CT-derived LVOT diameter refines aortic stenosis assessment in TAVI candidates with suboptimal echocardiographic image quality
E Beneki, P Antiochos, D Meier, S Fournier, M Akodad, L Henri, A Salihu, G Fahrni, D Rotzinger, P Blanke, J Leipsic, O Muller, P Monney, G TzimasAbstract
Background
Transthoracic echocardiography (TTE) can underestimate left ventricular outflow tract (LVOT) diameter (LVOTdECHO) leading to discordant aortic stenosis (AS) grading, particularly in patients with suboptimal image quality. Cardiac computed tomography (CT), routinely performed before transcatheter aortic valve implantation (TAVI) allows accurate LVOT assessment. Our aim was to assess whether inserting CT-derived LVOT diameter (LVOTdCT) into the continuity equation to calculate indexed AVA (AVAi_CT), improves AS grading compared with echocardiography-derived AVAi (AVAi_ECHO), particularly when echocardiographic image quality is suboptimal.
Methods
We retrospectively analyzed 426 TAVI candidates (82.3±7.3 years; 50.2% women) who underwent both CT and echocardiography. LVOTdCT was measured on a plane replicating the parasternal long-axis view and used to compute AVAi_CT. Image quality was graded (good/fair/poor). Reclassification was defined as AVAi_ECHO ≤0.6 cm²/m² and AVAi_CT >0.6 cm²/m². Association with echocardiographic parameters (dimensionless index, DI, acceleration time/ejection time, AT/ET) and CT-derived aortic valve calcium score (AVC) and annulus-indexed AVC (AVCdCT) were examined.
Results
LVOTdECHO were smaller than CT (median 2.0 [1.7–2.3] vs 2.2 [1.9–2.5] cm; p<0.001). Agreement declined with image quality (ICC good/fair/poor: 0.900/0.689/0.481). AVAi_CT exceeded AVAi_ECHO (0.82±0.22 vs 0.70±0.18 cm²/m²; p<0.001). Overall, 51/426 (12.0%) were reclassified, 82.4% of whom had fair/poor image quality (OR 5.508; 95% CI 2.6–11.6; p<0.001). Most reclassification occurred in normal-flow/low-gradient AS (38.1%). Reclassified patients had DI>0.25 (72.5% vs 20.2%; p<0.001), AT/ET≤0.32 (52.9% vs 38.5%; p=0.043), and lower AVC/AVCdCT.
Conclusions
Incorporating LVOTdCT into the continuity equation improves AS grading, particularly in normal-flow, low-gradient AS patients and suboptimal echocardiographic quality, and may refine TAVI selection.