percent for the 805 patients with ischemic cardiomyopathy [7]. Special populations include those with alcoholic cardiomyopathy, postpartum cardiomyopathy, or myocarditis, all of which may or may not be associated with improvement in ventricular function with optimal medical therapy and reversal or treatment of causative factors. In a study of 127 patients with alcoholic cardiomyopathy wearing the WCD a median of 51 days, 5.5 percent had appropriate shocks for VT/VF [36]. Improved LVEF occurred in 33 percent, and 23.6 percent received an ICD. In the PROLONG study of 156 patients (111 with nonischemic cardiomyopathy) with newly diagnosed LVEF 35 percent wearing a WCD for an average of 101 days, WCD shocks for VT/VF were experienced by 7.2 percent, compared with 6.7 percent in the 45 patients with https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 12/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate ischemic cardiomyopathy [37]. The event rates were 21.1 percent in the 19 patients with postpartum cardiomyopathy, 0 percent in the six patients with myocarditis, and 4.7 percent in patients with other forms of nonischemic cardiomyopathy. In a separate study of 107 women with peripartum cardiomyopathy, who were matched to 159 nonpregnant women with nonischemic dilated cardiomyopathy, the event rate was 0 in the peripartum cardiomyopathy over an average WCD use of 124 days, compared with two shocks in one patient with nonperipartum nonischemic cardiomyopathy [38]. With such low event rates, the utility of the WCD for newly-diagnosed nonischemic cardiomyopathy has been debated. However, from the WEARIT II registry, the number of VT/VF events per 100 patient-years was 1.5 for treated events versus 12 for untreated events [7]. Presumably, some of the untreated events led to earlier ICD implantation and may represent a nontreatment yield from the WCD monitoring functions. As data remain limited for such patients, the decision on whether to use a WCD remains based on clinical judgment for patients assessed to have high-risk severe newly diagnosed nonischemic cardiomyopathy while undergoing optimization of medical therapy, awaiting improvement in LV function, ICD implantation, or if needed, cardiac transplantation. (See "Treatment and prognosis of myocarditis in adults", section on 'Therapy for arrhythmias'.) Bridge to heart transplant Patients with severe heart failure awaiting heart transplantation represent a group at particularly high risk for SCD [17]. ICD implantation is often recommended for such patients, particularly those discharged to home while awaiting transplantation. The WCD may be a reasonable noninvasive alternative approach, though data on its use in patients awaiting heart transplantation are limited: In one study of 91 cardiac transplant candidates discharged to home (UNOS Status 1B patients receiving home inotrope infusion), among whom 25 had an ICD and 13 used a WCD, two patients died suddenly at home, one who was not wearing his WCD and another who declined use of a WCD [39]. In the 13 patients wearing the WCD, three asymptomatic events occurred with one shock delivered for rapid atrial fibrillation. In a German study of 354 WCD patients, 6 percent wore the WCD while awaiting heart transplantation, with an incidence of ventricular arrhythmias of 11 percent [4]. In the WEARIT study of WCD use in 177 patients with NYHA functional class III or IV heart failure (not listed for heart transplant but with similar functional status to patients who might be listed for heart transplant), one patient received two successful defibrillations [3]. https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 13/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate In a registry of 121 patients prescribed a WCD as a bridge to heart transplantation, seven patients (6 percent) received appropriate shocks over an average use of 127 days (median 39 days) [40]. The International Society for Heart and Lung Transplantation Guidelines state as a class I recommendation that an ICD or WCD should be provided for status 1B patients who are discharged home given that the wait for transplantation remains significant [41]. The WCD may also be appropriate in patients whose anticipated waiting time to transplant is short (ie, blood types A and B) if an ICD is not already present [41]. WCD in patients with VADs The role for ICD and WCD therapy remains unclear in patients with ventricular assist devices (VADs). With VADs, circulatory support is often adequate even in the event of a ventricular tachyarrhythmia. However, one study reported the presence of an ICD was associated with improved survival in patients undergoing VAD support [42]. Whether the WCD could