B-po04-154 time of day of ventricular tachyarrhythmias after myocardial infarction: results from the vest trial

Sudden cardiac death is common in the early post-myocardial infarction (MI) period. It is not known if ventricular tachyarrhythmias (VT/VF) are more common in certain parts of the day. To analyze the time of day of VT/VF events leading to appropriate shocks among participants in the VEST Trial. In the VEST trial, patients with MI and an ejection fraction of ≤35% were randomized to a wearable cardioverter-defibrillator (WCD) plus guideline-directed medical therapy (GDMT), or GDMT alone. Among those with VT/VF leading to appropriate shocks, their demographics, comorbidities, and timing of shocks were summarized. Among 2302 participants in the VEST trial, 21 participants had an appropriate shock. The median age was 55.3 years (interquartile range [IQR] 50.5-64.4), with 86% male. The median body-mass index was 28.1 kg/m2 (IQR 26.0-33.3). Comorbidities included diabetes (52%), hypertension (38%), and prior MI (33%). Participants had a post-MI ejection fraction of <25% (43% of participants) or 25-35% (57%). There were 44 appropriate shocks for VT/VF, with a median of 1 (IQR 1-3) shock(s) per participant. Shocks were most common in the morning (6am-12pm, 59%, Fisher's exact p<0.001; Figure), compared to other time periods: afternoon (12pm-6pm, 9%), evening (6pm-12am, 14%), and overnight (12am-6am, 18%). The first shock by WCD was successful in all VT/VF episodes; however, 6/21 (29%) participants died during the 3-month follow-up. In patients with recent MI, VT/VF occurred more frequently during the morning hours, possibly related to sympathetic surges. Therapies aimed at decreasing morning sympathetic surges may be beneficial.