Prevalence of pulmonary embolism in patients with syncope

Background: The prevalence of pulmonary embolism (PE) in patients presenting with syncope to the emergency department (ED) is largely unknown. This information, however, is necessary to balance the potential medical benefit or harm of systematic PE screening in patients presenting with syncope to the ED. Objectives: This study sought to determine the prevalence of PE in patients with syncope. Methods: Unselected patients presenting with syncope to the ED were prospectively enrolled in a diagnostic multicenter study. Pre-test clinical probability for PE was assessed using the 2-level Wells score and the results of D-dimer testing using age-adapted cutoffs. Presence of PE was evaluated by imaging modalities, when ordered as part of the clinical assessment by the treating ED physician or by long-term follow-up data. Results: Long-term follow-up was complete in 1,380 patients (99%) at 360 days and 1,156 patients (83%) at 720 days. Among 1,397 patients presenting with syncope to the ED, PE was detected at presentation in 19 patients (1.4%; 95% confidence interval [CI]: 0.87% to 2.11%). The incidence of new PEs or cardiovascular death during 2-year follow-up was 0.9% (95% CI: 0.5% to 1.5%). In the subgroup of patients hospitalized (47%), PE was detected at presentation in 15 patients (2.3%; 95% CI: 1.4% to 3.7%). The incidence of new PEs or cardiovascular death during 2-year follow-up was 0.9% (95% CI: 0.4% to 2.0%). Conclusions: PE seems to be a rather uncommon cause of syncope among patients presenting to the ED. Therefore, systematic PE-screening in all patients with syncope does not seem warranted. (BAsel Syncope EvaLuation Study [BASEL IX]; NCT01548352)