impart similar survival benefits in patients awaiting transplantation with VAD support has yet to be studied. (See "Treatment of advanced heart failure with a durable mechanical circulatory support device".) WCD use in hemodialysis patients Patients with end-stage kidney disease on hemodialysis are at high risk for SCD, but they are also at higher risk for infection, bleeding, and other complications of implantable device therapies, which may lead to underutilization of ICDs. Although the arrhythmia event rates for patients on hemodialysis wearing a WCD are not published, a study of 75 hemodialysis patients who experienced sudden cardiac arrest events while wearing a WCD reported that 78.6 percent of events were due to VT/VF and 21.4 percent were due to asystole [43]. Survival was 71, 51, and 31 percent at 24 hours, 30 days, and one year, respectively, which was reported to be improved compared with historical controls. LIMITATIONS AND PRECAUTIONS In spite of its overall efficacy for terminating life-threatening ventricular arrhythmias, the WCD does have some limitations. The device must be fitted to each patient, and some patients may not have a good fit due to body habitus. Its external nature does not allow for pacemaker functionality and introduces a component of patient interaction and compliance as well as the potential for external noise leading to inappropriate shocks. The device must be removed for bathing, but no protection is afforded while the device is off. Therefore, it is advisable that caregivers or other persons be nearby during these periods when the WCD is not worn. Comfort may also be an issue for some patients due to the size and weight of the device. https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 14/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate Patient size The WCD can only be fitted on patients with a chest circumference less than 57 inches (144 cm); therefore, it may not be an option for morbidly obese patients. However, among 574 patients from the WCD registry, which included normal weight (body mass index [BMI] between 18 and 24.9; n = 157), overweight (BMI between 25 and 29.9; n = 186), and obese (BMI 30; n = 231, including 55 with BMI 40) patients who experienced 623 ventricular tachycardia/ventricular fibrillation (VT/VF) events while wearing the WCD, the median daily wear time (21 hours), first shock success rate (93 to 94 percent), and 24-hour post-shock survival (92 to 94 percent) were similar across all BMI groups [44]. There are also limited data on WCD use in children, in whom the device may not fit properly if the child is small. (See 'Use of the WCD in children' below.) Lack of pacemaker functionality Because of its external nature, the WCD is not able to function as a pacemaker, which limits the possible therapies it can deliver in two ways: The WCD cannot deliver pacing therapies to treat bradycardia or asystole. In the German study, two patients developed asystole while wearing the WCD, and both patients died [4]. In the US post-approval registry study, 23 of 3569 patients (0.6 percent) experienced asystole, with an associated mortality of 74 percent [5]. In the post-myocardial infarction (MI) registry of 8453 patients, 34 died (0.4 percent) with bradycardia-asystole events [6]. In the WEARIT-II registry, 6 of 2000 patients (0.3 percent) had asystole, and all three of the deaths that occurred while wearing the WCD during the study (0.2 percent) occurred following an asystole event [7]. The WCD cannot provide antitachycardia pacing for VT, which can reduce patient shocks, when effective. When considering these limitations, an implantable cardioverter-defibrillator (ICD) would be preferred, if indicated, in a patient who is pacemaker-dependent or in whom antitachycardia pacing is desired as the initial therapy for VT. (See "Implantable cardioverter-defibrillators: Overview of indications, components, and functions".) Use in patients with a preexisting permanent pacemaker With certain precautions, the WCD can be used in patients with a preexisting permanent pacemaker. The manufacturer recommends that the device not be worn if the pacemaker stimulus artifact exceeds 0.5 millivolts, as this may mask underlying ventricular fibrillation and prevent appropriate device therapy. Conversely, the VT threshold of the WCD should be set higher than the maximal pacing rate to avoid an inappropriate WCD shock due to oversensing paced beats. Following any WCD shock, the patient's pacemaker should be interrogated to ensure that there has been no damage to the pacemaker or any changes in the pacemaker setting. https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 15/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate