Usefulness of a complete echographic evaluation of the atrial dimensions for the diagnosis of idiopathic atrial fibrillation

: Left atrial enlargement may occur sometimes through only the increase of the supero-inferior (S-I) diameter, with normality of the antero-posterior (A-P) and latero-medial dimensions. In this study, both the largest dimensions of the left atrium and S-I and transversal dimensions of the left atrium and S-I and transversal dimensions of the right atrium were investigated, among the 98 pts suffering from recurrent paroxysms of atrial fibrillation (FAP). On the basis of the clinical, ECGraphic and echocardiographic data, a subgroup of 78 pts has been found, with FAP reliable to heart disease, which mostly appeared as accompanying a finding of atrial enlargement--left or right or both--. The remaining 20 pts distinguished, by means of the echocardiographic findings, as following: a) "idiopathic" FAP, neither dependent on heart disease nor on atrial enlargement (no. 11 pts); b) FAP dependent on "unexplained" atrial enlargement, i.e. unreliable to definite cardiac pathology (no. 9 pts). Among the b) pts, 7 showed the only, isolated S-I dimension increased. Therefore, the determination of the all largest dimensions of the atria, in pts with recurrent FAP, appeared able to more carefully distinguish the true cases of "idiopathic" FAP.