Syncope is a well-known initial manifestation of pulmonary embolism (PE)1. However, given the varied causes of syncope, determining the prevalence of PE among patients hospitalized for syncope is important.
A multicenter prospective study2 enrolled 560 patients not already on anticoagulation who were hospitalized for a first episode syncope. Of patients who had either a high pretest probability for PE, positive D-dimer assay or both, PE was diagnosed in 17%, or nearly 1 of 6 of enrolled patients, based on CT or ventilation/perfusion scan. PE was found more frequently among patients with syncope of undetermined cause than those with an alternative explanation (25.4% vs 12.7%).
Another multicenter prospective study (2019), however, found a much lower prevalence of PE (0.6%) among patients evaluated in the ED for syncope, including those who were not hospitalized.3 A related commentary on the article reported a prevalence of 4.1% in the total study population, assuming a “worst-case scenario calculation.” 4
Given these divergent results, perhaps the best advice is to consider PE as cause of syncope in the proper context and minimize over testing when suspicion remains low.
- Thames MD, Alpert JS, Dalen JE. Syncope in patients with pulmonary embolism. JAMA 1977;238:2509-2511. https://www.ncbi.nlm.nih.gov/pubmed/578884
- Prandoni P, Lensing AWA, Prins MH, et al. Prevalence of pulmonary embolism among patients hospitalized for syncope. N Engl J Med 2016;375:1524-31. http://www.nejm.org/doi/full/10.1056/NEJMoa1602172
- Thiruganasambandamoorthy V, Sivilotti MLA, Rowe BH, et al. Prevalence of pulmonary embolism among emergency department patients with syncope: a multicenter prospective cohort study [published online January 25, 2019]. Ann Emerg Med. doi:10.106/j.annemergmed.2018. https://www.annemergmed.com/article/S0196-0644(18)31535-X/fulltext
- Anonymous. Pulmonary embolism uncommon in syncope hospitalizations. Pulmonology Advisor. February 6, 2019. https://www.pulmonologyadvisor.com/pulmonary-embolism-uncommon-in-syncope-hospitalizations/printarticle/832069/
Contributed in part by Rebecca Berger MD, Department of Medicine, Mass General Hospital, Boston, MA
If you liked this post, sign up under MENU and receive future pearls straight into your mailbox!