Wearable Defibrillator Research Articles

Primary prevention of sudden cardiac death through a wearable cardioverter-defibrillator

Nowadays, the implantable cardioverter-defibrillator is the gold standard for the prevention of sudden cardiac death due to tachyarrhythmias. However, its use is not free from short and long-term risks. In the last years, the wearable cardioverter-defibrillator (WCD) has become a widespread option for patients who need a safe and reversible protection against ventricular tachyarrhythmias. Notwithstanding this, its everyday application is restricted by several limitations, including the risk of inappropriate shocks, the device size and the need for strict compliance of both patients and caregivers. In this review, we report the most relevant literature data on WCD usage along with the main fields of applications and future perspectives.

突然死予防の最新デバイス―Wearable Cardioverter Defibrillator―

突然死予防の最新デバイス―Wearable Cardioverter Defibrillator―

Quinine Syncope Diagnosed by Life Vest

We present the case of a patient with ischemic cardiomyopathy using quinine as a remedy for leg cramps. A wearable cardioverter defibrillator (WCD) (LifeVest, Zoll Medical Corporation) recorded a sustained episode of polymorphic ventricular tachycardia resulting in syncope. Electrolyte concentrations were normal while QT interval was prolonged which improved after cessation of quinine and grapefruit juice.

Wearable sensors in syncope management.

Syncope is a common disorder with a lifetime prevalence of about 40%. Implantable cardiac electronic devices, including implantable loop recorders (ILR) and implantable cardioverter-defibrillators (ICD), are well established in syncope management. However, despite the successful use of ILR and ICD, diagnosis and therapy still remain challenging in many patients due to the complex hemodynamic interplay of cardiac and vascular adaptations during impending syncopes. Wearable sensors might overcome some limitations, including misdiagnosis and inappropriate defibrillator shocks, because a variety of physiological measures can now be easily acquired by a single non-invasive device at high signal quality. In neurally-mediated syncope (NMS), which is the most common cause of syncope, advanced signal processing methodologies paved the way to develop devices for early syncope detection. In contrast to the relatively benign NMS, in arrhythmia-related syncopes immediate therapeutical intervention, predominantly by electrical defibrillation, is often mandatory. However, in patients with a transient risk of arrhythmia-related syncope, limitations of ICD therapy might outweigh their potential therapeutic benefits. In this context the wearable cardioverter-defibrillator offers alternative therapeutical options for some high-risk patients. Herein, we review recent evidence demonstrating that wearable sensors might be useful to overcome some limitations of implantable devices in syncope management.

Abstract 12637: Utility of the Wearable Cardioverter-Defibrillator for Patients With Newly Diagnosed Non-Ischemic Cardiomyopathy?

Introduction: The wearable cardioverter-defibrillator (WCD) is approved for prevention of sudden cardiac death in patients with newly diagnosed cardiomyopathy and LVEF < 35% who do not yet meet criteria for implantation of an implantable cardioverter-defibrillator (ICD). While there are some data supporting WCD use in patients with ischemic cardiomyopathy (ICM), data in patients with nonischemic cardiomyopathy (NICM) are lacking. Methods: This was a retrospective review of outcomes for all NICM patients prescribed a WCD at a large tertiary academic center from 6/2004 - 1/2014 for a newly diagnosed cardiomyopathy and no prior sustained ventricular arrhythmia. During this time period, 454 patients were prescribed a WCD, of whom we excluded 161 patients with ICM. Results: The 183 (40%) patients with NICM consisted of 70% men, aged 57 +/- 15 years old, with mean EF 23% +/- 8% and LV end-diastolic dimension 4.5 +/- 2.8 cm. DM and HTN were prevalent (20% and 51%, respectively). At NICM diagnosis, 21% had LBBB and 36% had known history of AF. Patients wore the WCD for 13,124 patient-days, each averaging 72 +/- 55 days and with fairly high compliance (18.3 +/- 5.7 hours/day). Medication use consisted of 90% beta-blockers, 88% ACE inhibitors, 85% diuretics, 16% digoxin, and 17% anti-arrhythmic drugs. NSVT was documented in 42% of patients prior to WCD prescription. During follow-up, 60 (33%) patients improved LVEF to > 35%, obviating an indication for ICD implantation, whereas 79 (43%) patients received an ICD. The remainder died (n=17), were lost to follow-up (n=20), refused ICD implant (n=5), or are still wearing the WCD (n=2). No appropriate WCD shocks were delivered in any NICM patient, yet 3 inappropriate shocks were delivered (1.6%). Based on estimated rental costs provided by the manufacturer, the total cost of WCD use in this population was $1,449,360. Conclusions: In this large, tertiary care center registry of patients with newly recognized NICM, no patient received an appropriate shock from the WCD whereas several inappropriate shocks were delivered, despite nearly one-half of patients having documented significant ventricular ectopy. Given the significant expense and inconvenience of the WCD, its use in this population requires prospective study.

