# Proximal pulmonary artery wall shear stress derived from computational fluid dynamics: A noninvasive biomarker for CTEPH and perfusion mismatch

## TL;DR

This study explores using computational fluid dynamics to detect a lung disease called CTEPH through noninvasive measurements of blood flow stress in arteries.

## Contribution

The study introduces proximal pulmonary artery wall shear stress as a novel noninvasive biomarker for CTEPH and perfusion mismatch.

## Key findings

- TAWSS was significantly reduced in CTEPH and CTEPD groups compared to controls.
- TAWSS strongly correlates with perfusion mismatch status and accurately predicts it with high specificity.
- CFD-derived TAWSS shows promise as a noninvasive indicator of chronic thromboembolic burden.

## Abstract

Chronic thromboembolic pulmonary hypertension (CTEPH) is a severe complication of pulmonary embolism (PE), often diagnosed late due to nonspecific symptoms and limitations of current screening tools like V/Q scintigraphy. This study investigated whether computational fluid dynamics (CFD)‐derived hemodynamic parameters, specifically time‐averaged wall shear stress (TAWSS) and oscillatory shear index (OSI), in the proximal pulmonary arteries could serve as noninvasive biomarkers for CTEPH and chronic thromboembolic disease without pulmonary hypertension (CTEPD, non‐CTEPH with V/Q mismatches). We retrospectively analyzed 90 patients (30 CTEPH, 30 CTEPD, and 30 controls without mismatch) using patient‐specific 3D CFD models reconstructed from CTPA, with RCR boundary conditions tuned to RHC data. We found significantly reduced median TAWSS in CTEPH (16.5 dyn/cm2) and CTEPD (27.5 dyn/cm2) groups compared to controls (42.0 dyn/cm2) (p < 0.001), with TAWSS also significantly lower in CTEPH versus CTEPD. OSI showed no significant inter‐group differences. Importantly, TAWSS exhibited a strong inverse correlation with V/Q mismatch status (ρ = −0.673, p < 0.001). ROC analysis revealed that TAWSS accurately predicted perfusion mismatches (AUC = 0.918), with an optimal cutoff of 27.0 dyn/cm2 yielding 100.0% specificity and 70.0% sensitivity. These findings demonstrate that CFD‐derived proximal pulmonary artery TAWSS is a promising noninvasive indicator of chronic thromboembolic burden, including subclinical perfusion abnormalities, offering a potential tool to enhance early detection and management of CTEPH.