The aim of this study was to evaluate echographically anatomic and functional features of the left ventricle in adult patients with valvular aortic stenosis according to the presence or absence of congestive heart failure and the level of ventricular performance. Fifty-six adult patients with moderate-to-severe aortic stenosis underwent echocardiographic Doppler examination in order to evaluate left ventricular mass and dimensions, systolic function and filling dynamics. Twenty-seven patients had no heart failure and were symptomatic for angina (5), syncope (4) or were symptom-free (group I); the other 29 had heart failure (group II): 16 with normal left ventricular systolic performance (fractional shortening > 25%, group IIa) and 13 with systolic dysfunction (fractional shortening ≤ 25%, group IIb). Despite a similar left ventricular mass, compared to group IIa, group IIb showed a significant left ventricular dilatation (end-diastolic diameter: 61 ± 6.5 vs. 45.5 ± 6.1 mm, p < 0.001) and mild or no increase in wall thickness (11.5 ± 1.6 vs. 14.9 ± 2 mm, p < 0.001). Indices of left ventricular filling on Doppler transmitral flow were also significantly different between the two groups, with a higher early-to-late filling ratio and a shorter deceleration time of early filling in group IIb (2.8 ± 1.9 vs. 1.2 ± 0.85, p < 0.01, and 122 ± 66 vs. 190 ± 87 ms, p < 0.05, respectively), both indirectly indicating higher left atrial pressure. Finally, heart failure was generally more severe in group IIb patients. In some patients with aortic stenosis, symptoms of heart failure may be present despite a normal left ventricular systolic function and seem to depend on abnormalities of diastolic function. The presence of systolic or isolated diastolic dysfunction appears to be related to a different geometric adaptation of the left ventricle to chronic pressure overload.