Since Prandoni et al published their findings in the NEJM's October 2016 issue (reporting a 17.3% incidence of pulmonary embolism among patients admitted with first time syncope), there has been controversy swirling in the EM community. Questions have been raised regarding the impact of this study, its generalizability, and its implications for clinical practice. Specifically, emergency physicians are now wondering whether routine assessment for PE in patients with first time syncope should be universally pursued.

At this month’s journal club, we broke down the findings in the Prandoni study as well as looked at two other studies (Castelli et al and Altinsoy et al) that examined the clinical characteristics of patients with PE who presented with syncope.

PRANDONI ET AL:

While the prevalence of PE among the 560 admitted patients with first time syncope was 17.3% (97 out of 560), 75.3% of those patient had clinical signs or symptoms of VTE. This leaves 24.7% (24 out of 97) patients with clinically “silent” PE. If we look at this in relation to the entire cohort of admitted patients, it is actually 24 out of 560 patients who had no signs of VTE who had PE (4.3%). This number is much less startling than the 17.3% incidence that has been so widely discussed. What was also not discussed was the clinical significance of PE in these 4.3% of patients (size/location/etc).

CASTELLI ET AL AND ALTINSOY ET AL:

Approximately 10-13% of patients with PE will present with syncope. Among those with syncope, there is an increased rate of central PE (83% vs 43%) and increased rates of RV dysfunction and positive troponin assays. However, this did not translate to a statistically significant difference in 30-day mortality.

Summary: The majority of patients (75%) with first time syncope who also have PE, will have clinical signs or symptoms of venous thromboembolism. Furthermore, in patients with syncope as their presenting sign of PE, it is understood that there is an increased rate of central PE (which has been associated with worse outcomes in prior research), as well as RV dysfunction and positive troponin results. Questions that remain include how to identify the small subset of patients with first time syncope who have clinically silent PE and whether these asymptomatic patients had any significant impact on morbidity or mortality from their clot burden.

Written by Christine Hein, M.D.

Edited and posted by Jeffrey A Holmes, M.D.