Wearable defibrillator registry (WEARIT-II) update

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At Cardiostim/EHRA Europace (18–21 June, Nice, France), Ilan Goldenberg (Heart Center, Sheba Medical Center, Tel Hashomer, Israel) presented an update on one-year follow-up results from the prospective WEARIT-II registry of 1,404 patients using the Lifevest wearable cardioverter defibrillator (Zoll) who were enrolled in the USA from August 2011 through December 2013.

Last year, at the Scientific Sessions of the Heart Rhythm Society, Goldenberg presented results of the first 882 patients enrolled in the USA between August 2011 and April 2013, which found that-in a real-world setting-the Lifevest is an effective and safe strategy to bridge a decision for appropriate implantable cardioverter defibrillator (ICD) in patients with acquired, inherited and congenital heart disease. The results presented at Cardiostim 2014, according to Goldenberg, continue supporting this initial finding. “The Lifevest offers safe termination of life-threatening arrhythmic events, avoidance of unnecessary therapies for non-life-threatening arrhythmias, and low rate of inappropriate therapies,” he said.

Goldenberg told delegates that current guidelines suggest a class I recommendation for primary implantation of an ICD in patients with ejection fractions of less than 35%. They also provide a general recommendation for primary implantation of an ICD in high-risk patients with inherited arrhythmic disorders or congenital heart disease. However, he said: “Not all patients implanted with an ICD derive the significant survival benefit from the device at one year follow-up”. For example, he explained, data from MADIT II and MADIT-RIT suggest the need for improved selection of patients before a decision for primary ICD implantation is made.

The Lifevest wearable cardioverter defibrillator, Goldenberg noted, can be used as a strategy to bridge a decision for appropriate ICD in several high-risk populations for cardiac arrest such as post myocardial patients, following coronary revascularisation, for patients with new onset dilated (non-ischaemic) cardiomyopathy or for those with inherited arrhythmic or congenital disorders. An important feature of the device, he highlighted, is that it allows the patient to use a response button to avoid inappropriate shocks.

WEARIT-II includes patients in the USA, Europe and Israel, the general prescription of the device is two to six months, and patients are followed up for 12 months. In total, Goldenberg said, 2,000 will be enrolled in USA and 1,000 in Europe and Israel.

Speaking on the results of the current analysis, Goldenberg said that of the 1,404 patients (average age 60±13 years, 31% females) included, 1,278 presented with acquired cardiomyopathy (45% with ischaemic cardiomyopathy and 55% with non-ischaemic cardiomyopathy) and 184 patients with congenital/inherited syndromes, among those long QT syndrome and Brugada syndrome. The average ejection fraction was “relatively low” (25±10%).

Regarding arrhythmic events (average wearing days: 81), the rate of proper guidance therapy with the Lifevest for ventricular tachycardia/ventricular fibrillation was seven events per 100 patient/years. The rate of sustained ventricular tachyarrhythmias which were withheld from therapy by use of the response button and subsequently spontaneously terminated was 26 events per 100 patient/years. “This suggests that the use of the response button probably avoided a relatively high rate of unnecessary shock therapies, as may have occurred if an ICD were implanted.”

Goldenberg highlighted that the rate of adverse events during device description was “very low, with only 0.3% of the patients receiving inappropriate shocks.”

Compliance of the device was “relatively high” with a median of 21 hours per day. “It increased within the first weeks of use, and remained very high and stable thereafter,” he noted.

“Arrhythmias that were detected with the Lifevest affected the end of use decision,” said Goldenberg. Overall, 35.7% patients received an ICD, 14.3% continue with the wearable cardioverter defibrillator and 37.3% recovered without device.

Goldenberg also presented one-year mortality results from the first 882 patients enrolled. Twenty one (2.4%) patients died during one-year follow-up. Seven of those died during device prescription (four deaths without wearing the Lifevest and three with the device, but due to asystole) and 14 patients died following end of use (76% cardiac deaths, 65% with an ICD vs. 35% without and ICD).

Data from 2,000 patients enrolled in the USA will be presented at the European Society of Cardiology (29 August – 3 September, Barcelona, Spain) Goldenberg announced.