Longer longitudinal atrial dimension in patients with idiopathic paroxysmal atrial fibrillation: A possible cause of atrial fibrillation

Background The ostium of the superior pulmonary veins or superior vena cava has been reported to be an important source of the ectopic beats that initiate paroxysmal atrial fibrillation (PAF). The structural details of the atria in patients with idiopathic PAF, however, remain unknown. Methods We studied 113 patients (92 men and 21 women) with idiopathic PAF and 128 normal control subjects (100 men and 28 women). None of the subjects in either group were found to have any evidence of structural cardiac disease. The echocardiographic measurements were performed in the apical 4-chamber view during end-systole of sinus rhythm. Results The longitudinal dimension of the left and right atria was longer in patients with PAF who were not administered any drugs (non–drug-taking patients) than in the control subjects (P < .001 and P < .01, respectively). However, there were no significant differences in the transverse dimension of either atrium between such patients and control subjects. The longitudinal and transverse dimensions and volume determinations of atria were greater in the patients with idiopathic PAF who were administered class 1 antiarrhythmic drugs than in non–drug-taking patients (P < .05 to .001). In non–drug-taking patients, prolongation of the atrial longitudinal dimension did not depend on either age, the total frequency of PAF, or the interval from the first episode of PAF. The longitudinal dimension of the left and right atria was longer even in the patients with a short history of PAF (<1 month) as compared with control subjects (P < .001 and .05, respectively). Conclusions These observations suggest that there is prolongation of the longitudinal dimension in patients with idiopathic PAF independent of PAF frequency and age (and that PAF is probably a consequence of the prolongation). (Am Heart J 2001;142:669-78.)