WEARIT-II: Wearable Defibrillator Safe, Helps in ICD Decision-Making

Marlene Busko

September 12, 2014

BARCELONA, SPAIN — Data recorded by a wearable cardiac defibrillator (WCD) can help physicians assess whether a patient at high risk of sudden cardiac death should receive an implantable cardioverter defibrillator (ICD), researchers report[1].

Moreover, patients who wore the defibrillator "vest" for three months experienced no safety issues, Dr Valentina Kutyifa (University of Rochester Medical Center, NY) said when she presented the study at the European Society of Cardiology (ESC) 2014 Congress.

This results come from more than 2000 patients enrolled in the WEARIT-II registry who were prescribed the LifeVest WCD (ZOLL Medical, Pittsburgh, PA) between August 2011 and February 2014.

At the end of the WCD use, ICDs were implanted in 785 of the patients (39%) and were most often not implanted because of improved LVEF.

"In a real-world setting, a management strategy that incorporates the WCD can be safely used to bridge a decision for appropriate ICD therapy in patients with acquired, inherited, and congenital heart disease," said Kutyifa.

A Bridge Until ICD Decision Time?

In a previous study[2], as reported by heartwire , the WCD was used to successfully treat 1.4% of more than 8000 patients who had had an MI and were enrolled in the WEARIT-II registry between September 2005 and July 2011. Patients wore the defibrillator vest for a mean of 69 days while waiting the mandated 40 or 90 days (if they had received acute revascularization) before being eligible for an ICD.

The current study prospectively enrolled a diverse group of real-world patients who received a WCD more recently; only some patients had had an MI, others had new-onset cardiomyopathy.

American Heart Association/American College of Cardiology/Heart Rhythm Society 2012 guidelines suggest that ICDs can be implanted in patients with an LVEF of 35% or less or at high risk of inherited arrhythmias, Kutyifa noted. However, there is a need for improved selection of patients for primary ICD therapy based on the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) and MADIT - Reduce Inappropriate Therapy (MADIT-RIT) findings, which showed a very low rate of appropriate ICD therapy.

Thus, a WCD might be used as a bridge prior to deciding whether an ICD should be implanted.

The current prospective WEARIT-II registry study included 2000 patients in the US who had ischemic cardiomyopathy (40.3%), nonischemic cardiomyopathy (46.4%), or congenital or inherited heart disease (13.4%). Participants had a mean age of 62 years and median LVEF of 25%, and 30% were women. "Importantly," more than half reported heart-failure symptoms at the time of enrollment.

Patients wore the WCD for a median of 22.5 hours a day for a median of 90 days.

While wearing the defibrillator vest, 41 patients (2.1%) had 120 treated ventricular-tachycardia/ventricularfibrillation events or spontaneously terminated instances of sustained ventricular tachycardias.

A total of 22 patients (1.1%) had 30 ventricular-tachycardia/ventricular-fibrillation events for which they received WCD shocks.

There were 164 sustained ventricular-tachycardia events in 28 patients (1.4%) and 561 atrial arrhythmias or sustained ventricular-tachycardia events in 72 patients (3.6%).

Whether or not arrhythmias were detected while a patient wore the WCD helped physicians decide whether that patient should receive an ICD afterward. A total of 85% of patients who had a ventricular tachycardia or ventricular fibrillation and a WCD shock were implanted with an ICD compared with only 39% of patients who had no arrhythmias.

There were no deaths related to use of the vest. In addition, the rate of inappropriate WCD shocks was very low (0.5%).

Easy to Use, Potentially Cost-Effective

"What do the patients think about this? Second, what are the costs?" assigned discussant Dr Chris Gale (University of Leeds, UK) wanted to know.

Although the study did not assess quality of life or include a cost analysis, "I think that although the device has a high up-front cost, in the long term this will be cost-effective," Kutyifa replied, because it will avoid costs associated with implanting an ICD in a patient who may not need one.

Concerns have been raised in the past about the concept of a "wearable" defibrillator, most of them centered around the lack of randomized clinical-trial data using hard outcomes showing that wearing a vest can actually save lives compared with best medical care. The VEST trial, launched in 2008, is designed to address the mortality question in 1900 patients, but is listed on the ClinicalTrials.gov website as still actively enrolling patients with an expected completion date of September 2015. There are also concerns about patient quality of life.

On the last point, however, Kutyifa insisted to heartwire that "patients don't have issues using [the WCD] and the use is very simple." The device has an alarm that sounds to notify the patient that it is detecting arrhythmias and is about to deliver a shock, and they can press a response button to cancel a shock, she noted.

The WEAR-IT registry is supported by ZOLL Medical. Kutyifa has received a research grant from Zoll.

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