Abstract 120: Early Defibrillation Benefit in Patients Wearing a Wearable Defibrillator
Background: Early defibrillation through public access to defibrillation has been met with some success (e.g., casinos) in treating sudden cardiac arrest (SCA) but is limited by the need for a witness. Wearable defibrillators (WD) can perform defibrillation without a witness but cannot provide any other bystander benefit (i.e., CPR and engaging the emergency medical system). We describe the effectiveness of the WD in treating SCA and survival outcomes.
Methods: The WD (LifeVest, ZOLL, Pittsburgh, PA) automatically records and treats sustained (>30 seconds) ventricular tachycardia and ventricular fibrillation (VT/VF). ECG recordings and customer call reports from July 1, 2001 through May 8, 2010 were retrospectively reviewed for VT/VF. SCA events were defined as all unconscious, sustained VT/VF occurring within a single 24-hour period. Patients who reported they were conscious during VT/VF treatment were excluded. Reason for WD use was determined by the patient's medical orders. As hospital discharge records were not available, survival was defined through call reports as arriving conscious to a hospital or not needing to go.
Results: There were 315 VT/VF events (287 VT, 28 VF) identified in 255 patients. All events were detected and recorded by the WD, and 303 were converted out of VT/VF to an organized rhythm (297) or asystole (6). First shock conversion was 96.1%. Event survival was 91.7%. Four of six post-shock asystole events resulted in survival. Median time to shock from arrhythmia onset was 44.0 seconds (range 30 to 1893). Most shocks (83%) were delivered within 60 seconds. VT programming (60 seconds of alarms before treatment) and response button use (test of consciousness) were the most frequent cause of shock delay. Survival for VT was 93.6% and for VF 88.8%. LifeVest use was due to a recent SCD event (14.1%), delayed ICD implant or explantation (30.2%), recent MI/CABG (30.2%), NICM (9.4%), genetic (2.0%), and Other (14.1%).
Conclusions: Early defibrillation as delivered by WD resulted in 91.7% SCA survival. Post-shock asystole was unusual.
- © 2010 by American Heart Association, Inc.