Impact of Tricuspid Regurgitation Severity and Right Ventricular Function on the Correlation and Agreement Between Transthoracic Echocardiography- and Right Heart Catheterization-Derived Systolic Pulmonary Artery Pressure.

Background Accurate estimation of systolic pulmonary artery pressure (SPAP) is essential for evaluating pulmonary hypertension (PH). Transthoracic echocardiography (TTE) provides a noninvasive alternative to right heart catheterization (RHC). This study aimed to assess the correlation and agreement between TTE- and RHC-derived SPAP and to evaluate the influence of tricuspid regurgitation (TR) severity, right ventricular (RV) function, and PH subtype on the reliability of TTE-derived measurements. Methods A retrospective analysis was conducted on patients who underwent TTE and RHC within a seven-day interval. Patient demographics, as well as TTE and RHC parameters, were represented using the median and interquartile range (IQR). Correlation and Bland-Altman analyses were performed, with subgroup evaluations based on RV function, TR severity, and PH subtype (pre-, post-, and combined PH). Regression analysis was used to assess the impact of RV function (measured by tricuspid annular plane systolic excursion (TAPSE)) and TR (assessed by vena contracta (VC)) on the difference between TTE and RHC (ΔSPAP) measurements. Results A total of 112 patients were included. The median SPAP was 47 mmHg by TTE compared to 44.5 mmHg by RHC (p = 0.36). Bland-Altman analysis revealed wide limits of agreement (-27.6 to +30.0 mmHg), with 46% (n = 52) of measurements differing by >10 mmHg. Linear regression analysis did not reveal any significant effects of TAPSE and VC on ΔSPAP (R² = 0.018, p = 0.496). The overall correlation between TTE-SPAP and RHC-SPAP was moderate (ρ = 0.61, p < 0.001). In subgroup analysis, a stronger correlation was observed in preserved RV function (ρ = 0.78 vs. 0.48 in impaired RV function). Moderate correlation was found in both precapillary (ρ = 0.68, p < 0.01) and combined PH (ρ = 0.66, p < 0.001), while postcapillary PH showed nonsignificant correlation (ρ = 0.37, p = 0.197). Conclusion TTE provides a useful noninvasive estimate of SPAP but remains limited in terms of accuracy and consistency in specific clinical settings. The lack of predictive value of RV function and TR severity suggests that other physiological factors underlie the observed discordance with RHC. Therefore, RHC should remain the reference standard for precise assessment of pulmonary artery pressure.