Elective Replacement Indicator Research Articles

Redox imbalance in patients with heart failure and ICD/CRT-D intervention. Can it be an underappreciated and overlooked arrhythmogenic factor? A first preliminary clinical study.

Introduction: Redox imbalance and oxidative stress are involved in the pathogenesis of arrhythmias. They also play a significant role in pathogenesis of heart failure (HF). In patients with HFand implanted cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D), the direct current shocks may be responsible for additional redox disturbances and additionally increase arrhythmia risk. However, the precise role of oxidative stress in potentially fatal arrhythmias and shock induction remains unclear. Methods: 36 patients with diagnosed HF and implanted ICD/CRT-D were included in this study. Patients were qualified to the study group in case of registered ventricular arrhythmia and adequate ICD/CRT-D intervention. The control group consisted of patients without arrhythmia with elective replacement indicator (ERI) status. Activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) in erythrocyte (RBC), SOD, GPx activity and reactive oxygen/nitrogen species (ROS/RNS) concentration in plasma were determined. The values were correlated with glucose, TSH, uric acid, Mg and ion concentrations. Results: In the perishock period, we found a significant decrease in RBC and extracellular (EC) SOD and RBC CAT activity (p = 0.0110, p = 0.0055 and p = 0.0002, respectively). EC GPx activity was also lower (p = 0.0313). In all patients, a decrease in the concentration of all forms of glutathione was observed compared to the ERI group. Important association between ROS/RNS and GSH, Mg, TSH and uric acid was shown. A relationship between the activity of GSH and antioxidant enzymes was found. Furthermore, an association between oxidative stress and ionic imbalance has also been demonstrated. The patients had an unchanged de Haan antioxidant ratio and glutathione redox potential. Conclusion: Here we show significant redox disturbances in patients with HF and ICD/CRT-D interventions. Oxidative stress may be an additional risk factor for the development of arrhythmia in patients with HF. The detailed role of oxidative stress in ventricular arrhythmias requires further research already undertaken by our team.

Cardiac MRI safety assessment of patients with congenital heart disease and cardiac implantable electronic devices with abdominal pulse generators and epicardial leads

Abstract Funding Acknowledgements Type of funding sources: None. Background Reports about cardiac MRI safety and utility in pediatric and adult patients with non-MR-conditional cardiac implantable electronic devices with abdominal pulse generator and epicardial leads remain underreported. Purpose To retrospectively assess safety of cardiac MRI with non-MR-conditional abdominal pulse generators and epicardial leads in pediatric and adult patients with congenital heart disease. Methods Between 04/2020 and 01/2023 25 patients aged 2–32 years (mean 12.7±8.3 years) with abdominal pulse generators and up to three epicardial leads underwent cardiac MRI at 1,5T. SAR was limited to 2W/kg. 19/25 (76%) patients carried pacemakers, 1/25 (4%) ICD, 4/25 (16%) CRTs. 12/25 (48%) of the examinations were performed under general anesthesia. Patients were continuously monitored during cardiac MRI. Results of thresholds, sensing and impedances of the devices were assessed before and after MRI examination. Results In 24/25 (96%) the examination could be finished without significant changes in thresholds, sensing and impedances of the abdominally placed devices. One examination was terminated early because of a major adverse event of heating/abdominal discomfort. Three minor adverse events in three different patients were inability to program back to previous setting (patient 1), alert that the elective replacement indicator (ERI) was reached (patient 2), and significantly elevated impedance (patient 3). Patient 1 and 2 remained in MRI mode and had to be monitored after the MRI examination. Reconfiguration was possible in both patients after 24 hours. Patient 3 had normal results for impedances in the pacemaker query 24 hours after the cardiac MRI examination. Conclusion Our data suggest that cardiac MRI in patients with non-MR-conditional abdominal pulse generators and epicardial leads in pediatric and adult patients with congenital heart disease can be imaged safely in an experienced and multidisciplinary environment. The potential increased risks of MRI in these patients should be balanced against the value of the diagnostic information that can be obtained.

