Essentials• The platelet thrombin receptor, PAR4, is an emerging anti‐thrombotic drug
target.• We examined the anti‐platelet & anti‐thrombotic effects of PAR4 inhibition in human
blood.• PAR4 inhibition impaired platelet procoagulant activity in isolated cells and during
thrombosis.• Our study shows PAR4 is required for platelet procoagulant function &
thrombosis in human blood. Summary: Background Thrombin‐induced platelet activation is
important for arterial thrombosis. Thrombin activates human platelets predominantly via …