Predictors of residual pulmonary vascular obstruction after anticoagulation monotherapy in patients with intermediate-risk pulmonary embolism

BACKGROUND: Patients with intermediate-risk pulmonary embolism (PE) can be treated with anticoagulation monotherapy. However, clinicians are concerned as to whether anticoagulation monotherapy is sufficient to reduce mortality in patients with a large embolic burden, and to resolve vascular obstruction. We investigated whether anticoagulation monotherapy was appropriate in patients with intermediate risk PE in terms of the occurrence of residual pulmonary vascular obstruction (RPVO), and the factors that independently predict the occurrence of RPVO. METHODS: This was a multicenter retrospective observational study of patients at intermediate risk of PE who were admitted to three hospitals between January 2012 and December 2017. RESULTS: Of total 91 patients, the median age was 72 years and 37 (40.7%) were male. Twenty-five patients (27.5%) were diagnosed with RPVO during follow-up. Multivariate logistic regression revealed chronic lung disease [odds ratio (OR), 4.14; 95% confidence interval (CI), 1.243–13.797; P=0.021] and the ratio of the diameters of the main pulmonary artery and ascending aorta ratio (P/A ratio) >1.0 documented on a chest computed tomography (CT) at presentation (OR, 3.46; 95% CI, 1.113–10.770; P=0.032) were significant independent predictors of RPVO occurrence. The incidence of RPVO in patients without these two factors was only 9.7%, but in those with the two factors it was 60% (P=0.004). CONCLUSIONS: Anticoagulation monotherapy did not seem to be a sufficient treatment to reduce RPVO, but the outcome was similar to that of patients treated with other therapies. Therefore, considering the risk-benefit ratio, we do not need to change the initial treatment as systemic thrombolytic therapy or catheter-based therapy in patient with intermediate risk PE. Underlying chronic lung disease and a P/A ratio >1 on the initial chest CT predicted the occurrence of RPVO. Therefore, we should carefully assess persistent of dyspnea and exercise limitations using various methods in patients with these risk factors, to detect the occurrence of chronic thromboembolic pulmonary disease (CTEPD) earlier.