BACKGROUND Echocardiographic assessments including E/e' are a good predictor of elevated left ventricular (LV) filling pressure during sinus rhythm. However, the evaluation of LV filling pressure using classic echocardiographic assessment has been challenging in the setting of atrial fibrillation (AF). The aim of this study was to investigate the methods for predicting LV filling pressure in patients with chronic AF. METHODS Clinical data, echocardiography findings, and brain natriuretic peptide (BNP) levels were assessed in 59 patients with chronic AF who were undergoing diagnostic left-heart catheterization. LV end-diastolic filling pressure (LVEDP) and standard echocardiographic measurements including pulmonary arterial systolic pressure (PASP) were evaluated. Blood samples were taken for serum BNP measurements within 24 h of the echocardiographic examination. RESULTS E/e' correlated well with LVEDP (r = 0.558, p < 0.001). Using receiver operating characteristic analysis, the optimal cut-off for E/e' was 16 (sensitivity, 64 %; specificity, 82 %) to predict LVEDP of > 15 mmHg. PASP was also well correlated with LVEDP (r = 0.503, p < 0.001). PASP greater than 32 mmHg predicted elevated LVEDP (> 15 mmHg) with a sensitivity of 64 % and a specificity of 71 %. CONCLUSIONS E/e' and PASP were well correlated with LVEDP in patients with AF. PASP greater than 32 mmHg and E/e' greater than 16 may suggest elevated LVEDP (> 15 mmHg) in patients with chronic AF.