Abstract 16255: Wearable Cardioverter Defibrillator Treatment Characteristics and Outcomes in Recent Myocardial Infarction Patients With Heart Failure

Introduction: Previous studies report patients (pts) with acute myocardial infarction (MI) complicated by heart failure (HF) have poorer outcomes than non-ischemic HF pts. We determined the clinical and arrhythmia characteristics and outcomes in recent (< 40 days) MI pts with HF versus non-ischemic (NICM) HF pts treated by the wearable cardioverter defibrillator (WCD). Methods: WCD pts with a medical history of HF treated for VT or VF between 1/2007 and 11/2013 were identified from the manufacturer-maintained registry. Pts were classified as recent MI if they were identified as having a “recent MI with ejection fraction (EF) ≤ 35%” or given an ICD-9 diagnostic code of 410.xx (acute MI). Pts were classified as non-ischemic if they had no epicardial coronary vessels with ≥ 75% stenosis, no history of myocardial infarction, and no coronary revascularization. Data were reviewed for demographics, ECG recordings, and 24-hour survival. Electrical storm was defined as 3 or more unique VT/VF events requiring WCD therapy over a 24-hour time period. Results: Total of 346 pts met the study criteria, with 56% classified as recent MI with HF (MI-HF). MI-HF group was more likely to have risk factors for ischemic disease such as being older, male, hypertensive, diabetic, etc. (Table). The mean difference in EF between the two groups was less than 5%. MI-HF pts were 1.7 times more likely to be in VT versus VF at initial shock and 2.1 times more likely to have an electrical storm. Conversion of VT/VF events to slower rhythms by WCD treatment shock was 98% or greater in both groups. 24-hour post-treatment survival was 92% for all pts, with no difference between the two groups. CONCLUSIONS: Recent MI pts with HF who were treated by the WCD were likely to be older and male, with risk factors for ischemic disease. In addition, MI-HF pts exhibited increased incidence of VT versus VF events and electrical storm. The WCD was effective in terminating arrhythmic events with a high post-treatment survival in both groups.

Abstract 18973: Left Ventricular Function Improvement After Recent MI in Patients Using a Wearable Cardioverter Defibrillator

Introduction: The wearable cardioverter defibrillator (WCD) has been used to protect AMI patients with reduced LVEF (≤35%) until ICD evaluation is recommended. The rate of EF improvement (e.g. EF>35%) over the initial 8-12 weeks after AMI has not been reported. METHODS: The manufacturer-maintained registry was searched for AMI patients who received a WCD shock for VT/VF between 05/2008 and 02/2013. The treated group was matched (1: ~4) with event-free WCD patients by ICD-9 code (410.*), gender, age and prescription date. Chart notes were reviewed for clinical characteristics. Follow-up was assessed through the registry and Social Security Death Master File. RESULTS: There were 992 (age=63±12, female=20.2%) AMI patients included in the final analysis, 206 treated by WCD and 786 event-free patients. Median follow-up was 334 days. Mean length of WCD use was 67±506 (median=38) days. Subgroup clinical characteristics are presented in Table 1. In the event-free group, 289 (38.9%) patients showed EF improvement to >35%. Nine (4.5%) in the treated group continued wearing the WCD until EF recovery, while 125 (60.7%) received ICD. Absence of recorded heart failure and/or diabetes were associated with LVEF recovery (p<.0001). CONCLUSION: In our study, almost 40% of AMI patients with initial EF ≤35% had EF improvement in two months. The EF recovery group had lower rates of heart failure and diabetes. WCD allows time for left ventricular function recovery in low EF post MI patients, optimizing ICD implantation decisions.

