Whether the localization of non-massive pulmonary embolism (PE) is associated with the short and long-term prognosis of patients remains unknown. Our aim is to characterize associations of non-massive PE localization with risks of recurrent venous thromboembolism (VTE), major bleeding and mortality during and after anticoagulation.
Among participants of the RIETE registry with an incident symptomatic non-massive PE diagnosed by computerized tomography (CT), we compared risks of recurrent VTE, major bleeding and mortality during and after anticoagulation period between central PE (main pulmonary artery) and non-central PE (more peripheral arteries), using Cox proportional hazard adjusted models.
Of the 6674 participants, patients with central PE (40.5%) had similar age (mean 66 years), sex (46.9% male) and proportion of idiopathic (45.0%) and cancer-related (22.3%) PE as patients with non-central PE. During anticoagulation (5256.1 patient-years), the risk of recurrent VTE was similar between the two groups (2.5 vs. 2.1 per 100 patient-years; adjusted HR 1.32, 95%CI 0.91-1.90), as were risks of major bleeding and mortality. After anticoagulation was discontinued (2175.4 patient-years), participants with central PE had a borderline greater risk of recurrent VTE than participants with non-central PE (11.0 vs. 8.0 per 100 patient-years; adjusted HR 1.34, CI 95% 1.01-1.78), but not when restricting to participants after unprovoked PE (13.8 vs. 11.9 per 100 patient-years, HR 1.15, 95%CI 0.79-1.68, p= 0.48). Risks of major bleeding and mortality were similar.
Among non-massive PE, central localization of PE is associated with greater risk of recurrent VTE after anticoagulation cessation. However, the low magnitude of this association and the absence of association after unprovoked PE suggest that the clinical relevance of this finding is limited and that the duration of anticoagulation should not be tailored to PE localization after non-massive unprovoked PE.