Abstract 312: Hospital Personnel Interactions With Wearable Cardioverter Defibrillators During Sudden Cardiac Arrest: A Case Series Review

Abstract

Purpose: The wearable cardioverter defibrillator (WCD) automatically detects and treats lethal ventricular tachyarrhythmias (VT/VF). However, intervention during an event by medical personnel to resuscitate a patient may delay or even prevent WCD treatment during sudden cardiac arrest (SCA). This study assessed hospital staff and WCD interactions, and the impact on in-hospital SCA outcomes. Methods: All shockable SCA events experienced by patients wearing a WCD between 11/2003 and 4/2013 were identified and retrospectively retrieved from the manufacturer’s post-market database. A shockable SCA event was defined as all sustained VT/VF during a single 24-hour period. Only events that occurred during hospitalization or emergency room visit were reviewed in this study. Interactions with medical personnel included 1) belt disconnection or garment removal prior to WCD therapy or 2) use of response buttons (RBs) by someone other than the patient. Device recordings and customer call reports were reviewed for event details and 24 hour survival (acute survival). Results: A total of 209 in-hospital SCA events were included. Overall, 51 (24.4%) were on telemetry and 76 (36.4%) were witnessed. Acute survival was 82.8%. The WCD delivered at least 1 shock in 181 (86.6%) events with a median arrhythmia onset-to-shock (OS) time of 47 seconds (mean=90.4±307.48 seconds). When hospital staff used RBs (n=15, 7.2%), the OS time was longer (median=62.5 seconds, p<0.01). Three (1.7%) conscious patients were advised not to use RBs during sustained VT. No WCD therapy occurred in 28 (13.4%) events due to belt disconnection in 18 (64.3%), VT/VF rate below the pre-programed threshold in 8 (28.6%), RBs use by hospital staff in 6 (21.4%), resuscitation efforts creating ECG interference in 5 (17.9%), and device damage in 2 (7.1%). Only 4 (14.3%) patients survived acutely when WCD therapy was prevented, although 13 received defibrillation from hospital defibrillators. Conclusions: WCD therapy during in-hospital SCA resulted in a high acute survival rate. Interventions during an event by medical personnel to resuscitate a patient reduced the number of WCD therapies delivered and may have affected acute survival.