Echocardiographic Evaluation of Chronic Aortic Regurgitation: Comparison With Cardiac Magnetic Resonance and Implications for Guideline Recommendations

Abstract

Background: Guidelines for echocardiographic evaluation of aortic regurgitation (AR) have not been validated against an independent quantitative standard.

Objectives: The aim of this study was to evaluate the accuracy of the ASE (American Society of Echocardiography) AR guidelines against cardiac magnetic resonance (CMR) and to develop simplified approaches for detection of significant AR.

Methods: Patients with AR underwent echocardiography and CMR <4 hours apart. AR severity was graded according to ASE guidelines. Quantitation of regurgitant volume (RegV) was performed with pulsed Doppler at the mitral annulus and right ventricular outflow compared with left ventricular (LV) outflow, and with proximal isovelocity surface area.

Results: The authors studied 81 patients; median age was 52 years, and 58% had a bicuspid aortic valve. According to echo, 35 (43%) patients had mild AR, 18 (22%) moderate, 12 (15%) moderate to severe, and 16 (20%) had severe AR. The area under the curve (AUC) for detection of severe AR by CMR using ASE grading was 0.9 (82.4% sensitivity and 96.9% specificity). Feasibility of RegV quantitation was >88% using either echo volumetric method, and it was low for proximal isovelocity surface area (37%). The highest accuracy for echo parameters against CMR was seen with vena contracta width, jet width, and LV end-diastolic volume index (AUC: 0.86-0.89); pressure half-time had the lowest accuracy. Without RegV quantitation, a vena contracta width ≥0.5 cm and indexed LV end-diastolic volume ≥82 mL/m² had 95.5% positive predictive value and 87.5% negative predictive value for identifying ≥moderate to severe AR by CMR (AUC: 0.89).

Conclusions: The ASE guidelines display very good performance in identifying significant AR. A simplified approach using vena contracta width and LV volumes can be used to reliably identify significant AR. Further validation of the findings in larger cohorts and against clinical outcomes is needed.

Keywords: Doppler echocardiography; aortic regurgitation; aortic valve; cardiac magnetic resonance.