Creation of pacemaker remote monitoring networks between hospital and pharmacies during Covid-19 outbreak

IntroductionRemote Monitoring (RM) of Cardiac Implantable Electronic Devices (CIEDs) is proven to be safe and efficient. It has been adopted in our center since years. At the time of the recent Covid-19 outbreak, we introduced and tested a collaborative organizational model, through a new RM device (Totem), creating a network with the surrounding territory and limiting CIED patients’ presence in hospital. MethodsWe involved 4 neighbor pharmacies where Totem devices were installed; we called and informed 64 patients with Totem compatible pacemaker (PM) about the possibility to perform their PM follow-up (FU) in-pharmacy; 58 gave their consent and their data were inserted into our RM database. ResultsDuring an 18-month FU period, a total of 70 RM transmissions have been received: one alert of high atrial burden triggering a pharmacological optimization, one alert of high ventricular impedance leading to a new ventricular lead implantation and four alerts of elective replacement indicator. Fulfilled questionnaires revealed complete patient satisfaction. ConclusionsA collaborative network between our hospital and the surrounding territory to perform RM FUs of CIEDs during Covid-19 pandemic was feasible, leading to patient compliance and satisfaction and revealing important technical and clinical alerts.

PO-04-104 MANAGEMENT OF FROZEN PACEMAKER LEADS IN GENERATOR EXCHANGE

As the number of cardiac implantable electronic devices (CIEDs) increases, so does the need for generator exchanges. While rare, chronic pacemaker leads may become frozen in the header or may fracture when removal is attempted. This can lead to unnecessary lead implants and extractions if the lead is damaged while removal is attempted. We present a case and discuss our technique to safely remove these leads without damage to the lead itself during generator exchange. To highlight a technique to manage frozen pacemaker leads during generator exchange. N/A An 89 year old lady presented for elective generator exchange for elective replacement indicator. The leads were 31 years old (Intermedics Pacemakers Inc, Tx). When attempting to unscrew the right ventricular lead, Intermedics model 430-02, the pin became partially separated from the rest of the lead. Thus, the lead was pushed back into the header and a sterile saw was used to remove the header from the tip of the lead. We utilized two surgical clamps to create a guide so the saw stayed in the desired direction. Once the back of the header was cut out, the torque wrench was used to push the pin through intact. Though rare, the increasing number of CIED implants and generator exchanges makes encountering a frozen lead more likely in one’s career and successful management is imperative for patient outcomes, safety, and cost effectiveness. There have been rare reports of similar techniques using a variety of instruments, such as scalpels, drills, and bone cutters, to accomplish a similar effect. We have found a sterile saw to be the most effective way to manage these lead complications safely and effectively.

CTR-D without the left lead vs single/dual chamber ICD implantation: a cost saving strategy to avoid future upgrading of the latter?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction/Background: Implantation of cardioverter defibrillators (ICD) to prevent sudden death is common in patients with left ventricular dysfunction (LVD) (1).However, these devices are expensive and there is increasing controversy about their cost benefit ratio. More agreement is present about the benefits of cardiac resynchronization therapy (CRT) in patients with LVD and concurrent heart failure (HF) and left bundle branch block (LBB) (2). Nevertheless, LVD often presents without one these two conditions which may only develop at follow up. This makes unclear the benefits of CRT at the time of ICD implantation (CRT-D) in these patients. Some have advocated implanting a CRT-D without the left ventricle lead instead of a conventional single/dual chamber ICD which would give the possibility to add CRT pacing without replacing the device generator at follow-up. However, this practice has been never evaluated and it is unclear its potential impact on cost. Methods This study included all CRT devices implanted in our institution since 2005. Patients with LVD but just heart failure (HF) or left bundle branch block (LBB) were considered for CRT-D implantation without the left lead. The number of patients who needed implantation of a LV lead at follow-up was analyzed. Only patients who needed device replacement due to battery depletion were included in the final analysis Results A total of 913 CRT devices were implanted of which 115 (12.59%) were implanted without a left ventricular lead. The left ventricular lead was not implanted due to technical reasons in 46 cases (5%) and electively in the remaining. CRT device replacement (due to Elective Replacement Indicator (ERI) activation) was necessary in 38 patients of the latter and a LV lead had been never implanted in 32 (84.21%) of them during follow-up (7 +/- 2 years). In patients who needed a LV lead added, device replacement (because of battery depletion) was necessary during left ventricular lead implant procedure in 2 (6.25%). Using the average cost of these devices in our institution (22,000 euros), around 384,000 euros could have been saved if the CRT-D had not been implanted until left ventricular lead was. Conclusions Implantation of a CRT-D without the left ventricle lead instead of a conventional single/dual chamber ICD in patient with border line indication for CRT is not cost effective and does not result is significant savings in ICD generators.

