Silent pulmonary embolism in patients with proximal deep vein thrombosis in the lower limbs.

Background: One in every three patients with deep vein thrombosis (DVT) in the lower limbs may have silent pulmonary embolism (PE), but its clinical relevance has not been thoroughly studied.

Methods: We used the RIETE Registry data to study patients with proximal DVT and no PE symptoms, but with a systematic search for PE. We compared the outcome of DVT patients with silent PE and those with no PE.

Results: Of 2375 patients with DVT, 842 (35%) had silent PE and 1533 had no PE. During the first 15 days of anticoagulation, patients presenting with silent PE had a higher incidence of symptomatic PE events than those with no PE (0.95% vs. 0.13%; P = 0.015), with a similar incidence of major bleeding (0.95% vs. 1.63%; P = 0.09). In patients with silent PE, the incidence of PE events during the first 15 days was equal to the incidence of major bleeding (eight events each), but in those with no PE the incidence of PE events was eight times lower (3 vs. 25 bleeding events). Multivariate analysis confirmed that DVT patients with silent PE had a higher incidence of symptomatic PE events during the first 15 days than those with no PE (odds ratio, 4.80; 95% CI, 1.27-18.1), with no differences in bleeding.

Conclusions: DVT patients with silent PE at baseline had an increased incidence of symptomatic PE events during the first 15 days of anticoagulant therapy. This effect disappeared after 3 months of anticoagulation.