Seasonal variations in fatal pulmonary embolism

Fatal pulmonary embolism causes over 20000 deaths annually in Britain and accounts for a tenth of all deaths in hospital. 2 It also has a seasonal variation, with both postoperative and "spontaneous" emboli being significantly more common in winter. 3 4 The cause of many deaths due to pulmonary embolism may be registered as myocardial infarction in the absence of routine postmortem examination, and this may contribute to the seasonal increase in deaths registered as due to ischaemic heart disease.