Incorporating the Venous Excess Ultrasound Score (VExUS Score) Into Contemporary Haemodynamic Risk Assessment in Pulmonary Arterial Hypertension: The INVEXUS-PAH Study

Pulmonary arterial hypertension (PAH) is a progressive disorder characterised by increased pulmonary vascular resistance, right ventricular overload, systemic venous congestion, and high mortality. The ESC/ERS 2022 simplified four-strata model (low, intermediate-low, intermediate-high, high risk) guides treatment decisions using WHO functional class, 6-minute walk distance, and BNP/NT-proBNP levels.

However, biochemical markers may be costly or insufficiently sensitive to early haemodynamic deterioration.

VEXUS (Venous Excess Ultrasound Score), a point-of-care ultrasonographic method assessing hepatic, portal, and renal venous Doppler patterns, has shown promise in representing venous congestion.

This study evaluates whether VEXUS correlates with ESC/ERS risk categories and invasive haemodynamic parameters including right atrial pressure, mean pulmonary arterial pressure, pulmonary vascular resistance, cardiac output, and pulmonary output. The study further aims to explore whether integrating VEXUS into PAH follow-up may strengthen risk assessment.

Inclusion criteria

• Adults aged ≥18 years
• Established diagnosis of WHO Group 1 pulmonary arterial hypertension (PAH)
• Stable outpatient clinical status at the time of VExUS ultrasonography
• Venous Excess Ultrasound Score (VExUS) evaluation performed with adequate ultrasonographic acoustic windows
• Clinically indicated right heart catheterisation (RHC) performed within ±60 days of VExUS assessment
• Availability of ESC/ERS 2022 simplified risk assessment variables (WHO functional class, BNP/NT-proBNP, and 6-minute walk distance)
• Ability to provide written informed consent

Exclusion criteria

• Pulmonary hypertension other than WHO Group 1, including:

• PH due to left heart disease (WHO Group 2)
• PH due to chronic lung disease or hypoxaemia (WHO Group 3)
• Chronic thromboembolic pulmonary hypertension (CTEPH; WHO Group 4)
• Multifactorial PH (WHO Group 5)
• Eisenmenger syndrome
• Complex or unrepaired congenital heart disease
• Suspected pulmonary veno-occlusive disease (PVOD)
• Pulmonary capillary haemangiomatosis (PCH)
• Acute decompensated right heart failure
• Severe renal dysfunction (eGFR <30 mL/min/1.73 m²)
• Severe hepatic impairment (Child-Pugh Class C)
• Congestive hepatopathy
• Active infection
• Pregnancy
• Inability or unwillingness to provide informed consent
• Poor ultrasonographic acoustic window preventing adequate VExUS scoring