Changes in Left and Right Atrial Size After Cardioversion of Atrial Fibrillation: Role of Mitral Valve Disease

Objectives. The aim of this study was to examine the effect of cardioversion on left and right atrial volume in patients with chronic atrial fibrillation and to determine the influence of mitral valve disease on atrial size.Background. Atrial enlargement is a common finding in atrial fibrillation and has been associated with an increased risk for embolic stroke. In addition, atrial enlargement may hamper long-term maintenance of sinus rhythm after cardioversion.Methods. Forty one patients with chronic atrial fibrillation (mean duration +/- SD, 45 +/- 62 months) underwent two-dimensional echocardiography before and 6 months after cardioversion to determine left and right atrial dimensions. Underlying heart disease was present in 26 patients: mitral valve disease in 12 (stenosis in 5, regurgitation in 5 and a combination in 2 patients) and other heart diseases in 14. Fifteen patients had lone atrial fibrillation. Patients with sustained sinus rhythm were compared with those who had a relapse of the arrhythmia 6 months after cardioversion.Results. Six months after cardioversion, 28 patients still had sinus rhythm, whereas 13 patients had a relapse of the arrhythmia. In the 28 patients who had sinus rhythm after 6 months, left and right atrial volume decreased from a mean (+/- SD) 72.6 +/- 15.1 to 58.5 +/- 13.8 cm(3) (-20%, p <0.05) and from 68.7 +/- 14.6 to 58.6 +/- 11.6 cm(3) (-14%, p <0.05), respectively. Atrial dimensions also decreased significantly in the subgroup of patients with mitral valve disease. In contrast, no change in atrial size occurred in the 13 patients who had a relapse of atrial fibrillation. Left ventricular function did not change between the two echocardiographic studies, although New York Heart Association class improved in patients who had sinus rhythm after 6 months.Conclusions. Restoration of sinus rhythm reverts the process of left and right atrial enlargement in patients with chronic atrial fibrillation and mitral valve disease. Therefore, cardioversion may reduce the incidence of thromboembolic complications and prevent the arrhythmia from becoming refractory to medical therapy.