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Comparison between cardiovascular magnetic resonance and transthoracic Doppler echocardiography for the estimation of effective orifice area in aortic stenosis.

Garcia J, Kadem L, Larose E, Clavel MA, Pibarot P - J Cardiovasc Magn Reson (2011)

Bottom Line: The intra- and inter- observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.Underestimation of ALVOT by TTE is compensated by overestimation of VTILVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA.CMR was associated with less intra- and inter- observer measurement variability compared to TTE.

View Article: PubMed Central - HTML - PubMed

Affiliation: Québec Heart and Lung Institute, Laval University, Québec, Canada.

ABSTRACT

Background: The effective orifice area (EOA) estimated by transthoracic Doppler echocardiography (TTE) via the continuity equation is commonly used to determine the severity of aortic stenosis (AS). However, there are often discrepancies between TTE-derived EOA and invasive indices of stenosis, thus raising uncertainty about actual definite severity. Cardiovascular magnetic resonance (CMR) has emerged as an alternative method for non-invasive estimation of valve EOA. The objective of this study was to assess the concordance between TTE and CMR for the estimation of valve EOA.

Methods and results: 31 patients with mild to severe AS (EOA range: 0.72 to 1.73 cm2) and seven (7) healthy control subjects with normal transvalvular flow rate underwent TTE and velocity-encoded CMR. Valve EOA was calculated by the continuity equation. CMR revealed that the left ventricular outflow tract (LVOT) cross-section is typically oval and not circular. As a consequence, TTE underestimated the LVOT cross-sectional area (ALVOT, 3.84 ± 0.80 cm2) compared to CMR (4.78 ± 1.05 cm2). On the other hand, TTE overestimated the LVOT velocity-time integral (VTILVOT: 21 ± 4 vs. 15 ± 4 cm). Good concordance was observed between TTE and CMR for estimation of aortic jet VTI (61 ± 22 vs. 57 ± 20 cm). Overall, there was a good correlation and concordance between TTE-derived and CMR-derived EOAs (1.53 ± 0.67 vs. 1.59 ± 0.73 cm2, r = 0.92, bias = 0.06 ± 0.29 cm2). The intra- and inter- observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.

Conclusion: Underestimation of ALVOT by TTE is compensated by overestimation of VTILVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA. CMR was associated with less intra- and inter- observer measurement variability compared to TTE. CMR provides a non-invasive and reliable alternative to Doppler-echocardiography for the quantification of AS severity.

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Comparison of valve effective orifice area (EOA) measured by TTE versus by CMR. Panel A shows the Pearson correlation plot. The solid line is the regression line and the dashed line is the identity line. Panel B shows the Bland-Altman plot. The solid line is the mean bias and dashed lines are ± 1.96 standard-deviations lines.
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Figure 5: Comparison of valve effective orifice area (EOA) measured by TTE versus by CMR. Panel A shows the Pearson correlation plot. The solid line is the regression line and the dashed line is the identity line. Panel B shows the Bland-Altman plot. The solid line is the mean bias and dashed lines are ± 1.96 standard-deviations lines.

Mentions: Overall, there was a good correlation and concordance between EOATTE and EOACMR (1.53 ± 0.67 cm2 vs. 1.59 ± 0.73 cm2, r = 0.92, bias = +0.06 cm2, agreement limits: -0.50 to +0.62 cm2; Figure 5). Nonetheless, 12 (39%) patients had a change in AS severity class when using the EOACMR rather than the EOATTE (Figure 6). Four (13%) patients were re-classified in a more severe class and 8 (26%) in a less severe class. Two (6%) patients with severe AS on the basis of EOATTE were re-classified as moderate by EOACMR and three (9%) patients with moderate AS on the basis of EOATTE were classified as severe by EOACMR.


Comparison between cardiovascular magnetic resonance and transthoracic Doppler echocardiography for the estimation of effective orifice area in aortic stenosis.

Garcia J, Kadem L, Larose E, Clavel MA, Pibarot P - J Cardiovasc Magn Reson (2011)

Comparison of valve effective orifice area (EOA) measured by TTE versus by CMR. Panel A shows the Pearson correlation plot. The solid line is the regression line and the dashed line is the identity line. Panel B shows the Bland-Altman plot. The solid line is the mean bias and dashed lines are ± 1.96 standard-deviations lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108925&req=5

Figure 5: Comparison of valve effective orifice area (EOA) measured by TTE versus by CMR. Panel A shows the Pearson correlation plot. The solid line is the regression line and the dashed line is the identity line. Panel B shows the Bland-Altman plot. The solid line is the mean bias and dashed lines are ± 1.96 standard-deviations lines.
Mentions: Overall, there was a good correlation and concordance between EOATTE and EOACMR (1.53 ± 0.67 cm2 vs. 1.59 ± 0.73 cm2, r = 0.92, bias = +0.06 cm2, agreement limits: -0.50 to +0.62 cm2; Figure 5). Nonetheless, 12 (39%) patients had a change in AS severity class when using the EOACMR rather than the EOATTE (Figure 6). Four (13%) patients were re-classified in a more severe class and 8 (26%) in a less severe class. Two (6%) patients with severe AS on the basis of EOATTE were re-classified as moderate by EOACMR and three (9%) patients with moderate AS on the basis of EOATTE were classified as severe by EOACMR.

Bottom Line: The intra- and inter- observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.Underestimation of ALVOT by TTE is compensated by overestimation of VTILVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA.CMR was associated with less intra- and inter- observer measurement variability compared to TTE.

View Article: PubMed Central - HTML - PubMed

Affiliation: Québec Heart and Lung Institute, Laval University, Québec, Canada.

ABSTRACT

Background: The effective orifice area (EOA) estimated by transthoracic Doppler echocardiography (TTE) via the continuity equation is commonly used to determine the severity of aortic stenosis (AS). However, there are often discrepancies between TTE-derived EOA and invasive indices of stenosis, thus raising uncertainty about actual definite severity. Cardiovascular magnetic resonance (CMR) has emerged as an alternative method for non-invasive estimation of valve EOA. The objective of this study was to assess the concordance between TTE and CMR for the estimation of valve EOA.

Methods and results: 31 patients with mild to severe AS (EOA range: 0.72 to 1.73 cm2) and seven (7) healthy control subjects with normal transvalvular flow rate underwent TTE and velocity-encoded CMR. Valve EOA was calculated by the continuity equation. CMR revealed that the left ventricular outflow tract (LVOT) cross-section is typically oval and not circular. As a consequence, TTE underestimated the LVOT cross-sectional area (ALVOT, 3.84 ± 0.80 cm2) compared to CMR (4.78 ± 1.05 cm2). On the other hand, TTE overestimated the LVOT velocity-time integral (VTILVOT: 21 ± 4 vs. 15 ± 4 cm). Good concordance was observed between TTE and CMR for estimation of aortic jet VTI (61 ± 22 vs. 57 ± 20 cm). Overall, there was a good correlation and concordance between TTE-derived and CMR-derived EOAs (1.53 ± 0.67 vs. 1.59 ± 0.73 cm2, r = 0.92, bias = 0.06 ± 0.29 cm2). The intra- and inter- observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.

Conclusion: Underestimation of ALVOT by TTE is compensated by overestimation of VTILVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA. CMR was associated with less intra- and inter- observer measurement variability compared to TTE. CMR provides a non-invasive and reliable alternative to Doppler-echocardiography for the quantification of AS severity.

Show MeSH
Related in: MedlinePlus