Echocardiographic left atrial dimension as a predictor of maintaining sinus rhythm after conversion of atrial fibrillation.

Twenty-six patients with lone atrial fibrillation were studied prospectively by M-mode echocardiography less than two months before and one month after cardioversion (CV). Seven patients had reverted to atrial fibrillation (AF) one month after CV. These patients (AF group) differed significantly with regard to mean left atrial dimension (LA) from the 19 patients (73%) who maintained sinus rhythm (S group) (p less than 0.001). Initial LA was 38.6 +/- 4.9 mm in the S group and 47.6 +/- 2.3 mm in the AF group. These values had not changed significantly in either group when measured one month after CV. The radiological heart size index showed a closely corresponding pattern. On the other hand, the mean heart size in both groups (441 +/- 100 and 544 +/- 98 ml/m2 BSA, respectively) was well below the upper normal limit (700 ml/m2) that is conventionally used as exclusion criterion from CV. In conclusion, in patients with AF and only moderate cardiac enlargement on chest X-ray, the echocardiographic LA can be used as predictor of maintaining sinus rhythm for at least one month following CV.