Author + information
- Andrew E. Arai, MD,
- Eric S. Leifer, PhD and
- Vandana Sachdev, MD∗ ()
- ↵∗Cardiology and Pulmonary Medicine Branch, NHLBI, National Institutes of Health, 10 Center Drive, CRC, 5NE-Room 1436, Bethesda, Maryland 20892-1650
We thank Drs. Uretsky and Wolff for raising questions about the assessment of severe mitral regurgitation (MR) by echocardiography and cardiac magnetic resonance (CMR). They are probably not aware that the National Heart, Lung, and Blood Institute is exploring the feasibility of a publicly funded study of echocardiography and CMR to manage patients with asymptomatic severe primary MR.
One rarely undertakes an expensive clinical trial based on data from a single small study. Uretsky and colleagues (1) advanced the discussion about whether it would be better to use CMR than echocardiography to triage patients with primary MR for surgery. However, Uretsky and Wolff may have underestimated the importance of concordance between the 2 modalities, which they criticize in their letter as purely comparative. When echocardiography and CMR are concordant, management strategies based on the 2 modalities would not be different. Thus, if concordance were 0.85, a comparative management trial may likely be negative.
To estimate concordance, we extracted data from Uretsky’s publication and our internal data that corresponded to our concept of inclusion criteria: clinicians would not typically consider surgery for less than severe primary MR and they would not consider CMR for less than moderate MR. Extracting regurgitant volume data from Uretsky’s Figure 4 and limiting the analysis as described previously revealed a concordance of 0.54 between echocardiography and CMR (24 patients measured; 5 patients severe by both tests, 8 patients not severe) (1). Our data had a concordance of 0.81 (27 patients; 10 patients severe by both tests, 12 patients not severe) when restricted to the same data range (2). A management trial would be far more feasible (and important) for 0.54 concordance than 0.81 concordance. However, these are only 2 concordance estimates based on small sample sizes.
The story is further complicated by the current American Society of Echocardiography guidelines on assessing MR severity, which include other factors besides regurgitant volume. As noted in our letter, use of the echo integrated method significantly degraded the agreement between echo and CMR compared with regurgitant volume alone. The American College of Cardiology/American Heart Association Guidelines describe left atrial enlargement, left ventricular enlargement, and pulmonary hypertension in a stepwise progression associated with severity of MR. However, the guidelines may be misleading because there are multiple causes of each of these important cardiovascular characteristics that may be unrelated to the valve disease.
The cardiac imaging field should develop a better approach to triaging patients for mitral valve surgery. Additional data are needed comparing CMR, individual echocardiographic quantitative metrics, and the echo integrated method. Determination of concordance rates between tests in a prospective multicenter study is an important preliminary step before a large clinical trial to manage patients with severe MR using either or both modalities can be designed. Please contact us if you would like to participate in a multicenter clinical study based on these concepts.
Please note: This research was supported by the Intramural Research Program of the National Heart Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services. Dr. Arai has a research agreement with Siemens for magnetic resonance imaging. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Uretsky S.,
- Gillam L.,
- Lang R.,
- et al.
- Sachdev V.,
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- et al.