Impaired transport function of the left atrium in patients with lone paroxysmal atrial fibrillation

Background: Although lone paroxysmal atrial fibrillation (LPAF) is clinically defined as an arrhythmia that occurs in the absence of structural heart disease, it has been suggested that the presence of anatomical substrate is related to LPAF. The aim of the present study is to determine whether structural and functional remodeling of the left atrium (LA) occurs in patients with LPAF, and to identify whether frequent episodes of atrial fibrillation (AF) contribute to LA remodeling. Methods and Results: Forty-five patients who diagnosed as LPAF and age-, gender-, and body mass index-matched healthy control subjects (n = 45) were enrolled. Patients were grouped based on the frequency of AF episodes. An echocardiography was performed >2 weeks after last episode of AF without antiarrhythmic drugs. There were no statistical differences in left ventricular (LV) diastolic and systolic functions as well as baseline characteristics between patients and controls, whereas, patients had significantly larger LA volume (LAV), lower active LA emptying fraction (LAEF_active, P = 0.009) and total LAEF (LAEF_total, P = 0.005) compared with controls. Passive LAEF (LAEF_passive) was not different between patients and controls (P = 0.664). LAEF_active was significantly depressed in patients with frequent episodes of AF than the others (P = 0.034). Conclusions: Compared with healthy controls, patients with LPAF had increased LAV and depressed LAEF_active and LAEF_total without accompanying compensatory increase in LAEF_passive. LAEF _active was influenced by frequent episodes of AF. These findings may support the hypothesis that LPAF is "not-so-lone AF" and related to the concealed cardiac dysfunctions. (Echocardiography 2011;28:44-51)