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Syncope in PE – More Evidence for a Lower Prevalence.

September 9, 2019

Written by Bo Stubblefield

It’s my pleasure to introduce Bo Stubblefield, new EM faculty member and research fellow with an interest in VTE. Welcome to JF! ~Clay

Spoon Feed
Pulmonary embolism is an uncommon cause of syncope among patients presenting to the ED.

Why does this matter?
Syncope is a common ED presentation, and possible diagnoses run the gamut from relatively benign to potentially life-threatening. In the setting of PE, syncope has been shown to have worse short-term outcomes (1). Existing literature provides conflicting estimates of prevalence, and few studies provide long-term follow-up data (2-6). This begs the question: What is the true prevalence of PE in patients presenting to the ED with syncope, and what is the incidence of PE if we follow these patients over a long period of time? Have we missed PEs in these patients at 1 year? 2 years? 

Not all that syncopizes….is a PE
Previously reported prevalence – A Brief Lit. Review…

  • 2016 NEJM – PESIT Investigators report prevalence of 17% of PE in patients hospitalized with syncope (2)

  • 2017 Am J Emerg Med – 1.4% prevalence in all patients presenting to the ED with syncope (3)

  • 2018 JAMA Int. Med – <1% prevalence in all patients presenting to ED with syncope and <3% in all hospitalized patients (4)

  • 2018 Am J Emerg Med – Systematic review and meta-analysis showing pooled prevalence of 0.8% in ED syncope patients and pooled prevalence of 1.0% in hospitalized patients (5)

  • 2019 Annals of EM – 0.6% prevalence of PE in all syncope patients presenting to ED with syncope (6) 

What did these investigators have to say?

This was a prospective, multicenter international study conducted by the BASEL IX (BAsel Syncope EvaLuation) investigators who assessed the prevalence of PE in syncope patients presenting to the ED as well as the incidence of new PEs or cardiovascular death over a 2-year period. 1,397 patients were enrolled.  The authors used a 2-level Wells score as clinical pre-test assessment in conjunction with a D-dimer to rule out PE in low-risk patients, with remaining patients undergoing CTPA or V/Q scan. There was a subset of patients who were observed and did not receive imaging.

Prevalence of PE was reported at 1.4%, and long-term follow-up in 1,380 of patients (99%) at 1 year and 1,156 patients (83%) at 2 years showed only 0.9% incidence of new PE or cardiovascular death.

From cited article, Figure 1

From cited article, Figure 1

The authors concluded that PE is a rather uncommon cause of syncope among ED patients and, “systematic PE-screening does not seem warranted.” Additionally, the incidence of new PEs at two years was very low. As always, context and characteristics of syncope such as a patient’s age, history of syncopal events, and relevant co-morbidities should inform our clinical gestalt and workup.

Another Spoonful

Prevalence of Pulmonary Embolism in Patients With Syncope. J Am Coll Cardiol. 2019 Aug 13;74(6):744-754. doi: 10.1016/j.jacc.2019.06.020. 

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Works Cited:

  1. Impact of syncope and pre-syncope on short-term mortality in patients with acute pulmonary embolism. Eur J Intern Med. 2018 Aug;54:27-33. doi: 10.1016/j.ejim.2018.04.004. Epub 2018 Apr 11.

  2. Prevalence of Pulmonary Embolism among Patients Hospitalized for Syncope. N Engl J Med. 2016 Oct 20;375(16):1524-1531.

  3. Prevalence of pulmonary embolism in patients presenting to the emergency department with syncope. Am J Emerg Med. 2018 Feb;36(2):253-256. doi: 10.1016/j.ajem.2017.07.090. Epub 2017 Jul 31.

  4. Prevalence of Pulmonary Embolism in Patients With Syncope. JAMA Intern Med. 2018 Mar 1;178(3):356-362. doi: 10.1001/jamainternmed.2017.8175.

  5. Prevalence of pulmonary embolism in patients presenting with syncope. A systematic review and meta-analysis. Am J Emerg Med. 2018 Apr;36(4):551-555. doi: 10.1016/j.ajem.2017.09.015. Epub 2017 Sep 14.

  6. Prevalence of Pulmonary Embolism Among Emergency Department Patients With Syncope: A Multicenter Prospective Cohort Study. Ann Emerg Med. 2019 May;73(5):500-510. doi: 10.1016/j.annemergmed.2018.12.005. Epub 2019 Jan 26.

  7. Pulmonary Embolism in Patients With Syncope: Horse or Zebra? J Am Coll Cardiol. 2019 Aug 13;74(6):755-758. doi: 10.1016/j.jacc.2019.04.070.

Reviewed by Clay Smith and Thomas Davis

What are your thoughts?