Diurnal and Seasonal Variation of Stroke Incidence in Patients with Cardioembolic Stroke due to Atrial Fibrillation

Abstract

A seasonal variation with an incidence peak during the colder period of the year, as well as a circadian distribution with a single peak of stroke onset in the morning hours are described in various countries. Cardioembolic stroke seems to be the most frequent stroke subtype among Greek patients. Atrial fibrillation is identified as the most frequent cause of stroke. Analysis of the temporal pattern of symptom onset in a series of over 300 Greek patients with first-ever cardioembolic acute stroke due to atrial fibrillation revealed a circannual distribution with a peak during winter and a decline of stroke occurrence during summer. Analysis of the diurnal variation of symptom onset in this stroke subgroup showed a distribution with 2 incidence peaks between 08:00–10:00 and 16:00–18:00. A relation between the second, however lower, frequency peak and the traditional Greek habit of afternoon sleep (siesta) could be assumed. Possible clustering of cardiologic events in patients with atrial fibrillation, especially during the time interval after awakening from night and afternoon sleep, could be a plausible explanation, which certainly deserves to be further investigated.

Seasonal Variation in Stroke and Stroke-Associated Mortality in Patients with a Hospital Diagnosis of Nonvalvular Atrial Fibrillation or Flutter

“…These results are in accordance with previous fi ndings of excess risk of stroke in atrial fi brillation during winter reported from a small study from Athens, Greece [6].…”

“…Recently, a small study from Athens, Greece, reported that the risk of stroke in patients with atrial fi brillation is highest during the winter [6]. We undertook the present study to further examine the potential of the risk of stroke during winter in patients with atrial fi brillation.…”

Does sleep protect against ischemic stroke? less frequent ischemic strokes but more severe ones

“…Stroke frequency during the nocturnal hours changes in different reports. Most studies, however, agree in finding a lower frequency than expected for this time [8,33]. Some mechanisms have been postulated as an explanation for this pattern, especially the circadian variation in arterial pressure [13,18,30].…”

Seasonality, incidence and prognosis in atrial fibrillation and stroke in Denmark and New Zealand

“…16 One small series of approximately 300 Greek patients with first-ever cardio embolic acute stroke due to AF also revealed a seasonal peak during winter and a decline of stroke occurrence during summer. 17 Assuming a seasonal variation in hospital admissions with stroke in patients with AF, we would expect to see similar temporal patterns in countries from different parts of the world. However, we are unaware of any data comparing seasonal changes over a comparable time period between two countries, irrespective of seasonality shift by being in the northern or southern hemisphere.…”