P2281Inadequate heart rate control begets sustained ventricular arrhythmias in a large cohort of women

Background The Wearable Cardioverter Defibrillator (WCD) is an effective therapy for treating ventricular arrhythmias (VT/VF) in at-risk patients, while providing continuous heart rate (HR) monitoring. Because women are under-represented in defibrillator trials, we chose to specifically focus on HR control in women prior to VT/VF events. Purpose To evaluate HR profiles preceding sustained VT/VF in women fitted with a WCD. Methods Data from women fitted with WCD (≥30 days use) from 2015 to 2018 were obtained from the manufacturer's database. HR is expressed as a weekly resting nighttime median (midnight to 7 am). Men (random sample) with the same inclusion criteria served as a control. Results A total of 21,440 women, age 67±15 years, were included for analysis. Over a median WCD use of 90 days (59–116 days), 118 women (0.6%) and 133 men (0.8%) received shocks for VT/VF (p=0.01). Resting HR one-week preceding VT/VF was above the target of 70bpm in 55% of shocked women (65 of 118) versus 44% of non-shocked women (9,272 of 21,322, p=0.01) (figure). HR one week before WCD shock was similar in women and men (71 bpm vs. 72 bpm; p=0.60). Younger women (≤50 years) had higher HR prior to shock than older women (HR 80 bpm vs. 70 bpm p=0.003). Among shocked patients, 24-hour-survival was 89% in women and 88% in men. During three-month follow-up, the same percentage of men and women died after receiving adequate WCD shock therapy (18%). Heart rate profiles Conclusions Women with adequate heart rate control experienced significantly less spontaneous VT/VF than those with higher heart rates. The WCD can be utilized as a diagnostic tool to monitor HR in at-risk women in addition to treating sustained VT/VF.