Inappropriate shocks Both the WCD and the ICD may inappropriately deliver shocks due to electronic noise, device malfunction, or detection of supraventricular tachycardia above the preprogrammed rate criteria. Studies of ICDs have reported an incidence of inappropriate shock of 0.2 to 2.3 percent of patients per month [32,45-51]. Comparable rates of inappropriate shocks have been reported among users of the WCD, with rates ranging from 0.5 to 1.4 percent per month [3-7]. In a systematic review and meta-analysis which included 33,242 patients from 28 studies (the randomized VEST trial and 27 nonrandomized studies), inappropriate shocks occurred at a rate of 2 per 100 persons over three months (0.67 percent per month) [18]. Inappropriate shocks with a WCD can be potentially reduced due to the ability to abort shocks while awake by pressing response buttons. (See 'Avoiding inappropriate shocks' above.) Patient compliance and complaints Patients may not comply with wearing the WCD for a variety of reasons, chief among them device size and weight, skin rash, itching, and problems sleeping. However, efficacy of the WCD in the prevention of sudden cardiac death is highly dependent on patient compliance and appropriate use of the device [3-5,7]. In the WEARIT/BIROAD study, 23 percent of the 289 subjects withdrew before reaching a study endpoint, with size and weight of the monitor being the most frequent reason for withdrawal [3]. Skin rash and/or itching were also reported by 6 percent of patients. In the US postmarket study, median and mean daily use were 21.7 hours and 19.9 hours, respectively [5]. Daily use was >90 percent (>21.6 hours) in 52 percent of patients and >80 percent (>19.2 hours) in 71 percent of patients. Longer duration of monitoring correlated with higher compliance rates. WCD use was stopped prematurely in 14 percent, primarily because of comfort issues related to the size and weight of the WCD. In the WEARIT-II registry, median daily use was 22.5 hours [7]. Similar to the US postmarket study, longer duration of monitoring (15 or more days) was associated with higher rates of compliance. In the nationwide German cohort, median daily use among 6043 patients was 23.1 hours for a median of 59 days [8]. Lower rates of compliance were reported in a study of 147 patients from two academic medical centers in Boston, in which median daily use was 21 hours for a median of 50 days [52]. In an international registry of 708 patients, appropriate WCD shock was documented in 2.2 percent, inappropriate shock in 0.5 percent, and mean wear time was 21.2 4.3 hours/day (and was lower in younger patients) [53]. https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 16/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate In the WEARIT-France cohort study of 1157 patients, median daily wear time was 23.4 hours, with younger age associated with lower compliance [54]. In the VEST randomized trial after MI, median and mean daily wear times were only 18 and 14 hours, respectively, with over half of patients assigned to the WCD not wearing it by the end of the 90-day study [24]. Among 48 total deaths in the WCD group, only 12 patients (25 percent) were wearing the WCD at the time of death. In the as-treated and per-protocol analysis of VEST [25], better WCD compliance was predicted by cardiac arrest during index MI, higher creatinine, diabetes, prior heart failure, ejection fraction 25 percent, Polish enrolling center, and number of WCD alarms. Worse compliance was associated with being divorced, Asian race, higher body mass index, prior PCI, or any WCD shock. In a study of 130 patients with an ICD and fitted with an ASSURE WCD programmed for detection only and followed for 30 days, median daily use was high at 23 hours [11]. Rates of WCD discontinuation appear similar to reported rates of compliance with other prescribed therapies. One study reported that 15 percent of patients stop using aspirin, ACE inhibitors and beta-blockers within 30 days of a MI [55]. Improved compliance and acceptance of the WCD may be seen with newer devices, which are 40 percent smaller in size and weight or which offer multiple sizes and gender-specific fitting. USE OF THE WCD IN CHILDREN In December 2015, the US Food and Drug Administration (FDA) approved the WCD for use in children, although the WCD was used off-label prior to FDA approval [56]. As such, there are relatively few peer-reviewed publications documenting experience with the WCD in children [57- 59]. In a retrospective review of all patients <18 years of age who were prescribed the WCD between 2009 and 2016 (n = 455 patients), median duration of use was 33 days and wear time 20.6 hours [59]. Eight