Wearable cardioverter-defibrillators: A review of evidence and indications

Therapy duration and improvement of ventricular function in de novo heart failure: the Heart Failure Optimization study

BACKGROUND AND AIMS

In patients with de novo heart failure with reduced ejection fraction (HFrEF), improvement of left ventricular ejection fraction (LVEF) is expected to occur when started on guideline-recommended medical therapy. However, improvement may not be completed within 90 days.

METHODS

Patients with HFrEF and LVEF ≤ 35% prescribed a wearable cardioverter-defibrillator between 2017 and 2022 from 68 sites were enrolled, starting with a registry phase for 3 months and followed by a study phase up to 1 year. The primary endpoints were LVEF improvement > 35% between Days 90 and 180 following guideline-recommended medical therapy initiation and the percentage of target dose reached at Days 90 and 180.

RESULTS

A total of 598 patients with de novo HFrEF [59 years (interquartile range 51-68), 27% female] entered the study phase. During the first 180 days, a significant increase in dosage of beta-blockers, renin-angiotensin system inhibitors, and mineralocorticoid receptor antagonists was observed (P < .001). At Day 90, 46% [95% confidence interval (CI) 41%-50%] of study phase patients had LVEF improvement > 35%; 46% (95% CI 40%-52%) of those with persistently low LVEF at Day 90 had LVEF improvement > 35% by Day 180, increasing the total rate of improvement > 35% to 68% (95% CI 63%-72%). In 392 patients followed for 360 days, improvement > 35% was observed in 77% (95% CI 72%-81%) of the patients. Until Day 90, sustained ventricular tachyarrhythmias were observed in 24 wearable cardioverter-defibrillator carriers (1.8%). After 90 days, no sustained ventricular tachyarrhythmia occurred in wearable cardioverter-defibrillator carriers.

CONCLUSIONS

Continuous optimization of guideline-recommended medical therapy for at least 180 days in HFrEF is associated with additional LVEF improvement > 35%, allowing for better decision-making regarding preventive implantable cardioverter-defibrillator therapy.

Revascularization and Left Ventricular Dysfunction for ICD Eligibility

Common triggers for sudden cardiac death (SCD) are transient ischemia, hemodynamic fluctuations, neurocardiovascular influences, and environmental factors. SCD occurs rapidly when sinus rhythm degenerates into ventricular tachycardia (VT) and/or ventricular fibrillation (VF), followed by asystole. Such progressive worsening of the cardiac rhythm is in most cases observed in the setting of ischemic heart disease and often associated with advanced left ventricular (LV) impairment. Revascularization prevents negative outcomes including SCD and heart failure (HF) due to LV dysfunction (LVD). The implantable cardioverter-defibrillator (ICD) on top of medical therapy is superior to antiarrhythmic drugs for patients with LVD and VT/VF. The beneficial effects of ICD have been demonstrated in primary prevention of SCD as well. However, yet debated is the temporal management for patients with LVD who are eligible to ICD prior to revascularization, either through percutaneous or surgical approach. Restoration of coronary blood flow has a dramatic impact on adverse LV remodeling, while it requires aggressive long-term antiplatelet therapy, which might increase complication for eventual ICD procedure when percutaneous strategy is pursued; on the other hand, when LV and/or multiorgan dysfunction is present and coronary artery bypass grafting is chosen, the overall risk is augmented, mostly in HF patients. The aims of this review are to describe the pathophysiologic benefits of revascularization, the studies addressing percutaneous, surgical or no revascularization and ICD implantation, as well as emerging defibrillation strategies for patients deemed at transient risk of SCD and/or at higher risk for transvenous ICD implantation.

Risk Factors for Arrhythmic Death, Overall Mortality, and Ventricular Tachyarrhythmias Requiring Shock After Myocardial Infarction

The VEST (Vest Prevention of Early Sudden Death Trial) showed a trend toward decreased sudden death and lower overall mortality with a wearable cardioverter-defibrillator (WCD) in the postmyocardial infarction (post-MI) period. However, it is unclear which patients should receive WCD therapy. We aimed to identify the risk factors for arrhythmic death, all-cause mortality, and ventricular tachyarrhythmias requiring appropriate shock to identify patients most likely to benefit from a WCD. The VEST trial included patients with acute MI with ejection fraction ≤35%. Using logistic regression, 7 risk factors were evaluated for association with arrhythmic death, all-cause mortality, and appropriate shock. Among 2,302 participants, 44 had arrhythmic death (1.9%) and 86 died of any cause (3.7%). Among 1,524 participants randomized to WCD, 20 experienced appropriate shock (1.3%) over 90 days. In the multivariable analyses, lower systolic blood pressure (SBP; odds ratio [OR] 1.64 per 10 mm Hg) and higher heart rate at discharge (OR 1.19 per 10 beats/min) were associated with arrhythmic death. Lower SBP (OR 1.37) and higher heart rate (OR 1.10) were associated with all-cause mortality. Higher heart rate (OR 1.20) was associated with appropriate shock. Patients with both SBP ≤100 and heart rate ≥100 were at increased odds of arrhythmic death (OR 4.82), all-cause mortality (OR 3.10), and appropriate shock (OR 6.13). In patients with acute MI and reduced ejection fraction, lower SBP and higher heart rate at discharge were strongly associated with arrhythmic death and all-cause mortality. In conclusion, these risk factors identify a select group at high risk of adverse events in a setting where WCD therapy is reasonable.

