Circadian variation in the occurrence of fatal pulmonary embolism. Differences depending on sex and age.

Published studies have indicated a circadian variation in the occurrence of several acute cardiovascular events, e.g., myocardial ischemia, myocardial infarction, sudden cardiac death and cardiac arrest. The aim of this study was to determine if there is a circadian variation in the occurrence of fatal pulmonary embolism, and to evaluate possible differences in the temporal pattern in relation to sex and age. 230 cases of fatal pulmonary embolism (74 out-of-hospital and 156 hospitalized) observed in a general hospital over a 9-year period were considered. The total sample was stratified both by sex and into four groups by age including, respectively, subjects aged less than 60 years (group A), between 60 and 69 (group B), between 70 and 79 (group C) and 80 years and over (group D). The data were analyzed by the single cosinor method. A significant morning pattern was found for the total population (p = 0.011), females (p = 0.033), and age subgroups C and D (p = 0.015 and 0.008), with respective acrophases at 11.57, 11.23, 10.54 and 13.24. A morning pattern in the onset of fatal pulmonary embolism is confirmed for the total population, although sex and age seem also to play an important role.