patients received at least one shock (seven episodes of ventricular tachycardia/ventricular fibrillation [VT/VF] in six patients, two inappropriate shocks due to oversensing), with four of the seven episodes of VT/VF terminated with a single shock and all seven episodes successfully terminated by the WCD. There were seven deaths (1.5 percent); none were wearing the WCD at the time of death. Children require special attention to assure compliance and correct fitting for optimal use. A variety of device harness sizes are available, but the smallest option may still be too large for https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 17/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate smaller children. Additional data on clinical efficacy, compliance, and complications should be collected in children as WCD use increases. SOCIETY GUIDELINE LINKS Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Arrhythmias in adults" and "Society guideline links: Inherited arrhythmia syndromes" and "Society guideline links: Ventricular arrhythmias" and "Society guideline links: Cardiac implantable electronic devices".) SUMMARY AND RECOMMENDATIONS Introduction The wearable cardioverter-defibrillator (WCD) is an external device capable of automatic detection and defibrillation of ventricular tachycardia (VT) or ventricular fibrillation (VF) ( picture 1). In cases where the need for an implantable cardioverter- defibrillator (ICD) is felt to be temporary or implantation of the ICD must be deferred, a WCD may be an acceptable alternative approach for the prevention of sudden cardiac death (SCD). (See 'Description and functions of the WCD' above.) Device functions In addition to delivering therapeutic shocks for life-threatening ventricular arrhythmias, the WCD stores data regarding arrhythmias, patient compliance with the device, and noise or interference with its proper functioning. Arrhythmia recordings from the WCD are available for clinician review once stored data are transmitted to the manufacturer's network. (See 'Storage of ECGs and compliance data' above.) Efficacy When worn properly, the WCD appears to be as effective as an ICD for the termination of VT and VF, with successful shocks occurring in nearly 100 percent of cases. In addition, inappropriate shock rates from the WCD appear to be comparable to and in some studies lower than those reported for ICDs. (See 'Efficacy in terminating VT/VF' above and 'Inappropriate shocks' above.) Indications The WCD is an option as temporary therapy for select patients with a high risk for SCD: Among patients with left ventricular ejection fraction (LVEF) 35 percent who are less than 40 days post-myocardial infarction (MI), we discuss the potential benefits and risks of WCD use and offer it to highly motivated patients with NYHA functional class II or III, or LVEF <30 percent and in NYHA class I, as these patients would be candidates for ICD https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 18/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate implantation after 40 days. Reevaluation of LVEF should occur one to three months after the MI. If LVEF remains 35 percent on follow-up assessment, despite appropriate medical therapy, ICD implantation is indicated and should be considered. (See 'Early post-MI patients with LV dysfunction' above and "Primary prevention of sudden cardiac death in patients with cardiomyopathy and heart failure with reduced LVEF".) Among patients with LVEF 35 percent who have undergone coronary revascularization with coronary artery bypass graft (CABG) surgery in the past three months, we offer a WCD to highly motivated patients for primary prevention against SCD. LVEF should be reassessed three months following CABG. If a sustained ventricular tachyarrhythmia has occurred, or if the LVEF remains 35 percent three months after CABG, implantation of an ICD is usually indicated. (See 'Patients with LV dysfunction early after coronary revascularization' above and "Secondary prevention of sudden cardiac death in heart failure and cardiomyopathy" and "Primary prevention of sudden cardiac death in patients with cardiomyopathy and heart failure with reduced LVEF".) In selected patients with severe but potentially reversible cardiomyopathy, such as tachycardia- or myocarditis-associated cardiomyopathy, the WCD may be useful for the prevention of SCD due to ventricular arrhythmias while awaiting improvement in LV function, ICD implantation, or if needed, cardiac transplantation. (See 'Newly diagnosed nonischemic cardiomyopathy' above.) Patients with severe heart failure awaiting heart transplantation represent a group at particularly high risk for SCD in whom ICD implantation is