The known etiologies of atrial fibrillation(AF) were valvular heart disease, coronary artery disease, hypertension(left ventricular hypertrophy), hypertrophic cardiomyopathy, dilated cardiomyopathy, and congenital heart disease and so on. Mitral stenosis, mitral regurgitation, and tricuspid regurgitation account for more than 2/3 of AF related to valvular heart disease. We evaluated the effect of mitral stenosis and mitral regurgitation on development of AF respectively, and the relation between mitral valve disease and that.

The medical records of patients who was performed transthoracic echocardiography at Dongsan medical center between January 1997 and July 1998 were reviewed retrospectively. Among them, we analyzed the 222 patients who had isolated mitral valve disease without any other cardiac disease. We divided them to 4 group according to left atrial size (group 1: <4.0cm, group 2: >4.0cm and (5.0cm, group 3: (3) 5.0cm and <6.0cm, group 4: (3)6.0cm), then evaluated the effects of disease entity.

1) 94 out of 222(42.3%) patients had atrial fibrillation. The mean age was 51.8±15.1 years old. The number of men was 55. 2) The mean left atrial size in the group of AF and sinus rhythm were 5.14±0.93cm and 4. 44±0.66cm respectively. The mean age in the groups were 57.0±11.9 and 48.1±16.1 respecitvely. The differences between them were statistically significant(p<0.05). 3) The prevalences of AF in each groups were 12.5%(group 1), 35.6%(group 2), 60.8%(group 3), 86.7%(group 4). More increased the left atrial size, the prevalance of AF was increased significantly(p<0.05). 4) The prevalence of AF was not related to the severity of mitral regurgitation. However, the relation between the severity of mitral stenosis and the prevalence of AF was statistically significally(p<0.01). 5) Increasing the age, the prevalence of AF was increased significantly(p<0.01). 6) The effect of mitral stenosis and regurgitation on the development of AF did not differ significantly in group 1, 2, 3. But in group 4, the AF was present in 100% of patients who had mitral stenosis and 60% of mitral regurgitation. The difference was significant.

In patients with mitral valve disease, the development of AF was related to age and the size of left atrium. The relation between the severity of mitral regurgiation and the development of AF was not evident, but in mitral stenosis, the relation was significant. If the size of left atrium is similar, the effect of mitral stenosis and regurgitation itself seem to be not related to the development of atrial fibrillation.