Sleep-disordered breathing and wake-up stroke: a differential association depending on etiologic subtypes

Abstract Background and purpose Obstructive sleep apnea (OSA) is a modifiable risk factor for stroke, but there are limited data on which stroke subtypes are associated with OSA. The aim of this study was to assess the risk for wake-up stroke (WUS) associated with OSA according to each etiologic subtype to elucidate the pathophysiologic mechanism of OSA-associated stroke. Method We investigated 557 consecutive patients who were admitted with acute ischemic stroke in two regional comprehensive stroke centers using a standardized protocol including the Berlin questionnaire to identify symptoms of OSA prior to stroke. The collected stroke data included the time of onset, risk factors, and etiologic subtype. Stratified analysis according to sex was conducted because sex has been reported to be an effect modifier of OSA on cardiovascular outcomes. The association between preexisting OSA symptoms and WUS depending on etiologic subtypes was assessed using multivariate logistic regression analysis. Results Preexisting OSA symptoms were associated with the risk of overall WUS in men. Snoring was associated with WUS in large artery atherosclerosis [adjusted odds ratio, 2.67 (1.15–6.23)], and apnea was associated with WUS in small vessel occlusion [adjusted odds ratio, 8.21 (1.15–58.53)], whereas OSA symptoms were not significantly associated with WUS in cardioembolism. Associations between OSA and WUS were not found in women. Conclusion This study demonstrated the differential influences of OSA on WUS depending on etiologic subtypes, suggesting more vulnerability in large artery atherosclerosis and small vessel occlusion. Sex is a significant effect modifier of the association between OSA and WUS.