Safety and efficacy of radiofrequency ablation of benign thyroid nodules in patients with a history of implantable cardioverter defibrillators (ICDs), permanent pacemakers (PPMs), and implantable cardiac monitors (ICMs)

Introduction

Benign thyroid nodules are widespread, and while most are asymptomatic, the decision to treat them depends on compressive symptoms such as dysphagia, hoarseness, local pain, and swelling. Management has traditionally relied on medication with antithyroid agents for metabolically active nodules and surgical therapy for definitive treatment. However, the popularity of a minimally invasive approach using radiofrequency ablation (RFA) has increased over the last decade. RFA has demonstrated safety and efficacy in the treatment of benign thyroid nodules of varying characteristics in a spectrum of patient cohorts (1-5). However, as the procedure has yet to be widely adopted in the United States, specific patient populations, such as those with cardiac implantable electronic devices (CIEDs), including implantable cardioverter defibrillators (ICDs), implantable cardiac monitors (ICMs), and permanent pacemakers (PPMs), still lack substantial data. In fact, significant efficacy and safety analysis of RFA in the United States has excluded patients with cardiac implants on the grounds of risk reduction (5-8). As the use of CIEDs and RFA for thyroid nodules both increases, this circumstance will undoubtedly arise frequently, and ensuring safety in this population is paramount. In North America, monopolar RFA remains the standard technique for thyroid ablation because bipolar RFA systems are not yet FDA-approved for thyroid indications, and microwave ablation was not available at our institution during the study period. The current Heart Rhythm Society (HRS)/American Society of Anesthesiologists (ASA) guidelines for RFA of thyroid nodules in patients with a history of ICD/PPM have been in part extrapolated from similar studies examining RFA for other indications in the same setting of ICD/PPM (9). There has been a significant investigation into the safety of cardiac RFA in the setting of CIEDs, with evidence of a bidirectional effect of the procedure on the implant and vice versa. For example, inappropriate anti-tachycardia pacing, unnecessary defibrillations, lead dislodgement, and ablation impedance parameters have been observed in the setting of cardiac RFA (10-12). Although cardiac ablation undoubtedly carries a higher risk as the cardiac tissue itself is being ablated, it is reasonable to retain concern that RFA with any adjacency to a CIED should be done cautiously. A study examining 20 RFA and microwave ablation cases of various lung, kidney, bone, and liver nodules found only two CIED disturbances in 22 cases (13). However, specific work examining thyroid nodule RFA in the setting of CIED is sparse. By analyzing the results and adverse effects of RFA on benign thyroid nodules in seven patients with various cardiac implants, including ICDs, PPMs, and ICMs, we aim to further corroborate the safety of this procedure in a select patient population. We present this article in accordance with the STROBE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2025-440/rc).

Methods

Study design and patient selection

This retrospective analysis focused on patients with benign thyroid nodules who underwent RFA between 2019 and 2023, specifically in those with CIEDs, including ICDs, PPMs, and ICMs. Data from patients seen at Tulane University School of Medicine were used for this study. The inclusion criteria were adult patients with benign thyroid nodules, those with a diagnosis of an implantable cardiac device, and availability of follow-up data for at least 6 to 12 months after the procedure. Patients who were lost to follow-up or had incomplete data were excluded from the study.

RFA procedure

RFA was performed under ultrasound guidance using a radiofrequency generator and an internally cooled electrode. Local anesthesia was administered, and the moving-shot technique was employed to ablate the entire nodule, with power output adjusted based on echogenic changes. Dispersive grounding pads were placed on the anterior thighs in all cases. Grounding pad location does not influence risk to the recurrent laryngeal nerve (RLN) as its function is unrelated to the current return path. RLN protection was achieved through hydrodissection, use of the moving-shot technique, and real-time intra-procedural monitoring for voice change.

RFA safety

All CIEDs were interrogated both before and after the procedure. During RFA, a magnet was placed over ICDs to inhibit inappropriate device activation, with continuous electrocardiogram (ECG) monitoring performed to detect arrhythmias or mode switching. All patients were managed under the care of a cardiologist, with prior approval obtained and documented in the patient’s medical record. Coordination with the cardiac device manufacturer was considered to ensure on-site support for device interrogation during the RFA procedure, if necessary.

Study variables and statistical analysis

The volume reduction rate (VRR) was calculated as: VRR (%) = [(initial volume − final volume) / initial volume] × 100. The follow-up time from the RFA was recorded for each patient. Continuous data are presented as medians [interquartile ranges (IQRs)] and compared using the Mann-Whitney U test. Categorical data are expressed as n (%) and compared with the χ² or Fisher’s exact test, as appropriate. Statistical analyses were performed in SPSS version 28.

Ethical statement

This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Review Board of Tulane University School of Medicine (No. 2025-277-EJGH). Given the retrospective design and use of de-identified data, informed consent was waived by the Institutional Review Board.