“Stable” Asystole In A Patient With Left Ventricular Assist Device

The use of Left Ventricular assist devices (LVADs) for mechanical circulatory support has become a standard therapy for some patients with end-stage heart failure. Although presentation and consequences of ventricular arrhythmias (VA) in LVAD supported patients are well described and often stabilized by the mechanical support, presence of asystole is less commonly reported. Our patient is a 75-year-old male with advanced ischemic cardiomyopathy requiring cardiac resynchronization therapy-defibrillator (CRT-D) and ultimately HeartMate II LVAD. Post implantation, his CRT-D was abandoned after it reached the elective replacement indicator as he had no VAs and was not pacer dependent. He now presented with a new onset of low flow alarms that started earlier in the day. He appeared stable, pleasant and in a humorous mood. He reported lightheadedness but denied syncope. While in the ED, the patient was noted to be asystolic. His mean arterial pressure was in the 50s. Physical exam was unremarkable with the expected LVAD hum and lack of pulses. LVAD parameters revealed decreased Flow (2.5 from baseline 5.1) and Pulsatility Index (2.7 from baseline 4.9). Patient subsequently underwent implantation of a new battery with reactivation of his previously abandoned pacemaker leads with resultant hemodynamic improvement. Ultimately, he was discharged home in stable condition. Discussion: Very few cases of asystolic LVAD patients without immediate hemodynamic collapse are described. Similarly to ventricular arrhythmias, the hypothesized physiology for stability is this quasi-Fontan circulation, where low pulmonary vascular resistance with elevated central venous pressure allows pulmonary vasculature perfusion and left atrial filling. In this case, low flow alarms and decreased PI were due to decreased left ventricular preload in the setting of asystole. Ventricular arrhythmias remain common after LVAD implantation, asystole, as in the present case can equally be an issue. This is particularly true as many of LVAD supported patients have CRT-Ds implanted in the setting of pre-existent left bundle branch blocks, which can progress to complete heart block or asystole. Thus, It might not always be the case that LVAD supported patients don't benefit from maintaining ICD function. Conclusion: Traditionally unstable asystole and ventricular arrhythmia can be well tolerated in the LVAD population due to quasi-Fontan physiology. ICD role in LVAD patients is currently unclear, and should be a part of shared decision making with the patient. Yes, there may be such a thing as, "stable" asystole.

Postmortem Interrogation of Cardiac Implantable Electronic Devices: A 15-Year Experience.

This study sought to define the feasibility and utility of postmortem cardiac implantable electronic device (CIED) interrogation. The diagnostic yield of routine postmortem interrogation of CIEDs including pacemakers, defibrillators, and implantable loop recorders has not been established. The study reviewed all CIED interrogations in deceased individuals undergoing medicolegal investigation of sudden or unexplained death by the Victorian Institute of Forensic Medicine between 2005 and2020. A total of 260 patients (68.8% male, median age 72.8 years [interquartile range: 62.7-82.2 years]) underwent CIED interrogation (202 pacemakers, 56 defibrillators, and 2 loop recorders) for investigation of sudden (n=162) or unexplained (n=98) death. CIEDs were implanted for median of 2.0 years (interquartile range: 0.7-5.0 years), with 19 devices at elective replacement indicator and 5 at end of life. Interrogation was successful in 256 (98.5%) cases. Potential CIED malfunction was identified in 20 (7.7%) cases, including untreated ventricular arrhythmias (n=13) and lead failures (n=3, 2 resulting in untreated ventricular arrhythmia). Interrogation directly informed cause of death in 131 (50.4%) cases. A total of 72 (27.7%) patients had abnormalities recorded in 30days preceding death: nonsustained ventricular tachycardia (n=26), rapid atrial fibrillation (n=17), elective replacement indicator or end-of-life status (n=22), intrathoracic impedance alarms (n=3), lead issues (n=3), or therapy delivered (n=1). In 6 cases in which the patient was found deceased after a prolonged period, interrogation determined time of death. In 1 case, CIED interrogation was the primary means of patient identification. Postmortem CIED interrogation frequently contributes important information regarding critical device malfunction, premortem abnormalities, mechanism, and time of death or patient identity. Device interrogation should be considered for select patients with CIEDs undergoing autopsy.

