Marked bilateral atrial dilation of unknown cause.

Four elderly women with marked bilateral atrial dilation but no evidence of significant structural or functional cardiac abnormalities other than atrial fibrillation are described. All patients demonstrated severe cardiomegaly on chest radiographs. Three patients have remained in good condition during the follow-up of 6 to 16 years except for occasional edema or pleural effusion, which was easily treated with diuretics and/or digitalis. The other patient had had only one episode of pleural effusion and leg edema at age 90 years before she died of colon cancer at age 100 years.