Background:Left atrial dilatation is often considered as one of the important causes for atrial fibrillation. In this study we sought to examine the relationship between right atrial dilatation and left ventricular function in patients with atrial fibrillation, and the association with the documented duration of the dysrrhythmia.Material/Methods:56 consecutive patients with atrial fibrillation were investigated by means of clinical history, electrocardiography and echocardiography.Results:Right atrial dilatation was found in 34, left atrial dilatation in 36 and bi-atrial dilatation in 31 patients. Patients with a dilated right atrium had a larger left atrium, lower left ventricular shortening fraction, and higher transmitral flow velocity than those with a normal right atrium. A history of atrial fibrillation of over 6 months was associated with enlarged atria, reduced left ventricular shortening fraction and increased transmitral flow compared to that of 3 months or less. Functional mitral and tricuspid regurgitation were only found in patients whose atrial fibrillation was over 6 months in duration.Conclusions:Dilatation of both right and left atria is common in chronic atrial fibrillation, and is associated with impaired left ventricular function. A longer duration of atrial fibrillation predisposes to atrial dilatation, left ventricular dysfunction, and functional atrio-ventricular regurgitation. These findings suggest that atrial fibrillation may have a significant contribution to morphological and functional cardiac changes, and raise the possibilities that early cardioversion or adequate rate control might prevent these changes and may improve prognosis in the elderly.

Keywords: Aged, 80 and over, Atrial Fibrillation, Dilatation, Pathologic, Echocardiography, Doppler, Pulsed, Electrocardiography, Heart Atria - pathology, Heart Atria - physiopathology, Ventricular Dysfunction, Left, Aged, 80 and over, Atrial Fibrillation, Dilatation, Pathologic, Echocardiography, Doppler, Pulsed, Electrocardiography, Heart Atria - physiopathology, Ventricular Dysfunction, Left