Cardiac MRI reclassified 38% of moderate AR and 50% of moderate-to-severe AR patients as having significant AR, guiding surgical decisions beyond echocardiography.
Does cardiac MRI improve the severity assessment and clinical decision-making for aortic regurgitation compared to transthoracic echocardiography?
Cardiac MRI provides significant incremental value over TTE in evaluating aortic regurgitation, frequently reclassifying severity and guiding surgical decision-making in borderline cases.
Abstract Introduction Transthoracic echocardiography (TTE) is the primary imaging modality for evaluating aortic regurgitation (AR) and plays a central role in surgical decision-making. However, TTE has limitations in assessing AR severity, particularly in cases with eccentric regurgitant jets or borderline findings. Cardiac MRI (cMRI) has emerged as a complementary tool, providing precise volumetric and functional data. This study aims to validate the role of cMRI in refining AR severity. Methods This retrospective, single-center study included patients with AR who underwent cMRI between 2019-2024. Patients with a time gap 6 months between TTE and cMRIwereexcluded.ARseverityonTTEwasgradedusingthePISAmethod,alongwithvenacontracta,jetwidth,andholodiastolicflowreversalwhenapplicable. On cMRI (1.5T), phase-contrast velocity-encoded sequences quantified aortic regurgitant volume and regurgitant fraction (RF), with significant AR defined as RF ≥ 35%assuggestedbyseveralpapers. Results A total of 177 patients (mean age 65 years, 67% male) were analyzed. Mean left ventricular ejection fraction (LVEF) by cMRI was 49±15%. Left ventricular (LV) volumes were consistently underestimated by TTE compared to cMRI (dilated LV in 45.2% vs. 59.3%, median LVEDVi: 81 mL/m2 IQR 63–98 vs. 110 mL/m2 IQR 87–139). Median regurgitant volume and RF on cMRI were 18 mL (IQR 7–37) and 22% (IQR 10–36). Figure 1a shows AR severity reclassification achieved with cMRI. Among 63 patients with moderate AR on TTE, cMRI reclassified 24 (38.1%) as significant AR. Of 12 moderate-to-severe AR cases, 6 (50%) were reclassified as significant AR. All 13 severe AR cases identified by TTE were confirmed by cMRI. The agreement between TTE and cMRI in identifying severe aortic regurgitation was poor (Cohen’s Kappa = 0.11; p0.001). In patients with LV dilation or dysfunction but no significant AR (n = 78), cMRI provided alternative diagnoses in 47 cases (60%): ischemic late-gadolinium enhancement (LGE) in 19, non-ischemic LGE in 22, and both in 6 patients. During follow-up, 22 patients underwent surgery for isolated AR (Figure 1b). Only 12 met guideline-recommended criteria for intervention (8 Class I, 2 Class Ib, 2 Class IIa/IIb). Cardiac MRI findings guided the surgical decision-making in the remaining 10 patients. Conclusion Cardiac MRI provides significant incremental value in evaluating aortic regurgitation, particularly in borderline and complex cases. While TTE remains the cornerstone imaging modality, cMRI can refine AR severity assessment and guide clinical decision-making, optimizing patient management.
AZEVÊDO et al. (2025) studied this question. Cardiac MRI reclassified 38% of moderate AR and 50% of moderate-to-severe AR patients as having significant AR, guiding surgical decisions beyond echocardiography.