International Ongoing Study Finds Low Prevalence of PE in Patients Presenting to the ER with First Time Syncopal Episode Study Demonstrates Low Incidence of Pulmonary Embolism In Patients Presenting with Syncope to The Emergency Department

Amandeep Singh, M.D.
By Amandeep Singh, M.D. on

In an ongoing diagnostic multicentric prospective study being conducted to evaluate and improve the management of patients in the emergency room (ER) presenting with syncope, an analysis was done to look for the prevalence of pulmonary embolism (PE). Results of the analysis performed by Patrick Badertscher et al were recently published in JACC  and it was found that PE was uncommon in patients admitted to the ER and hence does not need screening in patients presenting with syncope.

The investigators wanted to perform this analysis because previous studies were unclear about the prevalence of PE in patients who presents to the ER with syncope. An Italian study, PESIT (Pulmonary Embolism in Syncope Italian Trial) claimed PE to be a common cause (1 in 6) of syncope in patients presenting to the ER. The investigators also tried to asses the clinical significance of small perfusion defects on CT pulmonary angiography (CTPA).

“This study has important methodological strengths that differentiate it from previous studies on the prevalence of PE in syncope patients: prospective design, global representation of patients, and long-term follow-up. Although not all patients underwent a systematic workup for PE with imaging modalities, we were able to determine whether PE was diagnosed in the subsequent time period in 99% and 83% of patients at 360 and 720 days, respectively, after their ED visit. We would expect clinically relevant PE accounting for syncope to manifest itself during the 720-day follow-up period.” -Dr. Patrick Badertscher, M.D.

BASEL IX (Basel Syncope Evaluation Study) is being conducted in 3 regions as an ongoing multicentric prospective diagnostic study and the analysis by Patrick Badertscher et al included patients older than 40 years of age, who have had provided informed consent and presented to the ER within 12 h of first time syncopal episode. Patients who received anticoagulation therapy were excluded from the analysis. The recruited patients (1397), were assessed clinically and their D-dimer levels were measured along with 2-level Wells score. Patients were followed up for 2 years and the diagnosis of PE was made on a positive CTPA and V/Q scan. For continuous variables, the Mann-Whitney U test was done while categorical variables were analyzed by Pearson chi-square and Fischer exact test.

In the 1397 analyzed patients, prevalence of PE at presentation to the ER was 1.4% (95% CI: 0.87 to 2.11) and the incidence of new pulmonary emboli and cardiovascular deaths during the 2-year follow-up was 0.9% (95% CI: 0.5 to 1.5). In patients hospitalized for syncope and patients hospitalized for a first syncopal episode, the prevalence slightly increased to 2.3% and 4.3%, respectively. The diagnostic yield of imaging for PE in syncope patients was 14%  with CTPA or V/Q scans (95% CI: 9 to 22). It was 16% (95% CI: 9 to 25) in hospitalized patients and 29% (95% CI: 15 to 46) in those hospitalized for a first episode of syncope. It is also important to note that the hospitalization rate among the 13 centers in 3 regions was highly variable and ranged from 28% to 87%.

“The third side of the PESIT versus BASEL IX story might involve applying the best attributes of each study in our daily clinical practice. For patients with the first-time syncope, a minimal workup for PE with a clinical probability assessment and D-dimer makes sense. If this workup points to a high probability for PE, imaging should be obtained. In the current era, where the threshold for being hospitalized is high, first-time syncope patients should be worked up for PE even if they are going to be discharged home after ED evaluation. Perhaps the relation between syncope and PE is best described as the “progeny of a horse and a zebra.”-Dr. Samuel Z. Goldhaber M.D.


The study done by Patrick Badertscher et al had some limitations. It was based on the ER patients and cannot be generalized to other settings, such as in primary care. Patients presenting after 12 h were excluded and therefore, were not be analyzed. Longer follow-up period and exclusion of patients receiving anticoagulation may have overestimated the true prevalence.

Dr. Samuel Z. Goldhaber, in his editorial comments, mentions the clinical significance of both studies for estimation of PE, “The third side of the PESIT versus BASEL IX story might involve applying the best attributes of each study in our daily clinical practice. For patients with the first-time syncope, a minimal workup for PE with a clinical probability assessment and D-dimer makes sense. If this workup points to a high probability for PE, imaging should be obtained. In the current era, where the threshold for being hospitalized is high, first-time syncope patients should be worked up for PE even if they are going to be discharged home after ED evaluation.”

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