OBJECTIVE: We aimed to evaluate myocardial diastolic function in patients with beta-thalassemia major (beta-TM) using pulsed-tissue Doppler imaging (TDI) and flow propagation (VP), in relation to BNP levels. METHODS: We enrolled 192 consecutive patients with beta-TM (88 men (25 +/- 6 years) and 104 women (26 +/- 6 years), with normal left ventricular (LV) systolic function. By TDI, diastolic myocardial velocities were sampled at the lateral section of the mitral annulus (Smv, Emv, Amv). From the apical four-chamber view diastolic transmitral flow velocities, including measures of E- and A-waves were performed. The propagation velocity of early flow into the LV cavity was measured by color M-mode Doppler. Plasma BNP levels were measured in all patients. RESULTS: A nonlinear relationship was found between BNP levels and E/A ratio (beta coefficient for the second-order term = 1.4 +/- 0.4, P = 0.001). We also found a positive association of BNP levels with Amv (r = 0.28, P = 0.023), and a reverse with Smv (r =-0.59, P = 0.01) and Emv/Amv (r =-0.36, P = 0.019). Moreover, an inverse relationship was observed between BNP and Vp (r =-0.43, P = 0.012) levels. Finally, a strong positive linear relationship was found between E/Vp ratio and BNP levels (r = 0.76, P < 0.001). CONCLUSION: A U-curved association of E/A ratio of transmitral Doppler velocity was revealed with BNP levels, while the tissue Doppler of the Emv/Amv of the mitral annulus movement showed a negative linear association with BNP levels.