Pulmonary embolism risk stratification by European Society of Cardiology is associated with recurrent venous thromboembolism: Findings from a long-term follow-up study

- The cumulative incidences of recurrent VTE after PE were 4.5%, 7.3%, and 13.9% after 1, 2, and 5 years of follow-up.
- ESC high-risk and intermediate-risk PE has heavier clot burden (reflected by Qanadli score), and increases recurrent risk.
- Longer anticoagulation was a protective factor against recurrence, especially in ESC higher risk and unprovoked PE patients.

Venous thromboembolism (VTE) recurrence carries significant mortality and morbidity. Accurate risk assessment and effective treatment for patients with acute pulmonary embolism (PE) is important for VTE recurrence prevention. We examined the association of VTE recurrence with risk stratification and PE treatment. We enrolled 627 patients with a first episode of confirmed PE. Baseline clinical information was collected. PE severity was assessed by the European Society of Cardiology's (ESC) risk stratification, the simplified PE Severity Index (sPESI) and the Qanadli score of clot burden. Patients were followed for 1-5 years. The cumulative recurrent VTE and all-cause death were documented. The association between recurrent VTE and risk factors was analyzed. The cumulative incidences of recurrent VTE were 4.5%, 7.3%, and 13.9% at 1, 2, and 5 years of follow-up, respectively. The VTE recurrence was associated with higher (high- and intermediate-) risk stratification predicted by ESC model (HR 1.838, 95% CI 1.318-2.571, P < 0.001), as well as with unprovoked PE (HR 2.809, 95% CI 1.650-4.781, P b 0.001) and varicose veins (HR 4.747, 95% CI 2.634-8.557, P < 0.001). The recurrence was negatively associated with longer (≥ 6 months) anticoagulation (HR 0.473, 95% CI 0.285-0.787, P = 0.004), especially in patients with higher risk (HR 0.394, 95% CI 0.211-0.736, P = 0.003) and unprovoked PE (HR 0.248, 95% CI 0.122-0.504, P < 0.001). ESC high-risk and intermediate-risk PE, unprovoked PE and varicose veins increase recurrence risk. Longer anticoagulation treatment reduces recurrence, especially in higher risk and unprovoked PE patients.