The Wearable Defibrillator - A New Method to Prevent Sudden Death
Ulf Meltendorf, MD, Anke Wollbrueck, RN, Angelo Auricchio, MD, Sven Reek, MD, Christoph J. Geller, MD, Helmut U. Klein, MD, University Hospital Magdeburg, Germany
Risk stratification of sudden death (SCD) has still a low positive predictive accuracy, mainly in patients (pts) with poor ventricular function, in the acute phase of myocardial infarction (AMI), after CABG or prior to decision making for an implantable defibrillator (ICD). We are currently testing a wearable automatic defibrillator vest (WCD, LIFECOR, Pittsburgh) in pts considered bearing a temporary high risk of SCD in whom ICD implantaion is still debatable. The WCD consists of a garment with installed ECG- and shock-electrodes, an alarm and monitor system and a take home interrogation base station connected to the hospital via computer or a modem system. The weight of the WCD is 1.5 kg, maximal energy output is 285 Joules. Until now 39 pts (32 men, 7 women), mean age 59 years, received the WCD after AMI, CABG or with a new unstable arrhythmic risk. Six pts had one episode of ventricular fibrillation with acute AMI, 17 pts were in Killip class III or IV and/or had LV EF <30% and 16 pts showed episodes of nonsustained VT (NSVT) with poor ventricular function. The planned duration to wear the WCD is about four months prior to definitive risk assessment with EP testing.
Results: Up to now 18 of 39 pts had the WCD for four months. The mean wearing time was 23.1 h/day. After two or three days of training and adaptation the WCD was mostly well tolerated and pts were discharged from the hospital. Only two pts (5%) interrupted the planned follow up time after 35 and 68 days respectively. In three of the four episodes of rapid VT/VF were correctly terminated. Two of the 3 pts received and ICD thereafter. No pt experienced inappropriate WCD discharges. According to the programmed detection algorithm NSVT was promptly recognized but energy discharge was correctly withheld. In 15% of WCD pts true artefact alarms occurred.
Conclusion: The WCD is a safe and effective new approach to bridge a period of arrhythmic risk until the indication for an ICD can be clearly established. It may prevent unnecessary ICD implementation, however, its widespread application needs to be proven by already launched prospective trials.