Background and aims: Circadian variability of blood pressure (BP) and hypercoagulation in the morning have been proposed as underlying mechanisms of wake-up stroke (WUS). The aim was to determine the impact of cerebral microbleeds (CMBs), showing BP fluctuation and background hypercoagulability, on WUS.
Methods: Consecutive patients with acute ischemic stroke onset-to-door time within one week were screened. WUS was defined as an ischemic stroke that occurred during sleep at night. CMBs were categorized into three: "strictly Lobar", "strictly Deep (D) and/or Infratentorial (I)", and "Mixed". Moderate to severe CMBs were defined as having more than three in total. First, whether CMBs are associated with WUS was examined. Second, the same analysis was performed according to the stroke subtype classified as large-artery atherosclerosis (LAA), cardioembolism (CE), and small-vessel occlusion (SVO).
Results: A total of 1477 patients (1059 [72%] male, median age 69 years) were included, and WUS was observed in 363 (25%) patients. On Poisson regression analysis with a robust variance estimator in the total cohort, moderate to severe strictly D and/or I CMBs (PR 1.505, 95% CI 1.154-1.962, p = 0.003) were associated with WUS. From the perspective of stroke subtype, the same result was confirmed in LAA (PR 2.223, 95% CI 1.036-4.768, p = 0.040) and CE (PR 1.668, 95% CI 1.027-2.709, p = 0.039), not SVO.
Conclusions: The presence of moderate to severe strictly D and/or I CMBs might be associated with the development of WUS. By stroke subtype, the same result was confirmed in LAA and CE.
Keywords: Cerebral microbleeds; Circadian variability; Stroke subtype; Wake-up stroke.
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