Korean Circ J.  2017 Jan;47(1):82-88. 10.4070/kcj.2016.0126.

Role of Transesophageal Echocardiography in the Diagnosis of Paradoxical Low Flow, Low Gradient Severe Aortic Stenosis

• Abudiab MM
• Pandit A
• Chaliki HP

• KMID: 2365286
• DOI: http://doi.org/10.4070/kcj.2016.0126

Abstract

BACKGROUND AND OBJECTIVES
Prior studies indicate that up to 35% of cases of severe aortic stenosis (AS) have paradoxical low flow, low gradient despite preserved left ventricular ejection fraction (LVEF). However, error in left ventricular outflow tract (LVOT) diameter may lead to misclassification. Herein, we determined whether measurement of LVOT diameter by transesophageal echocardiography (TEE) results in reclassification of cases to non-severe AS.
SUBJECTS AND METHODS
Patients with severe AS with aortic valve area (AVA) <1 cm2 by transthoracic echocardiography (TTE) within 6 months were studied. Paradoxical low flow, low gradient was defined as mean Doppler gradient (MG) <40 mm Hg and stroke volume index (SVI) ≤35 mL/m². Preserved LVEF was defined as ≥0.50.
RESULTS
Among 108 patients, 12 (15%) had paradoxical low flow, low gradient severe AS despite preserved LVEF based on TTE measurement. When LVOT diameter by TEE in 2D was used, only 5 (6.3%) patients had low flow, low gradient severe AS (p<0.001). Coefficients of variability for intraobserver and interobserver measurement of LVOT were <10%. However, the limits of agreement between TTE and TEE measurement of LVOT ranged from 0.43 cm (95% confidence interval [CI]: 0.36 to 0.5) to -0.31 cm (95% CI: -0.38 to -0.23).
CONCLUSION
TEE measured LVOT diameter may result in reclassification to moderate AS in some patients due to low prevalence of true paradoxical low flow, low gradient (PLFLG) severe AS.

Keyword

Transthoracic echocardiography; Transesophageal echocardiography; Aortic valve stenosis; Ventricular ejection fraction

MeSH Terms

Aortic Valve
Aortic Valve Stenosis*
Diagnosis*
Echocardiography
Echocardiography, Transesophageal*
Humans
Prevalence
Stroke Volume

Figure

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  Fig. 1 Measurement of left ventricular outflow tract diameter by transthoracic and transesophageal echocardiography. (A) On transthoracic echocardiography, left ventricular outflow tract diameter (arrow) is measured in mid-systole from inner edge to inner edge just below insertion of the aortic valve leaflets. (B) On transesophageal echocardiography, left ventricular outflow tract diameter (arrow) is measured in mid-systole from inner edge to inner edge. Sinotubular junction diameter (arrow with rounded edges) is also shown.

• 

  Fig. 2 TEE reclassification of patients with severe AS and normal LV ejection fraction. By transesophageal echocardiography, a significant number of patients with severe aortic stenosis are reclassified, particularly in the low flow and low flow, low gradient severe aortic stenosis groups. TTE: transthoracic echocardiography, AS: aortic stenosis, LV: left ventricle, TEE: transesophageal echocardiography.

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  Fig. 3 Bland-Altman plot demonstrating trend of underestimation by TTE. The wide limits of agreement between transthoracic and transesophageal echocardiography measurement likely explains reclassification of patients on the basis of left ventricular outflow tract diameter measurement. TEE: transesophageal echocardiography, LVOT: left ventricular outflow tract, TTE: transthoracic echocardiogram, SD: standard deviation.

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