Backgrounds: A new index of aortic stenosis (AS), valvuloarterial impedance (Zva) has the meaning of global left ventricular (LV) load. Plasma levels of N-terminal pro-B-type Natriuretic Peptide (NT-pro-BNP) has been known to correlate with AS severity as well as LV hemodynamic burden. We hypothesize that Zva is better correlated with NT-pro-BNP compared to standard indices of AS. Methods: We reviewed 74 consecutive patients (age 75.47짹9.46, male 37.8%) with significant AS who had preserved LV systolic function and didn���t have aortic regurgitation, significant mitral valve disease and renal disease. We correlated plasma level of NT-pro-BNP with echo indices of AS severity; maximal velocity on aortic valve (Vmax), aortic valve area (AVA), mean transvalvular pressure gradient (meanPG), and Zva. Zva was calculated by dividing the estimated LV systolic pressure (systolic arterial pressure + mean transvalvular gradient) by the stroke volume index. Results: Mean values of Vmax (m/s), AVA (cm2), meanPG (mmHg), Zva (mmHg•m2/ml) and LN NT-pro-BNP were 3.61짹1.08, 1.03짹0.38, 33.24짹21.83, 3.53짹1.16, and 4.82짹2.28, respectively. Pearson correlation coefficient of LN NT-pro-BNP with Vmax, AVA, meanPG and Zva were 0.435 (p=0.001), -0.498 (P<0.001), 0.432 (p=0.001), and 0.446 (p=0.001), respectively. In the subgroup analysis in patients with moderate to severe AS (Vmax > 3.0, n=49, age 74.10짹9.29, male 44.9%), mean values of Vmax, AVA, meanPG, Zva and LN NT-pro-BNP were 4.17짹0.86, 0.89짹0.34, 43.08짹20.51, 3.61짹1.29, and 5.39짹2.34, respectively. Pearson correlation coefficient of LN NT-proBNP with Vmax, AVA, meanPG, and Zva were 0.350 (p=0.046), -0.534 (P=0.001), 0.351 (p=0.045), and 0.616 (p<0.001), respectively. Conclusions: Zva is better correlated with NT-pro-BNP compared to standard indices of AS such as Vmax, AVA, and meanPG in patients with moderate to severe AS. It suggests that hemodynamic meaning of Zva may be more valid in moderate to severe AS.