['The aim of the study was to investigate the association of plasma amino-terminal propeptide of procollagen type III (PIIINP) with subclinical left ventricular (LV) systolic dysfunction in patients with aortic stenosis (AS) and normal LV ejection fraction.', 'The study was performed in 57 AS patients with normal LV ejection fraction and in 30 control subjects with normal aortic valve and normal LV ejection fraction. Tissue Doppler and speckle tracking image were performed to assess LV diastolic and systolic function. Plasma PIIINP level was measured by specific radioimmunoassay.', 'In AS patients, LV systolic longitudinal strain was significantly reduced (-17.1 ± 2.1 vs. -18.8 ± 1.4%, P<0.001) and plasma PIIINP was increased compared with controls (2.5 ± 0.6 vs. 2.1 ± 0.4 μg/l, P<0.001). A significant correlation was found between LV systolic longitudinal strain and PIIINP (r=-0.67, P<0.001). In patients with abnormal LV diastolic function, LV systolic longitudinal strain was reduced compared with patients with normal LV diastolic function (-16.3 ± 1.5 vs. -18.8 ± 2.1%, P<0.001) and plasma PIIINP was increased (2.8 ± 0.5 vs. 2.0 ± 0.3 μg/l, P<0.001). A stepwise multivariate regression analysis revealed that LV systolic longitudinal strain and diastolic blood pressure were independent predictors of plasma PIIINP (multiple r=0.71, P<0.001).'] Is plasma amino-terminal propeptide of procollagen type III associated with subclinical left ventricular systolic dysfunction in aortic stenosis?