Wearable cardioverter defibrillator
The wearable cardioverter defibrillator (WCD) is worn by patients at risk for sudden cardiac arrest (SCA), allowing their physician time to assess their long-term arrhythmic risk and make appropriate plans.
The WCD is lightweight and easy to wear, allowing patients to return to their activities of daily living, while having the peace of mind that they are protected from SCA. The WCD is non-invasive and consists of two main components – a garment and a monitor. The garment, worn under the clothing, detects arrhythmias and delivers treatment shocks. The monitor is worn around the waist or from a shoulder strap and records the arrhythmias. The WCD continuously monitors the patient’s heart and, if a life-threatening heart rhythm is detected, the device delivers a treatment shock to restore normal heart rhythm. The entire event, from detecting a life-threatening arrhythmia to automatically delivering a treatment shock, usually occurs in less than a minute. Timely defibrillation is the single most important factor in saving an SCA victim’s life. A treatment shock must be delivered within a few minutes after an event to be effective; with each passing minute, a patient’s chances of survival drops 10 percent. The WCD does not require bystander intervention and has a 98 percent first treatment shock success rate for resuscitating patients from SCA.
The WCD may be prescribed for patients at high risk of SCA following a heart attack, before or after bypass surgery or stent placement, as well as for those with cardiomyopathy or congestive heart failure that places them at particular risk.
The WCD is a therapeutic option, listed along with implantable cardioverter defibrillators (ICDs), in the ACC/AHA/ESC Guidelines for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. It is also a Class I recommendation in the International Society for Heart and Lung Transplantation Guidelines for the Care of Cardiac Transplant Candidates.
Contents
History
In 1986, Dr. M. Stephen Heilman and a team of former Intec employees who developed the first implantable cardioverter defibrillator (ICD) founded Lifecor and began development of the WCD. The WCD was extensively tested for three years in 17 major medical centers across the United States and Europe. The clinical data collected from those trials allowed Lifecor to obtain FDA approval for use of the WCD in the United States.
In 2002, the FDA approved the LifeVest wearable cardioverter defibrillator. The Lifecor business was acquired by ZOLL Medical Corporation in 2006. Since its initial launch, the LifeVest has gone through four product generations, reducing size and weight and advancing the technology and performance. The LifeVest is currently marketed in the United States and Europe.
According to ZOLL, the company that manufactures the LifeVest, as of September 2009, the LifeVest has been prescribed to more than 18,000 patients.
Insurance coverage in the United States
The WCD is covered by most health plans in the United States, including commercial, state, and federal plans as Durable Medical Equipment (DME) for those patients at high risk of cardiac arrest, including:
- Primary prevention [ Ejection fraction (EF) ≤35% and either Myocardial Infarction (MI) or Non Ischemic Cardiomyopathy (NICM)] including:
- Immediately after a MI (Coverage during the 40-day ICD waiting period)
- Before and immediately after CABG or PTCA (Coverage during the 90-day ICD waiting period)
- Listed for cardiac transplant
- Recently diagnosed NICM (Coverage during the three-to-nine month ICD waiting period)
- New York Heart Association (NYHA) Class IV heart failure
- Terminal disease with life expectancy of less than one year
- All ICD indications
- Any ICD explantation
Assessment of benefits
The wearable cardioverter defibrillator can be useful in cases after the need has been established but prior to implantation of an implantable cardioverter-defibrillator (ICD) and in cases where and ICD is contraindicated. Use of a WCD also avoids complications that could arise from implanting an ICD, However, both contraindications to and complications from ICD implantation are few, so in the main an ICD is the recommended option. Further, patients who are too sick for an ICD are unlikely to benefit from any defibrillator. "Since complications of AICD placement are low and contraindications few, it is unlikely that the WCD can improve outcomes, even in patient populations where the need for an AICD is temporary."[1]
The California Technology Assessment Forum reported in March 2009 that the WCD "does not meet CTAF TA criteria 2-5 for efficacy and improvement in health outcomes."[2]
Footnotes
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- Reek et al., “Clinical Efficacy of the Wearable Defibrillator in Acutely Terminating Episodes of Ventricular Fibrillation Using Biphasic Shocks,” PACE, 2002, 25(4, part II):577.
- Wase, “Wearable Defibrillators: A New Tool in the Management of Ventricular Tachycardia/Ventricular Fibrillation,” EP Lab Digest, 2005; 12:22-24
- Feldman et al., “Use of a Wearable Defibrillator in Terminating Tachyarrhythmias in Patients at High Risk for Sudden Death: Results of WEARIT/BIROAD”, PACE, 2004, 27:4-9.
- Reek et al., “Clinical Efficacy of the Wearable Defibrillator in Acutely Terminating Episodes of Ventricular Fibrillation Using Biphasic Shocks,” PACE, 2002, 25(4, part II):577.
- Keller et al., “Using the LifeVest as a Bridge to ICD implantation: One Urban Community Hospital’s Experience,” EP Lab Digest, 2008; Vol. 8– Issue 8.
- Elrod, “Measuring the Effectiveness of Wearable Defibrillators and Implantable Devices: EP Lab Digest Speaks with Jeffrey Olgin, MD about the VEST/PREDICTS study,” EP Lab Digest, 2008; Vol. 8– Issue 7.
