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Background: In 2022 and 2023, Medtronic recalled implantable defibrillators because they may deliver less than full-energy shocks. The 2022 problem truncates the second phase of the waveform (SCP-T2), resulting in ∼32-J shocks, and is mitigated by downloadable software. The 2023 malfunction truncates the first phase of the waveform, resulting in 0- to 12-J shocks due to a glassed feedthrough problem (GFT-T1) that might be avoided by programming B>AX shock polarity., Objective: The purpose of this study was to assess the consequences of GFT-T1 and SCP-T2 shocks in the Food and Drug Administration's Manufacturers and User Facility Device Experience (MAUDE) database and to estimate the incidences of GFT-T1 and SCP-T2., Methods: We analyzed MAUDE reports supplemented by Medtronic data; lead failures were excluded. The incidences of SCP-T2 and GFT-T1 were estimated using USA volumes for devices with glassed feedthroughs., Results: One hundred thirty-two devices delivered truncated shocks: 27 (20.5%) were GFT-T1; 103 (78.0%) were SCP-T2; and 2 (1.5%) truncated both phases (BOTH-T1&2). Of 54 ventricular fibrillation (VF) patients, 21 (38.9%) were not defibrillated by truncated shocks: 8 (38.1%) received GFT-T1 shocks, 12 (57.1%) received SCP-T2 shocks, and 1 received a BOTH-T1&2 shock; 2 patients suffered unrelated deaths; 1 was externally rescued; 1 outcome was unknown; the others were defibrillated by subsequent shocks or terminated spontaneously. The majority of patients (79.1%) shocked for ventricular tachycardia (VT) were converted, primarily (94.1%) by SCP-T2 shocks. Estimated incidences of GFT-T1 and SCP-T2 were 0.0078%-0.0088% and 0.1062%-0.1110%., Conclusion: GFT-T1 and SCP-T2 shocks can result in failure to terminate VF/VT, but they may be preventable. Although the incidences of these truncated shocks are very low, heightened surveillance is warranted., Competing Interests: Disclosures The authors have no conflicts to disclose., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The LifeVest® wearable cardioverter-defibrillator (WCD) prevents sudden cardiac death in at-risk patients who are not candidates for an implantable defibrillator. The safety and efficacy of the WCD may be impacted by inappropriate shocks (IAS)., Objective: The purpose of this study was to assess the causes and clinical consequences of WCD IAS in survivors of IAS events., Methods: The Food and Drug Administration's Manufacturers and User Facility Device Experience database was searched for IAS adverse events (AE) that were reported during 2021 and 2022., Results: A total of 2568 IAS-AE were found (average number of IAS per event: 1.5 ± 1.9; range 1-48). IAS were caused by tachycardias (1255 [48.9%]), motion artifacts (840 [32.7%]), and oversensing (OS) of low-level electrical signals (473 [18.4%]) (P <.001). Tachycardias included atrial fibrillation (AF) (828 [32.2%]), supraventricular tachycardia (SVT) (333 [13.0%]), and nonsustained ventricular tachycardia/fibrillation (NSVT/VF) (87 [3.4%]). Activities responsible for motion-induced IAS included riding a motorcycle, lawnmower, or tractor (n = 128). In 19 patients, IAS induced sustained ventricular tachycardia or ventricular fibrillation that subsequently were terminated by appropriate WCD shocks. Thirty patients fell and suffered physical injuries. Conscious patients (n = 1905) did not use the response buttons to abort shocks (47.9%) or used them improperly (20.2%). IAS resulted in 1190 emergency room visits or hospitalizations, and 17.3% of patients (421/2440) discontinued the WCD after experiencing IAS, especially multiple IAS., Conclusions: The LifeVest WCD may deliver IAS caused by AF, SVT, NSVT/VF, motion artifacts, and oversensing of electrical signals. These shocks may be arrhythmogenic, result in injuries, precipitate WCD discontinuation, and consume medical resources. Improved WCD sensing, rhythm discrimination, and methods to abort IAS are needed., (Copyright © 2023. Published by Elsevier Inc.)

