Structural and Functional Correlates of Gradient-Area Patterns in Severe Aortic Stenosis and Normal Ejection Fraction

Area of Science:

• Cardiology
• Cardiac Imaging
• Aortic Stenosis

Background:

• Severe paradoxical low-gradient aortic stenosis (LG-AS) was recently suggested to be a more advanced form of AS.
• This advanced form was thought to involve reduced longitudinal deformation, adverse left ventricular (LV) remodeling, and increased interstitial fibrosis.

Purpose of the Study:

• To characterize the functional and structural myocardial phenotypes in moderate-to-severe aortic stenosis (AS).
• To determine if severe paradoxical LG-AS is specifically linked to LV remodeling and fibrosis.

Main Methods:

• 147 patients with moderate-to-severe AS (normal LV ejection fraction) and 75 controls underwent 2D speckle-tracking echocardiography and cardiac MRI.
• Evaluated myocardial deformation, LV remodeling, and extravascular volume fraction (ECV).
• Classified AS patients into moderate AS, severe high-gradient AS (HG-AS), and severe paradoxical LG-AS groups.

Main Results:

• Reduced longitudinal deformation was observed in 21% of AS patients; increased ECV and absence of normal LV geometry predicted this.
• Increased ECV predicted reduced circumferential deformation.
• Over 29 months, reduced longitudinal deformation and higher transvalvular gradients increased the risk of death or aortic valve replacement.

Conclusions:

• Severe paradoxical LG-AS patients showed less reduced longitudinal deformation, LV hypertrophy, and myocardial fibrosis than HG-AS patients.
• Interstitial fibrosis was observed only when reduced longitudinal deformation and severe HG-AS coexisted.
• Reduced longitudinal deformation and higher transvalvular gradients adversely affect patient outcomes.