Abstract of presentation made by Dr. Arthur Feldman at American College of Cardiology Meeting on March 18, 2002, in Atlanta, Georgia
New Therapeutic Option for Patients With Time-Dependent Risk of Sudden Cardiac Arrest: Application of Novel Wearable Cardioverter-Defibrillator
Background: Outpatient populations with temporary risk for sudden cardiac arrest (SCA), such as patients awaiting cardiac transplant, post-myocardial infarction patients (p_MI) or post-CABG patients (p-CABG), often rely on emergency medical services (EMS) for defibrillation therapy. Success rates for EMS resuscitation are poor. A new therapeutic option, the completely automatic (no bystander intervention) wearable cardioverter-defibrillator (WD), may provide better protection for these populations.
Arthur M. Feldman, Helmut Klein, Patrick Tchou, The WEARIT & BIROAD Investigators, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, Otto Von Guericke University, Magdeburg, Germany.
Methods: A multicenter trial studied the use of the WD (WCD system, LIFECOR, Inc., Pittsburgh). WD provides automatic detection and treatment of ventricular tachycardia and fibrillation (VT/VF) using unique non-stick ECG electrodes and self-gelling therapy electrodes. WEARIT sub-population: patients on the cardiac transplant list or equivalent in cardiac status. WEARIT subjects used WD until transplanted, hospitalized for transplant or circulatory assist device, or receiving an active ICD. BIROAD sub-population: patients not receiving an ICD who were p-MI or p-CABG and had either VT/VF within 48 hours, an ejection fraction <.30 or Killip class> II after 72 hours, or syncopal VT/VF after 48 hours. BIROAD used WD for ~4 months. The effectiveness objective was >25% resuscitation success with 90% confidence. The safety objective was <2.3% false shocks per patient-month with 90% confidence (500 patient-months minimum).
Results: There were 8 VT/VF SCA events in 6 patients (4 BIROAD, 2 WEARIT). 6 were successfully treated. 2 were unsuccessful with VT/VF detected but treatment prevented by incorrect patient assembly of WD (therapy electrode in pocket backward, gel released away from body). A redesign occurred to prevent this from reoccurring. 6 false shock episodes occurred in 873 patient-months. The most frequently reported adverse event (20) was temporary skin rash under electrodes. 285 patients were enrolled over 3 years. Daily use averaged 21 hours for BIROAD and 19.2 hours for WEARIT.
Conclusion: WD is a safe (<2.3% false shocks per patient-month) and effective (>25% effective resuscitation) alternative to EMS for outpatient populations with a temporary risk of SCA.
Category: Defibrillation/Implantable Antiarrhythmia Devices
Keyword: Sudden death; Defibrillation, ventricular; Arrhythmias, treatment of; Ventricular arrhythmia