BARCELONA – Use of the LifeVest wearable cardioverter defibrillator for 3 months is a safe and effective means of buying time to decide whether to place a permanent implantable cardioverter defibrillator for primary prevention of sudden cardiac death in potential candidates, according to the first report from a large prospective U.S. registry.
The wearable cardioverter defibrillator (WCD) simultaneously provides patient monitoring and reliable protection against fatal arrhythmias while physicians wait to see if, for example, a patient’s left ventricular ejection fraction, depressed to less than 35% immediately post-MI, will recover over the first several months or if life-threatening arrhythmias will arise warranting implantable cardioverter defibrillator (ICD) implantation, Dr. Valentina Kutyifa explained while presenting the results of the WEARIT-II registry at the annual congress of the European Society of Cardiology.
Dr. Valentina Kutyifa
"The WCD seems to be a powerful risk-assessment tool to identify patients at a high risk for sudden cardiac death who need subsequent ICD implantation. The WCD can be used as a bridge to a decision for appropriate ICD implantation in patients with a low ejection fraction who are immediately post-MI, or following coronary revascularization, or with new-onset dilated cardiomyopathy who are at high risk for sudden cardiac death until stabilization, or who have an inherited arrhythmia or congenital disorder," said Dr. Kutyifa of the University of Rochester (N.Y.).
She reported on 2,000 U.S. patients in those categories who participated in the prospective WEARIT-II (Prospective Registry and Follow-Up of Patients Using the Wearable Defibrillator) registry. All received from their physicians a 3-month prescription for the LifeVest WCD, which is covered by Medicare and by most health plans. Of the 2,000 patients, 927 had a left ventricular ejection fraction (LVEF) of 35% or below owing to nonischemic cardiomyopathy, 805 had ischemic cardiomyopathy, and 268 had an inherited or congenital arrhythmogenic disorder, such as long QT syndrome or arrhythmogenic right ventricular dysplasia.
Participants’ median ejection fraction at enrollment was 25%, and 52% of subjects had heart failure symptoms at that time. Patients wore the WCD for a median of 22.5 hours per day, with no difference in wear time by disease etiology.
In terms of WCD safety, the inappropriate shock rate was just 0.5% in 2,000 patients during 3 months. No study deaths occurred related to unsuccessful attempts at termination of ventricular tachycardia (VT) or ventricular fibrillation (VF) by the WCD. Three patients died while wearing the WCD, and in all three cases the WCD detected asystole at the time of death.
During 90 days of WCD wear, 2.1% of patients experienced VT or VF, for an event rate of 22 per 100 person-years. The WCD administered a shock for VT/VF in 1.1% of patients. Sustained VT or VF occurred in 1.4% of patients, while 3.6% of participants experienced atrial arrhythmias or supraventricular tachycardia, with an event rate of 121 per 100 person-years.
At the end of the 3-month period of WCD use, 42% of patients with ischemic cardiomyopathy got an ICD, as did 36% of those with nonischemic cardiomyopathy and 46% who had a congenital or inherited condition. The main reason for not implanting an ICD was a boost in ejection fraction.
The WCD frequently detected arrhythmias which facilitated the decision whether to implant an ICD or not. Eighty-five percent of patients with VT/VF treated with a WCD shock got an ICD, as did 65% of those with sustained VT that terminated spontaneously during the wearable device’s detection time. Of patients with WCD-detected atrial arrhythmias, 48% received an ICD, as did 39% of those with no arrhythmias during the 3-month period.
Dr. Kutyifa characterized the WCD as helping to fill an unmet need for improved selection of patients for primary ICD therapy. In the landmark MADIT-II trial, for example, only 4% of patients received an appropriate ICD shock during 4 years of follow-up (N. Engl. J. Med. 2002;346:877-82).
Asked about the cost-effectiveness of WCD as a bridge to the ICD decision, she replied that such data weren’t included in the WEARIT-II registry.
"The up-front cost of the device may seem rather high, but if you think about the fact that if we use the WCD and are then able to make the decision to not implant an ICD in patients who don’t need it, we really need to look at the long-term savings: the cost of the ICD, battery changes, and issues of possible lead extraction. So I think long-term this management strategy would be cost-effective," the electrophysiologist said, adding that the WCD is also rentable.
At the congress-closing conference highlights overview session, Dr. Sylvia G. Priori singled out the WEARIT-II registry as one of the top developments in the field of arrhythmias presented at this year’s meeting. She noted that the WCD has been available for several years – Medicare covers it, as do most U.S. health plans – yet until now many physicians have wanted to see stronger evidence of safety and effectiveness before incorporating the WCD into their own practices. WEARIT-II, she said, provides that supporting evidence.