ABSTRACTLeft ventricular filling dynamics were investigated in 24 patients with aortic stenosis (AS). Biplane cineangiography was performed with simultaneous micromanometry in these 24 patients and in six control subjects. Twelve of the patients with AS had moderate hypertrophy with a left ventricular muscle mass index of less than 180 g/m2 (AS 1 group) and 12 had severe hypertrophy with an index of 180 g/m2 or more (AS2 group). Filling dynamics were also evaluated postoperatively in eight patients in the AS 1 and six patients in the AS2 group. Preoperatively, end-diastolic and end-systolic volume indexes were larger and ejection fraction was lower in the AS2 compared with the control or AS 1 group. Percent volume increase during the first half of diastole (%V 1) was smaller in the AS 1 than in the AS2 group. Peak filling rate in the first half of diastole (PFRl) was higher in the AS2 than in the control or in AS l group, while peak filling rate in the second half of diastole (PFR2) was considerably greater in the AS 1 group than in the other two groups. The time constant of left ventricular pressure decline, an index of the rate of relaxation, was prolonged in the AS2 group. In contrast, mitral valve opening pressure (MVOP) was significantly higher in this group than in the other two groups. The constant of left ventricular chamber stiffness was slightly but not significantly greater in both AS groups than in the control subjects. After surgery in patients in the AS 1 group, preoperatively reduced %V had increased and preoperatively enhanced PFR2 had decreased. In patients in the AS2 group, excluding one with a persistent low ejection fraction after surgery, preoperatively enhanced PFR1 decreased in association with a decrease in MVOP. Thus, left ventricular filling dynamics vary in patients with AS depending on the degree of left ventricular hypertrophy and systolic function. In patients with AS and moderate hypertrophy %V1 is slightly reduced but is compensated for by a forceful atrial contraction. In those with severe hypertrophy and systolic dysfunction increased driving pressure allows %VV1 to remain within normal limits, despite prolonged left ventricular relaxation and decreased elastic recoil. Both changes in left ventricular filling dynamics tend to normalize after surgery in association with a reduction in left ventricular hypertrophy and/or an improvement of systolic function.