Risk for Recurrent Venous Thromboembolism in Patients With Subsegmental Pulmonary Embolism Managed Without Anticoagulation : A Multicenter Prospective Cohort Study.

BACKGROUND

The incidence of pulmonary embolism has been increasing, but its case-fatality rate is decreasing, suggesting a lesser severity of illness. The clinical importance of patients with pulmonary embolism isolated to the subsegmental vessels is unknown.

OBJECTIVE

To determine the rate of recurrent venous thromboembolism in patients with subsegmental pulmonary embolism managed without anticoagulation.

DESIGN

Multicenter prospective cohort study. (ClinicalTrials.gov: NCT01455818).

SETTING

Eighteen sites between February 2011 and February 2021.

PATIENTS

Patients with isolated subsegmental pulmonary embolism.

INTERVENTION

At diagnosis, patients underwent bilateral lower-extremity venous ultrasonography, which was repeated 1 week later if results were negative. Patients without deep venous thrombosis did not receive anticoagulant therapy.

MEASUREMENTS

The primary outcome was recurrent venous thromboembolism during the 90-day follow-up period.

RESULTS

Recruitment was stopped prematurely because the predefined stopping rule was met after 292 of a projected 300 patients were enrolled. Of the 266 patients included in the primary analysis, the primary outcome occurred in 8 patients, for a cumulative incidence of 3.1% (95% CI, 1.6% to 6.1%) over the 90-day follow-up. The incidence of recurrent venous thromboembolism was 2.1% (CI, 0.8% to 5.5%) and 5.7% (CI, 2.2% to 14.4%) over the 90-day follow-up in patients with single and multiple isolated subsegmental pulmonary embolism, respectively. No patients had a fatal recurrent pulmonary embolism.

LIMITATION

The study was restricted to patients with low-risk subsegmental pulmonary embolism.

CONCLUSION

Overall, patients with subsegmental pulmonary embolism who did not have proximal deep venous thrombosis had a higher-than-expected rate of recurrent venous thromboembolism.

PRIMARY FUNDING SOURCE

Heart and Stroke Foundation of Canada and French Ministry of Health Programme Hospitalier de Recherche Clinique.