Quantification of Functional Mitral Regurgitation by Real-Time 3D Echocardiography: Comparison With 3D Velocity-Encoded Cardiac Magnetic Resonance

OBJECTIVES: The aim of this study was to evaluate feasibility and accuracy of real-time 3-dimensional (3D) echocardiography for quantification of mitral regurgitation (MR), in a head-to-head comparison with velocity-encoded cardiac magnetic resonance (VE-CMR). Background: Accurate grading of MR severity is crucial for appropriate patient management but remains challenging. VE-CMR with 3D three-directionalacquisition has been recently proposed as the reference method.

METHODS: A total of 64 patients with functional MR were included. A VE-CMR acquisition was applied to quantify mitral regurgitant volume (Rvol). Color Doppler 3D echocardiography was applied for direct measurement, in “en face” view, of mitral effective regurgitant orifice area (EROA); Rvol was subsequently calculated as EROA multiplied by the velocity-time integral of the regurgitant jet on the continuous-wave Doppler. To assess the relative potential error of the conventional approach, color Doppler 2-dimensional (2D) echocardiography was performed: vena contracta width was measured in the 4-chamber view and EROA calculated as circular (EROA-4CH); EROA was also calculated as elliptical (EROA-elliptical), measuring vena contracta also in the 2-chamber view. From these 2D measurements of EROA, the Rvols were also calculated.

RESULTS: The EROA measured by 3D echocardiography was significantly higher than EROA-4CH (p < 0.001) and EROA-elliptical (p < 0.001), with a significant bias between these measurements (0.10 cm2 and 0.06 cm2, respectively). Rvol measured by 3D echocardiography showed excellent correlation with Rvol measured by CMR (r = 0.94), without a significant difference between these techniques (mean difference = –0.08 ml/beat). Conversely, 2D echocardiographic approach from the 4-chamber view significantly underestimated Rvol (p = 0.006) as compared with CMR (mean difference = 2.9 ml/beat). The 2D elliptical approach demonstrated a better agreement with CMR (mean difference = –1.6 ml/beat, p = 0.04).

CONCLUSIONS: Quantification of EROA and Rvol of functional MR with 3D echocardiography is feasible and accurate as compared with VE-CMR; the currently recommended 2D echocardiographic approach significantly underestimates both EROA and Rvol. Dalvin Cook Womens Jersey

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3 Comments

  1. See related from November 14: Real-time three-dimensional transoesophageal echocardiography in the assessment of aortic valve stenosis.

  2. This is a very well-designed study on 64 continuous patients with functional mild-to-severe MR.
    It shows Real-Time 3d echo to be a feasible and reproducible mean for directly assessing MR when compared with MRI. Additionally, 2D echocardiography (currently the most commonly used test) was also compared revealing it to underestimate the MR measurements, especially when asymmetric regurgitant orifices were present.
    While methodologically this is an important manuscript, its clinical significance and the effect that using RT3DE will have in patient treatment and outcome needs to be investigated.

  3. Echocardiography continues to be the most important and practical tool in the assessment of mitral regurgitation. Over the past few years, more emphasis has been placed on the quantitative analysis of valvular heart disease. Evaluation of the effective regurgitant orifice area (EROA) and regurgitant volume (Rvol) have demonstrated not only to provide an assessment of mitral regurgitation severity but also provide prognostic information. For this reason, a quantitative approach in the evaluation of mitral regurgitation is recommended. This can be done with 2-d echocardiography by using the proximal isovelocity surface area (PISA) which can help us derive an EROA and Rvol, or can also help us perform a more direct assessment with the vena contracta width. However, prior studies have already demonstrated that the geometry of the EROA is complex and asymmetric. A three dimensional echocardiographic approach, especially by utilizing an “en face” view, can provide a more accurate estimation of the EROA.

    The investigators compared quantitative echocardiography (2d and 3d) with 3-directional velocity encoded MRI.
    The following were the conclusions of the study: first of all, the quantitative analysis of mitral regurgitation by 3d echocardiography was feasible and reproducible. Secondly, there was a consistent underestimation of EROA by 2d echocardiography when compared with real time 3d echocardiography, especially in those patients with the most asymmetric EROA. Third, there was a strong correlation between 3d echocardiography quantitative values and those calculated with MRI.

    Conclusions:

    – Echocardiography continues to be the preferred and most practical method of assessment of mitral regurgitation.
    – This study adds to the growing evidence supporting the use of three dimensional echocardiography for the quantitation of mitral regurgitation.
    – The vena contracta width (4-chamber and 2-chamber views) is not routinely used to estimate the EROA.
    – The comparison results between 2d echocardiography and 3d echocardiography might have been different should the PISA method would have been used.
    – As of today, it is unlikely that a patient will be referred for a cardiac MRI exclusively for the assessment of mitral regurgitation.
    The current study showed an excellent correlation between 3d echocardiography and VE-CMR in the estimation of regurgitant volumes.
    – The same group that did this study their findings when comparing the more commonly used 2D (single direction) phase contrast MRI vs. 3D phase contrast MRI technique, and showed a slight overestimation (15%) of mitral valve flow of 2D measurements when compared with 3D. When is this overestimation clinically significant to require the use of longer, more effort-consuming 3D techniques? Probably in a very small number of selected patients.

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