Structured Surveillance Rarely Used for Patients with Subsegmental Pulmonary Embolism Despite Recommendations


In addition to the low use of structured surveillance overall, modified CHEST criteria only identified a small portion of patients with subsegmental pulmonary embolism eligible to receive structural surveillance.

Despite guidelines from the American College of Chest Physicians (CHEST), the use of structured surveillance without anticoagulation for patients with subsegmental pulmonary embolism (PE) was low among the small proportion of patients who were eligible, according to the results of a study published in the Journal of the American Medical Association.

Image credit: Khunatorn -

Image credit: Khunatorn -

Structural surveillance is an alternative to anticoagulation and consists of close follow-up, careful directions for when to seek urgent medical care, and compression ultrasonography to evaluate for deep vein thrombosis (DVT).

Questions have arisen over whether select patients with low-risk subsegmental PE may be better served with structured surveillance over the risks, costs, and inconvenience of months of anticoagulation. There have been no clinical trials to guide clinicians, but CHEST has published cautious recommendations in 2016 and 2021 endorsing surveillance for select patients.

Study investigators sought to determine 2 primary outcomes, the first of which being the prevalence of structured surveillance without anticoagulation and the second being the commonness of surveillance eligibility among 2 groups: those with lower-risk subsegmental PE and all patients with subsegmental PE.

There was a total of 666 outpatients with acute subsegmental PE included in the study, but the researchers examined the 229 with lower-risk characteristics. Of those 229 patients, 223 (97.4%) received anticoagulation initially and 203 patients (88.6%) had follow-up with the anticoagulation management service within 1 week.

The investigators identified only 1 patient (0.4%; 95% CI, 0.01%-2.4%) among the lower-risk cohort who underwent a guideline-recommended regimen of structured surveillance. Additionally, of the 229 patients who had lower-risk characteristics, 35 (15.3%) were eligible for structured surveillance in accordance with the modified CHEST criteria, which represents 5.3% of the full subsegmental PE cohort.

After applying enhanced CHEST criteria by adding age and clot number limitations, only 15 patients (6.6%) with lower-risk characteristics were eligible for surveillance, which represents 2.3% of the full cohort. Using their modified CHEST criteria, the investigators reported characteristics of patients who were and were not eligible for structured surveillance without anticoagulation. Compared with patients who were ineligible, the surveillance-eligible group was younger, had a lower frequency of comorbidities, and had a greater proportion of patients with low-risk PE.

There were multiple reasons the investigators discussed for the limited uptake. First, the exclusion criteria for structured surveillance are extensive, which makes the pool of eligible patients small and make implementation of guideline recommendations challenging. Additionally, specialty recommendations may be unfamiliar to primary care and emergency medicine clinicians who diagnose most cases of subsegmental PE in the Untied States.

Building off that point, surveillance contravenes the long-established procedure of anticoagulating PE unless contraindicated. Well-established practice patterns can be difficult to overturn, and if new trials of structured surveillance support the practice, a focused effort will be necessary to translate it into routine clinical practice, the study authors wrote.

Some limitations of the study exist that are inherent to its retrospective nature, which the researchers attempted to mitigate by adhering to established guidelines for medical record review-based studies. Further, the investigators wrote that their approach to surveillance was conservative and noted their limited 5-year period for the study.

“Although trials are ongoing to define which patients with subsegmental PE can safely undergo surveillance, widespread uptake of any new surveillance practice will require more than passive diffusion,” the study authors concluded.


Rouleau SG, Balasubramanian MJ, Huang J, et al. Prevalence of and eligibility for surveillance without anticoagulation among adults with lower-risk acute subsegmental pulmonary embolism. JAMA Netw Open. 2023;6(8):e2326898. doi:10.1001/jamanetworkopen.2023.26898

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