often recommended. The WCD may be a reasonable noninvasive alternative approach, particularly for patients whose anticipated waiting time to transplant is short if an ICD is not already present. (See 'Bridge to heart transplant' above.) Some patients with an indication for an ICD may require a delay in ICD implantation due to comorbid conditions (ie, infection, recovery from surgery, lack of vascular access). Additionally, some patients who have an ICD need it removed due to infection. In such patients, the WCD may provide protection against ventricular tachyarrhythmias until an ICD can be implanted or reimplanted. (See 'Bridge to indicated or interrupted ICD therapy' above.) Device limitations Limitations of the WCD (compared with a traditional ICD) include the lack of pacemaker functionality, the requirement for patient interaction and compliance, and potential discomfort due to the size and weight of the device. (See 'Limitations and precautions' above.) https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 19/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate Use of UpToDate is subject to the Terms of Use. REFERENCES 1. Sharma PS, Bordachar P, Ellenbogen KA. Indications and use of the wearable cardiac defibrillator. Eur Heart J 2016. 2. Reek S, Geller JC, Meltendorf U, et al. Clinical efficacy of a wearable defibrillator in acutely terminating episodes of ventricular fibrillation using biphasic shocks. Pacing Clin Electrophysiol 2003; 26:2016. 3. Feldman AM, Klein H, Tchou P, et al. Use of a wearable defibrillator in terminating tachyarrhythmias in patients at high risk for sudden death: results of the WEARIT/BIROAD. Pacing Clin Electrophysiol 2004; 27:4. 4. Klein HU, Meltendorf U, Reek S, et al. Bridging a temporary high risk of sudden arrhythmic death. Experience with the wearable cardioverter defibrillator (WCD). Pacing Clin Electrophysiol 2010; 33:353. 5. Chung MK, Szymkiewicz SJ, Shao M, et al. Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival. J Am Coll Cardiol 2010; 56:194. 6. Epstein AE, Abraham WT, Bianco NR, et al. Wearable cardioverter-defibrillator use in patients perceived to be at high risk early post-myocardial infarction. J Am Coll Cardiol 2013; 62:2000. 7. 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J Cardiovasc Electrophysiol 2022; 33:831. 12. Moss AJ, Hall WJ, Cannom DS, et al. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. Multicenter https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 20/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate Automatic Defibrillator Implantation Trial Investigators. N Engl J Med 1996; 335:1933. 13. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002; 346:877. 14. Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med 2005; 352:225. 15. Al-Khatib SM, Friedman P, Ellenbogen KA. Defibrillators: Selecting the Right Device for the Right Patient. Circulation 2016; 134:1390. 16. 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JACC Clin Electrophysiol 2017; 3:243. 20. Solomon SD, Zelenkofske S, McMurray JJ, et al. Sudden death in patients with myocardial infarction and left ventricular dysfunction, heart failure, or both. N Engl J Med 2005; 352:2581. 21. Piccini JP, Al-Khatib SM, Hellkamp AS, et al. Mortality benefits from implantable cardioverter- defibrillator therapy are not restricted to patients with remote myocardial infarction: an analysis from the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). Heart Rhythm 2011; 8:393. 22. Hohnloser SH, Kuck KH, Dorian P, et al. Prophylactic use of an implantable cardioverter- defibrillator after acute myocardial infarction. N Engl J Med 2004; 351:2481. 23. Steinbeck G, Andresen D, Seidl K, et al. Defibrillator implantation early after myocardial infarction. N Engl J Med 2009; 361:1427. 24. Olgin JE, Pletcher MJ, Vittinghoff E, et al. Wearable Cardioverter-Defibrillator after Myocardial Infarction. 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Prediction of long-term mortality after percutaneous coronary intervention in older adults: results from the National Cardiovascular Data Registry. Circulation 2012; 125:1501. 29. Shahian DM, O'Brien SM, Sheng S, et al. Predictors of long-term survival after coronary artery bypass grafting surgery: results from the Society of Thoracic Surgeons Adult Cardiac Surgery Database (the ASCERT study). Circulation 2012; 125:1491. 30. Zishiri ET, Williams S, Cronin EM, et al. Early risk of mortality after coronary artery revascularization in patients with left ventricular dysfunction and potential role of the wearable cardioverter defibrillator. Circ Arrhythm Electrophysiol 2013; 6:117. 31. Verdino RJ. The wearable cardioverter-defibrillator: lifesaving attire or "fashion faux pas?". J Am Coll Cardiol 2010; 56:204. 