Abstract 17506: A Young Man with a Great Fall: Putting the Pieces Together

A 35 year-old-male with hypertension and schizoaffective disorder presented with a first episode of non-prodromal syncope and traumatic fall resulting in a mandibular fracture. Physical examination revealed orthostatic tachycardia, normal cardiovascular examination, and no abnormalities with carotid sinus massage. Electrocardiogram showed NSR at 66 bpm, a single PVC, QTc interval 493 ms, and abnormal ST-T wave contour in V2-V3. Laboratory evaluation revealed normal electrolytes, mildly elevated troponin (0.763), and no leukocytosis. Postural orthostatic tachycardia syndrome was considered unlikely given that syncope did not occur after prolonged standing, and that his use of trazodone and risperidone can both cause orthostatic tachycardia. Transthoracic echocardiography (TTE) revealed decreased systolic function (EF 45%), paradoxical septal motion, normal LV wall thickness, and no valvular disease. Cardiac MRI showed moderate biventricular systolic dysfunction, LVEF 43%, RVEF 33%, mild 4-chamber dilatation, and a small pericardial effusion. Mild T2 hyperintensity in the mid-ventricular septum and anteroseptum, and scattered foci of patchy delayed gadolinium enhancement within the mid-anteroseptal, anterior and anterolateral LV segments were consistent with acute myocarditis. The reported prevalence of myocarditis among patients with sudden death is highly variable and ranges from 2-42%. Various types of myocarditis are associated with arrhythmias, including lymphocytic myocarditis which was the likely diagnosis in our patient. Despite lack of guideline recommendations, we opted to protect our patient with a wearable cardioverter-defibrillator given case reports of successful use for recurrent malignant arrhythmias in myocarditis. Follow-up TTE two months later was normal with EF 60%. Although syncope in the younger population is often appropriately attributed to a neurally-mediated etiology, the current case highlights the need for clinicians to be attuned to the possibility of subclinical myocarditis causing malignant arrhythmias in this setting, in which case the patient may be at risk for recurrent arrhythmia and sudden death and may benefit from the use of a wearable cardioverter-defibrillator.

Risk for ventricular fibrillation in peripartum cardiomyopathy with severely reduced left ventricular function-value of the wearable cardioverter/defibrillator.

The true incidence of life-threatening ventricular tachyarrhythmic events and the risk of sudden cardiac death in the early stage of peripartum cardiomyopathy (PPCM) are still unknown. We aimed to assess the usefulness of the wearable cardioverter/defibrillator (WCD) to bridge a potential risk for life-threatening arrhythmic events in patients with early PPCM, severely reduced left ventricular ejection fraction (LVEF) and symptoms of heart failure. Twelve consecutively admitted women with PPCM were included in this single-centre, prospective observational study between September 2012 and September 2013. Patients with LVEF ≤35% were considered to use the WCD for 3 months or even 6 months when considered necessary for LVEF recovery. Nine of the 12 women had a severely reduced LVEF (mean 18.3%) at the time of study enrollment; seven women received a WCD, while two patients refused to wear a WCD. During a median WCD follow-up of 81 days (range 25-345 days), we observed a total of four events of ventricular fibrillation with appropriate and successful WCD shocks in three of the seven women receiving a WCD. No syncope or sudden arrhythmic deaths occurred in women not using the WCD during a median follow-up of 12 months (range 5-15 months). All women showed impressive improvement of LVEF during follow-up. PPCM patients with severely reduced LVEF have an elevated risk for ventricular tachyarrhythmias early after diagnosis. Therefore, use of the WCD should be considered in all women with early-stage PPCM and severely reduced LVEF during the first 6 months after initiation of heart failure therapy.

Bridging to Recovery: Experience with the Wearable Cardioverter Defibrillator in Patients with Tachycardia-Induced Cardiomyopathy

Tachycardia-induced cardiomyopathy (TIC) is considered a reversible form of left ventricular dysfunction. Although patients with TIC are at high risk of sudden cardiac arrest, once the heart rate is under control rapid clinical improvement is expected. Hence, an implantable defibrillator (ICD) may not be an optimal clinical solution before a permanent risk is identified. Moreover, the tachycardia burden (usually of supraventricular origin) makes TIC patients more susceptible to false shocks. Previous studies have reported the effectiveness of a wearable cardioverter defibrillator (WCD) in terminating life-threatening ventricular arrhythmias (VAs).

Electrocardiographic characteristics of ventricular fibrillation in patients with a wearable cardioverter defibrillator

Introduction: Surface electrocardiographic (ECG) changes in ventricular fibrillation (VF) waveform characteristics at its onset in patients experiencing cardiac arrest have not been quantified. The amplitude spectral area (AMSA) method was developed to analyze surface ECG VF amplitude and frequency characteristics and contains information related to VF rotor stability and myocardial viability. We aimed to characterize changes in AMSA at the onset of VF to gain insight into myocardial dynamics in patients with a wearable cardioverter defibrillator (WCD).

