In olden times, pulmonary embolism actually presented as pulmonary infarction with the “classic” triad of pleuritic pain, hemoptysis, and signs of deep venous thrombosis. Now, nearly 10% are virtually incidental subsegmental PE of uncertain clinical significance – yet, recommendations for treatment remained systemic anticoagulation.
This new guideline states patients with subsegmental PE, without another identifiable VTE source, and at low risk for recurrent VTE, have the option of watchful waiting. They cite no new groundbreaking evidence, but generally recognize the low rates of recurrent VTE in retrospective and observational studies. They also recognize a diagnosis of subsegmental PE is quite likely to be a false-positive, as covered in my last ACEPNow column, unless the following conditions are met:
We suggest that a diagnosis of subsegmental PE is more likely to be correct (i.e. a true-positive) if: (1) the CT pulmonary angiogram (CTPA) is of high quality with good opacification of the distal pulmonary arteries; (2) there are multiple intraluminal defects; (3) defects involve more proximal sub-segmental arteries (i.e. are larger); (4) defects are seen on more than one image; (5) defects are surrounded by contrast rather than appearing to be adherent to the pulmonary artery; (6) defects are seen on more than one projection; (7) patients are symptomatic, as opposed to PE being an incidental finding; (8) there is a high clinical pre-test probability for PE; and D-Dimer level is elevated, particularly if the increase is marked and otherwise unexplained.Patients discharged without anticoagulation should be provided prospective guidance on seeking care for new or progressive symptoms. These recommendations are appropriately GRADE category 2C, reflecting moderate/weak certainty and a low level of evidence – but, it at least provides a framework to have a reasonable conversation and shared decision-making with a patient.
It also appropriate raises a question about testing for PE: if a patient has a PE meeting criteria for non-treatment, does it need to be found in the first place? Should the acceptable miss rate for PE – assuming the quoted prevalence of subsegmental disease – be ~10%?
“Antithrombotic Therapy for VTE Disease: CHEST Guideline”