LOW-PREVALENCE OF FACTOR-V-Q506 IN 41 PATIENTS WITH ISOLATED PULMONARY-EMBOLISM

In 70-80% of cases, pulmonary embolism is the consequence of lower ext remity deep vein thrombosis. It has been demonstrated that the most co mmon coagulation defect predisposing to venous thrombosis. resistance to activated protein C (APC), is not associated with an increased risk for pulmonary embolism, but the evidence was based on a functional as say to diagnose APC resistance and no information about concomitant de ep vein thrombosis was provided. The aim of our study was to evaluate the prevalence of factor V:Q506, the gene mutation responsible for APC resistance, in patients with symptomatic non-fatal pulmonary embolism , whether or not associated with deep vein thrombosis. Patients with u ncomplicated deep vein thrombosis and healthy controls were investigat ed as comparison groups. The overall prevalence of factor V:Q506 in 10 6 patients with pulmonary embolism was 12.3%, lower than that found in 106 patients with deep vein thrombosis (22.6%, OR 0.5, 95% CI 0.2-1.0 ) but significantly higher than that found in 212 healthy subjects tak en as controls (2.8%, OR 4.8, 95% CI 1.8-13.0). In the 41 patients wit h isolated pulmonary embolism, i.e., without the presence of deep vein thrombosis, the prevalence was 4.9%. similar to that in controls (OR 1.8, 95% CI 0.3-9.6), while in the remaining 65 patients with pulmonar y embolism associated with deep vein thrombosis the prevalence was sig nificantly higher (16.9%, OR 5.5, 95% CI 2.0-15.8). In conclusion, the prevalence of factor V:Q506 is high in patients with pulmonary emboli sm associated with deep vein thrombosis. whereas in patients with isol ated pulmonary embolism it is similar to that found in control subject s. This intriguing finding is of difficult interpretation and needs co nfirmation by further studies.