Risk of recurrent venous thromboembolism and bleeding in patients with acute isolated subsegmental pulmonary embolism

Introduction: Approximately 10 % of all diagnosed pulmonary embolism are isolated to the subsegmental vessels. The risk of recurrent venous thromboembolism (VTE) in patients with an acute subsegmental pulmonary embolism (SSPE) managed with or without anticoagulant therapy remains poorly understood. Methods: This is an observational cohort study including consecutive adult patients diagnosed with acute isolated SSPE between June 01, 2019, and August 31, 2022. We excluded patients with a concomitant diagnosis of deep vein thrombosis and those who had an indication for long-term anticoagulation. The primary outcome was objectively confirmed recurrent VTE. Results: Overall, 118 patients with acute SSPE were included in the analysis. The mean ( +/- standard deviation [SD]) age of the participants was 59 +/- 17 years and 44 % of them had active cancer. Mean ( +/- SD) duration of follow-up was 438 +/- 426 days. Seventy-seven patients (65 %) were initially treated with anticoagulation, whereas 41 patients (35 %) were not. Of the 77 patients receiving anticoagulant therapy, 23 (30 %) received extended -duration anticoagulation (beyond 3 months) for secondary prevention. Overall, recurrent VTE events occurred in 6/118 (5 %, 95 % CI 2.4 to 10.7) patients. Four events (4/77 = 5.2 %, 95 % CI 2.0 to 12.6) occurred in initially treated patients. Two recurrent VTE occurred in patients initially left untreated (2/41 = 4.9 %, 95 % CI 1.4 to 16.1). Half of the recurrent VTE occurred in patients with active cancer. Conclusions: Most patients diagnosed with an acute SSPE received anticoagulation. The incidence of recurrent VTE detected over time was relatively high, especially in patients with cancer.