Abstract 21093: Time Dependence of Sudden Cardiac Arrest in a Wearable Cardioverter-Defibrillator Population
Introduction: The wearable cardioverter-defibrillator (WCD) is an external device capable of automatic detection and defibrillation of sustained ventricular tachyarrhythmias. The device records the time and date of all treatment shocks delivered. It has been reported that risk for sudden cardiac arrest (SCA) is highest during the early morning hours. We examined the relationship, if any, between WCD SCA events and time of day.
Methods: Treatment data from the WCD (LifeVest, ZOLL Cardiac Management Solutions) was retrospectively analyzed. All sustained VT/VF treatments within 24 hours were considered a single event (first treatment was used for time of day). Only patients with daily compliance greater than 20 hrs per day and residing in a state in the eastern time zone states were analyzed. These qualifications were chosen in an effort to minimize the influence of missing an event due to non-compliance and avoid errors associated with time-zone programming errors. The day was segmented into twelve two-hour intervals and the time of each SCA event sorted.
Results: From July 2004 through November 2009, there were 80 VT/VF treatment events in 73 patients, that met the criteria. The analysis shows distribution of events peak between 8 AM and 10 AM, and again between 6 PM and 8 PM. The proportion of observed VT/VF events are significantly different during these time periods (p<0.005).
Conclusions: WCD treatment for sustained VT/VF was more frequent between 8 and 10 AM, and again between 6 and 8 PM. During these time periods, routine removal of the WCD, such as for bathing, should be discouraged. Figure 1.
- Sudden cardiac death
- Arrhythmias, treatment of
- Ventricular tachycardia
- Ventricular defibrillation
- © 2010 by American Heart Association, Inc.