Translational insights into mechanisms underlying residual venous obstruction and the role of factor XI, P-selectin and GPVI in recurrent venous thromboembolism.

BACKGROUND: Residual venous obstruction (RVO) after deep vein thrombosis (DVT) is considered a risk factor of recurrent venous thromboembolism (VTE), arterial events and post-thrombotic syndrome (PTS). We hypothesized thrombo-inflammatory markers might be associated with RVO and clinical outcomes. MATERIALS AND METHODS: In a DVT cohort with routine RVO-assessment and 5-year follow-up, patients were invited for blood withdrawal after stopping anticoagulants. Thrombin generation potential, coagulation enzyme:inhibitor complexes, soluble platelet markers and clinical markers were measured in platelet-poor plasma. Associations were represented as odds ratio (OR) or hazard ratio (HR) per standard deviation. RESULTS: Patients with RVO (102/306, 33 %) had higher rates of PTS (24 vs. 12 %, p = 0.008), but similar rates of recurrence (16 vs. 15 %, p = 0.91) and arterial events (7 vs. 4 %, p = 0.26). RVO was associated with thrombin peak height (OR 1.40 [1.04-1.88]), endogenous thrombin potential (ETP, OR 1.35 [1.02-1.79]), and CRP (OR 1.74 [1.10-2.75]). Recurrent VTE was associated with ETP (HR 1.36 [1.03-1.81]), FXIa:C1-inhibitor (HR 1.34 [1.04-1.72]), thrombin:antithrombin (HR 1.36 [1.16-1.59]), soluble P-selectin (HR 2.30 [1.69-3.11]), soluble glycoprotein VI (sGPVI, HR 1.30 [1.01-1.69]), D-dimer (HR 1.56 [1.31-1.86]), and factor VIII (HR 1.44 [1.15-1.82]). Arterial events were associated with sGPVI (HR 1.80 [1.25-2.59]). PTS was not associated with any marker. CONCLUSIONS: Our findings indicate RVO was associated with thrombo-inflammation, but this did not predict clinical outcomes in this setting. Importantly, we found recurrent VTE was associated with ongoing coagulation and platelet activation in patients well beyond the acute phase of DVT. Furthermore, sGPVI indicated an increased risk of arterial events, highlighting the role of platelets in arterial thrombosis following DVT.