Purpose: Patients who have nonmassive acute pulmonary embolism and a high risk of bleeding or contraindication to anticoagulants, such recent surgery or gastrointestinal bleeding, present a clinical dilemma. We sought to estimate whether such patients could be safely left untreated if serial compression ultrasound or serial impedance plethysmography were negative and cardiorespiratory reserve was adequate.
Subjects and methods: The frequency of recurrent pulmonary embolism among patients with nonmassive acute pulmonary embolism and negative serial noninvasive leg tests who were not treated was estimated from two prospective studies of the noninvasive management of patients with suspected pulmonary embolism. One of the studies used serial impedance plethysmography of the lower extremities; the other used serial compression ultrasound. The prevalence of pulmonary embolism in patients with nondiagnostic ventilation/perfusion lung scans was determined from the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED).
Results: The estimated frequency of fatal recurrent pulmonary embolism was 1% [95% confidence interval (CI), 0% to 5%) among untreated patients with nonmassive pulmonary embolism who had negative serial impedance plethysmograms and 0% (95% CI, 0% to 4%) among those with negative serial compression ultrasonograms. The frequency of nonfatal recurrent pulmonary embolism among untreated patients was 3%, regardless of whether they had negative serial impedance plethysmograms or negative serial compression ultrasonograms. These results were comparable with the frequency of recurrent pulmonary embolism among patients treated with anticoagulants or with inferior vena cava filters.
Conclusion: Withholding treatment of nonmassive acute pulmonary embolism, if serial impedance plethysmograms or serial venous ultrasonograms are negative and cardiopulmonary reserve is adequate, is a possible strategy for the management of patients with a high risk of bleeding or other contraindication to anticoagulants. This strategy may be associated with fewer adverse events than treatment with anticoagulants or an inferior vena cava filter. Prospective trials comparing alternative treatments are needed.