Physical activity is reduced prior to ventricular arrhythmias in patients with a wearable cardioverter defibrillator

Appropriate use of wearable defibrillators with multiparametric evaluation to avoid unnecessary defibrillator implantation

INTRODUCTION

Wearable cardioverter-defibrillators (WCD) have emerged as a valuable tool in the management of patients at risk for life-threatening arrhythmias. These devices offer a non-invasive and temporary solution, providing continuous monitoring and the potential for prompt defibrillation when needed. In this study, we explore the use of WCD and evaluate arrhythmic events through comprehensive monitoring.

METHODS

From November 2022 to May 2024, we conducted an outpatient follow-up of 41 patients receiving WCD. Regular check-ups, remote monitoring and comprehensive echocardiography were performed to optimise a tailored therapy.

RESULTS

The average age of the patients was 59.2.4±16.5 years, with 78% being male. Among the cohort, 54% had hypertension, 41% were smokers and 66% had dyslipidaemia, while 27% were diabetic. WCD was assigned according to the Italian Association of Hospital Cardiologists position paper focussing on the appropriate use of WCD and European Society of Cardiology guidelines on ventricular arrhythmias and the prevention of sudden cardiac death: 24 (58%) patients had a de novo diagnosis of heart failure with reduced ejection fraction, 11 (27%) patients had a recent acute coronary syndrome and ejection fraction <35%, 3 (7%) patients had a cardiac electronic device extraction and 3 (7%) patients had myocarditis with features of electrical instability. The average follow-up was 62±38 days according to specific aetiology, with a daily wearing time of 22.7±1.3 hours. No device interventions were recorded. At the end of the follow-up period, 15 patients still required an implantable cardioverter-defibrillator (ICD). Among these, 12 patients (29%) underwent ICD implantation. Two patients (5%) declined the procedure.

CONCLUSIONS

The use of WCD for patients at high risk of arrhythmias allowed to optimise therapy and limit the indications for ICD. Inappropriate implantation of ICD was avoided in 69% of patients who received WCD. The device showed a good safety profile, low incidence of device interventions and adequate patients' adherence to WCD use.

Cardiovascular Rehabilitation With a WCD-Data From the CR3 Study (Cardiac Rehab Retrospective Review)

PURPOSE

Patients at risk for sudden cardiac death may temporarily need a wearable cardioverter-defibrillator (WCD). Exercise-based cardiac rehabilitation (CR) has a class I recommendation in patients with cardiac disease. The aim of this study was to evaluate the safety and feasibility of undergoing CR with a WCD.

METHODS

We performed a retrospective analysis of all patients with a WCD who completed a CR in Austria (2010-2020).

RESULTS

Patients (n = 55, 60 ± 11 yr, 16% female) with a median baseline left ventricular ejection fraction (LVEF) of 36 (30, 41)% at the start of CR showed a daily WCD wearing duration of 23.4 (22, 24) hr. There were 2848 (8 [1, 26]/patient) automatic alarms and 340 (3 [1, 7]/patient) manual alarms generated. No shocks were delivered by the WCD during the CR period. One patient had recurrent hemodynamically tolerated ventricular tachycardias that were controlled with antiarrhythmic drugs.No severe WCD-associated adverse events occurred during the CR stay of a median 28 (28, 28) d. The fabric garment and the device setting needed to be adjusted in two patients to diminish inappropriate automatic alarms. Left ventricular ejection fraction after CR increased significantly to 42 (30, 44)% ( P < .001). Wearable cardioverter-defibrillator therapy was stopped due to LVEF restitution in 53% of patients. In 36% of patients an implantable cardioverter-defibrillator was implanted, 6% had LVEF improvement after coronary revascularization, one patient received a heart transplantation (2%), two patients discontinued WCD treatment at their own request (4%).

CONCLUSION

Completing CR is feasible and safe for WCD patients and may contribute positively to the restitution of cardiac function.

Telemonitoring Potential of Wearable Cardioverter-Defibrillators during the Follow-Up of Patients with Heart Failure

Background: Wearable cardioverter-defibrillators (WCDs) are a well-established tool to bridge the recovery time of left ventricular ejection fraction (LVEF) until the implantation of an implantable cardioverter defibrillator (ICD), as recommended by the current guidelines. Besides their function to detect and treat malignant arrhythmias, WCDs may be used as a telemonitoring system. In this study, we sought to illustrate and discuss the telemonitoring potential of WCDs and to analyze physical activity in specific patient cohorts. Methods and Results: We retrospectively included 140 patients with reduced LVEF who were prescribed WCDs in our clinic. We analyzed the patients’ physical activity (n = 105 with a WCD compliance above 21 h/day), body position and resting position. We found a reduced physical activity in women and in patients over the age of 65 compared to younger patients. Furthermore, the patients who were overweight or obese showed significantly reduced physical activity compared to the patients with a normal weight (6365 ± 3572 vs. 4972 ± 2476 vs. 7045 ± 3521, p = 0.02). Conclusion: WCDs may be used as a telemonitoring and intervention tool in patients with reduced LVEF. Specific patient groups may benefit from guidance from their treating physician regarding physical activity.