Should they stay, or should they go: Do we need to remove the old cardiac implantable electronic device if a new system is required on the contralateral side?

BackgroundIpsilateral approach in patients requiring cardiac implantable electronic device (CIED) revision or upgrade may not be feasible, primarily due to vascular occlusion. If a new CIED is implanted on the contralateral side, a common practice is to explant the old CIED to avoid device interaction.ObjectiveThe purpose of this study was to assess a conservative approach of abandoning the old CIED after implanting a new contralateral device.MethodsWe used an artificial intelligence algorithm to analyze postimplant chest radiographs to identify those with multiple CIEDs. Outcomes of interest included device interaction, abandoned CIED elective replacement indicator (ERI) behavior, subsequent programming changes, and explant of abandoned CIED. Theoretical risk of infection with removal of abandoned CIED was estimated using a validated scoring system.ResultsAmong 12,045 patients, we identified 40 patients with multiple CIEDs. Occluded veins were the most common indication for contralateral implantation (n = 27 [67.5%]). Fifteen abandoned CIEDs reached ERI, with 4 reverting to VVI 65. One patient underwent explant due to device interaction, and 2 required device reprogramming. Of 32 patients with an implantable cardioverter-defibrillator, 8 (25%) had treated ventricular arrhythmia. There were no failed or inappropriate therapies due to interaction. Eighteen patients (45%) had hypothetical >1% annual risk of hospitalization for device infection if the abandoned CIED had been explanted.ConclusionIn patients requiring new CIED implant on the contralateral side, abandoning the old device is feasible. This approach may reduce the risk of infection and concerns regarding abandoned leads and magnetic resonance imaging scans. Knowledge of ERI behavior is essential to avoid device interactions.

Defibrillation success after subcutaneous implantable cardioverter-defibrillator generator replacement is not affected by impedance increase

Abstract Funding Acknowledgements Type of funding sources: None. Background Routine defibrillation testing during implant and replacement of the subcutaneous implantable cardioverter-defibrillator (S-ICD) is recommended per current guidelines. Recently, concerns have been raised about an increase in shock impedance and consequent shock failure during defibrillation testing in S-ICD patients undergoing a generator replacement. Purpose We aim to describe the defibrillation success rate in relation to the shock impedance in patients undergoing S-ICD generator replacement in our large tertiary center. Methods In this retrospective analysis, data from replacement procedures were collected from all patients who underwent an S-ICD generator replacement in our center from June 2014 to December 2020. Defibrillation testing was performed with at least one shock of ≤65J, and a successful shock was defined as terminating the ventricular arrhythmia within 5 seconds after the shock. Results A total of 133 patients underwent an S-ICD generator replacement, 5.8 ± 0.9 years after initial implant. Reasons for replacement were: reaching of elective replacement indicator (n = 119), early battery depletion (n = 9), complaints of generator pocket (n = 3) and device malfunction (n = 2). Defibrillation testing was performed in 111 patients (86.5%) undergoing a replacement procedure. Shock impedance data from both the implant and replacement procedure were available in 101 patients. The median shock impedance of these patients during their replacement procedure was significantly higher than during their implant, 79Ω (IQR 66-94) and 66Ω (IQR 57.5-81) respectively (Z = -5.552, p < 0.001). Despite the higher shock impedance, first shock during defibrillation testing was successful in 105/111 patients (94.6%), with a success rate of 97.3% after two attempts. In the remaining three patients, the ventricular arrhythmia could only be terminated with a 80J shock. This was the case during both their initial implant and their replacement procedure. Shock impedance increase between implant and replacement was not significantly higher in patients with a successful first shock compared to patients with an unsuccessful first shock (Δ+11.1 ± 20.0Ω versus Δ+12.7 ± 27.6Ω, p = 0.86). Conclusion In this large retrospective analysis, we have shown a first shock success rate during S-ICD generator replacement of 94.6%, which is similar to the success rate of defibrillation testing after initial implant. After multiple attempts, defibrillation testing success rate was 100%. Even though the median shock impedance during replacement was significantly higher than during the initial implant, there was no difference in impedance increase in patients with a successful shock compared to patients with an unsuccessful shock. Abstract Figure. Defibrillation success

