Patch Wearable Defibrillator: Excellent Therapy, But Patient Acceptance Is a Sticky Issue

Despite early intervention with revascularization and medical therapy, management of malignant ventricular arrhythmias soon after diagnosis of a cardiomyopathy remains a principal concern. In the postmyocardial infarction (MI) population, multiple studies have demonstratedthat the risk of sudden cardiac arrest (SCA) increasesas the left ventricular ejection fraction (LVEF) decreases, is highest the first month after the MI, and decreases over time after the MI or as LVEF recovers. This temporal pattern of fluctuating risk of SCA after MI is also noted in the management of non ischemiccardiomyopathy. Recognizing this pattern, however, has not facilitated an easy intervention. Trials such as DINAMITE^[1] and IRIS^[2] confirmed no benefit of earlyintervention with an implanted cardioverter-defibrillator (ICD).

The LifeVest (ZOLL Medical) wearable cardioverter-defibrillator (WCD) and the ASSURE WCD (KestraMedical Technologies) were approved based on theconcept that the WCD provides bridge therapy forautomatic defibrillation during a transient high-risk period until a final treatment strategy has beendetermined (recovery of LVEF, implantation of an ICD, bridge to transplant, etc). However clinical trials have demonstrated that an important limitation to WCD ispatient acceptance and compliance.

In this issue of JACC, Hummel et al^[3] present datafrom the Jewel IDE trial (Element Science) on the useof a unique water-resistant patch-WCD (P-WCD). Thisis a multicenter, prospective, descriptive study using the P-WCD in adult patients at risk for SCA. The duration of wear was based on the physician prescription or up to 180 days. In brief, the P-WCD con-sists of a disposable upper adhesive electrode patch(6.8 x 5 inches), positioned on the anterior chest just inferior to the right clavicle, and a disposable loweradhesive electrode patch (11.3 x 5.3 inches), positioned over the left 7th rib, centered at the anterioraxillary line. Attached to the lower adhesive patch isthe disposable battery unit and the reusable moni-toring and defibrillation unit (8.6 x 3.8 x 1.4 inches, weight 500 g). A disposable connection cable provideselectrical communication between the upper andlower adhesive electrode patches. The 2 disposable adhesive patches are to be worn continuously for upto 8 days, even during showering and physical activity, and then replaced. The P-WCD uses a proprietaryalgorithm for detection of malignant ventricular arrhythmias (duration 24 seconds) and then delivers abiphasic shock (150 J, 162 J), with 5 shocks available for a single ventricular event. Similarly to other WCDs,the device issues an alarm before therapy, and the patient can defer shock delivery by pushing a controlbutton; at the time of shock delivery, the device gives verbal instructions to bystanders not to touch the patient and to call 911 and start cardiopulmonary resuscitation. The device also alerts bystanders if asystole is detected. The primary safety endpoint of the study was the rate of clinically significant cutaneous adverse device effect (ADE), defined as a skin reaction related to the patch resulting in the physician (not the patient) withdrawing the patient from the study. The primary effectiveness endpoint was therate of inappropriate shocks.

The study enrolled 305 patients, of which 290 pa-tients provided analyzable data. Population features included mean age 58 years, mean body mass index30 kg/m², and the most common indications for the P-WCD being a non ischemic cardiomyopathy and temporary contraindication for ICD. The mean duration of study participation was 59 ± 45 days. Seven of the 305 patients (2.3%) met criteria for a clinically signiicant cutaneous ADE, and thus the primarysafety endpoint was successfully achieved. Eleven shocks were delivered (n - 9) and 1 was deemed inappropriate (0.36/100 patient-months), meeting the primary effectiveness endpoint of <2.0 inappropriate shocks/100 patient-months. A total of 155 ADEs were reported and 71% were mild. The most common ADE was a skin rash (69%). There were no ADEs in 57% ofpatients and no severe ADEs.

