Look at the below link to NEJMs “Quick Take” and article. The results of this study seem practice changing, but probably are not (see analysis below).

Article:
http://www.nejm.org/doi/full/10.1056/NEJMoa1602172?query=TOC

Quick Take:
​http://www.nejm.org/do/10.1056/NEJMdo005093/full/?query=TOC

Prospective study. 11 Italian hospitals, 560 patients presenting with first syncope. All underwent CXR, ECG, Well’s Score assessment and D-Dimer testing (not age adjusted, as far as I can see). 

A total of 560 patients (mean age, 76 years) were included in the study. 

• Pulmonary embolism was ruled out in 330 of the 560 patients (58.9%) on the basis of the combination of a low pretest clinical probability of pulmonary embolism and negative d-dimer assay. 
• Among the remaining 230 patients, pulmonary embolism was identified in 97 (42.2%). 
• In the entire cohort, the prevalence of pulmonary embolism was 17.3%.
• Evidence of an embolus in a main pulmonary or lobar artery or evidence of perfusion defects larger than 25% of the total area of both lungs was found in 61 patients.
• Pulmonary embolism was identified in 45 of the 355 patients (12.7%) who had an alternative explanation for syncope and in 52 of the 205 patients (25.4%) who did not.
• Of the 97 patients with pulmonary embolism, 24 (24.7%) had no clinical manifestations of the diagnosis, including tachypnea, tachycardia, hypotension, or clinical signs or symptoms of deep-vein thrombosis.

Conclusion:
Pulmonary embolism was identified in nearly one of every six patients hospitalized for a first episode of syncope.

Analysis (based on blog by Rory Spiegel​ on EMCrit):

• This is not a cohort of 97 pulmonary embolisms in 560 patients as it has been portrayed. Rather this was 97 (3.8%) radiographic pulmonary embolisms in 2584 patients presenting to the Emergency Department for a syncopal event. 
• Only the patients admitted to the hospital after an Emergency Department workup for syncope were enrolled into the PESIT cohort.
• The majority of patients presenting to the Emergency Department were discharged home without further workup. 
• This means 1 in 26 patients presenting to the Emergency Department will have a pulmonary embolism found on imaging. The large majority of these will be incidental findings and the remainder will be clinically obvious.

To quote the conclusion of Rory Spiegel’s blog on EMCRit:
"There are times when our clinical experience is misleading. When empiric evidence should call into question our long standing practice patterns. But there are times when the evidence is in such conflict with our shared experience, there is nothing to be done but to questions its validity. There is no doubt that these results will be misinterpreted over the next few days, weeks and years. We will now be tasked with performing invasive diagnostic workups in patients with no clinical signs or symptoms of pulmonary embolisms. Any Emergency Physician will tell you not to order a CTPA on a patient in whom you do not wish to know the results. Likewise, do not order a D-dimer in a patient who you have no intention of acquiring further imaging. Prandoni et al have perpetrated the systematic equivalent of this diagnostic absurdity. To translate these results into meaning that all patients presenting to the Emergency Department after a syncopal event require a work-up for pulmonary embolism is not only statistical hoodwinkery, but is just bad medicine. These patients will be exposed to needless and harmful downstream workups, radiation and anticoagulation. We have chased the ghost of Pulmonary Embolism far beyond the reaches of good clinical practice. And this quixotic quest has left a path of over-diagnosis and unnecessary treatments in its wake. At some point someone has to stop this madness. I offer that time is here and now”.

Maybe not so practice changing after all. 
​
Danny Ben-Eli