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DENVER -- An external cardioverter-defibrillator worn like a vest saves lives for high-risk patients, and appears to aid in the decision to use an implantable device in a real-world setting, the WEARIT II registry showed.

The Lifevest device appropriately terminated life-threatening events at a rate of nine per 100 patient-years, Ilan Goldenberg, MD, of the University of Rochester Medical Center in Rochester, N.Y., and colleagues found.

Inappropriate shocks occurred at a rate of just 0.3%, a rate significantly lower than seen with implantable devices, the group reported here at the Heart Rhythm Society (HRS) meeting.

Those who received appropriate shocks were the ones most likely to get an implantable cardioverter-defibrillator (ICD) after wearing the vest (80%), whereas the rate was 40% to 50% in the other groups, including those without any monitored arrhythmia while wearing the device.

"In a real-world setting, a management strategy that incorporates the wearable cardioverter-defibrillator can be safely used to bridge a decision for appropriate ICD therapy," Goldenberg told attendees at a late-breaking HRS session.

Not all high-risk patients will benefit from an implanted device, as reflected in guidelines recommending a 40-day waiting period after a heart attack, he pointed out.

The wearable defibrillator could be a good solution for individual patients of high concern during that period, Michael Gold, MD, PhD, from the Medical University of South Carolina in Charleston, suggested at the HRS press conference he moderated.

"Studies show that if you put a defibrillator in early after a heart attack, you didn't save a life, probably because there were many very high-risk patients who were going to die regardless of the defibrillator," he explained. "If you're really worried about the patient, you can put on the Lifevest, see how they do over the 40 days, and if the heart's still bad, then that's the bridge to an [implanted] defibrillator."

Other scenarios the device would be useful in are while waiting for infection that necessitated ICD removal to clear up and while waiting to see if medication will work for patients who present with heart failure.

In heart failure, "it's hard to know who will get better and who won't," Gold added. "The guidelines properly say wait 3 months because many patients get better over that 3 months and we don't want them to be living with that device inside them if they didn't need it."

The analysis included the first 882 U.S. patients in the WEARIT II registry (mean age 60) who wore the Lifevest for 2 to 6 months and were followed to 12 months for outcomes from 2011 to March 2013.

The majority (711) had acquired heart disease, split fairly evenly among ischemic and nonischemic disease and other high-risk categories.

The largest category among the latter was congenital heart disease, followed by a variety of inherited conditions like long QT syndrome and hypertrophic cardiomyopathy. Goldenberg noted that the device can be useful for these groups when patients are suspected to be at high risk, but are still being evaluated and going through genetic testing.

The vest administered therapy in 17 cases of ventricular tachycardia or ventricular fibrillation in 10 patients, for an event rate of nine per 100 patient-years.

The inappropriate shock rate appeared to have been brought down by patients pushing a button to abort impending inappropriate shocks, which occurred at a rate of 27 per 100 patient-years (53 events in 11 patients).

Other events recorded were:

• 93 cases of nonsustained ventricular tachycardia in nine patients, for an event rate of 47 per 100 patient-years
• 126 cases of atrial arrhythmias or sustained ventricular tachycardia in 21 patients, for an event rate of 64 per 100 patient-years
• Five cases of asystole in two patients, for an event rate of three per 100 patient-years

Three patients died while not wearing the vest; one died from asystole while not wearing it. The overall death rate was 0.5%.

Patients wore the vest for a median 22 hours a day, as recommended, for a median 81 days. Compliance appeared to rise with days of wear rather than fall off as had been suggested by a small cohort study.

About 40% of the cohort had an improvement in ejection fraction by the end of use; another 40% received an ICD at the end of use.

The registry is ongoing, and planned to enroll a total 2,000 U.S. patients and 1,000 in Europe and Israel. The Lifevest is approved for use in the U.S. and Europe but isn't included in guidelines.

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