INTRODUCTION

Both deep venous thrombosis (DVT) and pulmonary embolism (PE) represent a spectrum of a single disorder called venous thromboembolism (VTE), which is a quite common disorder with an estimated incidence of 1 per 1000 inhabitants per year in the general population. Symptomatic VTE is associated with a high incidence of recurrent thrombosis; recurrence rates up to 30% after 8 to 10 years have been reported. Therefore the primary aim of treatment of symptomatic VTE is the prevention of recurrent VTE, including fatal PE.

In the prevention of arterial thrombosis, antiplatelet therapy plays a key role (see Chapters 23, 24, and 25). The use of antiplatelet agents in a variety of patients at increased risk for arterial thromboembolism was associated with a significant 22% risk reduction of a combined endpoint of myocardial infarction, stroke, or vascular death in a large meta-analysis by the Antithrombotic Trialists' Collaboration. Because platelets play a role in the initiation and propagation of VTE as well, antiplatelet agents may be important in the treatment and prevention of VTE.

Even before the use of antiplatelet therapy became widespread in arterial thromboprophylaxis, several small studies showed a protective effect in VTE prevention. In the above-mentioned meta-analysis on antiplatelet therapy in cardiovascular prevention, 32 trials provided information on the incidence of symptomatic PE.