Femoral venous stasis index infor prediction of elevated right atrial pressure and mortality in pulmonary hypertension

Introduction

Elevated right atrial pressure (RAP) is associated with poor prognosis regarding 1-year mortality in pulmonary hypertension (PH) patients. Unfortunately, there is currently no reliable non-invasive technique for estimating RAP in PH patients. Recently, femoral venous stasis index (FVSI) has been described as highly correlated to RAP in PH patients.

Objective

Our goal was to confirm the diagnostic accuracy of FVSI for estimating RAP, and compare the prognostic value of FVSI, RAP and renal venous stasis index (RVSI) at 2 years in PH patients.

Method

In this prospective cross-sectional study, we included 101 patients with suspected or known PH undergoing right heart catheterization (RHC) for 18 months. Each included patient underwent DUS of the femoral and renal veins within 4 hours prior to the RHC, to blindly assess FVSI and RVSI. FVSI and RVSI (no unit) was calculated as the percentage of non anterograde flow time over an index cardiac cycle, during a short apnea ([Index cardiac cycle(ms) − Anterograde flow time (ms)/Index cardiac cycle(ms)]). For RAP analysis, we chose the cut-off values based on the 2022 ESC/ERS guidelines (RAP < 8 mmHg, 8–14 mmHg and > 14 mmHg).

Results

FVSI was highly correlated to RAP (rs = 0.77, p < 0.001). On multivariate analysis, only FVSI remained significantly associated with RAP (p < 0.001) compared to clinical and biological signs, echocardiography and RVSI. With a cutoff of 0.18, FVSI can exclude a RAP > 8 mmHg with an 87% sensitivity (area under ROC curve (AUROC) = 0.88) and, with a cutoff of 0.45, can confirm a RAP > 14 mmHg with a 93% specificity (AUROC = 0.93). During 2-year follow-up, the composite endpoint (hospitalization; increase in PH-treatment and all-cause death) occurred in 32 patients (31.7%). FVSI independently predicted PH morbidity/mortality (FVSI ≥ 0.45 versus FVSI < 0.18: HR = 5.41 [1.53–19.2], p = 0.009) (Figure 1). Inter-observer reproducibility between junior and senior operators was excellent (intraclass coefficient of 0.97 [IC95% 0.95–0.98]).

Conclusion

We propose FVSI as the first non-invasive tool for estimating RAP, according to the recommended cut-off values, in PH patients.