Objective To analyze the correlation of regurgitant volume (RVol), effective regurgitant orifice area (EROA), and regurgitant fraction (RF) in tricuspid regurgitation (TR) quantitation, their relation to hemodynamic consequences, and their diagnostic power to determine severe TR.

Methods TR patients who underwent either isolated tricuspid surgery or combined mitral and tricuspid surgery thorough inter-atrial groove approach in Zhongshan Hospital, Fudan University from July 2018 to July 2019 were prospectively included. 2D and right-ventricle-focused 3D transthoracic echocardiography were performed. RVol, EROA, and RF were calculated. TR grades were transcribed from surgical records.

Results Totally, 148 patients were included in the final analysis. EROA and RVol were linearly correlated (r=0.93, P < 0.001) while RF was logarithmically correlated with EROA and RVol (r=0.86, P < 0.001; r=0.86, P < 0.001), with a flattened trend when RF exceeded 50%. EROA and RVol correlated more closely with right ventricular end-diastolic volume index (r=0.74, P < 0.001; r=0.66, P < 0.001) than did RF (r=0.47, P < 0.001). Receiver operator characteristic analysis revealed insignificant difference in area under the curve (AUC) between RVol and EROA (Z=0.885, P=0.376 1), while AUC of RF was significantly lower than either RVol or EROA (Z=2.271, P=0.023 1; Z=2.731, P=0.006 3). Multiple linear regression analysis showed that RF was affected by heart rate, cardiac output, EROA, right ventricular end-diastolic volume index, RVEF, and systolic pulmonary arterial pressure (R²=0.86, P < 0.001).

Conclusions EROA and RVol could more accurately show the severity degree of TR when RF exceeds 50%, and are more closely related to the hemodynamic consequences of TR and have higher diagnostic power for severe TR than RF.