Ongoing Risk of Ventricular Arrhythmias and All-Cause Mortality at Implantable Cardioverter Defibrillator Generator Change: A Systematic Review and Meta-Analysis.

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First Demonstration of Cardiac Resynchronization Therapy Defibrillator Service Life Exceeding Patient Survival in a Heart Failure with Reduced Ejection Fraction Cohort.

The occurrence of patient longevity exceeding implantable cardioverter-defibrillator (ICD) service life has important implications for patient outcomes and the cost of care. Battery capacity as measured in ampere-hours (Ah) is a strong predictor of survival to an elective replacement indicator (ERI) point and 2.1 Ah is the largest-capacity ICD battery in use at our facility. This was a long-term study of ICDs out of service (OOS) in patients with heart failure with reduced ejection fraction who received a 2.1-Ah cardiac resynchronization therapy defibrillator (CRT-D). All 2.1-Ah CRT-D systems implanted (n = 418) from August 1, 2008 through August 31, 2016 were included in this retrospective chart review. The primary endpoint was device OOS due to the battery reaching an ERI point, patient death, infection/erosion, advisory/recall, heart transplant, or unspecified. The maximum follow-up period was 10.3 years, with a mean follow-up length of 4.7 years. The most common reason for device OOS was patient death (65.6%), with only 5.7% of devices reaching the ERI point during the study. There was a period of OOS acceleration driven numerically by patient death in the sixth to ninth years of follow-up. Male sex, ischemic cardiomyopathy, elevated creatinine level, advanced age, and reduced ejection fraction were associated with OOS (p < 0.05). To our knowledge, this is the first study to report ICD battery life exceeding patient survival in a chronic heart failure cohort. During an accelerated time of CRT-D OOS (when it is expected that ~98% of 1.0-Ah and 1.4-Ah CRT-D systems reach an ERI point), patient death resulted in substantially more device OOS than battery replacement and avoided costs of complications and generator changes. These results help to explain the elevated risks of CRT-D generator changes in shorter-longevity devices.

Transient ICD malfunctions during oncologic radiotherapy: a multi-centre, randomized, in-vitro study

Abstract Background Direct exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered potentially harmful, or even unsafe, by manufacturers and current recommendations. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and malfunctions may present during exposure. Purpose To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy RT, forty-three contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (ERI) were evaluated in a real-time in-vitro session in three different centres. Methods All ICDs had baseline interrogation. Single chamber devices were programmed to the VVI/40 mode and dual or triple chamber devices were programmed to the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still active. A centring computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2-, 5- or 10-Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was randomly assessed by an in-vivo dosimetry. During radiotherapy, the ICDs were observed in a real-time session using manufacturer specific programmer, and device function (pacing, sensing, programmed parameters, arrhythmia detections) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure. Results During radiotherapy course, almost all ICDs (93%) recorded major or minor transient electromagnetic interferences. On detail, sixteen ICDs (37.2%) reported atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. Twenty-four ICDs (55.8%) recorded non clinically relevant noise, and no detections were observed. Only three ICDs (7%) reported neither transient malfunction nor minor noise, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. Malfunctions occurred regardless of either 2-, 5- or 10-Gy photon beam exposure. Conclusions Transient electromagnetic interferences were observed in most of the contemporary ICDs during radiotherapy course, regardless of photon dose. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or ICD reprogramming to the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure. Funding Acknowledgement Type of funding source: None

