Background: CT pulmonary angiography (CTPA) often detects distal, subsegmental pulmonary embolisms (SSPE) for which there is unclear clinical significance. For these isolated SSPEs, the 2016 CHEST guidelines recommend clinical surveillance in lieu of treatment. Such clinical surveillance has not been associated with an increased recurrence of venous thromboembolism (VTE) over 3 months.
Study design: Retrospective review.
Setting: Tertiary care center in Quebec.
Synopsis: A review of all CTPAs at McGill University in Montreal, from 2014-2016 yielded 222 acute pulmonary emboli (PEs), 71 of which were SSPEs without associated Doppler imaging positive for deep vein thrombosis. Of those 71, 62 (87%) were systemically anticoagulated, compared with 135/143 (94%) of the more proximal PEs. The adverse events of both groups of anticoagulated patients were common and similar. Over the following 3 months, 26 patients in the SSPE group visited the ED or were readmitted (42%; 95% confidence interval, 30%-55%), 21 had a drop in hemoglobin level of 2 g/dL or greater and/or received a blood transfusion (34%; 95% CI, 22%-47%), and 10 died from causes unrelated to VTE (16%; 95% CI, 8%-28%). Limitations of this study included the small number of participants and short time to follow-up.
Bottom line: Although SSPEs have unknown clinical significance, they are being treated with systemic anticoagulation at a similar rate to more proximal PEs and are associated with patient harm.
Citation: Raslan IA et al. Rates of overtreatment and treatment-related adverse effects among patients with subsegmental pulmonary embolism..
Dr. Shaw is an assistant professor in the division of hospital medicine, University of New Mexico.