Identification of pulmonary artery stiffening due to left heart disease by ultrasonography

AIMS: Pulmonary hypertension (PH) is a common complication of left heart disease (LHD) that leads to right heart failure and death. Pulmonary artery (PA) stiffening has recently emerged as an important diagnostic and prognostic parameter in PH. The present study aimed to develop and validate an ultrasonographic index to identify PA stiffening in PH due to LHD. METHODS AND RESULTS: First, ultrasonographic stiffness index (US-SI) was derived from pulmonary arterial (PA) radial strain (PA-RS), diameter, and stroke volume in rat model and correlated with ex vivo measured 'true' PA stiffness E. Then, US-SI was validated in a cohort of 24 LHD patients with or without PH prior to heart transplantation and again compared with 'true' PA stiffness measured ex vivo in collected PA specimens. In rats, ultrasonographic PA-RS and US-SI correlated closely with E, and both were able to detect 'true' PA stiffening with ≥80% sensitivity and specificity. In LHD patients, even though ultrasonographic right PA radial strain or US-SI correlated similarly with E, observer assessment and testing for diagnostic validity identified US-SI as more robust and accurate method that detects 'true' PA stiffening with 83.3% sensitivity and 95.8% specificity. CONCLUSIONS: Both PA strain and US-SI allow for ultrasonographic detection of PA stiffening in patients or animal models with LHD; however, US-SI identifies patients with stiffened PA with higher diagnostic validity and accuracy.