Accelerometer-assessed physical behavior and the association with clinical outcomes in implantable cardioverter-defibrillator recipients: A systematic review

Background

Current implantable cardioverter-defibrillator (ICD) devices are equipped with a device-embedded accelerometer capable of capturing physical activity (PA). In contrast, wearable accelerometer-based methods enable the measurement of physical behavior (PB) that encompasses not only PA but also sleep behavior, sedentary time, and rest-activity patterns.

Objective

This systematic review evaluates accelerometer-based methods used in patients carrying an ICD or at high risk of sudden cardiac death.

Methods

Papers were identified via the OVID MEDLINE and OVID EMBASE databases. PB could be assessed using a wearable accelerometer or an embedded accelerometer in the ICD.

Results

A total of 52 papers were deemed appropriate for this review. Out of these studies, 30 examined device-embedded accelerometry (189,811 patients), 19 examined wearable accelerometry (1601 patients), and 3 validated wearable accelerometry against device-embedded accelerometry (106 patients). The main findings were that a low level of PA after implantation of the ICD and a decline in PA were both associated with an increased risk of mortality, heart failure hospitalization, and appropriate ICD shock. Second, PA was affected by cardiac factors (eg, onset of atrial fibrillation, ICD shocks) and noncardiac factors (eg, seasonal differences, societal factors).

Conclusion

This review demonstrated the potential of accelerometer-measured PA as a marker of clinical deterioration and ventricular arrhythmias. Notwithstanding that the evidence of PB assessed using wearable accelerometry was limited, there seems to be potential for accelerometers to improve early warning systems and facilitate preventative and proactive strategies.

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.

Wearable Cardioverter-Defibrillator-Measured Step Count for the Surveillance of Physical Fitness during Cardiac Rehabilitation

Background: The wearable cardioverter–defibrillator (WCD) has a built-in accelerometer, which allows tracking of patients’ physical activity by remote monitoring. It is unclear whether WCD-measured physical activity, step count, and heart rate correlate with established tools for the assessment of cardiopulmonary fitness such as the 6-min walk test (6MWT). Objective: To correlate measurements of patient physical activity through the WCD with a supervised 6MWT during in-patient cardiac rehabilitation (CR) and to allow their use as surrogate parameters of cardiopulmonary fitness in an out-patient setting. Methods: Consecutive patients with a history of WCD use treated at our center and an in-patient CR following an index hospitalization were included. Baseline characteristics, measurements of WCD accelerometer (median daily step count, median daily activity level), median daily heart rate, and clinically supervised 6MWT at admission and discharge of CR were obtained. Results: Forty-one patients with a mean age of 55.5 (±11.5) years were included. Thirty-five patients (85.4%) were male and 28 patients (68%) had a primary prophylactic WCD-indication. The most common underlying heart diseases were ischemic heart disease (24 patients 58.6%) and dilated cardiomyopathy (13 patients, 31.7%). Median CR duration was 20 (IQR 19.75–26.25) days. 6MWT distance increased from a mean of 329 m (±107) to 470 m (±116) during CR (p < 0.0001). The median daily step count and activity level increased significantly, from 5542 steps (IQR 3718–7055) to 8778 (IQR 6229–12,920, p < 0.0001) and median 117 × 10⁶ (IQR 96 × 10⁶–142 × 10⁶) threshold value exceedance (TVE) to 146 × 10⁶ TVE (IQR 110 × 10⁶–169 × 10⁶, p < 0.0001), respectively. The median heart rate was 74.9 bpm (IQR 65.8–84.5) and 70.2 (IQR 64.1–77.3, p = 0.09) at admission and discharge, respectively. Of all three parameters, median daily step count showed the best correlation to the results of the 6MWT at admission and discharge (r = 0.32, p = 0.04 and 0.37, p = 0.02, respectively). Conclusions: Remote monitoring of median daily step count as assessed by the WCD’s accelerometer showed positive correlation with the 6MWT and could serve as a surrogate for cardiopulmonary exercise capacity. Assessment of daily step count and activity level measured remotely by the WCD could help to tailor optimal exercise instruction for patients not attending CR.

