A Novel Echocardiographic Parameter to Confirm Low-Gradient Aortic Stenosis Severity

Area of Science:

• Cardiology
• Echocardiography
• Medical Diagnostics

Background:

• Low-gradient aortic stenosis (LG-AS) diagnosis often requires advanced imaging like dobutamine stress echocardiography (DSE) or CT calcium scoring.
• Confirming true severe AS (TSAS) and guiding intervention in LG-AS patients presents a clinical challenge.

Purpose of the Study:

• To evaluate the diagnostic accuracy and prognostic value of the mean transvalvular pressure gradient to effective orifice area ratio (MG/EOA) in patients with low-flow, LG-AS.
• To determine if MG/EOA ratio can identify true-severe AS (TSAS) and predict clinical outcomes.

Main Methods:

• Retrospective assessment of MG/EOA ratio diagnostic accuracy in an in vitro dataset (93 conditions) and an in vivo dataset from the TOPAS study (188 patients).
• Utilized receiver operating characteristic curves to assess diagnostic accuracy for TSAS.
• Employed Cox proportional hazards regression to analyze the association between MG/EOA ratio and clinical outcomes.

Main Results:

• An optimal MG/EOA ratio cutoff of ≥25 mm Hg/cm² was identified for TSAS detection (85% correct classification in vivo, 100% in vitro).
• During a median follow-up of 1.41 years, 78% of patients reached the composite endpoint (aortic valve replacement or all-cause mortality).
• MG/EOA ratio ≥25 mm Hg/cm² was independently associated with a 2.36-fold increased risk of the composite endpoint (adjusted HR: 2.36 [95% CI: 1.63-3.42], P < 0.001).

Conclusions:

• The MG/EOA ratio, with a cutoff of ≥25 mm Hg/cm², is a valuable tool for confirming AS severity in low-flow, LG-AS.
• This ratio demonstrates diagnostic accuracy comparable to projected EOA by DSE.
• MG/EOA ratio may serve as a complementary diagnostic method alongside DSE or CT calcium scoring for LG-AS patients.