Permanent CIED malfunctions after oncologic radiotherapy: a multi-centre, randomized, in vitro evaluation

Abstract Background Direct photon exposure of pacemakers (PMs) or implantable cardioverter-defibrillators (ICDs) during oncologic radiotherapy may transiently or permanently affect normal device function. To evaluate potential malfunctions by direct exposure to doses up to 10 Gy in 6-MV oncologic radiotherapy, commonly considered unsafe or even not recommended, 145 PMs and 65 ICDs were observed in three different centres. Methods All devices had a baseline interrogation and reprogramming to VVI/40 or to DDD/40 mode, depending on type and model. Rate-adaptive function was disabled in all the devices, whereas in ICDs, even antitachycardia therapies were disabled with the ventricular tachycardia/fibrillation (VT/VF) windows left enabled. To build the corresponding treatment plan, a centring computed tomography was performed with different Treatment Plan Systems among the centres. The devices were blinded randomized to receive either 2-, 5- or 10-Gy direct exposure by a 6-MV linear accelerator (different among the three centres) in a water phantom (600 MU/min). The effective dose received was assessed by a random in-vivo dosimetry. All devices had a telemetry interrogation immediately after exposure and once monthly during a six-month follow-up. Results Immediately after photon exposure, no changes in device parameters or software errors were observed in 209 devices (99.5%). A non-reprogrammable reset to emergency back-up mode (VVI/65) occurred in a PM (0.5% overall; 0.7% among PMs). Seven PMs reached the Elective Replacement Indicator immediately after exposure (3.3% overall; 4.8% among PMs). Sixteen ICDs (7.6% overall; 24.6% among ICDs) had multiple VT/VF detections stored in the device memory. Two PMs (1% overall; 1.4% among PMs) reported atrial fibrillation detections. During a six-month follow-up, a non-reprogrammable software reset (back-up to VVI/65 mode) was reported in one PM three months after a single exposure of 2 Gy (0.5% overall; 0.7% among PMs). Abnormal battery drain was observed in thirteen PMs (6.2% overall; 9% among PMs), and in one ICD (0.5% overall; 1.5% among ICDs). All events presented regardless of exposure dose of either 2, 5, or 10 Gy. Conclusions Last-generation devices, both PMs and ICDs, withstood direct 6-MV photon exposure up to 10 Gy, commonly considered not recommended or even unsafe by manufacturer statements and clinical guidelines. The most common failures were referred to battery issues. Malfunctions occurred solely in less recent devices, regardless of photon dose. Funding Acknowledgement Type of funding source: None

Shortness of breath and palpitations in an elderly man: Bad device behavior or malfunction?

70-year-old male with sinus node dysfunction (SND) and paroxysmal atrial fibrillation presents with shortness of breath and palpitations. Presenting EKG shows AF with rapid ventricular rates requiring direct current cardioversion (DCCV). Post-DCCV EKG shows sinus rhythm with competing ventricular pacing. Device interrogation demonstrates the patient's generator at the elective replacement indicator (ERI) and has been forced to VVI 65bpm causing dyssynchronous ventricular pacing and inducing AF. This case highlights the importance of close device follow up with timely PPM generator change prior to ERI, especially in patients with Medtronic Adapta devices, to avoid unnecessary dyssynchronous ventricular pacing. In addition, device manufacturers should focus on maintaining AV synchrony in pacemakers when they reach ERI.

False remote monitoring alerts from explanted cardiac implantable electronic device: How is this possible?

