Pulmonary embolism (PE) is not common in individuals who present with syncope in emergency departments, according to a study published in the Annals of Emergency Medicine. This suggests that physicians need not give excessive time to investigating for PE, although it is sometimes a cause of syncope.

This study included 9091 individuals with syncope from 2 prospective studies ranging across 17 Canadian and US emergency departments. Eligibility criteria included visiting the emergency department within 1 day of a true syncope event. Results from PE-related examinations were recorded and included computed tomography pulmonary angiogram (CTPA) or ventilation-perfusion or D-dimer scan. In addition, records of outcomes within 1 month were collected, including mortality, acute hemorrhage, arrhythmia, myocardial infarction, or PE. The primary outcome was the identification of PE within 1 month of the index visit as having caused the syncope. An estimate of possible undetected PE in the unevaluated group was calculated via a sensitivity analysis.

Investigation for PE took place in 6.0% (n=547) of participants. Of these, 278 were given D-dimer scan, 39 were given ventilation-perfusion scan, and CTPA was administered to 347. Serious outcomes within 1 month occurred in 9.6% (n=874) of participants, non-PE serious outcomes occurred in 9.0% (n=818), and 0.9% died. A diagnosis of PE was assigned to 0.6% (95% CI, 0.5%-0.8%; n=56) of cases and 8 went to the hospital for index syncope. An underlying PE was identified in 11 participants with non-PE serious conditions. There was no difference in PE prevalence in subgroup analysis categorized by 60-year age threshold, syncope vs presyncope, or country. A worst-case scenario calculation resulted in 4.1% (95% CI, 3.7%-4.5%) of the total study population as potentially having PE.

Limitations to this study included potential verification bias, a lack of recorded risk factors, difference in the 2 countries’ cohorts, and no D-dimer measurements were recorded for patients in the United States.

The researchers concluded that “the prevalence of [PE] is very low among patients presenting to the [emergency department] with syncope, including among those hospitalized for syncope. Although [PE] can certainly cause syncope and in the right context should be suspected and investigated diligently if clinically appropriate, caution should also be used in regard to indiscriminate or dogmatic over investigations for [PE] after syncope.”

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Reference

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:10.1016/j.annemergmed.2018