Results

General characteristics

Table 1 shows the demographic characteristics of the study population. The total study population consisted of 7 participants. The mean age was 72.1±12.5 years. Regarding sex distribution, 5 (71.4%) participants were female and 2 (28.6%) were male. The racial composition was predominantly Black (71.4%), with 5 participants, while 2 (28.6%) were White. Regarding the type of CIED, four patients had an ICD (57.1%), two had a PPM (28.6%), and one had an ICM (14.3%). All 7 participants had benign nodules. The mean initial nodule volume was 1.1±1.2 cm³. The average total energy delivered was approximately 1.0 kJ, with an active ablation time of 5–15 minutes per session. The mean VRR at 3 months was 73.8%±24.9%. At 6 months, the average VRR was 72.8%±27%. Throughout the study, no instances of electromagnetic interference (EMI) were noted among the seven patients. Specifically, there were no occurrences of inappropriate sensing, shocks, or undersensing. Furthermore, no evidence of thermal injury to device leads was identified, as indicated by stable pacing thresholds, lead impedance, and sensing parameters. Continuous electrocardiographic monitoring revealed no arrhythmic disturbances, including bradycardia, asystole, or device mode switching during or following the ablation procedure. No device resets or permanent malfunctions were detected upon post-procedural interrogation. Additionally, no complications related to RFA were reported during the follow-up period.

Discussion

RFA in patients with cardiac implants

The use of RFA has demonstrated increasing safety and efficacy for benign thyroid nodules. This study focuses on the use of RFA specifically in patients with cardiac implants and found the procedure to be efficacious and safe in this population. Studies on the effects of RFA use in cardiac procedures have reported interactions between the cardiac devices and the ablation, including electronic interference and lead dislodgement (10). However, overall, with best practices, RFA is deemed safe even in cardiac settings in patients with cardiac implants (10-12). RFA creates EMI, which can be picked up by cardiac devices and interpreted as cardiac activity, potentially posing an issue in devices that rely on the sensation of intrinsic cardiac electric activity. This could present as oversensing, where a pacing device falsely detects the EMI from RFA as cardiac activity and pauses its pacing activity, resulting in bradycardia. Theoretically, a ventricular pacing device could also interpret EMI as atrial signaling and match its rate to the RFA cycling, leading to profound tachycardia. Additionally, there have been reports of pacing pauses during cardiac RFA due to device resetting (14). Chin et al. demonstrated in a canine model that radiofrequency energy delivered within 1cm of a pacing lead caused a spectrum of disturbances, such as false inhibition or noise-mode behavior, but that ablation performed further from the leads (>4 cm) had no significant effects (15). These findings suggest that the proximity of the RF field to the pacing system is a primary determinant of interference risk.

However, minimal literature exists on extracardiac RFA in patients with cardiac implants. In a combined cohort study examining patients undergoing either RFA or microwave ablation, Skonieczki et al. reported that device-related disturbances occurred exclusively during RFA sessions, not microwave ablation (13). The study included 15 RFA sessions for the lungs, kidneys, bones, and liver, with two RFA sessions having documented pacing inhibition and mode resetting, both of which required resetting the device. No permanent malfunctions occurred, and all devices remained fully functional after reprogramming (13). The pacemakers themselves were not damaged and were reset to their pre-operative settings following the session. The study notes that the patients remained in sinus rhythm for the duration of the session. A relevant case report by Donohoo et al. describes extracardiac RFA of a lung neoplasm causing electric reset of a pacemaker, resulting in altered pacing mode, activation of the elective replacement indicator requiring reprogramming to restore device function (16). This case highlights that although extracardiac RFA rarely affects pacemaker function, device resets can occur when the ablation field is in close proximity to implanted leads. Accordingly, our report of 7 patients undergoing thyroid RFA without adverse effects on cardiac implants is an essential addition to the growing body of evidence supporting its safety, but will rely on additional larger studies to generalize this conclusion.

Limitations

This study has several limitations. The small sample size of 7 patients may limit the generalizability of the study results. The study population is also limited and completed by a single operator. Further studies should include larger multicenter observational studies to confirm the safety profile of RFA in patients with CIEDs. Diverse prospective registries will ultimately provide the most meaningful safety data.

Conclusions

This paper aimed to corroborate the safety of the RFA procedure in a high-risk population of patients with cardiac implants, including ICDs, PPMs, and ICMs. Our preliminary findings support the potential utility of using RFA in this specific patient population, suggesting that further research can be conducted safely to better understand both the efficacy and safety of this procedure in the general population, as well as in more at-risk populations.

Acknowledgments

An abstract for this study was previously presented as a conference abstract at the 2025 American Thyroid Association (ATA) Annual Meeting hosted by Thyroid, the official journal of the American Thyroid Association, and is available online.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-440/rc

Data Sharing Statement: Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-440/dss

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-440/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2025-440/coif). E.K. serves as an Editor-in-Chief of Gland Surgery from May 2024 to April 2026. E.K. received honoraria from BAIRD for educational training courses and from STARMed for educational conferences. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Review Board of Tulane University School of Medicine (No. 2025-277-EJGH). Given the retrospective design and use of de-identified data, informed consent was waived by the Institutional Review Board.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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