... a prospective multicenter trial. J Am Coll Car- ... Reson Imaging 2013;37:1213-22. 5. Vincenti G, Masci PG, Rutz T, De Blois J, Prša M, Jeanrenaud X, et al.
LETTER TO THE EDITOR Is Cardiac Magnetic Resonance Imaging the New ‘‘Gold Standard’’ for Quantitation of Mitral Regurgitation? A Critical Appraisal To the Editor: In a recent issue of JASE, Uretsky et al.1 sought to assess the recommended echocardiographic parameters used in the integrated approach against mitral regurgitant volume by cardiovascular magnetic resonance imaging (CMR) as a reference modality. They developed and validated a weighting for each echocardiographic measure of primary mitral regurgitation (MR) severity. Previously, the same group2 reported that left ventricular reverse remodeling after mitral valve surgery was correlated with MR severity as assessed by CMR, but not by echocardiography. This finding suggested that CMR is a more accurate method than echocardiography to assess MR severity. However, this is based on only 26 patients with pre- and postoperative CMR scans. There is evidence supporting the conclusion that CMR is more reproducible than echocardiography regarding calculation of regurgitant volume.2 Nevertheless, it remains questionable whether patient management should depend on a single parameter, as there is no established ‘‘gold standard’’ to define severe MR by cardiac imaging.3 Several technical pitfalls limit the use of CMR as an ideal reference standard. Both arrhythmia and poor breath holding might compromise left ventricular volume quantification. In addition, although there might be a very good interobserver agreement for CMR in a study core laboratory, the difference of stroke volume measurement by CMR might be > 20 mL between readers depending on the method of left ventricular volume quantification in real-world settings (inclusion or exclusion of papillary muscles, selection of basal slice, correction for prolapsing volume in Barlow’s disease).4,5 This may have a significant effect on the calculation of regurgitant volume and of grading MR severity for individual patients. At present, there are not yet outcome data from randomized controlled trials comparing patient management on the basis of either CMR or echocardiography. We would like to address several other issues regarding the evidence favoring the implementation of CMR in routine clinical practice to guide patient management. In the present multicenter study, 112 patients were collected over a period of 7 years, an average of only 16 patients per year, raising the question of potential bias of selection and the feasibility of CMR in this setting. It is well known that patients with the same effective regurgitant orifice areas and different regurgitant volumes may have different degrees of MR severity (holosystolic vs mid to late systolic jets). The echocardiographic quantitative approach has some wellknown limitations, such as multiple and/or eccentric jets and/or nonholosystolic jets. Excluding these types of MR would lead to better agreement, as shown in a recent study by Penicka et al.6 In that study, a cutoff of regurgitant volume of >50 mL yielded a better area under
the curve to predict outcomes than a cutoff of >60 mL, which was validated for echocardiographic grading and which was used in the present study. Therefore, in the absence of a well-established cutoff to define severe MR by CMR and convincing evidence that patient outcomes are improved by routine implementation of CMR, this technique should be recommended only when an indication for intervention is being pursued and when echocardiographic images or data are limited or confusing.
Caroline M. Van De Heyning, MD, PhD Department of Cardiology Antwerp University Hospital Edegem, Belgium Julien Magne, PhD Department of Cardiology CHU Limoges Limoges, France Bernard Cosyns, MD, PhD, FESC Department of Cardiology Universitair Ziekenhuis Brussel Brussels, Belgium REFERENCES 1. Uretsky S, Argulian E, Supariwala A, Marcoff L, Koulogiannis K, Aldaia L, et al. A comparative assessment of echocardiographic parameters for determining primary mitral regurgitation severity using magnetic resonance imaging as a reference standard. J Am Soc Echocardiogr 2018;31: 992-9. 2. Uretsky S, Gillam L, Lang R, Chaudhry FA, Argulian E, Supariwala A, et al. Discordance between echocardiography and MRI in the assessment of mitral regurgitation severity: a prospective multicenter trial. J Am Coll Cardiol 2015;65:1078-88. 3. Hung J, Zeng X, Little SH. Quantifying mitral regurgitation: how much should we lean on PISA? J Am Soc Echocardiogr 2018;31:1000-1. 4. Miller CA, Jordan P, Borg A, Argyle R, Clark D, Pearce K, et al. Quantification of left ventricular indices from SSFP cine imaging: impact of real-world variability in analysis methodology and utility of geometric modeling. J Magn Reson Imaging 2013;37:1213-22. 5. Vincenti G, Masci PG, Rutz T, De Blois J, Prsa M, Jeanrenaud X, et al. Impact of bileaflet mitral valve prolapse on quantification of mitral regurgitation with cardiac magnetic resonance: a single-center study. J Cardiovasc Magn Reson 2017;19:56. 6. Penicka M, Vecera J, Mirica DC, Kotrc M, Kockova R, Van Camp G. Prognostic implications of magnetic resonance-derived quantification in asymptomatic patients with organic mitral regurgitation: comparison with Doppler echocardiography-derived integrative approach. Circulation 2018;137:1349-60. https://doi.org/10.1016/j.echo.2018.08.014
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