Assessment of Functional Mitral Regurgitation Severity by Proximal Isovelocity Surface Area via 3D Transthoracic Echocardiography

Background: Accurate quantitative evaluation of MR severity remains challenging because limited scan plane orientation of 2D echocardiography does not provide direct measurement of the regurgitant lesion. Three-dimensional echocardiography, which has become a clinically established technique, has been shown to provide useful information for flow quantification and so has the potential to address the major drawbacks of 2D-based approaches.

Objectives: To assess the reliability of PISA measurement using real-time 3D color trans-thoracic echocardiographic imaging in clinical practice and to compare its derived EROA, regurgitant volume (Rvol) and regurgitant fraction with that obtained by 2D trans thoracic PISA.

Patients and Methods: This cross-sectional study, included 30 patients with at least moderate functional MR came for evaluation on clinical basis indications at Al-Hussein and Bab El-Shaareya University Hospitals during the period from November 2020 to July 2021. Two- and three-dimensional echocardiography was done to asses MR and calculate vena contract width, 2D PISA and derived EORA and regurgitant volume. Also, calculation of 3D EROA using PISA method by 3D probe.

Results: There was a significant positive correlation between 2D EPISA and 3D EROA using PISA method and EROA, p value was 0.0001. With higher values for 3D EROA using PISA method when compared with 2D PISA in different degrees of MR as summarized in “the mean value of EROA by 2D PISA in moderate MR was 0.25 ±0.042 cm2, while it was 0.32±0.059 cm2 by 3D EROA using PISA method. While the mean value of EROA by 2D PISA in severe MR was 0.58 ±0.14 cm2, and it was 0.47 ±0.049 cm2 by 3D EROA”. Also showed significant difference in different direction of MR jets especially in eccentric jet as shown by the mean value of EROA by 2D PISA in central MR was 0.41±0.19 cm2, while it was 0.41±0.87 cm2 by 3D method. While the mean value of EROA by 2D PISA in eccentric MR was 0.53 ±0.21 cm2, and it was 0.44 ±0.096 cm2 by 3D EROA using PISA method.

Conclusion: The use of 3D EROA using PISA method and simple calculation of a mean systolic regurgitation orifice area proved to be superior to 2D measures (VC, 2D-PISA) for distinguishing moderate from severe MR, evaluation, classification and grading of MR in a routine clinical cardiology setting. 3D EROA reduces assumptions and seemingly improves diagnostic value as compared with 2D-PISA.