Observational Study of Obstructive Sleep Apnea in Wake-Up Stroke: The SLEEP TIGHT Study

Abstract

Background: Wake-up stroke (WUS) accounts for a quarter of all ischemic strokes. Its conspicuous occurrence during sleep suggests that WUS may be associated with obstructive sleep apnea (OSA). We investigated the potential association among WUS, OSA, and measures of sympathetic hyperactivity. Methods: This is a cross-sectional analysis of data from the Sleep Apnea in Transient Ischemic Attack and Stroke (SLEEP TIGHT) study. Ischemic stroke patients were divided into WUS and non-WUS groups. Participants underwent polysomnography and ambulatory blood pressure monitoring. Collected data included demographic, medical, stroke characteristics (including severity by National Institutes of Health Stroke Scale), cholesterol, serum catecholamines, C-reactive protein, interleukin-6, B-type natriuretic peptide, blood pressure, and polysomnographic (apnea-hypopnea index (AHI); measures of hypoxia). Because both stroke and OSA affect men and women to varying degrees, the cohort was considered as a whole and by gender stratification. Results: Among 164 participants, 30.3% had WUS. The mean age was 62.0 ± 11.3 and the mean body mass index was 30.2 ± 7.9 kg/m2. One-hundred-and-five participants (63.6%) were males and 92 participants (56.8%) were Caucasian. Neither AHI nor OSA (AHI ≥5) frequency differed between WUS and non-WUS groups. Men tended to be more likely than women to have WUS (74.0 vs. 59.6%; p = 0.08), but this was not statistically significant. In gender-stratified analyses, men with WUS compared to men with non-WUS had significantly higher rates of severe OSA (AHI >30: 45.0 vs. 17.6%; p = 0.03) and tended toward more 3% oxygen desaturation events (57.0 ± 63.9 vs. 31.8 ± 22.9; p = 0.06). These differences were not seen in women. WUS patients tended to be of the male gender (74.0 vs. 59.6%; p = 0.08). History of stroke, hypertension, diabetes, dyslipidemia, or atrial fibrillation, serum catecholamines, and inflammatory biomarkers was no different between the groups. Low-density lipoprotein (LDL) was significantly higher in WUS (114.5 ± 36.3 vs. 101.4 ± 37.6; p = 0.04). Baseline diastolic blood pressure (DBP) was significantly greater in the WUS group. There was no difference in systolic or ambulatory blood pressure (including nighttime blood pressure) between WUS and non-WUS groups. Conclusions: WUS may be associated with severe OSA with more oxygen desaturation in men but not in women. WUS may be associated with high DBP and increased LDL cholesterol.