Assessment of left ventricular (LV) diastolic filling pressure provides important information on the hemodynamic status in the general population. The aim of our study was to investigate the reliability of tissue Doppler imaging (TDI) in estimating left ventricular filling pressure in patients with coronary artery disease (CAD). We prospectively studied 32 consecutive CAD-patients, mean age 64 +/- 12 years, in sinus rhythm. All patients underwent cardiac catheterization and echocardiography within the same hour. Catheterization investigated pre-A-wave pressure (preA) and LV ejection fraction (LVEF). Echocardiographic LVEF was calculated using wall motion indexes (WMI) with segmental division of LV wall. The following Doppler parameters were assessed: (1) PW Doppler signals from the mitral inflow (E), (2) PW TDI of the mitral annulus (E'), thus allowing to obtain the mitral inflow to annulus ratio (E/E'). The best correlation between invasive and echocardiographic LVEF was observed using WMI (r = 0.91). The correlations between preA and E, E', and E/E' were significant (r = 0.36, r = 0.38, and r = 0.60, respectively). In patients with LVEF >50%, no correlation between E/E' and preA was found (r = 0.18, P = 0.44), whereas with LVEF <50%, this correlation was strong (r = 0.76, P < 0.001). In patients with myocardial infarction, the correlation between E/E' and preA was significant whatever the localization of myocardial infarction (r > 0.71, P < 0.05). ROC curve analysis identified an E/E'>9 to be the best cut-off value related to preA > 15 mmHg. We conclude that the mitral inflow-to-annulus ratio is a reliable method in CAD patients and allows determination of LV filling pressure when LVEF <50%.