[Natural history of and risk factors for idiopathic atrial fibrillation recurrence (FAP Registry)].

INTRODUCTION AND OBJECTIVES The natural history of idiopathic atrial fibrillation is not well understood. The aim of this study was to investigate the frequency of and risk factors for disease recurrence. METHODS The study involved 115 patients with a first episode of paroxysmal atrial fibrillation of unknown origin who were included the FAP registry, which contains data from 11 district hospitals in Catalonia, Spain. All patients underwent comprehensive clinical, laboratory, electro-cardiographic and echocardiographic investigations at baseline and were followed up periodically every 6 months to identify the occurrence of new symptomatic episodes and their complications. RESULTS During a mean follow-up period of 912 (445) days, 32 (27.8%) patients experienced recurrence of atrial fibrillation. Those who experienced recurrence had a significantly higher left ventricular ejection fraction (P=.023) and smaller end-systolic volume (P<.001), and they were more likely to consume alcohol regularly (P=.013). Cox regression analysis confirmed that these variables had independent prognostic value. In contrast, the occurrence of syncope during the initial episode was associated with a lower likelihood of recurrence (P=.017). CONCLUSIONS The risk of recurrence of idiopathic atrial fibrillation was high, and was enhanced by moderate alcohol consumption and increased left ventricular activity, probably of sympathetic origin. This trend was less marked in paroxysmal atrial fibrillation of vagal origin.