Patient demographic and clinical features and circadian variation in onset of ischemic stroke

Background: Studies have reported circadian variation in the onset of ischemic stroke, which may carry important pathophysiological implications. However, there is no detailed information about circadian variations among the subtypes of stroke. Objective: To determine whether subgroups of patients with ischemic stroke with specific clinical characteristics would exhibit different circadian patterns, to more systematically examine the role of possible triggering or precipitating factors. Design and Setting: Analysis of the effects of demographic, medical, and pathophysiological factors on the circadian pattern of an unselected series of patients with ischemic stroke consecutively admitted to our hospital. Results: The study included 1656 patients. As in other studies, the peak of stroke onset occurred in the morning, with a second peak in the evening. Circadian variation in ischemic stroke onset was shown to be independent of clinical variables considered. Conclusions: Our study confirms the circadian rhythm of stroke reported in previous studies. There is a chronological pattern of ischemic stroke in the morning, which appears to be independent of the presence of risk factors and of clinical stroke subtypes. The role of circadian variability of blood pressure (present in patients with and without hypertension) and a concurrent morning hypercoagulability are suggested as possible determinants of this pattern. Preventive pharmacological interventions aimed at specifically targeting the morning rise in risk factors could be advantageous in reducing the overall risk of ischemic stroke.