**8. Patient factors**

There are specific patient factors that warrant consideration when prescribing this novel therapeutic option. Many patients will have no concept of what a WCD is or how it works.

#### **8.1 Patient education**

Manufacturer's representatives may be available to help train patients in the proper function of the WCD, and, if they are not available, the clinical team should make sure the patient knows how to wear the vest, how to adjust it for proper fit, how to replace the battery, how to charge the battery, and how to transfer data from the WCD to the network. For this reason, the WCD requires the patient be able to understand and manage these tasks and be willing to do them. An initial training session should make sure the patient can put on the vest and insert batteries that may last an hour or more. It may be helpful for a second follow-up contact with the trainer over the course of the next few days to help with any questions or problems the patient may still have. The manufacturer has a 24-h technical support hotline for urgent questions [5].

#### **8.2 Compliance**

Compliance is an issue in all areas of medicine but particularly in the case of the WCD which patients may find restrictive or uncomfortable. A postmarket registry study (n = 3569) found that patients who used the WCD for a longer duration of time (days of wear) were significantly more likely to wear in more hours per day (p < 0.001) [33]. Over time, the WCD has been redesigned to make it lighter in weight and more comfortable for extended wear. Remote monitoring can alert the clinic as to actual wear time for an individual patient [67]. Compliance may be encouraged by educating the patient as to the nature of ventricular tachyarrhythmias and how the device protects them.

#### **8.3 Psychological factors**

It has been speculated that patients prescribed a WCD may experience emotional distress and view the device as a constant worrisome reminder of their own mortality. Patients may also feel isolated if they do not know anyone else who has ever worn such a device. Patients have sometimes reported that they find the device symbolic of their own vulnerability [33]. Of course, such adverse emotions may occur in all patients facing the sudden news that they have a serious cardiovascular condition regardless of whether they are prescribed a WCD or some other therapy. Psychological distress is an important clinical consideration because it is potentially modifiable. There may be ways to reduce depressive or anxious symptoms in clinically meaningful ways. Depression worsens outcomes and actually serves as a predictor for both mortality and shock therapy [68, 69]. Depression has been associated with a nearly doubled risk for all-cause mortality in ICD patients [69]. Furthermore, depression and anxiety may adversely affect patient compliance, adherence to pharmacological therapy, and lifestyle.

#### *The Wearable Cardioverter-Defibrillator DOI: http://dx.doi.org/10.5772/intechopen.90663*

In another study of 123 patients considered WCD candidates, at baseline 21% showed signs of clinically depressive symptoms, and 52% had anxiety. Six weeks after WCD therapy commenced, rates of depression and anxiety dropped to 7 and 25%, respectively [32]. It is not clear if patients recovered their emotional equilibrium as a result of WCD therapy or as a matter of course as they got used to their new identities as cardiac patients.

#### **8.4 Device-device compatibility**

episode, the WCD cannot pace such patients, and there is a risk that an untreated

There are specific patient factors that warrant consideration when prescribing this novel therapeutic option. Many patients will have no concept of what a WCD is

Manufacturer's representatives may be available to help train patients in the proper function of the WCD, and, if they are not available, the clinical team should make sure the patient knows how to wear the vest, how to adjust it for proper fit, how to replace the battery, how to charge the battery, and how to transfer data from the WCD to the network. For this reason, the WCD requires the patient be able to understand and manage these tasks and be willing to do them. An initial training session should make sure the patient can put on the vest and insert batteries that may last an hour or more. It may be helpful for a second follow-up contact with the trainer over the course of the next few days to help with any questions or problems the patient may still have. The manufacturer has a 24-h technical support hotline

Compliance is an issue in all areas of medicine but particularly in the case of the WCD which patients may find restrictive or uncomfortable. A postmarket registry study (n = 3569) found that patients who used the WCD for a longer duration of time (days of wear) were significantly more likely to wear in more hours per day (p < 0.001) [33]. Over time, the WCD has been redesigned to make it lighter in weight and more comfortable for extended wear. Remote monitoring can alert the clinic as to actual wear time for an individual patient [67]. Compliance may be encouraged by educating the patient as to the nature of ventricular tachyarrhythmias and how

