Comparison of the ASE Algorithm to CMR in Mitral Regurgitation
- In patients with degenerative MR, there was suboptimal agreement between the severity of MR as judged by CMR and the 2017 American Society of Echocardiography (ASE) algorithm.
- 52% of patients with ‘definitely severe’ MR by ASE algorithm had severe MR by CMR regurgitant volume vs. 38% with moderate and 10% with mild MR volume by CMR.
- Severe MR by CMR was an independent predictor of LV reverse remodeling after mitral valve intervention, whereas ‘definitely severe’ MR, the highest grade of MR severity according to the ASE algorithm, was not.
How does the American Society of Echocardiography (ASE) algorithm for grading the severity of mitral regurgitation (MR) compare to cardiac magnetic resonance imaging (CMR)? How well does each predict post-mitral intervention left ventricular (LV) reverse remodeling?
Patients with degenerative MR were enrolled in a prospective multicenter study and underwent both echocardiography and CMR to assess MR severity. Patients were excluded if they had secondary MR, atrial fibrillation, or lacked a full set of echocardiographic or CMR data. Echocardiograms were graded per the ASE guidelines algorithm as ‘definitely mild,’ grade I, grade II, grade III, grade IV, or ‘definitely severe’ MR. As per guidelines, these six categories were also collapsed into mild, moderate, and severe. CMR grading was based on MR volume: mild (<30 ml), grade II moderate (30-44 ml), grade III moderate (45-59 ml), or severe (≥60 ml). A subgroup of 63 patients underwent successful mitral valve intervention (surgery or transcatheter edge-to-edge repair with MitraClip), of whom 48 had CMR 3-5 months post-procedure.
A total of 152 patients were included in the study (age 62 ± 13 years; 59% male). The median time between CMR and echocardiography was 6 days (interquartile range, 0-21 days). There were no significant differences in mean systolic or diastolic blood pressure or heart rate at the time of CMR and echocardiography. Only 52% of patients with ‘definitely severe’ MR by ASE algorithm had severe MR by CMR regurgitant volume versus 38% with moderate and 10% with mild MR volume by CMR. Amongst patients with high grade MR based on the ASE algorithm (grade IV or ‘definitely severe’), those with an eccentric MR jet actually had better agreement with CMR regurgitant volume than those with central MR jets.
In the subgroup undergoing mitral intervention, 68% received a mitral valve repair, 25% had mitral valve replacement, and 7% received a MitraClip. There was no statistically significant relationship between ASE categories of MR severity and post-intervention LV reverse remodeling (p = 0.07). In contrast, LV reverse remodeling increased with worsening MR severity when graded by CMR (p < 0.0001). Moreover, severe MR by CMR was an independent predictor of post-intervention LV reverse remodeling, whereas ‘definitely severe’ MR by ASE algorithm was not.
First, there was suboptimal agreement between the severity of MR, as judged by CMR, and the 2017 ASE algorithm. Second, 52% of patients with ‘definitely severe’ MR by ASE algorithm had severe MR by CMR versus 38% with moderate and 10% with mild MR volume by CMR. Third, severe MR by CMR was an independent predictor of LV reverse remodeling after mitral valve intervention, whereas ‘definitely severe’ MR was not.
This study finds considerable variation between the severity of degenerative MR (myxomatous mitral valve disease with prolapse ultimately progressing to flail leaflet), as judged by the 2017 ASE guidelines vs. CMR-based regurgitant volume. This could be clinically relevant, as the optimal timing of mitral intervention is often difficult to judge. If measurement of MR volume via CMR could help predict benefit in terms of LV reverse remodeling, this could support its role in evaluation of patients prior to intervention.
That said, there are a number of limitations which mandate further investigation. First, the discrepancy between echocardiography and CMR seems greater than one would expect. This may be due to the small study size and/or considerable chance of selection bias, since it is the most questionable cases that would be most likely to be referred for CMR. Indeed, the 2017 ASE guidelines recommend additional imaging (transesophageal echocardiography [TEE] or CMR) in cases where the MR mechanism and/or severity remain unclear after standard echocardiographic evaluation. Along these lines, it is not specifically clarified which modality of echocardiography (transthoracic vs. transesophageal) patients underwent. In daily practice, a substantial proportion of patients are likely to have a TEE prior to intervention and it would be interesting to know the level of agreement between transesophageal imaging (including 3D assessment) and CMR.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Valvular Heart Disease, Cardiac Surgery and VHD, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Mitral Regurgitation
Keywords: Blood Pressure, Cardiac Surgical Procedures, Cardiology Interventions, Diagnostic Imaging, Echocardiography, Echocardiography, Transesophageal, Heart Valve Diseases, Magnetic Resonance Imaging, Mitral Valve Insufficiency
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