Quantitative approaches to tricuspid valve regurgitation severity: identifying the most reliable method

Abstract Introduction Assessment of tricuspid regurgitation (TR) severity remains challenging due to the lack of a defined gold standard instrument and the limitations of using left-sided valve parameters. The proximal isovelocity surface area (PISA) method often underestimates the regurgitant orifice area (ROA) due to the complex, non-hemispheric shape of the tricuspid regurgitant orifice. ROA depends on peak tricuspid regurgitant velocity (TRV), which fluctuates with haemodynamic conditions, potentially affecting TR severity assessment. Vena contracta (VC) may improve accuracy, as it better reflects orifice geometry and is not influenced by TRV or ventricular compliance. Although VC width is strongly correlated with ROA, we hypothesize that extreme TRV values weaken this correlation, compromising ROA reliability. Purpose We aimed to analyze the influence of TRV on ROA calculation using PISA by comparing ROA with VC across different TRV values. We assessed whether TRV affects the reliability of ROA in grading TR severity in patients with severe, massive and torrential TR. Methods This prospective, multicenter, observational study enrolled consecutive patients diagnosed with severe TR via transthoracic echocardiography over 12 months in two Spanish centers. Baseline clinical and echocardiographic characteristics, including TRV, PISA radius, ROA and regurgitant volume, were recorded. Echocardiographic measurements were analyzed by a single operator following European guidelines. VC width, measured from a single 2D apical 4-chamber view, was used as the reference standard for TR grading: severe (≥7mm), massive (≥14mm), and torrential (≥21mm). Results A total of 130 consecutive patients (93 females, mean age 76.6 ± 9.4 years) were included; 87 (66.9%) had severe TR, 36 (27.7%) massive TR, and 7 (5.4%) torrential TR. The leading cause of TR was secondary to left heart failure (41.5%), mainly due to mitral regurgitation (18.5%). Basal characteristics are presented in Table 1. Spearman analysis showed a moderate positive correlation between VC and ROA (ρ = 0.57, p 0.001), which was weaker than the correlation between VC and the PISA radius (ρ = 0.64, p 0.001) (Figure 1A). TRV was stratified into four groups based on percentiles (p25, p50 and p75). The VC-ROA correlation remained stable in the first three groups (p 0.001) but significantly declined in the highest TRV group (p = 0.14), corresponding to TRV ≥ 3.28 m/s (Figure 1B). The PISA radius exhibits a stronger and more stable correlation with VC across all TRV levels (p 0.001), preserving accuracy in severe TR cases (Figure 1A). Conclusions The VC-ROA correlation weakens at TRV ≥ 3.28 m/s, suggesting that ROA becomes less reliable for assessing TR severity at high TRV values. Low TRV values show high VC and ROA values without compromising their correlation. The PISA radius exhibits a stronger and more stable correlation with VC across all TRV levels, preserving accuracy in severe TR cases.Table 1.Baseline characteristics Figure 1.Outcomes