Incidental PE seen on CT imaging spurs treatment questions

Patients with undetected incidental pulmonary embolism have a better short-term clinical outcome than those who are diagnosed and receive treatment, according to a study from the University of Munich. The research, presented at 2006 ECR, calls into question the value of detecting minor emboli with chest CT.

The Munich study adds to a growing body of evidence that withholding anticoagulation in a patient with suspected PE based on a negative CT pulmonary angiogram does not adversely affect outcome, said Dr. U. Joseph Schoepf, an associate professor of radiology and medicine at the Medical University of South Carolina.

A wide range of risks and adverse events is associated with anticoagulation therapy. Nevertheless, the established standard of care calls for anticoagulation therapy once PE is detected, however small and peripheral it may be, even after underlying deep venous thrombosis is ruled out, Schoepf said.

"Once a diagnosis of PE is established, the physician is practically forced to initiate anticoagulation therapy in order to avoid exposure to liability and potential litigation, although the risk of this regimen may outweigh the benefit of dissolving a small clot in the periphery of the pulmonary vasculature," he said.

Dr. Christopher Engelke and colleagues in the radiology department of the Technical University Munich retrospectively identified 117 PE-positive cases from more than 2500 consecutive chest CT scans. A file review was completed in 96 cases: 63 of them had active malignancy, and 58 showed incidental PE. Thirty-eight of the patients with incidental PE had a false-negative CT report.

"The most severe PE cases were detected, while the minor cases were more likely to be missed," said Engelke, a consultant radiologist at the university.

Of the PE-positive patients, 49 received a therapeutic anticoagulant treatment, 21 had prophylactic anticoagulant therapy, and 26 received no treatment. In some cases, therapy was not administered due to contraindications. Seven patients suffered bleeding complications related to anticoagulant therapy: two deaths and five major nonfatal hemorrhages.

Patients with incidental PE and false-negative CT results actually had a better survival rate after 30 days than those who received appropriate treatment, Engelke said. This outcome was due to the bleeding complications and low level of severity of PE, which was an important predictor of survival. Patients with massive PE had a worse outcome in the short term. Long-term survival was affected mainly by the presence of comorbidity, rather than PE.

"Although this new study is limited by the small number of patients who actually had PE and could be followed, it confirms earlier findings and again highlights the need to reevaluate and readjust our therapeutic algorithms for the treatment of small clots, in light of our increased ability to detect isolated peripheral PE," Schoepf said.