CHRONOBIOLOGY OF NON FATAL PULMONARY THROMBOEMBOLISM

Background. It as been demonstrated that acute myocardial infarction, sudden cardiac death, stroke, and fatal pulmonary embolism show an increased onset rate during certain periods of the day, week, or year. According to some authors, the highest risk appears to occur in the morning, on weekends and during winter. This paper, therefore, intends to examine whether a circadian, weekly, or annual rhythm in the incidence rate of deep vein thrombosis (DVT) and non-fatal pulmonary embolism (PE) in ageing patients does exists. Methods. A survey was conducted into 212 patients affected by DVT and PE, admitted to the Second Medicine Institute of Padua, Italy, over a period of two solar years. Thromboses were diagnosed via echo-Doppler examination of the legs and pulmonary embolism via perfusive and ventilatory scintiphotographs. Results. In the overall sample, a circadian variation was found, both for deep vein thrombosis (peak at 12:26 hrs, p=0.001), and pulmonary embolism (peak at 10:26 hrs, p=0.001). A weekly, rhythmic recurrence was also found for the two complaints, with a peak on Saturdays, while no significant annual rhythmic recurrence was found. There was, however, a tendency towards an increase during the winter and summer months. Conclusions. The results may have important clinical applications, both in prevention and in the "timing" of drug dosage.