Planimetry in aortic valve stenosis using computed tomography angiography - application in low gradient stenosis

Aortic valve stenosis (AS) severity as assessed by transthoracic echocardiography (TTE) can remain inconclusive when flow velocity (Vmax), mean pressure gradient (∆Pm), and calculated valve area (cAVA) are non-congruent. In particular, the combination of an cAVA<1.0cm², Vmax <4.0 m/s and ∆Pm <40mmHg (low gradient (severe) aortic stenosis (LG(S)AS)) is frequently problematic. We suggest AVA by computed tomography angiography (CTA)-planimetry (pAVACTA) as a 4th severity criteria marker to aid classification.

Defining the role of CTA-planimetry in LG(S)AS through integration of pAVACTA as 4th severity marker into the ESC/JASE flow-Charts for AS severity grading.

Patients who presented with a cAVATTE<1.0cm², Vmax<4m/s and ∆Pm<40mmHg to our institution and underwent a pre-TAVI-CTA-scan between 2012 and 2023 were included for analysis. The role of pAVACTA as a 4th severity marker was assessed by testing for AVA severity congruence between cAVATTE and pAVACTA. Based on data from a large cohort of patients with congruent severe AS (cAVATTE<1.0cm² & Vmax≥4m/s & ∆Pm≥40mmHg) we have recently proposed a pAVACTA cut-off of ≤0.95cm² to support and a pAVACTA ≥1.1cm2 to render unlikely the diagnosis of severe AS, with values in-between deemed indeterminate by planimetry.

A total of 81 patients presented with LFLG-AS (Low Flow SVI SVI<35ml/m², LVEF≥50%) and 173 patients with NFLG-AS (Normal Flow SVI≥35ml/m²). Congruence between cAVATTE and pAVACTA was high in both groups at 82.7% and 76.3%, respectively, with non-congruence low at 2.5% and 6.4%.

In our cohort, CTA-based planimetry confirms AVA indicative of severe AS in a high percentage of patients with LG-AS irrespective of flow. Adding pAVACTA to the diagnostic work-up as a 4th severity criteria may by useful by adding diagnostic certainty.

Proposed ESC Flow Chart Modification