Circannual rhythm of arterial and venous thromboembolic disease.

This study confirms previous reports of a seasonal variation in morbidity and mortality from coronary and cerebral arterial disease; these disorders are much less common in summer (e.g. July and August) than in winter (e.g. December and January). In coronary disease the shape of the curve for the annual morbidity is different from that for annual mortality and possible reasons for this are discussed. A similar circannual rhythm has been shown for venous thrombo-embolic disease.