Revealing hidden severity: three-dimensional transoesophageal echocardiography planimetry in low-flow, low-gradient aortic stenosis

Background Up to 30% of patients with aortic stenosis (AS) and reduced left ventricular ejection fraction (LVEF) show discordant echocardiographic parameters, leaving AS severity uncertain. Guidelines recommend dobutamine stress echocardiography (DSE) or aortic valve calcium (AVC) scoring by computed tomography (CT), but these tests are not systematically available. Three-dimensional transoesophageal echocardiography (3D-TEE) is widely used in imaging laboratories and may refine the assessment of low-flow, low-gradient AS (LFLG-AS) with reduced LVEF. Objectives To assess, in routine clinical practice, whether 3D-TEE planimetry of aortic valve area (AVA) improves severity grading of LFLG-AS with reduced LVEF compared with standard transthoracic echocardiography (TTE). In a CT subgroup, we also evaluated its concordance with sex-specific AVC scores. Methods We conducted a single-centre, retrospective study including patients with AS, mean gradient 20–40 mmHg, LVEF <50% and stroke volume index (SVI) ≤35 mL/m². AVA was measured by the continuity equation on TTE (AVA-CE) and by 3D-TEE planimetry (AVA-3D). According to ESC guidelines, severe AS was defined as AVA ≤1.0 cm². When available, CT-derived sex-specific AVC ratios were calculated, with values >1 indicating severe AS. Agreement was evaluated with contingency tables and standard concordance analyses. Results We screened 90 patients with suspected LFLG-AS, of whom 53 met all eligibility criteria (complete TTE and 3D-TEE and no significant concomitant valve disease). Baseline characteristics are presented in Table 1. On TTE, 46/53 (87%) were classified as severe, compared with 44/53 (83%) on 3D-TEE. Among TTE-moderate patients, 4/7 (57%) were upgraded to severe by 3D-TEE; 6/46 (13%) TTE-severe patients were downgraded to moderate. Overall, 3D-TEE reclassified 10/53 cases (19%). Using 3D-TEE as reference, TTE showed a sensitivity of 91% and specificity of 33% for detecting severe AS, with positive and negative predictive values of 87% and 43%, respectively. In the CT subgroup (n = 27), all TEE-moderate cases were confirmed as non-severe by AVC, and 16/25 (64%) TTE-severe cases were confirmed as severe, supporting reclassification provided by 3D-TEE. Bland–Altman analysis showed minimal systematic bias (mean difference AVA-CE – AVA-3D = 0.04 cm²) while highlighting that 3D-TEE and TTE provide complementary information (Figure 2). Conclusions In this real-world cohort, 3D-TEE planimetry reclassified about one fifth of patients, mainly uncovering additional severe cases among those considered moderate on TTE. While TTE reliably confirms severe AS, its limited ability to exclude severe disease highlights the added value of 3D-TEE whose grading is in line with sex-specific CT AVC scores. Incorporating 3D-TEE planimetry into a multimodality imaging strategy may enhance diagnostic confidence and guide timely valve intervention in this challenging population.Table 1.Baseline characteristicsFigure 2.Agreement between TTE and 3D-TEE