High-Sensitivity Thrombin Generation Profiling Identifies Divergent Coagulation States Across Peripheral Artery Disease Severity

Factor Xa inhibition has demonstrated clinical benefit in peripheral artery disease (PAD), yet the mechanisms underlying this effect remain poorly defined. Uncertainty also persists regarding which patient subgroups derive net benefit, particularly given concerns about bleeding risk. Conventional thrombin generation assays primarily capture late and amplified coagulation phases and may overlook subtle abnormalities in the early-phase. We therefore investigated stage-specific profiles of the initial activated Factor II (FIIa) generation (ITG) during the early phase of coagulation in PAD using two high-sensitivity thrombin generation assays. TF-driven ITG (TF-ITG) and FVIIIa/FIXa-dependent ITG (FVIIIa/FIXa-ITG) were measured in plasma samples from patients with intermittent claudication (IC), chronic limb-threatening ischemia (CLTI), and healthy controls. Tissue factor pathway inhibitor (TFPI) activity levels were also assessed. Distinct early-phase coagulation phenotypes emerged across PAD severity. Patients with IC showed selective intrinsic coagulation pathway hypercoagulability with significantly elevated FVIIIa/FIXa-ITG compared to controls ( p < 0.005), while TF-ITG remained normal. Conversely, patients with CLTI demonstrated paradoxical suppression of both TF-ITG and FVIIIa/FIXa-ITG ( p < 0.005), accompanied by elevated TFPI activity levels. The TFPI levels correlated negatively with both TF-ITG (r = -0.696, p = 0.0057) and FVIIIa/FIXa-ITG (r = -0.535, p = 0.049) only in CLTI. Early-phase thrombin generation differs fundamentally between IC and CLTI. These exploratory findings provide hypothesis-generating mechanistic insights for the variable clinical effects of Factor Xa inhibition in PAD. Prospective studies are warranted to determine whether early-phase thrombin generation profiling can inform biomarker-guided antithrombotic strategies. • Early claudication shows selective intrinsic pathway activation • Advanced ischemia paradoxically suppresses thrombin generation • TFPI elevation correlates with reduced coagulation in severe disease • Stage-specific coagulation profiles may guide anticoagulant selection • High-sensitivity assays detect changes missed by standard tests