Clinical characteristics of patients with peripheral pulmonary embolism.

BACKGROUND The clinical relevance of emboli limited to the segmental or sub-segmental pulmonary arteries and the role of anticoagulation in patients with these conditions remains to be clarified. OBJECTIVES To determine the clinical characteristics and treatment outcomes of peripheral pulmonary embolism (PE), and in particular, isolated sub-segmental PE (ISSPE). METHODS We reviewed the data for 334 patients who were diagnosed with a PE by computed tomographic (CT) pulmonary angiography and indirect CT venography. RESULTS All patients were classified into one of three groups: central (245 patients, 73.4%); segmental (67 patients, 20.1%), and sub-segmental (22 patients, 6.6%). An incidental CT finding (63.6%) was the most common presentation in the segmental and sub-segmental groups. Compared with the central group, the sub-segmental group had less frequent proximal deep venous thrombosis (14 vs. 47%, Bonferroni's corrected p = 0.002), and greater preservation of oxygenation levels (p < 0.05) without hemodynamic instability. The recurrence of PE and deaths related to PE did not occur in the sub-segmental group, although approximately 30% of the patients did not receive anticoagulation therapy. CONCLUSIONS Patients with ISSPE may have a more benign clinical presentation, as compared to the central type, and may follow a good clinical course without mortality or recurrence.