Sex‐specific differences in clot resolution 3 weeks after acute pulmonary embolism managed with anticoagulants—A substudy of the EINSTEIN‐PE study

Abstract

BackgroundIt is unknown whether differences in clot structure and resolution contribute to the reported risk differences of recurrent venous thromboembolism (VTE) between men and women. Patients/MethodsWe used data from the EINSTEIN‐PE study, a randomized, multicenter, non‐inferiority study in which patients 18 years and older with acute symptomatic pulmonary embolism (PE) were randomized to rivaroxaban or enoxaparin followed by a vitamin K antagonist. PE was diagnosed by computed tomography pulmonary angiography scan or high‐probability ventilation/perfusion scintigraphy. Three weeks after randomization a follow‐up scan was performed. An independent adjudication committee assessed the degree of vascular obstruction. Results and ConclusionsA total of 371 participants including 174 (46.9%) women and 197 (53.0%) men were included in the present analysis. At 3 weeks, there was no difference between men and women in complete clot resolution: 39.6% and 40.2%, respectively. The absolute reduction in pulmonary vascular obstruction at week 3 was also similar: 12.9% (95% confidence interval [CI]: 11.6–14.2) in men and 12.1% (95% CI: 10.4–13.7) in women, corresponding to a resolution ratio of 0.29 (95% CI: 0.24–0.33) and 0.35 (95% CI: 0.28–0.42), respectively. No differences in clot resolution were observed between men and women diagnosed with acute PE at 3 weeks after start of anticoagulant therapy. These findings suggest that the reported higher rate of VTE recurrence in men cannot be explained by decreased clot resolution.