0684 Impact of Hot Flash-Associated Sleep Disruption on the Cardiovascular System in Perimenopausal Women

Introduction Hot flashes (HFs) are a common symptom of menopause, occurring across the day and night in up to 80% of women, and persisting for a median duration of 7.4 years. Women with HFs are more likely to have disrupted sleep and insomnia disorder, and night-time HFs account for a significant proportion of total wakefulness after sleep onset in perimenopausal women. Recent data suggest that HFs are a marker of cardiovascular (CV) disease risk, however, there is little information as to whether HF events themselves impact CV measures, particularly for nocturnal HFs. Here, we investigated CV changes around nocturnal HF events, considering whether or not they were associated with sleep disruption. Methods More than 500 objective HFs detected from laboratory-based skin conductance measures and aligned with 30-s epochs of polysomnographic sleep stages were analyzed from 86 healthy women, mostly in the menopausal transition (age: 50.7±3.6 years). Beat-to-beat heart rate (HR), blood pressure (BP), and pre-ejection period (PEP) derived from impedance cardiography and reflecting cardiac sympathetic activity, were sampled and analyzed across HF events. Results HFs associated with sleep disturbance (awakenings/arousal) were more common (51.1%) than HFs not associated with sleep disturbance (28.6%). There was a surge in systolic and diastolic BP and a 20% increase in HR in association with HFs accompanied by awakenings/arousals. The CV activation was sustained over a couple of minutes following HF onset. In contrast, systolic BP dropped and HR slightly increased in association with HFs occurring in undisturbed sleep, probably reflecting increased skin vasodilation to dissipate heat. PEP decreased across HF onset, likely reflecting increased cardiac sympathetic activity, regardless of whether the HF was accompanied by an awakening/arousal or not. Conclusion Findings suggest that nocturnal HFs affect the CV system differently depending on whether or not they are accompanied by an awakening/arousal. There are significant surges in BP and HR during HF-associated sleep disruption, which could have a detrimental effect on nocturnal CV recovery in women with frequent and persistent nocturnal HFs. Support (If Any) Grant HL103688 (FCB)