It has been speculated that patients prescribed a WCD may experience emotional distress and view the device as a constant worrisome reminder of their own mortality. Patients may also feel isolated if they do not know anyone else who has ever worn such a device. Patients have sometimes reported that they find the device symbolic of their own vulnerability [33]. Of course, such adverse emotions may occur in all patients facing the sudden news that they have a serious cardiovascular condition regardless of whether they are prescribed a WCD or some other therapy. Psychological distress is an important clinical consideration because it is potentially modifiable. There may be ways to reduce depressive or anxious symptoms in clinically meaningful ways. Depression worsens outcomes and actually serves as a predictor for both mortality and shock therapy [68, 69]. Depression has been associated with a nearly doubled risk for all-cause mortality in ICD patients [69]. Furthermore, depression and anxiety may adversely affect patient compliance,

asystole may be fatal [66].

**8. Patient factors**

*Sudden Cardiac Death*

or how it works.

**8.1 Patient education**

for urgent questions [5].

the device protects them.

**8.3 Psychological factors**

**80**

adherence to pharmacological therapy, and lifestyle.

**8.2 Compliance**

When a patient has more than one electronic cardiac device, the potential of device-device interaction exists. The literature reports one case of a fatal devicedevice interaction between a permanent pacemaker and a WCD [70]. In this case, the patient received unipolar dual-chamber pacing, but when he developed VF, no therapy was delivered as the device inappropriately detected the large unipolar pacing spikes as cardiac signals [70].

A study sponsored by Zoll examined pacing in 60 patients testing the AAI, VVI, and DDD modes in both unipolar and bipolar device configurations to determine if the WCD would detect the pacing spikes; patients were signaled before shock delivery and could use the patient response buttons to avert the therapy delivery. Only unipolar DDD pacing was detected by the WCD's algorithm and only in 10% of patients (6/60). This study suggests that pacing may occur concomitantly with WCD use if unipolar configurations are avoided [2]. If unipolar pacing must be used in a particular patient, then the WCD is contraindicated. Another study of the concomitant use of the WCD and a pacemaker showed that double-counting and waveform alterations might also occur in certain bipolar pacing modes and in single-chamber as well as dual-chamber pacing [44]. Caution is urged in using the WCD in patients with pacing support from an implanted pacemaker system.

### **9. Costs**

The WCD is "rented" to patients for a monthly fee, and reimbursement provisions vary by country. Since costs can be substantial, there is a need to better stratify patients into those who truly need a WCD for arrhythmic rescue and those who might be unlikely to benefit from it [41]. Cost-effectiveness models show that the number needed to treat to save 1 life with a WCD falls in the range of 70–110 patients over a median of 53–57 days [26]. There are situations in which the WCD poses a decided cost advantage. For example, cardiomyopathy patients who might otherwise be considered a candidate for permanent primary prevention ICD implantation may benefit from using the WCD during a recovery period; data shows that 60% of such patients will recover to the point that an ICD implantation is not necessary [18, 33, 41]. Thus, the costs for the temporary use of the WCD may be offset by the decision not to implant an ICD. In patients whose ICD must be removed for infection, it is sometimes necessary to keep the patient in the hospital or discharge him or her to a skilled nursing facility for weeks during antimicrobial therapy and recovery. The patient is at risk for SCD throughout this time. A cost-effectiveness analysis found that the WCD was costeffective in this situation in that it allowed the patient to be discharged home; the analysis is based on the assumption that there was a 2-week 5.6% risk of SCD in the population and the patient had to wait at least 2 weeks before ICD replacement [71].

#### **10. Future directions**

The WCD technology effectively treats VT/VF, but bradycardia pacing support would likely prevent SCD to an even greater extent. Adding pacing capability to the WCD would be an important and life-saving step forward.

A major obstacle in WCD therapy remains patient adherence. Unfortunately, not all patients are motivated to comply with the prescription to use the WCD, and unnecessary deaths occur because of poor compliance. Therefore, motivating the patient to adhere to therapy is of utmost importance. A combined approach with technology reminders (e.g., text messages via smartphones) and close follow-up by device professionals is crucial.

Much has been accomplished in the past 30 years to better treat the risk of SCD, and the WCD is definitely an important milestone in our advancing knowledge. Nevertheless, much more needs to be done to reduce the rates of arrhythmic death even more.

A Class II recall of the WCD occurred in January 2018, covering 33,000 devices. This problem, in which certain vests displayed a warning message to the effect that they could not charge sufficiently to deliver therapy, has been addressed.
