Background

In patients with severe mitral regurgitation (MR), the American College of Cardiology/American Heart Association guidelines recommend surgery when there is left ventricular (LV) dysfunction, even in the absence of symptoms. Recently, physicians have debated whether these guidelines should be relaxed further, with proponents arguing that results are superior when there is earlier surgical intervention, even before LV dysfunction. In such cases as in others outlined in the study, MR becomes more accurate.

Methods

In this prospective multicenter trial, MR severity was assessed in 103 patients using both echocardiography and MRI. The investigators recruited patients from the echocardiography laboratories of the participating institutions and from physician referrals. The severity of MR, as determined by MRI and echocardiography, was compared using: 1) categories of mild, moderate, and severe; and 2) calculated regurgitant volume. Substantial discordance was defined as a difference of 2 grades.

Results

The most important findings are that there was a strong correlation between post-surgical LV remodeling and MR severity as assessed by MRI and no correlation between post-surgical LV remodeling and MR severity as assessed by echocardiography. Also of interest, Uretsky et al. found that when MR is identified as mild by echocardiography, it also tends to be identified as mild by MRI. The disparity arises when it is more than minimum or mild MR.

In the editorial comment, Drs. Kar and Sharma highlight several important points related to this original research paper, including:

1. The etiology of MR can be divided into primary and secondary classifications. The primary is due to the pathology of valve apparatus and secondary, which is due to a functional consequence of the ventricular dysfunction. Then, anatomically, the patient case becomes more complicated, requiring the valve to be replaced—oftentimes with a percutaneous approach, in which the mitral valve ends up with two orifices.
2. With the wide variability of echocardiography, it may not be an accurate assessment tool, especially because of operator dependency and the number of anatomical characteristics to take into account. While MRI can overcome some of these limitations, there is more limited availability of the modality, it can increase costs associated with the diagnostic assessment, and it is incompatible with many magnetic devices.
3. MRI should be the gold standard, except for when the mitral regurgitation is mild, because there is not much discordance between the modalities, until it is moderate to severe in its classification.
Perspective

Based on these results, it seems reasonable that echocardiography remain the first line diagnostic tool for suspected mitral regurgitation and echocardiography should be used to monitor patients with mild MR. However, in those patients with moderate to severe MR, particularly asymptomatic patients, an MRI exam may be indicated. It may be particularly advisable to assess the degree of severity using MRI in patients who are scheduled to undergo invasive therapy." Furthermore, an MRI may be particularly advisable to assess the degree the severity.

References

1. Uretsky, S, Gillam, L, Lang R, et al. Discordance Between Echocardiography and MRI in the Assessment of Mitral Regurgitation Severity: A Prospective Multicenter Trial. J Am Coll Cardiol. 2015;65(11):1078-1088.

Keywords: American Heart Association, Echocardiography, Humans, Mitral Valve, Mitral Valve Insufficiency, Prospective Studies, Referral and Consultation, Research Personnel, United States, Ventricular Dysfunction, Ventricular Dysfunction, Left, Ventricular Remodeling, Heart Valve Diseases

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