Assessment of Pulmonary Pressures by Transthoracic Echocardiographic (TTE) and Invasive Right Heart Catheterization (RHC) in a Real-World Pulmonary Hypertension Population – Does Tricuspid Regurgitation (TR) Severity Make a Meaningful Difference?

Abstract

Background: Non-invasive TTE evaluation of pulmonary hypertension requires accurate assessment of the TR spectral Doppler signal (For estimation of the right ventricular (RV) systolic pressure (RVSP) as a surrogate for pulmonary artery systolic pressure (PASP)) and RV systolic function. However, TR severity may also influence RVSP calculations, where severe TR can result in an underestimation due to rapid RV-right atrial pressure (RAP) equalisation, and unreliable determinations of RAP by the conventional TTE approach. Purpose: To characterise the impact of TR severity on TTE assessment of RVSP in comparison to RHC measurements. Methods: Patients undergoing TTE and RHC for assessment of pulmonary hypertension were included. Calculated RVSP (4 × TRvelocity2 + RAP), TTE indices of RV systolic function, and RHC haemodynamic data were retrospectively recorded from patients with varying TR severity. Results: 102 patients were included (66 ± 14 years; 60% Female; Mean pulmonary artery pressure 38 ± 13 mmHg). There was moderate overall correlation between TTE-RVSP and RHC-PASP (r = 0.76, p < 0.001) which remained preserved across the varying grades of TR (Mild: r = 0.65, p < 0.001; Moderate: r = 0.85, p < 0.001; Severe: r = 0.75, p < 0.001). There was a significant association between TTE- and RHC-derived RAP in the mild TR group. This was not seen in the groups with moderate or severe TR (mild p = 0.006, moderate p = 0.398 and severe p = 0.780). Conclusion: TTE-RVSP appears to have reasonable correlation with RHC-PASP independent of TR severity. TTE-RAP remains the “Achilles heel” in the overall equation where significant TR can result in false estimations of the RAP and misleading fluctuations in RVSP values.