32. Kadish A, Dyer A, Daubert JP, et al. Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy. N Engl J Med 2004; 350:2151. 33. Makati KJ, Fish AE, England HH, et al. Equivalent arrhythmic risk in patients recently diagnosed with dilated cardiomyopathy compared with patients diagnosed for 9 months or more. Heart Rhythm 2006; 3:397. 34. Singh M, Wang NC, Jain S, et al. Utility of the Wearable Cardioverter-Defibrillator in Patients With Newly Diagnosed Cardiomyopathy: A Decade-Long Single-Center Experience. J Am Coll Cardiol 2015; 66:2607. 35. Barsheshet A, Kutyifa V, Vamvouris T, et al. Study of the wearable cardioverter defibrillator in advanced heart-failure patients (SWIFT). J Cardiovasc Electrophysiol 2017; 28:778. 36. Salehi N, Nasiri M, Bianco NR, et al. The Wearable Cardioverter Defibrillator in Nonischemic Cardiomyopathy: A US National Database Analysis. Can J Cardiol 2016; 32:1247.e1. 37. Duncker D, K nig T, Hohmann S, et al. Avoiding Untimely Implantable Cardioverter/Defibrillator Implantation by Intensified Heart Failure Therapy Optimization https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 22/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate Supported by the Wearable Cardioverter/Defibrillator-The PROLONG Study. J Am Heart Assoc 2017; 6. 38. Saltzberg MT, Szymkiewicz S, Bianco NR. Characteristics and outcomes of peripartum versus nonperipartum cardiomyopathy in women using a wearable cardiac defibrillator. J Card Fail 2012; 18:21. 39. Lang CC, Hankins S, Hauff H, et al. Morbidity and mortality of UNOS status 1B cardiac transplant candidates at home. J Heart Lung Transplant 2003; 22:419. 40. Opreanu M, Wan C, Singh V, et al. Wearable cardioverter-defibrillator as a bridge to cardiac transplantation: A national database analysis. J Heart Lung Transplant 2015; 34:1305. 41. Gronda E, Bourge RC, Costanzo MR, et al. Heart rhythm considerations in heart transplant candidates and considerations for ventricular assist devices: International Society for Heart and Lung Transplantation guidelines for the care of cardiac transplant candidates 2006. J Heart Lung Transplant 2006; 25:1043. 42. Cantillon DJ, Tarakji KG, Kumbhani DJ, et al. Improved survival among ventricular assist device recipients with a concomitant implantable cardioverter-defibrillator. Heart Rhythm 2010; 7:466. 43. Wan C, Herzog CA, Zareba W, Szymkiewicz SJ. Sudden cardiac arrest in hemodialysis patients with wearable cardioverter defibrillator. Ann Noninvasive Electrocardiol 2014; 19:247. 44. Wan C, Szymkiewicz SJ, Klein HU. The impact of body mass index on the wearable cardioverter defibrillator shock efficacy and patient wear time. Am Heart J 2017; 186:111. 45. Sweeney MO, Wathen MS, Volosin K, et al. Appropriate and inappropriate ventricular therapies, quality of life, and mortality among primary and secondary prevention implantable cardioverter defibrillator patients: results from the Pacing Fast VT REduces Shock ThErapies (PainFREE Rx II) trial. Circulation 2005; 111:2898. 46. Poole JE, Johnson GW, Hellkamp AS, et al. Prognostic importance of defibrillator shocks in patients with heart failure. N Engl J Med 2008; 359:1009. 47. Daubert JP, Zareba W, Cannom DS, et al. Inappropriate implantable cardioverter-defibrillator shocks in MADIT II: frequency, mechanisms, predictors, and survival impact. J Am Coll Cardiol 2008; 51:1357. 48. Klein RC, Raitt MH, Wilkoff BL, et al. Analysis of implantable cardioverter defibrillator therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. J Cardiovasc Electrophysiol 2003; 14:940. 49. Wilkoff BL, Ousdigian KT, Sterns LD, et al. A comparison of empiric to physician-tailored programming of implantable cardioverter-defibrillators: results from the prospective https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 23/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate randomized multicenter EMPIRIC trial. J Am Coll Cardiol 2006; 48:330. 50. Wilkoff BL, Williamson BD, Stern RS, et al. Strategic programming of detection and therapy parameters in implantable cardioverter-defibrillators reduces shocks in primary prevention patients: results from the PREPARE (Primary Prevention Parameters Evaluation) study. J Am Coll Cardiol 2008; 52:541. 51. Wilkoff BL, Hess M, Young J, Abraham WT. Differences in tachyarrhythmia detection and implantable cardioverter defibrillator therapy by primary or secondary prevention indication in cardiac resynchronization therapy patients. J Cardiovasc Electrophysiol 2004; 15:1002. 52. Leyton-Mange JS, Hucker WJ, Mihatov N, et al. Experience With Wearable Cardioverter- Defibrillators at 2 Academic Medical Centers. JACC Clin Electrophysiol 2018; 4:231. 