High Incidence of Inappropriate Alarms in Patients with Wearable Cardioverter-Defibrillators: Findings from the Swiss WCD Registry

BACKGROUND

The wearable cardioverter defibrillator (WCD) uses surface electrodes to detect arrhythmia before initiating a treatment sequence. However, it is also prone to inappropriate detection due to artefacts.

OBJECTIVE

The aim of this study is to assess the alarm burden in patients and its impact on clinical outcomes.

METHODS

Patients from the nationwide Swiss WCD Registry were included. Clinical characteristics and data were obtained from the WCDs. Arrhythmia recordings ≥30 s in length were analysed and categorized as VT/VF, atrial fibrillation (AF), supraventricular tachycardia (SVT) or artefact.

RESULTS

A total of 10653 device alarms were documented in 324 of 456 patients (71.1%) over a mean WCD wear-time of 2.0 ± 1.6 months. Episode duration was 30 s or more in 2996 alarms (28.2%). One hundred and eleven (3.7%) were VT/VF episodes. The remaining recordings were inappropriate detections (2736 (91%) due to artefacts; 117 (3.7%) AF; 48 (1.6%) SVT). Two-hundred and seven patients (45%) had three or more alarms per month. Obesity was significantly associated with three or more alarms per month (p = 0.01, 27.7% vs. 15.9%). High alarm burden was not associated with a lower average daily wear time (20.8 h vs. 20.7 h, p = 0.785) or a decreased implantable cardioverter defibrillator implantation rate after stopping WCD use (48% vs. 47.3%, p = 0.156).

CONCLUSIONS

In patients using WCDs, alarms emitted by the device and impending inappropriate shocks were frequent and most commonly caused by artefacts. A high alarm burden was associated with obesity but did not lead to a decreased adherence.

Collaborative care for the wearable cardioverter defibrillator patient: Getting the patient and medical team "vested and active"

Patients with a reduced ejection fraction of 35% or less and a history of myocardial infarction (MI) are at increased risk of sudden cardiac death (SCD). These patients have a class I indication for an implantable cardioverter-defibrillator after allowing time for medical therapy optimization and potential cardiac recovery. The rates of SCD are highest in this "gap" period early after a cardiac event, and the wearable cardioverter-defibrillator (WCD) is an intervention that can be used to protect against SCD during this time period. There has been a clinical trial that randomized patients with a reduced ejection fraction at the time of MI to a WCD versus control. Results of the trial showed no statistically significant difference in the primary endpoint of SCD. There are many intricacies to the interpretation of the trial, including the importance of patient adherence to WCD therapy, which is affected by the patient experience and psychological factors. Patients with a new cardiomyopathy are affected by a mix of psychological factors, including the feeling of safety and protection from a WCD contrasted by the WCD providing a reminder of awareness and fear of ventricular arrhythmias and SCD. Beyond the capabilities of a WCD to defibrillate a life-threatening ventricular arrhythmia, the device can also provide activity and heart failure diagnostics monitoring. Patients need to be engaged in shared decision-making conversations about a WCD, so that patients can make a decision based on their own values construct, ultimately increasing adherence among the patients that want a WCD.

Physical activity is reduced prior to ventricular arrhythmias in patients with a wearable cardioverter defibrillator

INTRODUCTION

The utility of accelerometer-based activity data to identify patients at risk of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) has not previously been investigated. The aim of the current study was to determine whether physical activity is associated with manifesting spontaneous sustained VT/VF requiring emergent defibrillation in patients with an ejection fraction of ≤35%.

METHODS

Patients consecutively prescribed a wearable cardioverter defibrillator (WCD) from April 2015 to May 2018 were included. Shock data and 4 weeks of physical activity data, beginning with the first week of WCD wear, were analyzed.

RESULTS

Based on the ROC curve outcome generated from 4057 patients, average daily step count during the first week accurately predicted those patients with sustained VT/VF compared to those without (shocked (n = 81) vs nonshocked (n = 3976) area under the curve, c-index = 0.71, 95% CI = 0.65-0.77, P < .001). An average cutoff of 3637 daily steps during week 1 separated the groups. Patients who averaged fewer than 3637 steps per day during the first week of WCD use were 4.3 times more likely to experience a shock than those who walked more than 3637 steps per day (OR = 4.29, 95% CI = 2.58-7.15, P < .001).

DISCUSSION

Average daily step counts are lower in WCD patients who manifest spontaneous VT/VF. Whether these findings represent a causal or correlational relationship, future studies to encourage a minimum daily step count in high-risk patients may impact the incidence of sustained VT/VF.