Wan T, et al. - This trial was formulated in order to weigh the correlation between residual pulmonary embolism examined via baseline ventilation-perfusion scan upon the completion of 5-7 months of oral anticoagulant therapy. Researchers also gauged the risk of recurrent venous thromboembolism in patients with the first episode of unprovoked pulmonary embolism. A connection was brought to light between the residual pulmonary embolism with a statistically marked, higher risk of subsequent recurrent venous thromboembolism. Percentage of pulmonary vascular obstruction assessment by ventilation-perfusion scans could possibly serve as a beneficial instrument to aid in guiding the duration of oral anticoagulant therapy after a first unprovoked pulmonary embolism.