From the Guidelines
Yes, cardiac magnetic resonance imaging (CMR) is excellent for quantifying aortic regurgitation (AR). CMR provides highly accurate and reproducible measurements of regurgitant volume and fraction through phase-contrast velocity mapping and volumetric analysis, as supported by the most recent study 1. It can directly measure forward and backward flow across the aortic valve, allowing precise calculation of regurgitant volume and regurgitant fraction. CMR also evaluates left ventricular size, function, and remodeling in response to AR, which helps determine the optimal timing for intervention. The technique is particularly valuable in cases where echocardiography yields suboptimal or equivocal results.
Key Benefits of CMR for AR Quantification
- Highly accurate and reproducible measurements of regurgitant volume and fraction
- Direct measurement of forward and backward flow across the aortic valve
- Evaluation of left ventricular size, function, and remodeling in response to AR
- Comprehensive assessment without geometric assumptions, making it superior to other imaging modalities for AR quantification
Clinical Application
For patients undergoing CMR for AR assessment, no special preparation is typically needed beyond standard MRI safety screening, though the procedure takes approximately 45-60 minutes and requires breath-holding during certain sequences. CMR's accuracy stems from its ability to directly measure flow rather than relying on indirect parameters or geometric assumptions, as highlighted in the study 1. This is in line with the findings of other recent studies, including 1 and 1, which also support the use of CMR for quantifying AR. However, the most recent and highest quality study 1 is given priority in making this recommendation.
From the Research
Quantification of Aortic Regurgitation using Cardiovascular Magnetic Resonance
- Cardiovascular magnetic resonance (CMR) can accurately quantify aortic regurgitation (AR) and is associated with the future need for surgery 2.
- CMR-derived left ventricular end-diastolic volume and regurgitant fraction have good discriminatory ability in identifying patients who will progress to surgery 2.
- High degrees of CMR-quantified AR are associated with the development of symptoms or other indications for surgery 2.
Comparison with Transthoracic Echocardiography
- The concordance between CMR and transthoracic echocardiography (TTE) in quantifying AR is weak, with CMR re-grading some patients with severe AR by TTE into moderate AR 3.
- CMR provides more prognostic relevant information than TTE in assessing AR severity and left ventricular remodeling 4.
- The correlation of post-surgical left ventricular remodeling with CMR AR grade and AR volumes is stronger than with TTE 4.
Diagnostic and Prognostic Utility of CMR
- CMR has the potential to add important diagnostic and prognostic information in chronic AR, with holodiastolic retrograde flow (HRF) on CMR being significantly associated with outcome 5.
- CMR provides a comprehensive assessment of AR severity and left ventricular remodeling, with a weak or moderate agreement with TTE 6.
- The association of AR volume and left ventricular end-diastolic volume is stronger in CMR than in TTE 6.