To elucidate the mechanisms responsible for the impaired thrombus occlusion and thromboembolism observed in MICAL1-deficient mice under high shear, we investigated ex vivo platelet thrombus dynamics by perfusing anticoagulated whole blood over immobilized type I fibrillar collagen (which captures VWF from plasma and mimics injured blood vessels) at an arteriolar shear rate of 1500 s−1. Here, VWF is linked to Thromboembolism.