How is aortic regurgitation assessed according to American Society of Echocardiography (ASE) guidelines?

From the Guidelines

Aortic regurgitation is assessed through a comprehensive echocardiographic evaluation that integrates multiple parameters, including visualization of the aortic valve morphology, color Doppler imaging, and quantitative measurements such as vena contracta width, regurgitant volume, regurgitant fraction, and effective regurgitant orifice area, as recommended by the most recent guidelines 1. The assessment begins with visualization of the aortic valve morphology and identification of the mechanism of regurgitation. Color Doppler imaging is used to detect and semi-quantitatively grade the regurgitant jet, evaluating its width relative to the left ventricular outflow tract and the extent of the jet in the left ventricle. Key echocardiographic parameters supporting severe AR include:

• Vena contracta >0.6 cm
• Effective regurgitant orifice area (EROA) ≥0.3 cm2
• Regurgitant volume ≥60 mL/beat
• Holodiastolic flow reversal in the descending aorta
• Evidence of LV dilatation (left ventricular end systolic diameter (LVESD) >50 mm or >25 mm/m2) 1. Additional supportive findings include increased left ventricular size, and a pressure half-time <200 ms in severe cases. The guidelines recommend an integrated approach rather than relying on any single parameter, as each measurement has technical limitations. This comprehensive assessment is crucial for clinical decision-making regarding timing of intervention, particularly in asymptomatic patients where accurate quantification guides surgical referral. Some guidelines also mention Doppler jet width ≥65% of left ventricular outflow tract (LVOT) diameter, and regurgitant fraction ≥50% as supportive of severe AR 2.

From the Research

Assessment of Aortic Regurgitation

According to the American Society of Echocardiography (ASE) guidelines, aortic regurgitation (AR) is assessed using various echocardiographic parameters. The following are the key points to consider:

• The ASE guidelines recommend grading AR severity based on parameters such as vena contracta width, jet width, and left ventricular (LV) end-diastolic volume index 3.
• A study found that the ASE guidelines display very good performance in identifying significant AR, with an area under the curve (AUC) of 0.9 for detection of severe AR by cardiac magnetic resonance (CMR) 3.
• The guidelines suggest that a simplified approach using vena contracta width and LV volumes can be used to reliably identify significant AR, with a positive predictive value of 95.5% and a negative predictive value of 87.5% for identifying ≥ moderate to severe AR by CMR 3.
• Other studies have also emphasized the importance of echocardiography in the diagnosis and assessment of AR, including the use of transthoracic echocardiography and CMR 4, 5, 6.

Echocardiographic Parameters

The following echocardiographic parameters are used to assess AR severity:

• Vena contracta width: a width of ≥ 0.5 cm is associated with significant AR 3.
• Jet width: a wider jet is associated with more severe AR 3.
• LV end-diastolic volume index: an indexed volume of ≥ 82 mL/m2 is associated with significant AR 3.
• Regurgitant volume (RegV): quantitation of RegV can be performed using pulsed Doppler at the mitral annulus and right ventricular outflow compared with left ventricular outflow, and with proximal isovelocity surface area 3.

Clinical Implications

The assessment of AR severity has important clinical implications, including:

• Identification of patients who require surgical intervention 4, 5.
• Monitoring of disease progression and response to treatment 4, 5.
• Risk stratification and prediction of outcomes 6.