Is hands-on defibrillation safe when using insulating gloves? A clinical trial

Introduction: Surface electrocardiographic (ECG) changes in ventricular fibrillation (VF) waveform characteristics at its onset in patients experiencing cardiac arrest have not been quantified. The amplitude spectral area (AMSA)methodwas developed to analyze surface ECG VF amplitude and frequency characteristics and contains information related to VF rotor stability and myocardial viability. We aimed to characterize changes in AMSA at the onset of VF to gain insight into myocardial dynamics in patients with a wearable cardioverter defibrillator (WCD). Methods: Out of 30 patients randomly identified from a manufacturer-maintained registry, 25 patients (14 Male, 11 Female, Age=62±14 yr) were included. Remaining patients experienced either sustained monomorphic ventricular tachycardia or hadmotion artifact, precludingAMSAanalysis. Using theWCDECG, AMSA was calculated as the summed product of frequency and square root of power at that frequency from 2 to 48Hz with a continuous sliding 2.1 s Tukey window. The median time to shock for the WCD is 45 s. AMSA was calculated every 0.5 s and averaged every 1 s for up to 45 s after VF initiation. Results are presented as mean± standard error. Results: At onset of VF, AMSA was 33.6±3.3mVHz which decreased progressively to 23.4±2.2mVHz (p<0.01) after 45 sec of untreated VF (Fig. 1).

Effectiveness of wearable defibrillators: systematic review and quality of evidence.

The objectives of this systematic literature review were to identify all published literature on wearable defibrillators, assess the wearable defibrillator's efficacy and effectiveness in general and among specific patient groups, including post-myocardial infarction, post coronary artery bypass grafting or percutaneous coronary intervention, non-ischemic cardiomyopathy, and ischemic cardiomyopathy, and to evaluate the quality of evidence. The search and synthesis was informed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, and the quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation and the Newcastle Ottawa Scale. A total of thirty-six articles and conference abstracts from thirty-three studies were included in the review. It appears that wearable defibrillator use compared with no defibrillator use reduces the chance of ventricular tachycardia and ventricular fibrillation (VT/VF) associated deaths by an absolute risk reduction of approximately 1 percent, achieved by averting approximately 4/5th of all VT/VF associated deaths. The quality of evidence was low to very low quality, such that our confidence in the reported estimates is weak. To validate beneficial results, further investigation using robust study designs conducted by independent researchers is warranted.

EXPERIENCE WITH WEARABLE CARDIOVERTER-DEFIBRILLATOR IN NON-ISCHEMIC CARDIOMYOPATHY: A NATIONAL DATABASE ANALYSIS

The implantable Cardioverter-defibrillator (ICD) is an effective treatment for patients with persistent, drug-refractory non-ischemic cardiomyopathies (NI-CM) at risk of sudden cardiac death (SCD) due to sustained ventricular arrhythmias (VAs). The wearable Cardioverter-Defibrillator (WCD) is often

Wearable Cardioverter-Defibrillator in a Patient with Left Ventricular Noncompaction/Hypertrabeculation, Coronary Artery Disease, and Polyneuropathy

A 55-year-old Caucasian male with coronary heart disease was admitted because of dyspnea for 4 weeks. Echocardiography showed a dilated left ventricle with an ejection fraction of 34% and apical left ventricular hypertrabeculation/noncompaction with an apical thrombus. Neurologic examination revealed positional tremor and generally reduced tendon reflexes. During 8 weeks, his condition improved under pharmacotherapy. The patient was skeptical about implantable cardioverter-defibrillator (ICD) and expected further improvement from pharmacotherapy. Thus, he received a wearable cardioverter-defibrillator (WCD). We conclude that a WCD might be useful in noncompaction patients in whom improvement of systolic dysfunction is expected or who are skeptical about ICDs.

Usefulness of the wearable cardioverter-defibrillator in patients at high risk for sudden cardiac death.

Wearable cardioverter-defibrillators (WCD) have been available in Japan since April 2014, but their application is still limited. METHODS AND RESULTS: We report 9 patients with a WCD applied between April and September 2014. All patients were at high risk of life-threatening ventricular arrhythmias. During WCD use, 1 patient had sustained ventricular tachycardia and successful shock delivery; 6 (67%) subsequently underwent implantable cardioverter-defibrillator (ICD) therapy, while 2 had no requirement because of reduced risk, and 1 died of heart failure during WCD use. WCD is useful during acute-phase care of high-risk patients, and may help to avoid unnecessary ICD implantation.

