[Spontaneous return of sinus rhythm in mitralic fibrillation of long duration (author's transl)].

A case of mitral valvular disease in which spontaneous return of sinus rhythm occurred after 12 years of atrial fibrillation is reported. The course of the disease, complicated by A.V. and intraventricular conduction disturbances which made the insertion of a pacemaker necessary, suggests that return to sinus rhythm should not be considered necessarily an improvement in the clinical picture and in the prognosis in such patients.