[Epidemiology of atrial fibrillation].

Atrial fibrillation (AF) is the most frequent maintained arrhythmia and constitutes a major morbidity cause, especially because of its associated risk of ischemic stoke. Additionally, it represents an independent risk factor for global mortality. The incidence of AF varies, according to different studies, between a minimum of 0.25 per 1000 person/year (women) and 0.9 per 1000 person/year (men) and a maximum of 8.9 per 1000 person/year (women) and 11.5 per 1000 person/year (men). Several cross sectional and prospective studies indicate that the prevalence of AF is inferior to 1% in individuals who are less than 55 years old. It is estimated that this arrhythmia's suffers a significant increase throughout the entire life span, and that its highest raise occurs between the ages of 65 and 80. A Portuguese study performe d between June and November 2003, in the scope of Rede Médicos-Sentinela, showed an AF prevalence of 0.53% in a population of 32,185 Health Centres patients. The mean age of patients suffering from this disease is situated within the interval of 70 to 80 years old. It is inferior for those who suffer from a concomitant cardiovascular disease, being significantly higher for women versus men. The risk factors and comorbidities which are most commonly associated to AF are age, several cardiovascular conditions, alcoholism, family history of AF and hyperthyroidism. Considering the high rate of stroke mortality in Portugal and assuming that AF is present in 15% ischemic stroke triggering and that it increases its risk 2 to 7 times, it can be concluded that knowledge regarding AF's incidence and prevalence in the different age groups will be important in order to improve its level of control, which is essential for preventing stroke and better management of this condition's treatment in the cardiovascular diseases' general context.