Patient-reported outcomes using a wearable cardioverter-defibrillator: results from a systematic review

OBJECTIVES

The aim of this study was to assess the effect of the wearable cardioverter-defibrillator (WCD) on patient-reported outcomes (PRO) in adult patients with high risk for sudden cardiac arrest.

METHODS

We performed a systematic literature search in Medline (via PubMed) and Cochrane Library in February 2022 and included studies with a study population ≥18 years and prescribed WCD. PRO include health-related quality of life (QoL), symptoms, utilities, or satisfaction ratings. Study selection was done by two reviewers independently using predefined inclusion and exclusion criteria. Quality assessment of studies as well as data extraction was performed by one author and approved by a second author. Results of the included studies are presented quantitatively.

RESULTS

One randomized controlled trial (RCT), one comparative non-randomized trial, and three single-arm trials were included. QoL was assessed in four studies, but with different assessment tools. One study additionally evaluated the change in depressive symptoms and anxiety and one study focused on acceptability of WCD but evaluated items that are closely related to QoL. Results of the RCT show no statistically significant difference in QoL assessed by SF-36 and EQ-5D comparing WCD and Guideline-Directed Medical Therapy (GDMT) versus GDMT alone. One comparative study reports an improvement in depressive symptoms and anxiety within groups but no significant difference between groups. Further, one single-arm study reported improvement in QoL between baseline and day 90 and day 180.

CONCLUSIONS

The available evidence demonstrates that the usage of WCD is not affecting PRO, like QoL, depressive symptoms or anxiety negatively.

Usage of the wearable cardioverter-defibrillator during pregnancy

Background

Pregnancy can trigger or aggravate the risk for life-threating arrhythmias in cardiac diseases. Pregnancy is associated with reluctance for implantable cardioverter-defibrillators (ICD) due to concerns about radiation. Thus, the wearable cardioverter-defibrillator (WCD) might be an option during pregnancy. Aim of the study was to collect experiences about the use of WCD in pregnancy.

Methods and results

This study retrospectively included eight women who received a WCD during pregnancy. They suffered from ventricular tachycardia (VT) without known cardiac disease (n = 3), Brugada syndrome (n = 1), hypertrophic cardiomyopathy (n = 1), dilated cardiomyopathy (n = 1), non-compaction (n = 1), and survived sudden cardiac arrest during a preceding pregnancy (n = 1). WCD usage was started between 13 and 28 weeks of gestation. WCD wearing period ranged from 3 days to 30.9 weeks, WCD wearing time ranged from 13.0 to 23.7 h per day. Two women (25%) abandoned WCD already during pregnancy. Neither appropriate nor inappropriate WCD shocks were recorded. Antiarrhythmic management included beta-blockers (n = 5) and flecainide (n = 2). After delivery, ICD were implanted (n = 4), refused (n = 2) and estimated not necessary after successful catheter ablation (n = 2).

Conclusion

Uneventful pregnancy is possible in women at risk for sudden cardiac death by interdisciplinary monitoring and diligent pharmacotherapy protected by the WCD. Since no WCD shocks were recorded, the effectiveness of WCD during pregnancy is still unclear. However, arrhythmia detection by WCD was very good despite the changed anatomy in pregnancy. Nevertheless, further studies are necessary to assess effectiveness of WCD in pregnant women. Furthermore, efforts should be made to increase the wearing adherence of WCD during pregnancy.

Differences in Treating Patients with Palpitations at the Primary Healthcare Level Using Telemedical Device Savvy before and during the COVID-19 Pandemic

Background: Palpitations are one of most common reasons why a patient visits a general practitioner (GP) and is referred to a cardiologist. Coronavirus disease 2019 (COVID-19) has been associated with new-onset arrhythmias, which are difficult to diagnose at the primary healthcare level during pandemic-related lockdown periods. Methods: A total of 151 patients with a complaint of heart rhythm disorder were included from before and during the COVID-19 pandemic, as well as after the start of vaccination, in this cohort retrospective study. We used a telemedical device—namely, a personal electrocardiographic (ECG) sensor called Savvy—to investigate heart rhythm in patients. The primary outcome of the study was to evaluate the number of actual heart rhythm disorder patients and any differences that infection with or vaccination for COVID-19 had on patients handled in a primary healthcare setting. Results: We found a heart rhythm disorder in 8.6% of patients before the COVID-19 pandemic and in 15.2–17.9% of patients during the COVID-19 pandemic, where the difference was statistically significant (p = 0.002). During the COVID-19 pandemic, we found a heart rhythm disorder in almost 50% of patients that had tested positive for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus) more than one month ago. After the vaccinations started, we also found a heart rhythm disorder in almost 50% of non-vaccinated patients. Conclusions: Using a telemedical approach or remote consultation is a useful method, at the primary healthcare level, for diagnosing and treating patients with palpitations during times of lockdown.

