VWF and thrombotic thrombocytopenic purpura: Conversely, excess ultra‐high‐molecular‐weight VWF in the bloodstream (due to induced or genetic absence of the VWF‐cleaving metalloprotease ADAMTS‐13) results in the microvascular occlusions 15 of thrombotic thrombocytopenic purpura, and patients with elevated plasma VWF have an increased risk of cardiac events 14, 16 and stroke 17.