Abstract
Background: The optimal duration of oral anticoagulant therapy after a first, unprovoked venous thromboembolism is controversial due to tightly balanced risks and benefits of indefinite anticoagulation. Risk stratification tools may assist in decision making. Objectives: We sought to determine the relationship between residual pulmonary embolism assessed by baseline ventilation-perfusion scan after completion of 5–7 months of oral anticoagulant therapy and the risk of recurrent venous thromboembolism in patients with the first episode of unprovoked pulmonary embolism. Methods: We conducted a multicentre prospective cohort study of participants with a first, unprovoked venous thromboembolism enrolled after the completion of 5–7 months of oral anticoagulation therapy. The participants completed a mean 18-month follow-up. Participants with pulmonary embolism had baseline ventilation-perfusion scan before discontinuation of oral anticoagulant therapy and the percentage of vascular obstruction on baseline ventilation-perfusion scan was determined. During follow-up after discontinuation of oral anticoagulant therapy, all episodes of suspected recurrent venous thromboembolism were independently adjudicated with reference to baseline imaging. Measurements and main results: During follow-up, 24 of 239 (10.0%) participants with an index event of isolated pulmonary embolism or pulmonary embolism associated with deep vein thrombosis and central assessment of percentage of vascular obstruction on baseline ventilation-perfusion scan had confirmed recurrent venous thromboembolism. As compared to participants with no residual pulmonary embolism on baseline ventilation-perfusion scan, the hazard ratio for recurrent venous thromboembolism was 2.0 (95% CI 0.5–7.3) for participants with percentage of vascular obstruction of 0.1%–4.9%, 2.1 (95% CI 0.5–7.8) for participants with percentage vascular obstruction of 5.0%–9.9% and 5.3 (95% CI 1.8–15.4) for participants with percentage vascular obstruction greater than or equal to 10%. Conclusions: Residual pulmonary embolism assessed by pulmonary vascular obstruction on baseline ventilation-perfusion performed after 5–7 months of oral anticoagulant therapy for the first episode of unprovoked pulmonary embolism was associated with a statistically significant higher risk of subsequent recurrent venous thromboembolism. Percentage of pulmonary vascular obstruction assessment by ventilation-perfusion scans maybe a useful tool to help guide the duration of oral anticoagulant therapy after a first unprovoked pulmonary embolism. Trial registration: Registered at www.clinicaltrials.gov identifier: NCT00261014.
Original language | English (US) |
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Pages (from-to) | 104-109 |
Number of pages | 6 |
Journal | Thrombosis Research |
Volume | 162 |
DOIs | |
State | Published - Feb 1 2018 |
Keywords
- Cohort studies
- Pulmonary embolism
- Radionuclide imaging
- Recurrence
- Risk factors
ASJC Scopus subject areas
- Hematology