Right ventricular stroke work index from echocardiography in patients with pulmonary arterial hypertension, the role in follow-up assessment
Authors: Jumatate R , Werther-Evaldsson A , Ingvarsson A , Radegran G , Cronstedt Meurling C , Ostenfeld E 
Published: January 2025

Abstract

Background
Right ventricular (RV) failure cause high mortality in patients with pulmonary arterial hypertension (PAH) (1,2,3,4). RV stroke work index (RVSWI) poses as a possible invasive determinant of outcome. Non-invasively measured RVSWI could be argued useful (5, 6, 7, 8, 9). Echocardiography-derived RVSWI (RVSWIECHO) encompassing either systolic (sPAP) or mean pulmonary arterial pressure (mPAP) is associated with invasive RVSWI (RVSWIRHC). The aim of this study is to evaluate how RVSWI by echocardiography or right heart catheterization (RHC) is altered following PAH-treatment and if RVSWI at baseline is an indicator of outcome in PAH.

Methods
Fifty-four consecutive patients with PAH (65 ± 13 years, 36 women) analyzed at baseline and at first follow-up visit (141 ± 79 days) were included in the study. Echocardiography and RHC were performed within a median of 0 day [IQR 0-1 days]. PAH-treatment was initiated after baseline examinations. RVSWIRHC was computed as (mPAP-mRAP)xSVIRHC (mRAP: mean right atrial pressure; SVI stroke volume indexed to body surface area). From echocardiography, tricuspid regurgitant (TR) maximum velocity and mean pressure gradient (PG) and SVI were assessed. RVSWIECHO was computed as RVSWIECHO-Max=TRmaxPGxSVIECHO and RVSWIECHO-Mean=TRmeanPGxSVIECHO.

Results
Invasive sPAP, mPAP and pulmonary vascular resistance (PVR) decreased from baseline to follow-up (sPAP: 76±18 vs 65±20 mmHg; mPAP: 47±11 vs 39±12 mmHg; PVR: 10.3 ±5 to 6.5±3.3 WU; p&lt; 0.01 for all), and SVI increased (29±8 vs 37±10 ml/m2, p&lt;0.01). RVSWIRHC and RVSWIECHOMax-Mean did not differ from baseline to follow-up (RVSWIRHC: 1132±352 vs 1208±467 mmHg*mL*m-2 (p=0.1); RVSWIECHO-Max: 1904±568 vs 1967±727 mmHg*mL*m-2 (p=0.5); RVSWIECHO-Mean: 1090±306 vs 1192±482 mmHg*mL*m-2 (p=0.1)). At long-term follow-up, 40 patients had died. None of the echocardiographic or invasive measures at baseline (including RVSWI) differed between survivors and non-survivors. In univariate Cox proportional hazard analysis, none of the RVSWI methods were associated with long-term mortality. However, age&gt;65 years, six minutes’ walk distance test (6 MWT) &lt;160 m, WHO class III-IV and indexed right atrium volume were associated. Adding these parameters as input in a model of multivariate analysis showed that echocardiography derived RVSWI (RVSWIECHO-Max (HR =1.001; CI 1-1.001; p=0.016); RVSWIECHO-Mean (HR =1.001; CI 1-1.002; p=0.006)) were independently associated with mortality.

Conclusion
None of the RVSWI methods differed from baseline to follow-up in patients with PAH, despite substantial improvement in conventional hemodynamic parameters. The baseline RVSWI methods were not associated with long-term mortality in univariate analysis. However, when adjusting for clinical variables in a multivariate analysis a significant association between echocardiography-derived RVSWI and mortality could be detected.