Venous thromboembolism (VTE) includes superficial and deep vein thrombosis of the leg or pelvis and pulmonary embolism (PE).1 VTE affects an estimated 600 000 people in the US, with approximately 60 000 to 100 000 people dying from VTE and PE annually.2 Despite its prevalence, 25% to 40% of all VTE events are idiopathic, making diagnosis and prevention difficult.1