Incremental Value of Aortic Stenosis Assessment through Adjunctive Trans-Esophageal Echocardiography versus Transthoracic Echo Only in Sedated Patients

Background:
Sub-classification of aortic stenosis (AS) according to mean pressure gradient(MPG), stroke volume index (SVI) and left-ventricular ejection fraction (LVEF) may impact decision making. We sought to explore the added value of integrated trans-esophageal echocardiography (ITEE) compared with trans-thoracic echocardiography (TTE) only in such assessment.

Methods:
We prospectively studied 31 patients aged 80.1 years (76.6-86.5 IQR) with LVEF 60% (46-60 IQR) and moderate or severe AS on prior TTE. Concomitant TTE and TEE study during conscious sedation was performed. The left-ventricular-outflow-tract(LVOT) Velocity-time-integral(VTI) and the aortic valve VTI were measured on both modalities. Aortic Valve Area (AVA) was calculated through the continuity equation using 3D-planimetry of LVOT by TEE and the highest values of VTI of the AV and LVOT, whether from the TTE or TEE study. The highest trans-valvular mean gradients were also selected from the two integrated studies. AS severity and type was classified as NF-HG (Normal-Flow High-Gradient), Low-EF_LF-LG (Low-Flow Low-Gradient), Normal-EF_LF-LG, and NF-LG (Normal-Flow Low-Gradient), using the following cut-off values: LVEF – 50%, SVI – 35ml/m², MPG – 40 mmHg. This classification was determined first by TTE only and subsequently revised following ITEE. AS types were aggregated into Group-A (moderate AS and NFLG) which does not carry a strong surgical/percutaneous indication and Group-B (NF_HG, Low-EF-LFLG, and Normal EF-LFLG) which implies invasive treatment.

Results:
AS type shifted through ITEE assessment as detailed in attached Figure. Using ITEE, 6/14(42.9%) of patients with a TTE-based diagnosis of moderate AS were reclassified as severe AS. Conversely, 2/15(11.8%) of patients in Group-B were reclassified as Group-A through ITEE.

Conclusions:
Our study demonstrates added value for TEE integrated with TTE in improving AS classification, in that a large proportion of patients shifted into a category that warrants invasive intervention, whereas a minority “downgraded” to moderate or NFLG AS which does not mandate invasive treatment.