ABSTRACT NUMBER: ESOC2026A1989 DIURNAL PHASE DISPLACEMENT AT TIME OF ACUTE ISCHEMIC STROKE IS ASSOCIATED WITH SEVERITY AND FUNCTIONAL RECOVERY

Abstract Background and aims Heart rate naturally follows a 24-hour diurnal cycle, with characteristic peaks during waking hours and troughs during sleep. Rodent models have shown shifts in melatonin release following acute ischemic stroke disrupting the diurnal rhythm. However, methods to quantify such diurnal shifts (DS) in humans have been lacking. We aimed to achieve the quantification of DS using heart rate data and analyzed the association with stroke severity and recovery outcomes. Methods We retrospectively analyzed 877 acute ischemic stroke patients at Charité Universitätsmedizin Berlin and validated findings in 519 patients from a publicly available dataset. A harmonic model was fit to heart rate recordings in the first 24 hours post-stroke to infer the diurnal phase at time of stroke onset. DS was quantified as the deviation between this observed phase and the expected phase. Unlike previous work that measured DS via melatonin secretion, we use routinely collected heart rate data. Correlations with stroke severity, functional outcomes, lesion volume, and central autonomic network (CAN) involvement were examined. Results Greater DS was correlated with more severe admission National Institute of Health Stroke Scale (NIHSS) (r=0.27, p<0.0001) and worse recovery (ΔNIHSS r=0.23, p<0.0001). DS showed stronger correlations with clinical outcomes than other heart rate-derived parameters and established risk factors. Correlations between DS and lesion volume were significant for infarcts involving CAN structures (r=0.16, p<0.05), especially in the prefrontal cortex (r=0.35, p<0.001) and insula (r=0.38, p<0.003). Conclusions Diurnal shift is a promising candidate biomarker derived from routine monitoring that may offer complementary added prognostic value for stroke recovery. Conflict of interest All authors: nothing to disclose