Archief Roodbont

Seasonal variation in paroxysmal AF found

19 January 2007

Paroxysymal atrial fibrillation (AF) varies significantly with the seasons of the year, research shows.

Japanese investigators report that maximum and minimum incidences of paroxysmal AF occur in autumn and summer, respectively.

"Although circadian variations are known to affect paroxysmal AF, seasonal patterns have not been well characterized," Eiichi Watanabe (Fujita Health University School of Medicine, Toyoake) and team note.

To investigate, the researchers evaluated paroxysmal AF patterns in 237 patients, recorded over a 5-year period using 24-hour Holter electrocardiogram (ECG) monitoring.

Overall, they identified 258 paroxysmal AF episodes in 12,390 consecutive recordings.

The incidence of paroxysmal AF was highest in September and lowest in June, the researchers report in the journal Heart Rhythm.

The respective relative risks (RRs) of paroxysmal AF, determined with respect to the overall mean incidence, at these times were 1.40 and 0.52.

The incidence of paroxysmal AF also showed an autumn peak and a summer minimum among all patients, with RRs of 1.21 and 0.66, respectively.

The seasonal and monthly variations in paroxysmal AF were not influenced by age, or clinical variables such as underlying disease and medications.

In addition, the researchers found there was a significant inverse relationship between the incidence of paroxysmal AF and the length of daylight in patients aged under 65 years. In contrast, there was no correlation between paroxysmal AF and the mean outdoor temperature in any patients.

"The seasonal variation in paroxysmal AF demonstrated by our study, showing a peak incidence in the autumn months, could have important clinical implications," the authors conclude.

They add that understanding the role of the seasonal stresses and other mechanisms may lead to novel treatments of this arrhythmia.

Heart Rhythm 2007; 4: 27-31