Size-Adjusted Left Ventricular Outflow Tract Diameter Reference Values: A Safeguard for the Evaluation of the Severity of Aortic Stenosis

doi:10.1016/j.echo.2009.02.007

Journal of the American Society of Echocardiography

Volume 22, Issue 5, May 2009, Pages 445-451

https://doi.org/10.1016/j.echo.2009.02.007 Get rights and content

Objective

We sought to evaluate the relationship among left ventricular outflow tract diameter (LVOTd), gender, and body surface area (BSA) and to evaluate the usefulness of size-adjusted LVOTd reference values in patients with aortic stenosis (AS). AS grading is based on the echocardiographic calculation of the aortic valve area (AVA) and requires LVOTd measurements, one main potential source of error. Transesophageal echocardiography (TEE) is reputed to be more accurate than transthoracic echocardiography (TTE), but validation studies are rare. A safeguard for LVOTd measurements is thus desirable.

Methods

Since January 2006, 3 subsets of patients have been prospectively and concurrently enrolled: 1) TEE group: In 120 patients with and without AS, we prospectively measured LVOTd during both TTE and TEE. 2) Validation set: In 382 patients without aortic valve or ascending aorta diseases, we evaluated the relationship among LVOTd, gender, and BSA. 3) Testing set: In 173 patients with AS, we compared the AVA obtained using measured LVOTd (AVA_MEAS) and calculated LVOTd derived from a regression determined in the validation set (AVA_CALC).

Results

TTE did not differ from and correlated well with TEE measurements overall (23 ± 2 mm vs 23 ± 2 mm, P = .26; r = 0.95, P < .0001) and in patients with AS (N = 43) (24 ± 2 mm vs 24 ± 3 mm, P = .15; r = 0.92, P < .0001). LVOTd was linearly correlated to BSA independently of gender (LVOTd = 5.7 ∗ BSA+12.1; r = 0.55, P < .0001). In the testing set, AVA_CALC did not differ from and correlated well with AVA_MEAS (1.20 ± 0.42 cm² vs 1.23 ± 0.40 cm²; P = .08; r = 0.89; P < .0001).

Conclusion

TTE and TEE measurements of the LVOTd provided similar results. LVOTd was significantly associated to BSA and LVOTd, derived from a linear regression linked to BSA independently of gender, provided an acceptable approximation of the AVA. Thus, although accurate measurement of LVOTd is a crucial part of the echocardiographic evaluation of AS severity, the present equation may be used as a safeguard when this measurement is difficult or not possible with TTE.

Section snippets

Population

Three different patient subsets were prospectively and concurrently enrolled in the present study since January 2006.

TTE and TEE Measurements of LVOTd

LVOTd was measured during TTE and TEE in 120 patients (mean age 62 ± 16 years, 55 men), 43 with AS and 77 without AS. Mean weight was 74 ± 15 kg (median 73, range [35-112]), and mean BMI was 27 ± 5 kg/m² (median 27, range [13-43]). Mean LVOTd was 23 ± 3 mm (median 23, range [17-33]) using TTE and 23 ± 3 mm (median 23, range [17-34]) using TEE (P = .26). Correlation between methods was excellent (r = 0.95, P < .00001) (Figure 1C), and the quality-control plots using the Altman and Bland method

Discussion

In the present study we showed that TTE and TEE provided similar measurements. LVOTd was significantly larger in men than in women but was not significantly different between genders after indexation to BSA. LVOTd increased with BSA, and a linear regression between LVOTd and BSA independently of gender (LVOTd = 5.7 ∗ BSA + 12.1) provided an acceptable estimate of the AVA in patients with AS.

Study Limitations

First, this was not a feasibility study, and patients with unmeasurable LVOTd were excluded. However, our aim was to validate a size-adjusted estimation of the LVOTd for AVA calculation in patients with AS. Second, we did not compare TTE and TEE measurements with those obtained from another method because of the lack of a fully accepted gold standard. Three-dimensional and computed tomography imaging are emerging and deserve additional studies.17, 34 Third, the relationship between LVOTd and

Conclusions

We showed that TTE did not provide significantly different LVOTd measurements than TEE. LVOTd was significantly associated to BSA, and LVOTd derived from a linear regression linked to BSA independently of gender provided an acceptable approximation of the AVA in patients with AS. Thus, this regression may be a useful safeguard for AS evaluation, especially when LVOTd measurements are difficult or not possible using TTE.

Acknowledgment

We thank Dr Xavier Duval and the team at the Center of Clinical Investigation.

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: Dr Messika-Zeitoun was supported by a contrat d'interface INSERM. The COFRASA study is supported by a grant from the Assistance Publique–Hôpitaux de Paris (PHRC National 2005).

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Clinical InvestigationValvular Heart DiseaseSize-Adjusted Left Ventricular Outflow Tract Diameter Reference Values: A Safeguard for the Evaluation of the Severity of Aortic Stenosis

Objective

Methods

Results

Conclusion

Section snippets

Population

TTE and TEE Measurements of LVOTd

Discussion

Study Limitations

Conclusions

Acknowledgment

Lancet

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

Am J Cardiol

J Am Coll Cardiol Img

J Am Coll Cardiol

J Am Soc Echocardiogr

J Am Soc Echocardiogr

J Am Coll Cardiol

Ann Thorac Surg

J Thorac Cardiovasc Surg

Am J Cardiol

J Am Soc Echocardiogr

J Am Soc Echocardiogr

J Am Coll Cardiol Img

J Am Coll Cardiol

Clinical Investigation
Valvular Heart Disease
Size-Adjusted Left Ventricular Outflow Tract Diameter Reference Values: A Safeguard for the Evaluation of the Severity of Aortic Stenosis