Auricular fibrillation is one of the most frequent and important of the cardiac arrhythmias. It may arise under a variety of conditions. In some instances auricular fibrillation may occur in persons who are apparently in good health and altogether free of symptoms or signs of heart disease. Among those who have heart disease, the incidence of auricular fibrillation varies widely, depending on the type of heart disease that is present. It is relatively rare in syphilitic heart disease, in bacterial endocarditis and in congenital cardiovascular anomalies. It is frequent in rheumatic heart disease, coronary disease, hypertension and thyrotoxicosis.
Auricular fibrillation is essentially a disorder of adult life. In a series of 575 patients with auricular fibrillation reported by McEachern and Baker,1 only 0.5 per cent of the patients were under 10 and 4.2 per cent between 10 and 20 years of age.
Because of the infrequency of auricular fibrillation