Acute pulmonary thromboembolism: has its evolution been redefined?

Natural History Statistics Older statistics estimate that in the United States, acute pulmonary thromboembolism afflicts 500 000 to 600 000 persons annually and is either a primary or secondary cause of death in 150 000 to 200 000 of these individuals.1,2 Extrapolation of a population-based study from data accumulated in 1985 through 1986 in Worcester, Mass, suggests that each year there are '170 000 new cases of clinically recognized venous thromboembolism treated in short-stay hospitals and 99 000 hospitalizations for recurrent disease.3 When the disease process was followed from the time of clinical recognition, the 1-year mortality rate in a national multicenter project (PIOPED) was reported as '25%, with 2.5% dying from pulmonary embolism itself and most patients dying from the major diseases that are associated with pulmonary thromboembolism, including cancer, various infections, cardiovascular diseases, and other pulmonary diseases.4 Other studies have reported that in patients without preexisting cardiac or pulmonary disease, the 1-year mortality rate ranged from 3% to 9%.5,6 If a massive pulmonary embolism occurs associated with systemic hypotension, the in-hospital mortality rate is '18%.7 The persistence of pulmonary hypertension after embolization has been associated with increased mortality rates; the higher the pulmonary artery pressure, the lower the survival rate at 5 years.8 Furthermore, it has been predicted, with admitted imprecision, that 0.01% of patients develop what is now commonly referred to as chronic pulmonary thromboembolic pulmonary hypertension.9