Background: The prolongation of the P-wave duration is an accepted indicator of an interatrial conduction disturbance. It was reported that the P wave dispersion(PWD) is associated with an inhomogeneous propagation of the sinus impulse. This study investigated the clinical significance of an interatrial conduction disturbance and the inhomogeneous propagation of the sinus impulse in patients with CHF. Methods: This study included 61 patients with CHF whose left ventricular ejection fraction(LVEF) was <55%. The study population was classified into four goups: two groups according to the maximum P wave duration (���110msec or <110ms) and two groups according to the PWD (���40 msec or <40msec). The Left atrial volume index(LAVi), LVEF and diastolic function of all groups were measured by 2D and 3D echocardiography. The maximum P- wave duration(P max) and minimum P-wave duration(P min) were measured from a 12-lead ECG. The PWD was calculated as the difference between the P max and P min. Results: There were significant differences in the diastolic function and LAVi between patients with a P max ���110ms or PWD ���40ms and patients with a P max <110ms or PWD <40ms. The P max and PWD correlated with the E/A ratio, DT, E/E��� ratio and LAVi. LAVi was independently associated with interatrial conduction disturbance and inhomogenous propagation of sinus impulse. ROC curve showed that LAVi by 2D echocardiography and 3D echocardiography (LAVi ���44.70 ml/m2 and ���48.03 ml/m2 , respectively ) separates patients with interatrial conduction disturbance with a good sensitivity(73.8% and 78%, respectively) and specificity(84.2% and 89.5%. respectively). LAVi by 2D echocardiography and 3D echocardiography (LAVi ���44.99 ml/m2 and ���49.80 ml/m2 , respectively) also separates patients with inhomogeneous propagation of the sinus impulse with a good sensitivity(78.% and 80.6%, respectively) and specificity(72.4% and 79.3%, respectively). Conclusion : An interatrial conduction disturbance and inhomogenous propagation of the sinus impulse in patients with CHF is associated with the deleterious diastolic dysfunction with an increased LA volume.