A 72-year-old woman with a dual-chamber implantable cardioverter-defibrillator (Biotronik Lumax 540 DR-T) at elective replacement indicator presented for generator replacement. A new MicroPort generator (Platinium DR) was attached to her existing leads. Eight days later, multiple red alert messages were received on the Biotronik remote monitoring system from the explanted generator. Investigations revealed alert transmission via a CardioMessenger Smart mobile device registered to another patient that came into proximity of the explanted generator. The Biotronik remote monitoring system is unique in that red alerts could be sent through any CardioMessenger Smart device regardless of whether they were paired.

Letter: Evaluation and Surgical Treatment of Functional Neurosurgery Patients With Implanted Deep Brain Stimulation and Vagus Nerve Stimulation Pulse Generators During the COVID-19 Pandemic.

Author(s): Gross, Robert E; Buetefisch, Cathrin M; Miocinovic, Svjetlana; Bullinger, Katie L; Okun, Michael S; Ostrem, Jill L; Foote, Kelly D; Starr, Phillip A

Clinical implications of elective replacement indicator setting changes in patients with dual-chamber pacemaker devices.

This study sought to determine if single-chamber operation and/or loss of rate response (RR) during elective replacement indicator (ERI) in patients with dual-chamber pacemakers lead to increased symptom burden, healthcare utilization, and atrial fibrillation (AF). Dual-chamber pacemakers often change from dual- to single-chamber pacing mode and/or lose RR functionality at ERI to preserve battery. Single-chamber pacing increases the incidence of heart failure, AF, and pacemaker syndrome suggesting these changes may be deleterious. A retrospective analysis of 700 patients was completed. Three comparisons were analyzed: Comparison 1: mode change and RR loss versus no change; Comparison 2: RR loss only versus no change; Comparison 3: mode change only versus no change (in patients with no RR programmed at baseline). In Comparison 1, 121 (46%) patients with setting changes experienced symptoms (most often dyspnea and fatigue/exercise intolerance) versus 3 (4%) without setting changes (p < .0001). Similar results were noted in Comparisons 2 and 3 (p = .0016 and p = .0001, respectively). In Comparison 1, patients with setting change sought provider contact more than patients without setting changes (p = .0001). A significant difference was not noted in Comparison 2 or 3. Overall 14 (2%) patients were hospitalized, all of whom had setting changes. Setting changes at ERI including a change from dual- to single-chamber pacing and/or loss of RR results in a significantly increased symptom burden and increased healthcare utilization.

910Noise-related malfunctions in modern ICDs during oncologic radiotherapy: a multicentre, real-time, in-vitro observation

Abstract Funding Acknowledgements None Background Direct photon exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered not recommended, or even unsafe, by manufacturers and guidelines. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and electromagnetic interferences (EMIs) may present during exposure. Purpose To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy radiotherapy, 36 contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (E.R.I.) were evaluated in a realtime in-vitro session. Methods All ICDs had baseline interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber devices were programmed in the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still working. A centering computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was randomly assessed by an in-vivo dosimetry. During radiotherapy course, the devices were observed in a real-time session using manufacturer specific programmer, and ICD function (pacing, sensing, programmed parameters, detection) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure. Results During radiotherapy course, almost all ICDs (90.9%) recorded major or minor transient EMIs. On detail, 16 ICDs (44.4%) reported EMI-related atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. 16 ICDs (44.4%) recorded not clinically relevant minor EMIs, and no detections were observed. Only 4 ICDs (11.2%) reported neither transient malfunction nor minor EMIs, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. EMI-related malfunctions occurred regardless of either 2, 5 or 10 Gy photon beam exposure. Conclusions Transient EMIs were observed in most of the contemporary ICDs. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or reprogramming in the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure.