Background: Electronic products, including the iPhone 12, Apple Watch Series 6, and 2nd Generation AirPods, contain magnets to facilitate wireless charging. Permanent magnets may affect CIED magnet mode features by causing pacemakers to pace asynchronously and defibrillators to suspend arrhythmia detection. This study determined if CIEDs are affected by static magnetic fields from commonly used portable electronics (PE) at any distance and intends to reinforce FDA recommendations concerning consumer PE which contain permanent magnets., Methods: The maximum magnet field measurement was evaluated by a Gauss meter. The interaction between PE and CIEDs from Boston Scientific and Medtronic were tested ex vivo using a body torso model. The CIED was placed in physiologic saline, and the PE was placed at the surface and at increasing distances of 0.5, 1.0, and 1.5 cm. Interactions were recorded by assessment of magnet mode status., Results: The iPhone 12 had almost three times the static magnetic field measured at the surface as the iPhone XR, but magnetic field strength decreased dramatically with increasing distance. At the surface of the model, PE triggered magnet mode in all CIEDs. The maximum interaction distance for all combinations of CIEDs and Apple products was 1.5 cm., Conclusions: The iPhone 12 produces a stronger static magnetic field than previous iPhone models. Magnets in PE tested will not interact with CIEDs when they are 15 cm from the implanted device. Since no interaction was observed beyond 1.5 cm, it is unlikely that magnet mode activation will occur during most daily activities., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: We hypothesized that data in manufacturers' product performance reports (PPRs) can provide clinically valuable ICD and cardiac resynchronization defibrillator (CRT-D) reliability and longevity information., Methods: Data were obtained from 2019 PPRs. Kaplan-Meier (K-M) probabilities of freedom from malfunction, normal battery depletion (NBD), and NBD + malfunction were calculated for ICD and CRT-D pulse generators (PGs) with LiMnO2 or LiSVO/CFx batteries marketed in the USA from 2010 to 2019 and compared using the log-rank test. Malfunctions (MAL) included PGs that were found outside specifications., Results: Study population included 1,149,803 ICD and CRT-D PGs: Abbott (ABT; 35.1%), Biotronik (BIO; 4.6%), Boston Scientific (BSC; 23.5%), and Medtronic (MDT; 36.9%). Significant differences in reliability (p < 0.001), defined by freedom from MAL, were found between manufacturers; the majority of 6808 MAL occurred in ABT devices (n = 4045; 59.4%), followed by BSC (n = 2384; 35.0%), MDT (n = 338;5.0%), and BIO (n = 41; 0.6%). Battery failure (n = 890; 57.9%) was the most common cause of MAL compromising therapy; analysis of unique ABT battery MAL-indicated problem appeared a year prior to advisory. Significant differences (p < 0.001) in battery longevity, as defined by freedom from NBD, were found between manufacturers. Overall performance (freedom from NBD + MAL) favored BSC for CRT-D PGs and MDT and BIO for ICDs. BSC subcutaneous ICD reliability was inferior to its transvenous ICD (p < 0.001)., Conclusion: PPRs contain valuable data that can be aggregated and analyzed to inform physicians. Differences in product reliability exist between manufacturers. Battery longevity has improved, but MAL have significantly impacted performance. PPR data may be useful for assessing product problems and new technology., (© 2021. The Author(s).)

Purpose: We have reported the calcification of Endotak defibrillation leads that required replacement. The aim of this study was to assess calcified Endotak Reliance leads in the Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE) database and compare them to calcified Sprint Fidelis, Sprint Quattro Secure, Riata, and Durata leads in MAUDE., Methods: We searched the MAUDE database from 2008 to 2019 for defibrillation lead calcification using the terms "calcium," "calcification," and "calcified". Included were explanted leads whose manufacturers found calcium on the shocking and/or pacing electrode., Results: The MAUDE search identified 113 calcified defibrillation leads that qualified for the study, including 109 Endotak Reliance leads, 1 Sprint Quattro Secure lead, 2 Durata leads, 1 Riata ST lead, and no Sprint Fidelis lead. The sign of calcification was a gradual increase in shocking or pacing impedance. Average implant time was 7.4 ± 3.1 (range: 1.3-16.5) years. Only Endotak Reliance leads had shocking coil calcification (n = 72; 66.0%) and five (6.9%) of these failed defibrillation threshold (DFT) testing. Distal pacing electrode calcification affected 55 (50.4%) Endotak Reliance leads. The four other leads had pacing ring electrode calcification only., Conclusion: Endotak Reliance defibrillation leads appear prone to shocking coil and/or distal pacing electrode calcification. High impedances may compromise defibrillation and pacing therapy. Patients who have these leads should be monitored; those exhibiting high shocking impedances should be considered for DFT testing. Lead replacement should be considered for pacemaker-dependent patients whose leads exhibit progressively high impedances.

