Pulmonary artery effective elastance in patients with tricuspid valve regurgitation: a simple effective echo marker for risk stratification
Authors: Kane C , Anand V , Padang R , Naser J A , Lara-Breitinger K M , Bird J G , Thaden J J , Nkomo V T , Kane G C , Pislaru C , Scott C G , Pislaru S V 
Published: January 2025

Abstract

Background/Introduction
Tricuspid valve regurgitation (TR) is a common valvular disease associated with increased mortality. There is a need for tools to assess the interaction between the pulmonary artery (PA) circulation and the right ventricle (RV) in patients with TR and to investigate their association with outcomes. Various echo parameters have emerged that assess RV-PA coupling, including the ratio of TAPSE to RV systolic pressure (RVSP) and the PA pulsatility index (PAPi). The effective PA elastance (PA Ea) is a composite measure of RV afterload that refers to the measure of the pulmonary vascular load that the RV must overcome to eject blood into the PA. PA Ea is simple to estimate by echo and found to be an independent haemodynamic risk measure in various left heart and pulmonary hypertension (PH) diseases. Whether PA Ea discriminates risk in unselected patients with significant TR and how it compares to other measures of RV-PA coupling is untested.

Purpose
To ascertain the prognostic value of PA Ea in patients with TR.

Methods
In consecutive patients with a first diagnosis of ≥ moderate TR (regardless of aetiology), we compared all-cause mortality at five years based on the PA Ea (defined as the RVSP/stroke volume as measured by transthoracic echocardiography). As stroke volume was measured by Doppler at the left ventricular (LV) outflow tract, patients with &gt; moderate aortic valve regurgitation were excluded. The Tricuspid Regurgitation Impact on Outcomes (TRIO) score was calculated as previously described. PA Ea was separated into 4 groups for comparison based on the separation of quartiles of PA Ea rounded to one decimal place.

Results
In the 13,608 patients studied, PA Ea could be calculated in 12,682 patients (94.4%). The median PA Ea was 0.68 mmHg/mL (IQR 0.50, 0.92). Increasing levels of PA Ea were associated with clinical comorbidities including heart failure, liver and kidney disease and clinical markers of risk such as the TRIO score. Increasing levels of PA Ea were also associated with larger RVs, worse RV systolic function, higher NT-pro BNP levels, and greater degrees of right heart failure (Table). Each quartile of PA Ea was associated with a significant increase in all-cause mortality (Figure). After adjusting for age and sex, PA Ea was associated with higher risk of death (HR 2.41 (2.28-2.56); p&lt;.0001). While worsening degrees of PA Ea correlated with both declining levels of TAPSE/PASP and PAPi (Table), PA Ea was independently predictive of outcome in a combined model: PA Ea HR 1.65 (1.51-1.80, Chi-squ 120, p&lt;.0001); PAPi HR 0.84 (0.80-0.89, Chi-squ 48, p&lt;.0001) and TAPSE/PASP HR 0.32 (017-0.60, Chi-squ 12, p=.0004).

Conclusion(s)
In patients with significant TR, PA Ea is highly feasible and higher PA Ea is progressively associated with RV dysfunction, right heart failure, and worse survival. Incorporating PA Ea into the routine echo assessment may help stratify disease severity in patients with significant TR.
Table
Assoc. of PA Ea with mortality in TR