May sunshine protect women against paroxysms of atrial fibrillation?

Seasonal variation in the occurrence of atrial fibrillation (AF) has been documented, yet precise mechanisms and factors underlying the phenomenon remain unclear. We have previously observed the decrease in the number of AF paroxysms between May and August, when sunshine levels were highest. The objective of the present study was, in turn, to determine whether sunshine affects the incidence of AF episodes. Participants were 1,475 Caucasian subjects (mean age: 68.2 years) diagnosed with AF paroxysms, admitted to the Intensive Cardiac Care Unit (ICCU) between January 1, 2005 and December 31, 2008; 805 were women and 670 were men (mean age: 69.2 and 66.2, respectively). The average incidence of AF episodes was higher among female subjects, with 16.8 cases per month, compared to male subjects with 14.0 cases per month. Pearson's correlation coefficient (r) was used to find a relationship between monthly sums of sunshine duration and AF paroxysms. This relationship for women was clearly inversely proportional (r = -0.499); namely, most AF episodes were recorded from December to March, when sunshine levels were lowest. In contrast, there was no noticeable association in male patients between the occurrence of AF paroxysms and effective sunshine (r = -0.126). In conclusion, unlike in men, a marked, statistically confirmed relationship between AF episodes and effective sunshine was observed in women. Thus, sunshine may have a protective effect against AF paroxysms for women. Our findings may provide the basic information concerning the influence of environmental factors on human wellbeing and contribute to management of AF.

Episodes of atrial fibrillation and meteorological conditions.

BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. The natural history of AF tends to begin with short paroxysms which gradually evolve into longer episodes, frequently treatment-resistant, and finally take a permanent form. It is a polyaetiological condition and single paroxysms may be caused by a variety of factors. There is a prevailing belief that weather is a vital element affecting the functioning of the human organism. Accordingly, high variability in hospital admissions due to AF paroxysms may be associated with meteorological conditions. AIM: To investigate the relationship between the incidence of AF paroxysms and atmospheric phenomena. METHODS: A total of 739 patients participated in the study [52% females, aged 18-91 (mean=65 years)], hospitalised for AF paroxysms in the Cardiac Care Unit (CCU) in 2005-2006. Patients with AF secondary to acute coronary syndrome, recent myocardial infarction, myocarditis, pericarditis, thyrotoxicosis, and disorders of the respiratory system, were excluded from the analysis. Statistical relationships were sought between the frequency of AF paroxysms and meteorological elements, such as: temperature change, atmospheric pressure, relative humidity, cloudiness, and wind speed. Using synoptic maps, such phenomena as weather fronts occurrence and baric systems were analysed. RESULTS: A considerable influence of a cold front and occlusion of cold front type on increases in admissions to CCU for AF paroxysms was observed. The absence of arrhythmia for many consecutive days was noted during the presence of stationary high-pressure areas. There were no significant relationships between meteorological elements and AF paroxysms. A seasonal distribution of AF episodes was found, with the maximum incidence in winter months and a decrease in the number of patients hospitalised from May to August. The impact of cold fronts may be explained by the effect of electromagnetic waves occurring in the zone of atmospheric changes, which may penetrate into buildings. On account of the translocation speed of electromagnetic waves, the effects may be felt many hours before an atmospheric front approaches. CONCLUSIONS: Meteorological conditions may have some influence on the occurrence of paroxysms of atrial fibrillation. This study could serve as a starting point for further research investigating relationships between weather conditions and heart rhythm disorders.