The Jewel IDE study confirms what most electrophysiologists recognize, that WCDs can successfully sense and defibrillate malignant ventricular arrhythmias. The concept of using a WCD for short-term protection against SCA has gained acceptance with multiple professional societies with a Class IIb/IIaindication. However, important limitations with WCDs are patient compliance, education, and mental anxiety. In the WEARIT/BIROAD study, 5 sudden deaths occurred in patients not wearing the WCD, and 1 sudden death occurred in a patient who hadreversed the leads.^[4] In the randomized VEST, 16/25(64%) arrhythmic deaths occurred in patients notwearing the WCD at the time of death.^[5] In another study, the WCD was associated with reduced quality-of-life measures (mental health, discomfort, and restricted activity, daily routine, and self-care).^[6] Recognizing these limitations with previous WCDs,the Jewel P-WCD was designed to simplify patientuse. The concept of “stick it and forget it” adhesivede fibrillation patches that would last for 8 days was to provide a straightforward and reliable technique for enhancing compliance. The intended outcome was greater wear time per day as well as more days using the WCD, thus translating to life-saving therapy.

Do the Jewel IDE results demonstrate thatimprovement? The primary focus regarding the adhesives was the occurrence of an adverse skin reaction resulting in study exit, as deemed by the physician. This endpoint was reached in only a small percent of patients, 2.3%. In addition, the key parameter of wear time was an impressive 21.3 ± 4.5h/d, with a median of 23.5 h/d. However, despitethese encouraging results, patient acceptance of the device is still limited. According to Table 2 in thepaper, a large minority, 38%, of patients prematurely discontinued the study (patient-initiated exit + noncompliance), often within 30 days (Figure 2 in thepaper), before reaching a physician-initiated exit. There were a variety of reasons for patient-initiated exit, including 12% due to skin-related concerns. So, although the wear time per day was high, a large percentage of patients exited the study early.

Reduced compliance with, and acceptance of, medical therapies is a recognized challenge encompassing a broad scope of important therapies(eg, wearing sleep apnea devices, anticoagulation therapy). Management is often through engineering (eg, hypoglossal nerve stimulation, left atrial appendage occlusion); however, enhancing acceptance for a temporary therapy through technology is a tricky concept because the reasons for compliance are often not related to the WCD. An earlier study reported that early discontinuation of a WCD was associated with both patient- and physician-related variables: being from a Polish enrolling center, Asian, or divorced, or having diabetes, heart failure,LVEF ≤25% during the index MI, or any shock (remarkably inclusive of appropriate as well as inap-propriate shock).^[7] Thus, multiple features beyond the WCD influence utilization.

Although the patient experience in the Jewel IDE study is small, the P-WCD is certainly a successful WCD. It senses and defibrillates malignant ventricular arrhythmias, has a high wear time, a low in appropriate shock rate, and a low ADE rate. Nonetheless, even with the “stick it and forget it” adhesives, patient-initiated discontinuation remains a stumbling block. This issue applies to all WCDs despite diversetechnology. Perhaps one reason for reduced patient acceptance of this life-saving therapy is the absence of a perceived benefit. As a prophylactic device, the patient does not experience an improvement in physical health and thus positive feedback for the WCD is absent. To address this issue, a smaller study (n = 43) reported 100% patient use of the WCD until reaching a medical endpoint (median of 51 days) witha mean daily wear time of 23.1 hours.^[8] In addition to training at the time of prescribing the WCD, whichwas provided to patients in the Jewel IDE study, thisgroup also used remote monitoring for arrhythmia events and assessed daily wearing compliance. Patients with insuficient wear time were provided with further counseling to use the WCD. This method of continuous patient education seems to be an adjunctive intervention that is useful for all patients provided with a WCD. Ongoing counseling could even be automated via daily texts to encourage patients to use their WCD, because, of course, without patient acceptance, no WCD technology will stick.

J Am Coll Cardiol. 2024;84(6) © 2024 American College of Cardiology Foundation