Background: Left atrial (LA) volume (LAV) is related to left ventricular (LV) diastolic function and has a prognostically importance in patients with paroxysmal atrial fibrillation (PAF). Purpose: The aims of this study were to evaluate association between LAV using triplane three-dimensional (3D) echocardiography and LV diastolic function and investigate clinical utility of LAV in patients with PAF. Methods: Fifteen PAF patients (PAF group; 7 men, mean age 65±10 years) and 20 normal subjects (controls; 16 men, mean age 44±10 years) who underwent conventional echocardiography, tissue Doppler imaging, and 3D echocardiography were enrolled. LA diameter (LAD) was measured by M-mode echocardiography and corrected by body surface area (LADI). LAV was measured by using the biplane Simpson (BS) method from 4- and 2-chamber views (LAV-BS) and triplane 3D echocardiography (LAV-3D) and corrected by body surface area. Mitral early diastolic peak velocity (E) and myocardial early diastolic peak velocity (E′) at septal annulus was measured and the ratio of E to E′ (E/E′) was calculated. Results: LAD, LADI, LAV-BS, and LAV-3D in PAF group were significantly larger than those in controls. In PAF patients, LAV-3D significantly correlated with LAV-BS (p<0.001, r=0.92), LAD (p<0.01, r=0.50), and LADI (p<0.01, r=0.80). E/E′ significantly correlated with LAV-BS (p<0.01, r=0.38) and LAV-BS (p<0.01, r=0.32), but not with LAD or LADI (p=NS). Using optimal thresholds of LAD (>37 mm), LADI (>21 mm/m2), LAV-BS (>27 ml/m²), and LAV-3D (>29 ml/m²) for identifying patients with PAF, the sensitivity among the four groups was comparable, however, the specificity in LAD (75%, p<0.05) was significantly lower than that in LAV-BS (100%) and LAV-3D (100%). Conclusions: In PAF patients, LAV-BS and LAV-3D associate with LV diastolic function and appear to be superior to LAD for differentiation of controls from PAF patients.

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