EPIDEMIOLOGY

Present evidence suggests that venous thromboembolism is the third mos t common acute cardiovascular disease after cardiac ischemic syndromes and stroke. The frequency of the diagnosis of pulmonary embolism (PE) at a given hospital greatly increases if a referral unit for PE is se t up in the hospital. Pulmonary embolism is characterized by a continu ous spectrum of severity, from 2 to 3 to 15 to 16 embolized pulmonary segments (over a total of 19). Morbidity from PE increases with age an d male sex (males/females ratio: 1.24). In only a minority (10%) of pa tients with PE and/or deep-vein thrombosis (DVT), primary deficiencies of coagulation-inhibiting proteins have been shown. Primary abnormali ties of the fibrinolytic system seem even more rare. On the basis of t he clinical conditions preceding the embolic episode, patients may be divided into different groups: apparently primary or idiopathic PE (40 %), surgery or trauma (43%), heart disease (12%), neoplastic disease ( 4%), and systemic disease (1%). Patients with apparently primary or id iopathic PE often develop subsequent clinically overt cancer (9.1%), w hereas surgery or trauma patients rarely do (1.4%). Furthermore, the f ormer exhibit a significantly shorter survival than the latter mostly for causes of death that reflect increased predisposition to thromboge nesis. Thus, as for DVT, it is convenient to consider a primary or idi opathic form also for PE.