The danger is taking this paper at face value! Never has such an important paper in the NEJM required the reader to exercise such caution with interpretation.
These authors looked to find the prevalence of PE among syncope patients who were admitted to hospital from 11 Emergency Departments in Italy. Che bello!
They performed a systematic workup to investigate PE in all of these 560 patients. Patients with low risk by Wells Score were excluded with a negative D-dimer. All others got mostly CTPA’s and a few VQ scans.
The prevalence of PE was 17.3%!
Holy merda! We need to do a lot more CTPA’s in patients with syncope!
Remember, these were elderly patients with syncope admitted to hospital. If we include all patients with syncope (i.e. discharged from the ED) in the denominator the prevalence drops to 3.75%. But we’re still not done...
Of these admitted elderly patients, 40% had clinical signs of DVT, 20% had active cancer, and 10% had prolonged immobility. Is there any surprise that many of these patients might have a PE?
To be fair, there were 31 patients diagnosed with large PE’s that were admitted to hospital with an alternative diagnosis. This is about 5% of admitted patients or 1% of all patients that presented to the ED. Although this percentage is small, it does emphasize that we should continue to think, keep an open mind and avoid diagnosis momentum. But isn’t this what we should always be doing?
In addition, CTPA is not perfect. How many false positives did they have? And how many small PE’s were simple incidental findings that had absolutely nothing to do with their syncope? What is the number needed to kill by finding incidental “PE’s” and putting elderly patients on anticoagulation? What about other incidental findings, over-diagnosis, and contrast induced nephropathy?
Unfortunately none of the above issues were significantly highlighted in this paper. The authors, peer reviewers and journal editors should be ashamed. Fortunately, the NEJM is usually much better than this.
So what should we do?
Well, we should NOT perform indiscriminate CTPA’s on all patients with syncope. This will cause more harm than good. We should investigate PE if we think we should... keep an open mind; especially if they have risk factors and/or clinical signs & symptoms of DVT/PE.
But most of all, we should stai attento to the dangerous conclusions of this paper!
Prandoni P, Lensing A, Prins M, Sambuca Ilove, et al. Prevalence of Pulmonary Embolism among Patients Hospitalized for Syncope. N Engl J Med 2016;375:1524-31.