Planimetry in aortic valve stenosis using computed tomography angiography - cut-off determination

Aortic valve (AV) stenosis is quantified by transthoracic echocardiography (TTE). However, stenosis severity can remain inconclusive when TTE severity parameters are incongruent. AV-area (AVA) by CTA-planimetry (pAVACTA) may aid in these cases.

Defining the role of CTA-planimetry for tricuspid (TC) AV stenosis by cut-off determination. TTE of conclusive patients was used as Goldstandard.

Severity classification of AV stenosis was performed using TTE with classification into conclusive if all three of the following criteria were congruent: Vmax≥4m/s & ∆Pm≥40mmHg & cAVATTE<1.0cm² (3+ "severe", 3- "non-severe"). Retrospective, single center screening of 4059 pre-TAVI-CTA-scans (2012-2023) yielded 1161 conclusive TC cases. Cut-off values for pAVACTA as a 4th severity criteria marker were determined by first correlating pAVACTA to cAVATTE directly and second by comparing different pAVACTA values for predicting "severe" stenosis via receiver operator curve (ROC).

pAVACTA showed strong positive correlation with cAVATTE (Pearson-Correlation 0.673, p<0.001) with Linear Regression yielding a correlating factor (contraction coefficient CC) of 0.91 (95% CI [0.895, 0.915], p<0.001). ROC analysis (AUC 0.888, p<0.001) yielded a cut-off range with severe stenosis "likely" at pAVACTA≤0.95cm² (Sens. 87%, Spec. 78.9% via Youden’s index) and "unlikely" at ≥1.1cm² (-LR 0.092 at <1.1cm²).

For a given pAVACTA the expected cAVATTE is smaller as the correlating factor (CC) is <1.0. Adding pAVACTA as a 4th AV-stenosis severity marker utilizing a newly defined cut-off range could aid decision making in patients with inconclusive TTE results. Further research is required to validate and narrow cut-off ranges and to test for clinical relevance.