By Michael H. Crawford, MD, Editor
Synopsis: A small study of echocardiography compared to cardiac magnetic resonance (CMR) imaging in patients with chronic aortic regurgitation of variable severity has shown that the simple use of the color Doppler regurgitant jet vena contracta width and the end-diastolic left ventricular volume index by two-dimensional echocardiographic imaging can accurately predict who has clinically significant regurgitation.
Source: Attar R, Malahfji M, Angulo C, et al. Echocardiographic evaluation of chronic aortic regurgitation: Comparison with cardiac magnetic resonance and implications for guideline recommendations. JACC Cardiovasc Imaging. 2025;18(4):403-417.
Echocardiography is the go-to method for assessing the etiology and severity of aortic regurgitation (AR). However, its accuracy compared to cardiac magnetic resonance (CMR) imaging has not been evaluated systematically across the full range of AR severity. Thus, these investigators from Houston and Jeddah, Saudi Arabia, sought to assess the accuracy of echocardiography compared to CMR for quantitating AR at all levels of severity, and the ability of echocardiography to identify hemodynamically significant AR.
Between 2018 and 2022, patients referred for CMR evaluation of AR underwent echocardiography and CMR within four hours of each other. Excluded were patients with prosthetic valves, more than mild aortic stenosis or other valve disease, acute AR, those with congenital heart disease except for bicuspid aortic valve (BAV), and those in atrial fibrillation/flutter. The resulting 81 patientsʼ (median age 52 years, 74% men, 58% BAV, 90% ejection fraction > 50%) echocardiograms were analyzed blinded to the CMR results.
The following measurements were made by echocardiography (on the Doppler studies): vena contracta width (VCW), jet height over left ventricular (LV) outflow tract diameter ratio (jet/LVOT%), pressure half-time (PHT), proximal isovelocity surface area (PISA), and descending or abdominal aorta diastolic reversal velocity, flow, and ratio to forward flow (measured at mitral valve annulus [MA] or right ventricular [RV] outflow tract [RVOT]). Also, LV volumes and dimensions, and regurgitant volumes (LV stroke volume minus MA or RV stroke volume) were calculated on echocardiography and CMR.
Using the American Society of Echocardiography (ASE) criteria, 43% of patients had mild AR, 22% of patients had moderate AR, 15% of patients had moderate to severe AR, and 20% of patients had severe AR.1 These severity designations largely were concordant with CMR (64%) and rarely varied by more than one grade (< 4%). LV volumes correlated well between the two imaging modalities: end-diastolic volume index (EDVi, r = 0.92), end-systolic volume index (ESVi, r = 0.94), and ejection fraction (EF, r = 0.76).
Regurgitant volume (RVol) was measurable in 99% of echocardiograms using the MA for the forward flow and in 89% when the RVOT was used; PISA estimation of RVol was feasible in only 37%. Doppler jet characteristics were available in 78%; the remainder had eccentric jets.
The accuracy of the severity of AR estimate by echocardiography compared to CMR was best for VCW, jet width/LVOT%, and EDVi, and lowest for PHT. The clinically relevant classification of moderate to severe or severe AR based on a VCW > 0.5 cm and EDVi ≥ 82 mL/m had a positive predictive value of 96%, a negative predictive value of 88%, and an area under the curve of 0.89.
Holo-diastolic flow reversal in the abdominal aorta was 100% specific but only 61% sensitive for moderate or more AR. The authors concluded that a simplified echocardiography approach to estimating the severity of chronic AR using the VCW and EDVi is reliable for identifying clinically significant AR.
Commentary
Previous studies comparing echocardiography to CMR in patients with AR have only studied those with more severe AR because those are the patients usually referred for this more expensive test. The Attar et al study evaluated patients across the whole spectrum of AR severity. The authors found that two echocardiography measures were highly accurate at detecting clinically significant AR, and this accuracy was not improved by adding more measurements.
One of the measures was the VCW, which makes sense because this approximates the size of the hole permitting regurgitation. The other was the EDVi, which also makes sense because LV enlargement is the main cardiac feature of chronic AR. The bonus of these findings is that this approach is simple to do. The ASE guidelines recommend four key parameters be assessed to separate mild from severe AR: VCW, jet/LVOT%, PHT, and EDVi.1 If these do not provide a clear answer, then RVol, RF, and effective regurgitant orifice area are measured. This is much more complicated.
There are limitations to the Attar et al study. There is a selection bias toward those referred to CMR. However, this may have been because these patients were more challenging, which could be a strength. Also, there was a high percentage of relatively young men with BAV and eccentric jets. Of course, this is a more difficult group to quantitate AR, and, again, may be a strength of the study. The group with moderate to severe AR was small. No three-dimensional echocardiography imaging was used, nor was contrast used, both of which could have improved the EDVi results. Finally, there was no clinical information on symptoms or outcomes.
In summary, this study has shown that two simple and easily obtained measures by echocardiography can separate out the patients with clinically significant chronic AR by CMR who should be considered for an intervention to eliminate the leak. One hopes, in the near future, this will be a percutaneous method.
Michael H. Crawford, MD, is Professor Emeritus of Medicine and Consulting Cardiologist, UCSF Health, San Francisco.
Reference
1. Zoghbi WA, Adams D, Bonow RO, et al. Recommendations for noninvasive evaluation of native valvular regurgitation: A report from the American Society of Echocardiography developed in collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr. 2017;30(4):303-371.
A small study of echocardiography compared to cardiac magnetic resonance (CMR) imaging in patients with chronic aortic regurgitation of variable severity has shown that the simple use of the color Doppler regurgitant jet vena contracta width and the end-diastolic left ventricular volume index by two-dimensional echocardiographic imaging can accurately predict who has clinically significant regurgitation.
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