[Circadian rhythm in the incidence of sudden cardiac death].

Human mortality demonstrates a maximum incidence in the early morning, with a reduction in the late afternoon. In order to determine whether sudden cardiac death presents a circadian rhythm similar to that of overall human mortality, the time of the day has been analyzed in 269 cases of sudden cardiac death. The definitive criteria of sudden cardiac death were: death within 1 hour of the onset of symptoms and pathoanatomical findings. The cases of sudden cardiac death consisted of 161 males and 108 females, with ages ranging from 23 to 86 years, subdivided into 139 cases of acute myocardial infarction, 101 cases of coronary atherosclerosis, 12 cases of primary myocardiopathies, 4 cases of mitral valve prolapse and 13 cases with structurally healthy heart. All the deaths occurred outside the hospital, or immediately after resuscitation efforts had begun. The data were analyzed by means of chronograms, and with the "single cosinor" method, both for the total cases of sudden cardiac death, and for subdivisions into sex, pathoanatomical picture, and for age groups (less than 40, between 41 and 60, and more than 61 years). The results demonstrate a statistically significant (p less than 0.05) circadian rhythm of sudden cardiac death, with a peak from midnight to 8:00 am, and a minimum in the afternoon. Significant differences do not exist (p greater than 0.05) within the acrophases of sudden cardiac death between the 2 sexes, among the different age groups, or the pathoanatomical pictures of myocardial infarction and coronary atherosclerosis. No rhythm was detected regarding the sudden deaths by primary myocardiopathy, mitral valve prolapse, and "normal" heart.(ABSTRACT TRUNCATED AT 250 WORDS)