Threshold Values of Vena Contracta Area for Grading Secondary Tricuspid Regurgitation and its Association with Outcomes

Abstract

Background: Three-dimensional echocardiographic planimetry of vena contracta area (VCA), which avoids geometric assumptions about the regurgitant orifice, has emerged as a promising method for grading secondary tricuspid regurgitation (STR). The aims of this study were to (1) define VCA threshold values to grade the severity of STR using a five-grade system, (2) identify the VCA cutoff value associated with adverse clinical outcomes, and (3) assess the incremental prognostic value of VCA compared with conventional quantitative parameters of tricuspid regurgitation severity.

Methods: Three-dimensional echocardiography was used to obtain VCA from 204 outpatients (mean age, 77 ± 12 years; 44% men) with mild to torrential STR (52% with severe or greater STR) according to current guidelines, and its association with a composite outcome of all-cause death and hospitalization for heart failure was assessed.

Results: The VCA threshold values for STR severity were <0.43 cm² for mild, 0.43 to 0.67 cm² for moderate, 0.68 to 0.88 cm² for severe, 0.89 to 1.26 cm² for massive, and >1.26 cm² for torrential STR. Spline curve analysis identified a VCA threshold of 0.65 cm² as the optimal cutoff associated with an increased risk for experiencing the composite end point. Although not yet severe, patients with VCA > 0.65 cm² experienced an exponential increase in their risk. VCA > 0.65 cm² was associated with a threefold risk increase for the composite end point regardless of effective regurgitant orifice area (EROA; log-rank P = .00068). In multivariate analysis, VCA remained independently associated with the composite end point (adjusted hazard ratio, 1.06; 95% CI, 1.02-1.10; P = .004). Adding VCA to baseline models incorporating clinical and echocardiographic variables, including either EROA or regurgitant volume, significantly improved the prognostic performance of the model (P = .007 and P = .018, respectively).

Conclusions: VCA obtained from color Doppler three-dimensional echocardiography is a robust parameter to grade STR severity, showing incremental prognostic value in comparison with both EROA and regurgitant volume.

Keywords: Secondary tricuspid regurgitation; Severity grading; Three-dimensional echocardiography; Threshold values; Vena contracta area.