Few Eligible for Surveillance Without Anticoagulation Among Those With Subsegmental Pulmonary Embolism

Published on: 

This new research indicates that while there are ongoing trials seeking to define which individuals with subsegmental PE may be surveilled, greater uptake of newer surveillance actions may necessitate more than passive diffusion.

Only a limited number of individuals that have subsegmental pulmonary embolism (PE) are suitable for structured surveillance, according to recent findings, and patient adherence to the American College of Chest Physicians (CHEST) guideline for structured surveillance continues to be infrequent.1

These findings were the result of a study examining the frequency of structured surveillance use in community practice without anticoagulation for those with subsegmental pulmonary embolism, as well as to find how many could be candidates for structured surveillance with a modified CHEST criteria.

The authors of the American College of Chest Physicians (CHEST) indicated in the 2016 CHEST guideline and expert panel report that structured surveillance without anticoagulation should be used for ambulatory patients, and this was reiterated by the later 2021 CHEST guideline and expert panel report as well as the European Society of Cardiology and a multispecialty panel of VTE experts.2,3,4

The research was authored by David R. Vinson, MD, from the Department of Emergency Medicine at Kaiser Permanente Roseville Medical Center in Roseville, California.

“To test these 2 hypotheses, we undertook a cohort study of patients with lower-risk subsegmental PE to determine the prevalence of structured surveillance in a community-based setting and to ascertain hypothetical eligibility for surveillance based on modified CHEST criteria,” Vinson and colleagues wrote.

Background and Findings

The investigators used a retrospective cohort study design, and the trial took place in 21 community hospitals that had been within the Kaiser Permanente Northern California integrated health system. The team’s research took place from January of 2017 to December of 2021.

The period of data analysis by the investigators occurred from November of 2022 to February of 2023.The participants in the research team’s work were adult outpatients who had reported acute subsegmental pulmonary embolism.

The individuals recruited for the team’s study with higher-risk characteristics such as vital signs which indicated non-low risk (e.g., pulse ≥110 bpm, systolic blood pressure <90 mm Hg, or peripheral cutaneous pulse oximetry ≤92%), certain specific co-diagnoses necessitating hospitalization, previous utilization of anticoagulants prior to diagnosis, or under hospice care were excluded from the research.

The investigators’ primary objectives were to first determine the prevalence of surveillance use and, second, the suitability for surveillance through the use of 2 unique sets of specific criteria. The first criteria set was based upon a modified CHEST criteria, and it excluded those with either higher-risk characteristics or right ventricular dysfunction.

The second was a more stringent set of criteria and required involved patients to be younger than 65 years old and for them to have no more than a single embolus. The research team calculated structured surveillance occurrences and also determined through estimation the proportion of participants meeting the criteria for surveillance.

Overall, the investigators reported that a total of 666 outpatients with diagnoses of acute subsegmental pulmonary embolism were enrolled in the study. Among this group, 229 participants exhibiting lower-risk characteristics were determined to be suitable for their analysis.

The research team reported the median age of the subgroup to be 58 years, with an interquartile range of 42 - 68 years. Just over half of the participants were male, at 52.4%, and 55.9% self-identified as being non-Hispanic White.

At first, the team found that 2.6% of participants were not given anticoagulant treatment. Within the lower-risk cohort, the investigators found that only a single patient (0.4% [95% confidence interval: 0.01% - 2.4%]) was given structured surveillance, and this person did not report experiencing any sequelae over a 90-day timeframe

Among those in the lower-risk arm of the study, 15.3% of the participants and 5.3% of the total cohort were shown to have met the criteria for surveillance eligibility based on the modified CHEST criteria. Additionally, the investigators noted that the stricter criteria identified 15 individuals—6.6% of the lower-risk group and 2.3% of the total cohort—as being eligible for surveillance.

“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,” they wrote.


  1. Rouleau SG, Balasubramanian MJ, Huang J, Antognini T, Reed ME, Vinson DR. 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.
  2. Kearon C, Akl EA, Ornelas J, et al. Antithrombotic therapy for VTE disease: CHEST guideline and expert panel report. Chest. 2016;149(2):315-352. doi:10.1016/j.chest.2015.11.026.
  3. Stevens SM, Woller SC, Baumann Kreuziger L, et al. Executive summary: antithrombotic therapy for VTE disease: second update of the CHEST guideline and expert panel report. Chest. 2021;160(6):2247-2259. doi:10.1016/j.chest.2021.07.056.
  4. Konstantinides SV, Meyer G, Becattini C, et al; ESC Scientific Document Group. 2019 ESC guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41(4):543-603.