Wearable cardioverter defibrillator: A life vest till the life boat (ICD) arrives

It is well established that implantable cardioverter defibrillator (ICD) is a life saving device ensuring protection against life threatening ventricular arrhythmias. But there are certain situations like a recent myocardial infarction where the standard guidelines do not recommend the implantation of an ICD while the patient can still be at a risk of demise due to a life threatening ventricular arrhythmia. There could also be a temporary indication for protection while explanting an infected ICD system. The wearable cardioverter defibrillator (WCD) is a device which comes to the rescue in such situations. In this brief review, we discuss the historical aspects of the development of a WCD, technical aspects as well as the clinical trial data and real world scenario of its use.

Application of ICD guidelines and indications in a community-based academic hospital: a case series-based discussion

BackgroundImplantable cardioverter defibrillators (ICDs) are indeed beneficial in selected patients as evidenced by multiple large randomized controlled trials (RCTs) since 1980. A systematic method for stratification of patients and hospital-wide criteria/guidelines to ascertain appropriate device implantation became necessary.MethodsMajor ICD/CRT (cardiac resynchronization therapy) clinical studies and relevant guidelines were reviewed, and an institution-wide inclusion and exclusion criteria for ICD/CRT was formulated. A retrospective analysis of selected cases was performed to discuss the criteria and special clinical situations.ResultsWe have translated the evolving ICD/CRT studies into a standard of care at our hospital by formulating a standard, practical, and update-to-date ICD inclusion and exclusion criteria. Thirteen cases were selected to represent major indications and contraindications of ICDs in our practice. These cases cover indications of ICD for secondary prevention of sudden cardiac death (SCD), primary prevention of SCD in patients with CHF resulted from either ischemic or non-ischemic cardiomyopathy, as well as for infiltrative cardiomyopathy and inherited conditions. We discussed the application of CRT in patients with CHF associated with prolonged QRS duration. We then covered the potential benefits of ICD with/without CRT in certain special populations of patients that have not been adequately evaluated by currently available RCTs; these include alcoholic, elderly, female, and ESRD/HD patients. Finally, we addressed risks, complications and contraindications of ICD, as well as application of an external wearable defibrillator in AMI, or status post-CABG patient during the mandatory waiting period for an ICD.ConclusionsEstablishment of the ICD/CRT criteria represents a practical translation of emerging CRTs and helps to standardize patient care in our hospital. It also improves cost-effectiveness as well as appropriate utilization of institute and device resources.

Use of external defibrillator jacket to facilitate safe delivery of radiotherapy for lung cancer – A report of two cases

The increasing rate of implantable cardioverter defibrillator (ICD) implantation coupled with shared risk factors between lung cancer and ischemic cardiac disease means that the need for radiotherapy in cardiac device patients is set to become commonplace. We describe two cases referred to our electrophysiology service over a 6-month period. Both had been diagnosed with lung cancer in tissue directly posterior to a previously implanted ICD device. The cases highlight the risks to device function caused by ionizing radiation, the practical difficulties and ethical dilemmas of delivering radiotherapy to cardiac device patients safely and a novel setting for the use of a wearable defibrillator system.

Protection from outpatient sudden cardiac death following ICD removal using a wearable cardioverter defibrillator.

An implantable cardioverter defibrillator (ICD) is effective in preventing sudden cardiac death (SCD). Once an ICD is removed and reimplantation is not feasible, a wearable cardioverter defibrillator (WCD) may be an alternative option. We determined the effectiveness of WCD for SCD prevention in patients who were discharged after ICD removal. A retrospective study was conducted on all WCD (LifeVest, ZOLL, Pittsburgh, PA, USA) patients who underwent ICD removal due to cardiac device infections (CDIs) at two referral centers between January 1, 2005 and December 31, 2009. Clinical characteristics, device information, and WCD data were analyzed. Sudden cardiac arrest was defined as all sustained ventricular tachycardia (VT) and ventricular fibrillation occurring within a single 24-hour period. Ninety-seven patients (mean age 62.8 ± 13.3, male 80.4%) were included in the study. The median duration of antibiotic use was 14.7 days (interquartile range [IQR] 10-30). The median daily WCD use was 20 hours/day and the median length of use was 21 days (IQR 5-47). A total of three patients were shocked by WCD. Two patients had four episodes of sustained VT, successfully terminated by the WCD. A third patient experienced two inappropriate treatments due to oversensitivity of the signal artifact. Three patients experienced sudden death outside the hospital while not wearing the device. Five patients died while hospitalized. WCD can prevent SCD, until ICD reimplantation is feasible in patients who underwent device removals for CDI. However, patient compliance is essential for the effective use of this device.