Background: Internal insulation breaches (IBR) may result in implantable cardioverter-defibrillator lead failure and adverse clinical events. Concerns exist that the Durata lead may be prone to IBR., Objective: The goals of this study were to assess Durata failures in the Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE) database and compare them to failures in MAUDE for Endotak Reliance and Sprint Quattro Secure (QS) leads., Methods: We searched the MAUDE database from 2008 to 2018 for IBR and other failure modes. Included were explanted leads whose manufacturers found an insulation or conductor defect not caused by extrinsic factors., Results: The MAUDE search found 1011 qualifying leads. The cause of failure differed among leads (P < .001). The primary cause of Durata failure was IBR (293 of 316 leads [93%]), with IBR accounting for 47% (137 of 293); few QS (9 of 523 [1.7%]) and no Endotak Reliance leads failed because of IBR (P < .001). Durata IBR were responsible for 11 failures to treat ventricular tachycardia/ventricular fibrillation, and all were caused by high-voltage (HV) shorts between the proximal superior vena cava coil and a distal right ventricular coil cable (n = 10) or sensing conductor (n = 1); low values of HV impedance were found in these leads during defibrillation threshold testing (n = 3), after a shock or aborted shock (n = 7), and by an alert (n = 1). Inappropriate therapy was caused by 51 Durata IBR, but no QS IBR., Conclusion: Durata implantable cardioverter-defibrillator leads are susceptible to IBR that may result in failure to treat ventricular tachycardia/ventricular fibrillation or inappropriate therapy; such failures may occur without forewarning. HV testing of Durata leads may be indicated during pulse generator replacement or when an insulation defect is suspected., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Studies have shown mortality benefit for implantable cardioverter-defibrillators (ICDs) in ST-elevation myocardial infarction (STEMI) patients with reduced left ventricular ejection fraction (LVEF), but contemporary eligibility and appropriate utilization of ICDs is unknown., Objective: The purpose of this study was to determine the contemporary eligibility and appropriate utilization of ICDs post-STEMI., Methods: Using the prospective Minneapolis Heart Institute regional STEMI registry, LVEF before discharge and at follow-up were stratified into 3 groups: normal (LVEF ≥50%), mildly reduced (LVEF 35%-49%), and severely reduced (LVEF <35%)., Results: From March 2003 to June 2012, 3626 patients were treated. Patients with in-hospital death (n = 187), ICD in place (n = 21), negative cardiac biomarkers (n = 337), and undocumented in-hospital LVEF (n = 9) were excluded, leaving 3072 patients in the final analysis, including 1833 (59.7%) with LVEF ≥50%, 875 (28.5%) with LVEF between 35% and 49%, and 364 (11.8%) with LVEF <35% before hospital discharge. Overall, 1029 patients (33.5%) underwent follow-up echocardiography ≥40 days post-STEMI, including 140 of the 364 patients (38.5%) discharged with LVEF <35%. In total, 73 patients (7.1%) with follow-up echocardiography ≥40 days post-STEMI met criteria for an ICD (68 LVEF ≤30%, 5 LVEF 30%-35%, and New York Heart Association class II or greater). Only 26 of these patients (35.6%) underwent ICD placement within 1 year post-STEMI. Overall, only 10% to 15% of potentially eligible patients had an ICD implemented., Conclusion: Rates of ICD implantation in appropriate STEMI patients after 40 days are low. Strategies are needed to identify and expand access to these high-risk patients., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Purpose of Review: Prevention of ventricular arrhythmias and implantable cardioverter-defibrillator (ICD) therapies in patients with heart failure will be reviewed., Recent Findings: ICD utilization in patients with heart failure has resulted in significantly improved long-term survival. However, there is growing evidence that ICD shocks are associated with increased morbidity and mortality. As a result, there is increasing emphasis on the treatment strategies to avoid ICD therapies. Optimal heart failure management with medical as well as cardiac resynchronization therapy when indicated is an essential part of treatment; however, adjunctive measures may be necessary to suppress ventricular arrhythmias, prevent unnecessary shocks, and improve quality of life., Summary: Device programming can help avoid ICD therapies by delaying time to detection, increasing detection rate cutoffs, and discriminating between supraventricular and ventricular arrhythmias. Still, as patients live longer with advanced stages of heart failure, there will be a need to suppress sustained ventricular arrhythmias that would otherwise require ICD therapy. Antiarrhythmic drugs offer a noninvasive option to help suppress ventricular arrhythmias. With more experience and better catheter mapping and ablation techniques, there is a movement toward an early invasive strategy for ventricular tachycardia management in patients with heart failure.

