Chronic thromboembolic pulmonary hypertension (CTEPH) is an important consequence of pulmonary embolism (PE) that is associated with abnormalities in haemostasis. We investigated the ADAMTS13-VWF axis in CTEPH, including its relationship to disease severity, inflammation, ABO groups and ADAMTS13 genetic variants.

ADAMTS13 and VWF plasma antigen levels were measured in patients with CTEPH (n=208), chronic thromboembolic disease without pulmonary hypertension (CTED; n=35), resolved PE (n=28), idiopathic pulmonary arterial hypertension (n=30) and healthy controls (n=68). CTEPH genetic ABO associations and protein quantitative trait loci were investigated. ADAMTS-VWF axis abnormalities were assessed in CTEPH and healthy control subsets by measuring ADAMTS13 activity, D-dimers and VWF-multimeric size.

CTEPH patients had decreased ADAMTS13 (adjusted β (95% CI)=−23.4 (−30.9– −15.1)%, p<0.001) and increased VWF levels (β=+75.5 (44.8–113)%, p<0.001) compared to healthy controls. ADAMTS13 levels remained low after reversal of pulmonary hypertension by pulmonary endarterectomy surgery and were equally reduced in CTED. We identify a genetic variant near the ADAMTS13 gene associated with ADAMTS13 protein that accounted for ∼8% of the variation in levels.

The ADAMTS13-VWF axis is dysregulated in CTEPH. This is unrelated to pulmonary hypertension, disease severity or markers of systemic inflammation and implicates the ADAMTS13-VWF axis in CTEPH pathobiology.