Modern imaging technologies have put a virtual microscope into the human body and can find smaller and less significant disease. Our treatment of these conditions often falls under old recommendations meant for more substantial illness. Can treatment of mild disease result in more harm than benefit?
This question is particularly true when it comes to subsegmental PE. Does it require anticoagulation?
These researchers found 266 patients with low-risk subsegmental PE and referred them to a thrombosis clinic for management. The patients underwent lower extremity ultrasound to exclude DVT at the time of diagnosis and one week later. Patients without DVT had anticoagulation withheld and they were followed up for 90 days looking for evidence of recurrent VTE.
In the end, 8 (3% 95% CI, 1.6%-6.1%) out of the 266 patients developed VTE. The authors report higher rates in some subgroups but this analysis is not really justified given the low number of recurrences.
There are some important limitations to remember. These patients were low risk. They did not have cancer nor prior VTE. They all had repeated leg ultrasound to exclude DVT. Long term rates beyond 90 days were not assessed. In addition, false positive CTPA's may have skewed the results towards lower rates of recurrent disease.
What are we to conclude?
Recurrent VTE in low-risk patients with subsegmental PE is pretty low. This may be a good time for shared decision making.
Le Gal G, Kovacs M, Bertoletti L, et al. Risk for Recurrent Venous Thromboembolism in Patients With Subsegmental Pulmonary Embolism Managed Without Anticoagulation. Ann Intern Med. 2022;175:29-35 [link to article]