[Epidemiology, etiology and mechanism of atrial fibrillation].

Atrial fibrillation affects about 750 000 people in France, and its incidence is growing rapidly as the population ages. The main cause used to be rheumatic heart disease, but arterial hypertension is now responsible for about 80 % of cases. The mechanisms are complex. Many cases are due to pulmonary vein foci, but comorbidities can lead to different mechanisms.