Diastolic dysfunction in aortic stenosis is associated with greater damping of left ventricular recoil, and not myocardial stiffness.

Background: Aortic stenosis (AS) is associated with increasing severity of diastolic dysfunction as measured by conventional echocardiographic grading. The parameterized diastolic filling (PDF) method can describe diastolic function mechanistically, by analyzing filling using the physics of classical mechanics for spring recoil. Purpose: To use the PDF method to describe the mechanics of how diastolic dysfunction manifests in AS. Methods: Patients (n=73) undergoing echocardiography were included according to AS of varying severity (normal/mild AS: maximum Doppler velocity across aortic valve (Vmax) <3.0 m/s, moderate/severe AS: Vmax ≥3.0 m/s). Analysis of pulsed wave Doppler transmitral E-waves was performed using freely available software for PDF analysis. Results: Compared to normal/mild AS (n=41), patients with moderate/severe AS (n=32) had a left ventricle with a greater interventricular septal thickness (p=0.02) and higher E/é (p=0.007), but similar left ventricular ejection fraction (p=0.10) and left atrial volume index (p=0.21). PDF analysis (48 ± 9 E-waves per patient) showed that moderate/severe AS did not differ in myocardial stiffness (p=0.70), but had a higher myocardial viscoelasticity (p=0.02), higher load (p=0.04), longer derived time constant of isovolumetric pressure decay (tau, p=0.004), higher filling energy (p=0.02), higher peak driving (p=0.02) and resistive (p=0.004) force of filling, lower kinematic filling efficiency index (p<0.001), but no difference in the load-independent index of diastolic function (p=0.62). Conclusions: AS was primarily associated with a greater damping of LV recoil (viscoelasticity) and load, but without a change in myocardial stiffness. Diastolic dysfunction in AS manifests with pathophysiological changes that are mechanistically consistent with a greater severity of diastolic dysfunction.