P551Permanent cardiac implantable device damage during direct photon exposure for oncologic radiotherapy: a multicentre, in-vitro observation

Abstract Funding Acknowledgements None Backgroung. Direct photon exposure of cardiac implantable devices (CIEDs), both pacemakers (PMs) or implantable cardioverter defibrillators (ICDs), during oncologic radiotherapy (RT) courses may transiently or permanently affect normal device function. Purpose To evaluate CIED damage by direct exposure to doses up to 10 Gy in oncologic RT, commonly considered unsafe or even potentially harmful, 206 CIEDs (143 PMs and 63 ICDs) from three different centres, with at least 4 months to Elective Replacement Indicator (E.R.I.) were observed. Methods. All CIEDs had a baseline telemetry interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber ones were programmed in the DDD/40 mode. Rate adaptive function was disabled. In ICDs, antitachycardia therapies were disabled with the ventricular tachycardia/fibrillation window left enabled. A centering Computed Tomography was performed to build the corresponding treatment plan and CIEDs were blinded randomized to receive either 2, 5 or 10 Gy (direct exposure) by a 6 MV linear accelerator in a home-made water phantom. An in-vivo dosimetry randomly assessed the effective dose received by the CIEDs. All CIEDs were interrogated immediately after exposure and monthly during a three-month follow-up. Results. Immediately after photon exposure, no changes in device setting or software errors were observed in 205 CIEDs (99·5%). Reset to emergency back-up mode was observed in a PM (0·49% overall; 0·7% among PMs). Seven PMs reached the E.R.I immediately after exposure (3·4% overall; 4·9% among PMs). Sixteen ICDs (7·8% overall; 25·4% among ICDs) reported multiple ventricular tachycardia/fibrillation detections stored in the device memory. During follow-up, a non-reprogrammable software reset (emergency backup VVI/65 mode) was observed in one PM after a single dose of 2 Gy (0·49% overall; 0.7% among PMs), whereas an abnormal battery drain was observed in 6 PMs (2.9% overall; 4.2% among PMs). No battery issues were observed in ICDs. All reported events occurred regardless of either 2, 5, or 10 Gy direct exposure. Malfunctions were observed in only older CIEDs. Conclusions. Recent CIEDs have shown to be safe during oncologic RT, withstanding direct exposure up to 10 Gy, commonly considered not recommended or even unsafe by manufacturers statements and clinical guidelines. Malfunctions occurred solely in older devices.

P1134Cardiac pacemakers and transient electromagnetic interferences during radiotherapy courses: a multicentre, real-time, in-vitro evaluation

Abstract Funding Acknowledgements None Background The effects of high dose oncologic radiotherapy (RT) on cardiac pacemakers (PMs), at even less than 6 MV power, are unpredictable, depending on multiple factors. Normal PM function may be impaired during direct exposure, due to electromagnetic interferences (EMIs). Potentially life-threatening malfunctions may occur, expecially in PM-dependent patients, and both manufacturers and guidelines discourage direct exposure. Purpose To evaluate transient EMI-related PM malfunctions during direct exposure to doses up to 10 Gy during radiotherapy course, 17 wireless-telemetry-enabled PMs with sufficient residual battery charge for the purpose of the study (at least 4 months to elective replacement indicator, E.R.I.) were evaluated in three different centres. Methods All PMs underwent baseline interrogation. Single chamber devices were programmed in the VVI/40 mode while dual or triple chamber devices were programmed in the DDD/40 mode. To avoid the "run-away" phenomenon during exposure rate-adaptive function was disabled. A centering computed tomography was performed to build the corresponding treatment plan and the PMs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a 6 MV linear accelerator in a homemade water phantom (600 Um/min). The effective dose received by the PMs was randomly assessed by an in-vivo dosimetry. During RT course, the devices were observed in a real-time session using manufacturer specific equipment, and PM function (pacing and sensing, programmed parameters) was recorder by a video camera in the bunker throughout the entire radiation exposure. Results During RT course, 13 PMs (76.5%) recorded not clinically relevant minor transient EMIs, and no atrial and/or ventricular oversensing nor base-rate-pacing inhibition were observed. Only 4 PMs (23.5%) reported neither transient malfunction nor minor EMIs, withstanding direct radiation exposure. Transient EMI-related malfunctions were observed regardless of either 2, 5 or 10 Gy exposure. Conclusions Minor, not clinically relevant EMI-related interferences were observed in most of the PMs during direct exposure. Nevertheless, to avoid potentially life-threatening PM malfunctions, magnet application on the PM pocket site or reprogramming are still suggested in PM-dependent (high risk) patients ongoing even low energy RT exposure.