency of procedural and clinical results across multiple Mayo Clinic sites enhances generalizability. Longer-term surveillance will be essential to characterize chronic device performance, extraction feasibility, and late infection risk.
CONCLUSIONS
In this small multisite retrospective series, Aveir helix-fixation LP implantation in SOTRs was feasible and appeared safe over a median follow-up of approximately 9 mo. These findings support the feasibility of physiologic leadless pacing in transplant recipients and provide a rationale for broader evaluation in larger cohorts with longer-term follow-up to define durability, infection risk, and comparative effectiveness.
Footnotes
The authors declare no funding or conflicts of interest.
A.Y. and M.S. conceived and designed the study, performed data extraction and statistical analyses, prepared all figures, and drafted the article. J.L.R., B.A.A., A.R., P.C.P., and H.E.-M. contributed to study conception and design, provided critical revisions for important intellectual content, and approved the final article. All authors have read and approved the final version of the article and agree to be accountable for all aspects of the work.
Contributor Information
Julie L. Rosenthal, Email: rosenthal.julie@mayo.edu.
Bashar A. Aqel, Email: aqel.bashar@mayo.edu.
Andrew Rosenbaum, Email: rosenbaum.andrew@mayo.edu.
Parag C. Patel, Email: patel.parag@mayo.edu.
Hicham El-Masry, Email: elmasry.hicham@mayo.edu.
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