Many medical professionals are on the fence about whether to prescribe wearable cardioverter-defibrillators (WCDs) for patients who are at risk for sudden cardiac death (SCD). Questions persist about the devices’ efficacy and cost-effectiveness, whether payers will cover them and if patients will wear the devices as required to achieve the maximum benefit.

What to wear while waiting

The questions focus on the 40 to 90 days after a patient experiences an initial cardiac arrest or receives a diagnosis of sustained ventricular tachycardia or ventricular fibrillation. Although these arrhythmias are associated with one in three out-of-hospital cardiac arrests, often when defibrillation is unavailable, practice guidelines and appropriate use criteria indicate cardiologists should wait 40 days or more before installing  an implantable cardioverter-defibrillator (ICD) to be certain adequate risk assessments have been performed (J Am Coll Cardiol 2013;61[12]:1318-68). The Centers for Medicare & Medicaid Services requires a 90-day wait after revascularization before an ICD can be installed. The result is a gap during which patients may be at increased risk and WCDs could be beneficial. To date, however, published, randomized data aren’t available to confirm the value of WCDs, the first of which was approved by the Food and Drug Administration in 2002.

Addressing the gap is a science advisory published this year by the American Heart Association (AHA) and endorsed by the Heart Rhythm Society (Circulation 2016;133:1715-27). “We published this science advisory to educate the community about the state of the science, highlight what has and hasn’t been done, and identify areas of unmet needs in practice and research to identify which patients should really be getting these devices,” says Jonathan P. Piccini, Sr., MD, MHS, chair of the advisory writing group and a cardiologist at Duke University in Durham, N.C.

The AHA advisory defines two scenarios where prescribing WCDs “is reasonable,” two where WCDS “might be considered” and one where WCDs are believed to offer no benefit. (For details, see table on page 39.) The AHA notes that its guidance is based on the currently available data, which are from observational and national database studies, not randomized, controlled trials.

“The majority of the clinical community agrees that this is an area where further investigation is needed,” Piccini says.

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Bridging the knowledge gap

The biggest effect of the AHA’s advisory may be that it encourages more randomized clinical trials, says Byron K. Lee, MD, an electrophysiologist at the University of California-San Francisco Medical Center and co-principal investigator for VEST (Vest Prevention of Early Sudden Death Trial) and the VEST Registry, which are studying the use of WCDs in the three months after myocardial infarction to determine whether WCDs prevent SCD. Secondary endpoints include patient compliance, incidence of ventricular arrhythmias, mortality and adverse events attributable to WCDs.

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Lee says the AHA advisory already has influenced his research. In the past, he says, there were differences of opinion about WCDs even among physicians in the same cardiology practices, where some were “big believers” in WCDs and others were “non-believers,” which affected enrollment in VEST. Now, cardiologists’ interest in randomizing patients to WCD trials has increased, perhaps because some physicians have interpreted the advisory as the AHA “signing off” on the therapy. 

Even as the VEST investigators are working to answer questions about the safety and efficacy of WCDs, others are focusing on cost-benefit questions. “Part of the metric [used by payers] is that if they don’t pay for it, the patient might need to stay in the hospital until extensive therapy is given,” which would cost them more, Lee says. “When doctors don’t have [the WCD] option, they often feel compelled to keep patients in the hospital until they feel they can be safely discharged without protection. If you give doctors an ability to protect their patients outside the hospital, they can save money by discharging them a little bit earlier.”

In 2015, cardiothoracic surgeon Roger G. Carrillo, MD, of the Miller School of Medicine in Miami, and colleagues performed a cost-benefit analysis on patients who required removal of an ICD due to infection. They found that WCDs were cost-effective in protecting patients against SCD compared to keeping patients in the hospital or discharging them home or to a skilled nursing facility (Heart Rhythm 2015;12[7]:1565-73).

“These data have influenced physician choice, if not that of payers,” Carrillo says. He predicts the AHA advisory will speed up payers’ acceptance of the therapy.

Deciding together

A central recommendation of the AHA advisory is that decisions about WCD use should include the clinician and the patient and a “frank risk-benefit discussion … that acknowledges the uncertainty surrounding the efficacy and safety of the WCD.” Piccini and coauthors stressed that physicians must share concerns about the lack of randomized clinical trials when considering WCDs as part of a bridge therapy. Clinicians also need to be clear about how and when to use the devices for maximum benefit. 

Patients’ feedback on WCDs varies, cardiologists say. On one hand, the devices may make it possible for patients to leave the hospital sooner and resume mostly normal lives. On the other hand, some patients—especially those with language or mental status barriers—may find it difficult to use the devices as directed. Others complain that the device, particularly the early models, are bulky and uncomfortable. Patients who wear a WCD when they should not, such as while taking a shower, during sexual activity or while exercising, may receive inappropriate shocks.

Both Carillo and Lee say the patients they have studied have generally been compliant with the devices. The AHA cited studies reporting discontinuation rates between 14 and 22 percent; however, other studies, including two that analyzed nationwide data in U.S. and German cohorts, showed an average adherence between 21.7 and 23.2 hours per day (J Am Coll Cardiol 2010;56[3]:194-203; Circulation 2016;134[9]:635-43).

More research is needed to increase compliance, although the questions may be resolved as the technology evolves and more data are published, says Piccini. “The wearable defibrillator is definitely part of clinical practice in 2016,” he says. “Understanding how the wearable defibrillator works in terms of the detection and treatment of arrhythmias and understanding the risk of a patient receiving an inappropriate shock and the likelihood of them wearing the device—those are important things for every physician to have familiarity with.”