Wearable Devices for Physical Monitoring of Heart: A Review

Cardiovascular diseases (CVDs) are the leading cause of death globally. An effective strategy to mitigate the burden of CVDs has been to monitor patients' biomedical variables during daily activities with wearable technology. Nowadays, technological advance has contributed to wearables technology by reducing the size of the devices, improving the accuracy of sensing biomedical variables to be devices with relatively low energy consumption that can manage security and privacy of the patient's medical information, have adaptability to any data storage system, and have reasonable costs with regard to the traditional scheme where the patient must go to a hospital for an electrocardiogram, thus contributing a serious option in diagnosis and treatment of CVDs. In this work, we review commercial and noncommercial wearable devices used to monitor CVD biomedical variables. Our main findings revealed that commercial wearables usually include smart wristbands, patches, and smartwatches, and they generally monitor variables such as heart rate, blood oxygen saturation, and electrocardiogram data. Noncommercial wearables focus on monitoring electrocardiogram and photoplethysmography data, and they mostly include accelerometers and smartwatches for detecting atrial fibrillation and heart failure. However, using wearable devices without healthy personal habits will cause disappointing results in the patient's health.

Multiparameter Monitoring with a Wearable Cardioverter Defibrillator

A wearable cardioverter-defibrillator (WCD) is a temporary treatment option for patients at high risk for sudden cardiac death (SCD) and for patients who are temporarily not candidates for an implantable cardioverter defibrillator (ICD). In addition, the need for telemedical concepts in the detection and treatment of heart failure (HF) and its arrhythmias is growing. The WCD has evolved from a shock device detecting malignant ventricular arrhythmias (VA) and treating them with shocks to a heart-failure-monitoring device that captures physical activity and cardioacoustic biomarkers as surrogate parameters for HF to help the treating physician surveil and guide the HF therapy of each individual patient. In addition to its important role in preventing SCD, the WCD could become an important tool in heart failure treatment by helping prevent HF events by detecting imminent decompensation via remote monitoring and monitoring therapy success.

Wearable Cardioverter-Defibrillator Used as a Telemonitoring System in a Real-Life Heart Failure Unit Setting

BACKGROUND

In patients with reduced left ventricular ejection fraction (LVEF) who are at risk of sudden cardiac death, a wearable cardioverter-defibrillator (WCD) is recommended as a bridge to the recovery of LVEF or as a bridge to the implantation of a device. In addition to its function to detect and treat malignant arrhythmia, WCD can be used via an online platform as a telemonitoring system to supervise patients' physical activity, compliance, and heart rate.

METHODS

We retrospectively analyzed 173 patients with regard to compliance and heart rate after discharge.

RESULTS

Mean WCD wearing time was 59.75 ± 35.6 days; the daily wearing time was 21.19 ± 4.65 h. We found significant differences concerning the patients' compliance. Men showed less compliance than women, and younger patients showed less compliance than patients who were older. Furthermore, we analyzed the heart rate from discharge until the end of WCD prescription and found a significant decrease from discharge to 4, 8, or 12 weeks.

CONCLUSION

WCD can be used as a telemonitoring system to help the involved heart failure unit or physicians attend to and adjust the medical therapy. Furthermore, specific patient groups should be educated more intensively with respect to compliance.

Sensors for Context-Aware Smart Healthcare: A Security Perspective

The advances in the miniaturisation of electronic devices and the deployment of cheaper and faster data networks have propelled environments augmented with contextual and real-time information, such as smart homes and smart cities. These context-aware environments have opened the door to numerous opportunities for providing added-value, accurate and personalised services to citizens. In particular, smart healthcare, regarded as the natural evolution of electronic health and mobile health, contributes to enhance medical services and people's welfare, while shortening waiting times and decreasing healthcare expenditure. However, the large number, variety and complexity of devices and systems involved in smart health systems involve a number of challenging considerations to be considered, particularly from security and privacy perspectives. To this aim, this article provides a thorough technical review on the deployment of secure smart health services, ranging from the very collection of sensors data (either related to the medical conditions of individuals or to their immediate context), the transmission of these data through wireless communication networks, to the final storage and analysis of such information in the appropriate health information systems. As a result, we provide practitioners with a comprehensive overview of the existing vulnerabilities and solutions in the technical side of smart healthcare.