53. El-Battrawy I, Kovacs B, Dreher TC, et al. Real life experience with the wearable cardioverter- defibrillator in an international multicenter Registry. Sci Rep 2022; 12:3203. 54. Garcia R, Combes N, Defaye P, et al. Wearable cardioverter-defibrillator in patients with a transient risk of sudden cardiac death: the WEARIT-France cohort study. Europace 2021; 23:73. 55. Ho PM, Spertus JA, Masoudi FA, et al. Impact of medication therapy discontinuation on mortality after myocardial infarction. Arch Intern Med 2006; 166:1842. 56. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm466852.htm (Access ed on December 21, 2015). 57. Everitt MD, Saarel EV. Use of the wearable external cardiac defibrillator in children. Pacing Clin Electrophysiol 2010; 33:742. 58. Collins KK, Silva JN, Rhee EK, Schaffer MS. Use of a wearable automated defibrillator in children compared to young adults. Pacing Clin Electrophysiol 2010; 33:1119. 59. Spar DS, Bianco NR, Knilans TK, et al. The US Experience of the Wearable Cardioverter- Defibrillator in Pediatric Patients. Circ Arrhythm Electrophysiol 2018; 11:e006163. Topic 15824 Version 35.0 https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 24/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate GRAPHICS Wearable cardioverter-defibrillator The wearable cardioverter-defibrillator consists of a vest incorporating two defibrillation electrodes and four sensing electrocardiographic electrodes connected to a waist unit containing the monitoring and defibrillation electronics. Reproduced with permission from: ZOLL Medical Corporation. Copyright 2012. All rights reserved. Graphic 60103 Version 3.0 https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 25/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate Electrocardiogram sensing (A) Five ECG electrodes are positioned circumferentially around the torso at the level of the subxiphoid process, labelled left front (LF), right front (RF), left back (LB), right back (RB), and right leg drive (RLD). Red dashed arrows represent the four differential ECG vectors derived using RLD as a ground reference. (B) Garment interior depicting five embedded, cushioned ECG electrodes and defibrillation pads (two posterior and one anterior). ECG: electrocardiogram. From: Poole JE, Gleva MJ, Birgersdotter-Green U, et al. A wearable cardioverter de brillator with a low false alarm rate. J Cardiovasc Electrophysiol 2022; 33:831. https://onlinelibrary.wiley.com/doi/10.1111/jce.15417. Copyright 2022 Wiley Periodicals, LLC. Reproduced with permission of John Wiley & Sons Inc. This image has been provided by or is owned by Wiley. Further permission is needed before it can be downloaded to PowerPoint, printed, shared or emailed. Please contact Wiley's permissions department either via email: permissions@wiley.com or use the RightsLink service by clicking on the 'Request Permission' link accompanying this article on Wiley Online Library (https://onlinelibrary.wiley.com/). Graphic 140856 Version 1.0 https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 26/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate ASSURE WCD System noise management The A WCD employs three levels of protection to achieve a low false alarm rate due to noise. Level 1 (blue) minimize noise. Level 2 (red) detect and remove noise that does occur. Level 3 (yellow) allow time for remaining noise to subside before alarming. A-WCD: ASSURE WCD System; VT: ventricular tachycardia; VF: ventricular fibrillation; ECG: electrocardiogram. From: Poole JE, Gleva MJ, Birgersdotter-Green U, et al. A wearable cardioverter de brillator with a low false alarm rate. J Cardiovasc Electrophysiol 2022; 33:831. https://onlinelibrary.wiley.com/doi/10.1111/jce.15417. Copyright 2022 Wiley Periodicals, LLC. Reproduced with permission of John Wiley & Sons Inc. This image has been provided by or is owned by Wiley. Further permission is needed before it can be downloaded to PowerPoint, printed, shared or emailed. Please contact Wiley's permissions department either via email: permissions@wiley.com or use the RightsLink service by clicking on the 'Request Permission' link accompanying this article on Wiley Online Library (https://onlinelibrary.wiley.com/). Graphic 140843 Version 1.0 https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 27/28 7/6/23, 1:46 PM Wearable cardioverter-defibrillator - UpToDate Contributor Disclosures Mina K Chung, MD No relevant financial relationship(s) with ineligible companies to disclose. Richard L Page, MD No relevant financial relationship(s) with ineligible companies to disclose. Nisha Parikh, MD, MPH No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/wearable-cardioverter-defibrillator/print 28/28