Safety of withholding anticoagulant therapy in patients with suspected pulmonary embolism with a negative multislice computed tomography pulmonary angiography.

BACKGROUND: To assess the safety of withholding anticoagulant therapy in patients with clinically suspected pulmonary embolism with a negative multislice computed tomography pulmonary angiography (MCTPA).
METHODS: Three hundred and eighty six patients who were consecutively assessed in the emergency room of our institution for suspected pulmonary embolism were eligible for our study. Patients with either a low or an intermediate clinical probability of pulmonary embolism according to the Wells score and a negative MCTPA for pulmonary embolism were enrolled. Patients with anticoagulant therapy for other medical conditions were excluded from this study. We assessed the percentage of patients in whom venous thromboembolic events or death related to this condition within three months after the negative CT.
RESULTS: Two hundred and forty two patients were included in our series [mean age+/-standard deviation (SD) (63.1+/-18.1)]. Only one patient (0.41% [95% confidence interval -0.4%-1.22%]) showed a non-fatal pulmonary embolism during the three-month follow-up period after an initial negative CT scan (negative predictive value, 99.58%). Eleven patients died during the follow-up period due to conditions unrelated to venous thromboembolic disease (pneumonia [n=5], lung cancer [n=2], wasting syndrome [n=1], acute myocardial infarction [n=1], leiomyosarcoma [n=1], and severe pulmonary hypertension [n=1]).
CONCLUSIONS: Withholding anticoagulant therapy in patients with suspected venous thromboembolic disease with a negative result on MCTPA seems to be safe in our clinical setting.