Safety of Withholding Anticoagulant Therapy in Patients Who Have Clinically Suspected Pulmonary Embolism and Negative Results on Helical Computed Tomography

Abstract

Background: Several studies have focused on the safety of withholding anticoagulant therapy in patients with negative results on helical computed tomography (CT). However, these studies were either retrospective or had a selection bias, since spiral CT was performed only in selected patients. Moreover, no special attention has been directed towards an alternative diagnosis which might explain patients’ signs and symptoms. Objectives: To determine the safety of withholding anticoagulants in patients with clinically suspected pulmonary embolism (PE) and negative CT results when ultrasonography (US) was performed only in patients with clinical suspicion of deep vein thrombosis (DVT). Another goal was to evaluate the effect of CT findings on the final clinical diagnosis. Methods: Among 192 consecutive patients who underwent CT for possible acute PE, 98 patients had negative images and 88 of them – without clinical suspicion of DVT – were prospectively followed up for 3 months for evidence of subsequent thromboembolic disease. They did not receive anticoagulation. Clinical probability of PE was assessed applying the Geneva score. These patients were also classified into several diagnostic categories according to the CT findings and clinical presentation. In addition, all patients who were alive (or a member of his or her family) were interviewed by phone once the last patient’s follow-up was completed. Results: One patient was lost to follow-up. Among the remaining 87 patients (35 with low, 47 with intermediate and 5 with high clinical probability), subsequent thromboembolic disease was found in 1 (1.1%; 95%CI: 0.03–6.2%). Two patients died during the follow-up period, but no deaths were attributed to PE. Alternative diagnoses were: nonspecific thoracic pain (43.3%), nonspecific pleuritis (19.5%), pneumonia (18.4%), other (18.8%). The telephone survey was performed in 74 patients (median follow-up: 11 months; range: 4–23). None of them had newly diagnosed episodes of PE and none of them had received anticoagulation for any reason. Conclusions: With the limitations of a small single-center series, our data suggest that withholding anticoagulation in patients with suspected acute PE and negative CT results appears to be safe when the clinical probability of PE is assessed as low or intermediate. This technique also provides useful information to pose an alternative diagnosis. US could be avoided in patients without clinical suspicion of DVT.