Diagnostic safety of a structured algorithm with use of clinical decision rule, D-dimer and CT scan for clinically suspected recurrent pulmonary embolism

Background: Diagnostic strategies in patients with suspected pulmonary embolism (PE) are well defined but their value in patients presenting with clinically suspected recurrent PE has not been established. The aim of this study was to determine the performance of a simple diagnostic strategy using the Wells clinical decision rule (CDR), quantitative D-dimer testing and computed tomography pulmonary angiography (CTPA) in patients with clinically suspected recurrent PE. Methods: Five hundred and sixteen patients with suspected recurrent PE were included in this multicenter clinical outcome study. An unlikely clinical probability (Wells rule four points or less) in combination with a normal D-dimer (cut-off 500 ng/mL) test result excluded PE and all other patients underwent multislice CTPA. Anticoagulant treatment was started if PE was demonstrated and treatment was withheld in all other patients. Primary outcome was the 3-month venous thromboembolism (VTE) recurrence rate in patients with normal tests, who had not been treated with anticoagulation. Results: An unlikely probability was found in 176 of 516 patients (34%), and the combination of an unlikely CDR-score and normal D-dimer excluded PE in 88 (17%) patients, without recurrent VTE during follow-up (0%; 95% CI 0-3.3%). CTPA excluded PE in 253 patients. During follow-up eight patients had a recurrent VTE (3.2%; 95% CI 1.5-5.9%). All patients had recurrent PE, of which two were fatal. Conclusion: In patients with suspected recurrent PE, the combination of an unlikely Wells CDR score and normal D-dimer safely excludes pulmonary embolism. In patients with a high risk probability or abnormal D-dimer, a CTPA excluding PE, however, is associated with a high rate of recurrent PE. Additional studies using alternative diagnostic algorithms - including performing ultrasonography after normal CT - are urgently needed.