Background: A significant proportion of implantable cardioverter-defibrillators (ICDs) have been subject to Food and Drug Administration (FDA) advisories. The impact of device advisories on mortality or patient care is poorly understood. Although estimated risks of ICD generators under advisory are low, dependency on ICD therapies to prevent sudden death justifies the assessment of long-term mortality., Objective: To test the association of FDA advisory status with long-term mortality., Methods: The study was a retrospective, single-center review of clinical outcomes, including device malfunctions, in patients from implantation to either explant or death. Patients with ICDs first implanted at Cleveland Clinic between August 1996 and May 2004 who became subject to FDA advisories on ICD generators were identified. Mortality was determined by using the Social Security Death Index., Results: In 1644 consecutive patients receiving first ICD implants, 704 (43%) became subject to an FDA advisory, of which 172 (10.5%) were class I and 532 (32.3%) were class II. ICDs were explanted before advisory notifications in 14.0% of class I and 10.1% of class II advisories. Among ICDs under advisory, 28 (4.0%) advisory-related and 15 non-advisory- related malfunctions were documented. Over a median follow-up of 70 months, 814 patients died. Kaplan-Meier 5-year survival rate was 65.6% overall, and 64.2, 61.1, and 69.3% in patients with no, class I, and class II advisories, respectively (P = .17)., Conclusions: ICD advisories impacted 43% of the patients. Advisory-related malfunctions affected 4% within the combined advisory group. Based on a conservative management strategy, ICDs under advisory were not associated with increased mortality over a background of significant disease-related mortality., (Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Chronic kidney disease (CKD) has been independently associated with increased cardiovascular mortality. Little is known about the benefit of implantable cardioverter defibrillator (ICD) therapy for prevention of sudden death in this large, high-risk population. We sought to evaluate the impact of CKD on survival in patients who received an ICD for primary prevention of sudden death., Methods and Results: In this retrospective study of patients who underwent ICD implantation for primary prevention of sudden death, patients were stratified by CKD, defined as serum creatinine > or = 2 mg/dL or dialysis use. Primary endpoint was mortality. CKD was identified in 35 of 229 patients (15.3%). There were 33 deaths during a follow-up period of 18.0 +/- 15.2 months: 17 of 35 CKD patients and 16 of 194 patients without CKD (48.6% vs 8.2%, P < 0.00001 by log-rank). One-year survival for patients with and without CKD was 61.2% and 96.3%, respectively. Cox regression analysis controlling for age, sex, comorbidities, ejection fraction, and medications proved CKD to be the strongest independent predictor of death (hazard ratio 10.5; 95% confidence interval 4.8-23.1; P = 0.0001). This risk was dependant on severity of CKD; a 10 mL/min reduction in creatinine clearance was associated with a 55% increase in hazard of death (P < 0.0001)., Conclusions: In patients receiving an ICD for primary prevention of sudden death, CKD significantly reduced long-term survival. This poor prognosis may limit the impact of primary prevention ICD therapy in this patient population.