Pulmonary thromboembolic disease refers to the condition in which blood clot(s) (thrombus or multiple thrombi) migrate from the systemic circulation to the pulmonary vasculature (Fig. 73-1). The field of pulmonary thromboembolic disease has continued to evolve, and aspects of clinical care remain shrouded in controversy. What is certain is that the incidence of pulmonary embolism (PE) appears to be increasing over the past few decades, probably reflecting an increase in the availability and sensitivity of CT scanning. Despite this increase in diagnosis, the mortality related to acute PE continues to decline.
Large, well-organized embolism representing “cast” of a lower-extremity vein removed from pulmonary artery at pulmonary embolectomy.
Most of the thrombi arise from the deep veins of the lower and upper extremities (deep venous thrombosis, DVT). From a clinical perspective, DVT and PE can be considered a continuum of the same disease, and the two terms are often collectively referred to as venous thromboembolism (VTE). For the purposes of this chapter, we will focus on PE.
The exact annual incidence of PE in the United States remains uncertain but appears to be increased in incidence in recent years.1 In a retrospective analysis of data involving 2218 Olmsted County residents over a 10-year period, community residents who were not hospitalized within a 90-day period had an incidence of PE of 3.6 (95% confidence interval [CI], 3.2–4.0) per 10,000 person-years.2 A slightly lower incidence of 2.3 per 10,000 person-years was reported in an earlier study in Massachusetts.3 This translates to an annual incidence of approximately 100,000 cases in the United States. However, the true incidence of PE is likely to be much higher since many cases remain undiagnosed. A systematic review revealed that silent PE was present in 32% of patients with DVT.4 An earlier report estimated that as many as 630,000 patients develop PE every year in the United States with 200,000 related deaths, the majority in patients in whom the diagnosis was never made.5
Although considerable effort is directed toward the development of new diagnostic techniques and therapeutic agents, a considerable impact on PE-related mortality has resulted from the routine use of prophylactic strategies, an understanding of the often subtle clinical presentation of the disease, the appropriate application of existing diagnostic techniques, and the use of newer treatment modalities associated with better outcomes. This has translated to decreased PE-related mortality in recent years. In the RIETE Registry, the 30-day PE-related mortality decreased from 3.3% in 2001 to 1.8% in 2013 (p < 0.01) (Fig. 73-2).6,7
The incidence of PE has increased (left) while the mortality associated with PE has decreased (right). aPE listed as principal diagnosis. bAny listed code for pe was ...