Silent pulmonary embolism in patients with deep venous thrombosis. Incidence and fate in a randomized, controlled trial of anticoagulation versus no anticoagulation

Abstract

A high frequency of asymptomatic pulmonary embolism (PE) in patients with deep venous thrombosis (DVT) has been reported, but information about the outcome of the patients with PE remains sparse. The aims of the present study were to assess the prevalence of silent PE in patients with symptomatic, venographically proven DVT, and to evaluate the natural history of silent PE. Consecutive patients from one centre of primary care were included in a randomized, open study with blinded control. All patients gave written, informed consent. Eighty-seven consecutive patients with venographically proven DVT and with a perfusion-ventilation lung scintigraphy performed within 48 h of the DVT diagnosis were included. On the 10th and 60th days the lung scintigraphy was repeated in 80 and 60 patients, respectively. All the patients were followed for 3 months in the out-patient clinic. All patients were ambulated from the first day and were allocated randomly to no anticoagulant (non-AC) therapy or to AC therapy with intravenous heparin infusion for at least 6 days and oral AC therapy for 3 months. Forty-three of these patients had a high probability lung scintigraphy for PE. Distal vein and femoral vein thrombosis embolized in 33 and 53% of patients, respectively. The progression rate after 60 days was 3% in both the AC and the non-AC group and after 10 days the rates were 13 and 8%, respectively. A high frequency of silent PE in patients with DVT both above and below the knee is demonstrated. AC treatment did not influence the resolution rate of PE or the rate of clinical PE in a 3-month follow-up period.