Introduction: Recently an Italian (PESIT) study reported a 17.3% prevalence of pulmonary embolism (PE) among patients hospitalized for the first episode of syncope; PE was identified in 12.7% of patients non-PE serious conditions; and 25.4% of patients with unexplained syncope had underlying PE. The results of this study suggests that all syncope patients, need to be evaluated for PE including those with a clear non-PE serious condition.

Methods: We plan to conduct a RCT that will randomize ED adult syncope patients for whom PE investigations are not performed, to usual care or mandatory PE work-up. In the ED, if the physician chooses not to perform any investigations for PE, then the patient is eligible to be enrolled in the study after consent. Patients will be enrolled in the study when the disposition decision has been made by the ED physician and randomized using a computer randomization software. There will be allocation concealment; and the ED physician will be blinded to the trial arm allocation. The patient and the research assistant (RA) will not be blinded. Those assigned to the intervention arm will have the PE risk assessed using the PERC, Wells and Geneva tools. If PERC is positive, then d-dimer assay will be ordered. The patient will then be referred to thrombosis/internal medicine clinic for follow-up. Further investigations will be at the discretion of the thrombosis clinic physician.

Outcomes: The primary outcome will be a PE for which treatment with anticoagulation was required or considered. Secondary outcomes will be any PE identified. Telephone follow-up will be performed at 30-days, 90-days and at 1-year.

Questions:

1. Any suggestions regarding the inclusion/exclusion criteria (patients who had PE investigated will be excluded from this sub-study, but these patients will enrolled in the primary multicenter prospective syncope study. Hence, their details will be available. In contrast to the PESIT study, we will include patients even with previous syncope. However, patients will be enrolled only once. And the sample size calculation will be based on patients with first episode of syncope.
2. After enrollment should the patient wait for the d-dimer results, and if positive should we discuss with the ED physician regarding the use of oral anticoagulant.
3. Would you be interested to be a site? Ideally it would be preferable if your site can be also in the implementation phase with REMOSYNC and had abilities for follow-up of these patients in thrombosis clinic.