Comparison of Simultaneous Transthoracic Versus Transesophageal Echocardiography for Assessment of Aortic Stenosis.

Transthoracic echocardiography (TTE) is the gold standard for aortic stenosis (AS) assessment. Transesophageal echocardiography (TEE) provides better resolution, but its effect on AS assessment is unclear. To answer this question, we studied 56 patients with ≥moderate AS. Initial TTE (TTE1) was followed by conscious sedation with simultaneous TEE and TTE2. Based on conservative versus actionable implication, AS types were dichotomized into group A, comprising moderate and normal-flow low-gradient, and group B, comprising high gradient, low ejection fraction low-flow low-gradient, and paradoxical low-flow low-gradient AS. Paired analysis of echocardiographic variables and AS types measured by TEE versus TTE2 and by TEE versus TTE1 was performed. TEE versus simultaneous TTE2 comparison demonstrated higher mean gradients (31.7 ± 10.5 vs 27.4 ± 10.5 mm Hg) and velocities (359 ± 60.6 vs 332 ± 63.1 cm/s) with TEE, but lower left ventricular outflow velocity-time-integral (VTI1) (18.6 ± 5.1 vs 20.2 ± 6.1 cm), all p <0.001. This resulted in a lower aortic valve area (0.8 ± 0.21 vs 0.87 ± 0.28 cm2), p <0.001, and a net relative risk of 1.86 of group A to B upgrade. TEE versus (awake state) TTE1 comparison revealed a larger decrease in VTI1 because of a higher initial awake state VTI1 (22 ± 5.6 cm), resulting in similar Doppler-velocity-index and aortic valve area decrease with TEE, despite a slight increase in mean gradients of 0.8 mm Hg (confidence interval -1.44 to 3.04) and velocities of 10 cm/s (confidence interval -1.5 to 23.4). This translated into a net relative risk of 1.92 of group A to B upgrade versus TTE1. In conclusion, TEE under conscious sedation overestimates AS severity compared with both awake state TTE and simultaneous sedation state TTE, accounted for by different Doppler insonation angles obtained in transapical versus transgastric position.

Echocardiographic Assessment of Aortic Stenosis under Sedation Underestimates Stenosis Severity.

BACKGROUND: Sedation can impact aortic stenosis (AS) classification, which depends on left ventricular ejection fraction (<≥ [less than or greater than and/or equal to] 50%), aortic valve area (AVA<≥ 1 cm2), mean pressure gradient (<≥ 40 mm Hg), peak velocity <≥ 400 cm/sec, and stroke volume index (SVI <≥35 mL/m2). We compared AS classification by transthoracic echo (TTE) during wakefulness versus sedation. METHODS: Immediately following a baseline TTE performed during wakefulness, another TTE was done during sedation delivered for a concomitant transesophageal study in 69 consecutive patients with AS (mean age 78 ± 7 years, 32 males). AVA was calculated through the continuity equation using the relevant hemodynamic parameters measured by each TTE study and same left ventricular outflow tract. AS class was defined as moderate, severe high gradient (HG), low ejection fraction low flow low gradient (LF-LG), paradoxical LF-LG (PLFLG), and normal flow low gradient (NF-LG). Based on conservative versus invasive treatment implication, AS classes were aggregated into group A (moderate AS and NFLG) and group B (HG, low-EF LF-LG, and PLFLG). RESULTS: During sedation, systolic and diastolic blood pressure decreased by 14.3 ± 29 and 8 ± 22 mm Hg, respectively, mean pressure gradient from 30.4 ± 10.9 to 27.2 ± 10.8 mm Hg, peak velocity from 345.3 ± 57.7 to 329.3 ± 64.8 cm/m2, and SVI from 41.5 ± 11.3 to 38.3 ± 11.8 mL/m2 (all P < .05). Calculated AVA was similar (delta = -0.009 ± 0.15 cm2). Individual discrepancies in hemodynamic parameters between the paired TTE studies resulted in an overall 17.4% rate of AS intergroup misclassification with sedation, with a relative risk of 1.09 of downgrade misclassification from group B to A versus upgrade misclassification (P < .001). CONCLUSIONS: Sedation TTE assessment downgrades AS severity in a significant proportion of patients, with a conversely smaller proportion of patients being upgraded, and therefore cannot be a substitute for wakefulness assessment.

Incremental Value of Transesophageal Echocardiography Integrated with Transthoracic Echocardiography in the Assessment of Aortic Stenosis Severity.

BACKGROUND: Transthoracic echocardiography (TTE) is the standard method for evaluating the severity of aortic stenosis (AS), while transesophageal echocardiography (TEE) is useful for morphologic characterization. The study aim was to assess the impact of complementary TEE to TTE in refining hemodynamic assessment of AS severity. METHODS: A retrospective analysis was conducted of sequential TTE and TEE studies performed in 100 patients with moderate or severe AS confirmed on prior TTE. The left ventricular outflow tract (LVOT) velocity-time-integral (VTI1) and the aortic valve velocity-time integral (VTI2) were measured for both modalities. The highest values of VTI1 and VTI2 and mean gradients and peak velocities were selected from the sequential TTE/TEE study for indexed aortic valve area (AVAi) calculation and AS severity determination through an integrated assessment. RESULTS: AVAi determined by TTE was not significantly different from that determined by TEE (mean difference -0.008 cm2; p = 0.38). The dimensionless velocity index (DVI) was higher when assessed by TTE than by TEE (mean difference 0.0126 ± 0.04; p = 0.003). Using the integrated AS assessment, six of 13 patients with a TTE-based diagnosis of moderate AS were re-classified as severe AS. A slight lowering of the recommended TTE-derived DVI threshold for severe AS, from 0.25 to 0.24, improved the ability to discriminate moderate versus severe AS, as determined by the integrated assessment. CONCLUSIONS: TEE integrated with TTE may improve the detection of severe AS, particularly in patients with moderate AS criteria assessed by TTE, but with a DVI ratio ≤0.24.