Background. Results from unpublished data on the incidence of adverse vascular events and from several published studies are reevaluated chronobiologically. Methods and results. Cosinor methods indicate 1. a circadian variation in the incidence of paroxysmal supraventricular tachycardia (PST), of broadly classified ventricular arrhythmia (VAr), and of atrial fibrillation (AF); 2. a statistically significant difference in the timing of the circadian rhythm of PST and VAr versus that of AF; and 3. a further difference in the timing of these rhythms from that in the incidence of myocardial infarctions (MI). Electrocardiographic records for spans longer than 24h show the extent of day-to-day variability in circadian characteristics of the given patient and indicate the presence of even lower- frequency components, notably along the scale of a week, that may underlie weekly and half-weekly patterns of morbidity and mortality. Conclusion. Beyond alterations in the about 1-Hz periodicity of the heart, predictable changes along the scales of the day and the week may constitute a clue to the etiopathology of a given condition and provide a basis for treatment timing. The assessment of unfavorable changes in the lower frequency components may provide a lead time long enough to prompt the institution of preventive, rather than curative, intervention.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Jan 1 1994|