An analysis of current pulmonary embolism therapy

The clinical diagnosis of venous thromboembolism, and especially pulmonary embolism, is inaccurate due to the nonspecific nature of presenting symptoms and signs which overlap with other frequently coexistent conditions. In recent years, the operating characteristics of more objective diagnostic strategies (ie, ventilation/perfusion lung scan, impedance plethysmography, venous compression ultrasound) have been more clearly defined. However, data regarding the natural history of pulmonary embolism primarily come from an era when objective diagnostic tests were unavailable which calls into question the validity of such data. Furthermore, despite a long experienee there are few data regarding the clinical course of pulmonary embolism as currently treated with heparin/warfarin anticoagulation. Acute mortality correlates with the presence of systemic hypotension regardless of embolus size, suggesting that right heart functional reserve is the major determinant of acute survival. Long-term mortality has been attributed to underlying co-morbid disease. However, there are no studies of age- and sex-specific survival which control for co-morbid disease. Pulmonary embolism may be a marker for severe and immanently fatal co-morbid disease, or pulmonary embolism may add 'excess mortality' over and above that co-morbid disease. Thrombolytic therapy clears pulmonary artery thrombus more rapidly than heparin and can rapidly restore normal right heart function. Current research aims to identify the ideal plasminogen activator and dosing regimen which maximizes thrombolysis and minimizes disturbance of hemostasis. In addition, more data regarding the natural history and clinical course of pulmonary embolism is needed to stratify patients into subsets with better or worse prognosis. Finally, a study of sufficient sample size is needed which compares thrombolytic therapy to standard heparin/warfarin anticoagulation with acute and chronic mortality as primary efficacy endpoints.