Role of chronobiological rhythms in acute aortic dissection

Background

The chronobiological rhythms have been shown to cause an impact in the occurrence of a variety of cardiovascular disorders like acute myocardial infarction, sudden death and stroke. However, the effects of the chronobiological rhythms in patients with acute aortic dissection (AAD) have not been well studied. The International Registry of Acute Aortic Dissection (IRAD) observed that the frequency of AAD was significantly higher between 6:00 am and 12:00 noon, during the winter with a peak in January, and no variation was found for the day of the week. The objective was to know the chronobiological rhythms of our population with AAD.

Patients and methods

We evaluated in a cross-sectional and prospective study patients admitted to a chest pain unit, between March 1997 and May 2001, with a diagnosis of AAD. The authors carried out a descriptive analysis in the sample and they compared the proportions of the categorical variables between types A and B (Fisher test). Values of P < 0.05 were considered significant.

Results

We evaluated 34 patients with diagnosis-confirmed AAD, 26 patients (76.5%) of type A and eight patients (23.5%) of type B Stanford. Eighteen patients (52.9%) were male and 33 patients (97.1%) were blacks, presenting an average age of 63.5 ± 13.5 years. It was observed that the schedule of the day for an incidence of AAD was between 6:00 pm and 12:00 midnight (41.2%), and only 11.7% occurred in the period between 6:00 am and 12:00 noon. The day of biggest occurrence was Monday, with 26.4% of the cases. The months of May and July (14.7% each) were the most frequent, and the season of the year was winter (32.3%).

Conclusions

Like other cardiovascular conditions, AAD could exhibit chronobiological rhythms. In our population we observed the incidence of AAD in the nocturnal period of 6:00 pm and 12:00 midnight, on Mondays, and in the period of winter.