Pulmonary embolism (PE) is rarely identified in patients with syncope, and although PE should be considered in every patient, not all patients should undergo evaluation for PE, a recent study found. The retrospective, observational study analyzed data from 5 databases from 4 different countries (Canada, US, Denmark, and Italy) with data from all adult patients who presented to the emergency department (ED) screened to identify those with syncope codes at discharge. Researchers found:
- 1,671,944 unselected adults who presented to the ED for syncope were included.
- The prevalence of PE ranged from 0.06% to 0.55% for all patients and from 0.15% to 2.10% for hospitalized patients.
- The prevalence of PE at 90 days of follow-up ranged from 0.14% to 0.83% for all patients and from 0.35% to 2.63% for hospitalized patients.
- The prevalence of venous thromboembolism at 90 days ranged from 0.30% to 1.37% for all patients and from 0.75% to 3.86% for hospitalized patients.
Costantino G, Ruwald MH, Quinn J, et al. Prevalence of pulmonary embolism in patients with syncope. [Published online ahead of print January 29, 2018]. JAMA Intern Med. doi:10.1001/jamainternmed.2017.8175.
Understanding the likelihood of pulmonary embolus in patients presenting with syncope has become quite confusing. While pulmonary embolus has always been on the differential for syncope, it has generally been believed to be a cause only when the pulmonary embolus was very large, leading to a sudden hemodynamic shift causing decreased blood flow to the brain, and therefore not terribly challenging to diagnose. Last year, the Pulmonary Embolism in Syncope Italian Trial (PESIT) reported results of a standardized evaluation of syncope using a standardized algorithm to look for PE in all hospitalized patients after a first syncope episode. The study found a 17% prevalence of PE.1 This prevalence is much greater than that seen in practice. The current study has attempted to reconcile this variation between the new data generated by a standardized approach and most of our experience by looking at a large real-world data set to determine the prevalence of PE in patients evaluated for syncope. The strength of the current study is that the 90-day follow-up data means that it is unlikely that significant venous thromboembolic disease was missed during the hospital admission if it did not show up in 3 months of follow-up. The prevalence of syncope in this study was much lower, around 1% of all patients evaluated for syncope. The danger of a standardized diagnostic algorithm to identify PE in all patients presenting with syncope is that PE may be overdiagnosed, with discovery of both false-positives and non-clinically significant sub-segmental pulmonary emboli, with subsequent risk of unnecessary anticoagulation. — Neil Skolnik, MD
- Prandoni P, Lensing AWA, Prins MH, et al; PESIT investigators. Prevalence of pulmonary embolism among patients hospitalized for syncope. N Engl J Med. 2016;375(16):1524-1531. doi:10.1056 /NEJMoa1602172.
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