Seasonal variation in AF episodes
LUBLIN, POLAND. It has been known since the time of Hippocrates that the weather (atmospheric conditions) influences people's mood and health. As far back as the first half of the 19th century, Polish researchers reported an association between short-term weather changes and a worsening of angina, increased incidence of heart attacks, and more pronounced fluctuations in blood pressure. More recent research has shown that levels of the stress hormone cortisol are lower at high barometric pressures and that lower levels are associated with a lessening of depression. So, conceivably, a person with elevated cortisol levels would feel better on a sunny day.

Now Polish researchers report that weather conditions also affect the incidence of paroxysmal afib episodes. Their study involved 739 patients (52% females, average age of 65 years, range of 18-91 years) who were admitted to hospital because of an AF episode during the period 2005-2006. Patients with acute coronary syndrome, myocarditis, pericarditis, thyrotoxicosis, and respiratory problems were excluded from the study, as were those who had recently suffered a heart attack.

The researchers correlated the number of patients admitted each day with air temperature, atmospheric pressure, wind speed and cloudiness, and also investigated the effect of approaching cold fronts and warm fronts. On average, there was one admission per day related to afib episodes. However, there were 9 days on which 4 patients were admitted and 4 days on which 5 patients were admitted. There was a seasonal effect with more cases (2.4/day) reported in the winter (December to February) than in the spring and summer (1.7 cases/day during the period May to August).

The most interesting correlation though was between the approach of a cold front and the number of afib-related hospital admissions. All the high admission days (4-5 cases/day) occurred 24-36 hours prior to the arrival of a cold front. The researchers speculate that the effect may be due to the electromagnetic waves created in deep low-pressure systems and storm centers. These waves travel at the speed of light, whereas the front itself moves at 10-50 km/hr, thus explaining why the effect of an approaching cold front would be felt 24-36 hours in advance. The researchers found no relationship between afib incidence and the approach of a warm front. However, they did notice that periods of constant high atmospheric pressure were associated with a significant decline in hospital admissions for AF.

Gluszak, A, et al. Episodes of atrial fibrillation and meteorological conditions. Kardiologia Polska, Vol. 66, September 2008, pp. 958-63

Editor's comment: The speculation that a temporary increase in exposure to electromagnetic radiation may precipitate afib episodes is indeed an interesting one and, if proven correct, could perhaps partly explain the current AF epidemic, which certainly coincides with a vast increase in our exposure to electromagnetic radiation. As way of explanation the Polish researchers make the following remarks:

"Electromagnetic waves penetrate into the tissue to a depth depending on the electric resistance and wavelength. In the very low frequency generated by atmospheric conditions (up to 10 MHz) living tissue acts as a conductor in which an alternating electric field produces Foucault eddy currents practically induced in the entire body. These phenomena were also reported by Kozlowski, who claimed that electromagnetic field effects in the body tissues involve stimulation of particles and atomic movements which cause chemical reactions and bioelectric processes. Induction of these changes occurs in electromagnetic field of relatively low intensities. This was also underlined by Hessmann-Kosaris, who reported that even weak electromagnetic fields may affect metabolic processes of cells and cellular membranes".