Isolated atrial amyloid(IAA),one of the most common members of the family of age-related('senile')amyloids, seems to play a role in the pathogenesis of atrial fibrillation.The incidence of atrial IAA deposits increase with age, from 75% incidence in patients aged 51-60 years, to 86% incidence in those aged 81-90 years.Deposits are more pronounced in females than in males.Left atrial deposits are more pronounced than right atrial deposit.IAA deposits are heavier in patients with chronic atrial fibrillation than in those with sinus rhythm.Hypertension,diabetes mellitus,hypertrophy of the heart,coronary atherosclerosis,and dilatation of the atria show no significant relationship to the incidence or severity of atrial amyloidosis.