Diagnosis and characteristics of lone atrial fibrillation.

Thirty-two patients with LAF were studied. Nineteen (59 percent) were male subjects. Mean age was 46.8 years. They were followed up for 2 to 16 years. On admission, most patients (94 percent) were symptomatic and had palpitations, nine had nonspecific chest pain, and five had syncope or near syncope. Left atrial size measured by echocardiography was less than 40 mm in all patients. During the follow-up period, only one patient had a complication, ie, cerebral embolism. We conclude that LAF may be regarded as a relatively benign form of AF. According to our study, one of its features is left atrial size not larger than 40 mm in echocardiography.