Right ventricular stroke work index by echocardiography in adult patients with pulmonary arterial hypertension.

Background: In adult patients with pulmonary arterial hypertension (PAH), right ventricular (RV) failure may worsen rapidly, resulting in a poor prognosis. In this population, non-invasive assessment of RV function is challenging. RV stroke work index (RVSWI) measured by right heart catheterization (RHC) represents a promising index for RV function. The aim of the present study was to comprehensively evaluate non-invasive measures to calculate RVSWI derived by echocardiography (RVSWI) using RHC (RVSWI) as a reference in adult PAH patients.

Methods: Retrospectively, 54 consecutive treatment naïve patients with PAH (65 ± 13 years, 36 women) were analyzed. Echocardiography and RHC were performed within a median of 1 day [IQR 0-1 days]. RVSWI was calculated as: (mean pulmonary arterial pressure (mPAP)-mean right atrial pressure (mRAP)) x stroke volume index (SVI). Four methods for RVSWI were evaluated: RVSWI = Tricuspid regurgitant maximum pressure gradient (TR) x SVI, RVSWI = (TR-mRAP) x SVI, RVSWI = TR mean gradient (TR) x SVI and RVSWI = (TR-mRAP) x SVI. Estimation of mRAP was derived from inferior vena cava diameter.

Results: RVSWI was 1132 ± 352 mmHg*mL*m. In comparison with RVSWI in absolute values, RVSWI and RVSWI was significantly higher (p < 0.001), whereas RVSWI was lower (p < 0.001). No difference was shown for RVSWI (p = 0.304). The strongest correlation, with RVSWI, was demonstrated for RVSWI (r = 0.78, p < 0.001) and RVSWI ( r = 0.75, p < 0.001). RVSWI and RVSWI had moderate correlation (r = 0.66 and r = 0.69, p < 0.001 for all). A good agreement (ICC) was demonstrated for RVSWI (ICC = 0.80, 95% CI 0.64-0.88, p < 0.001), a moderate for RVSWI (ICC = 0.73 95% CI 0.27-0.87, p < 0.001) and RVSWI (ICC = 0.55, 95% CI - 0.21-0.83, p < 0.001). A poor ICC was demonstrated for RVSWI (ICC = 0.45, 95% CI - 0.18-0.77, p < 0.001). Agreement of absolute values for RVSWI was - 772 ± 385 (- 50 ± 20%) mmHg*mL*m, RVSWI - 600 ± 339 (-41 ± 20%) mmHg*mL*m, RVSWI 42 ± 286 (5 ± 25%) mmHg*mL*m and for RVSWI 214 ± 273 (23 ± 27%) mmHg*mL*m.

Conclusion: The correlation with RVSWI was moderate to strong for all echocardiographic measures, whereas only RVSWI displayed high concordance of absolute values. The results, however, suggest that RVSWI or RVSWI could be the preferable echocardiographic methods. Prospective studies are warranted to evaluate the clinical utility of such measures in relation to treatment response, risk stratification and prognosis in patients with PAH.