I don't have enough experience in the ED to have seen this myself, but apparently a patient presenting to the ED with new-onset atrial fibrillation (a-fib) is considered to be a possible pulmonary embolism (PE) patient. The Emergency Medicine literature is chock full of claims that this is a proven association, but tracking down the sources of this "fact" is tricky. There is a tremendous amount of cross-referencing in these articles, which upon closer inspection appears to have resulted in an absurd degree of assumption based on scant data.
Here's a relatively recent study:A Diagnosis of Pulmonary Embolism
Martins L, Reiss I
J Emerg Med. 2004 Feb;26(2):225-7.
New onset A-fib and signs of acute cor pulmonale occur anywhere from 15-26% in patients with pulmonary embolism
This study quotes two sources for that data, both of which are review articles. One gives no reference for that particular "fact." Here's a quote from the other:The electrocardiogram in acute pulmonary embolism.
Prog Cardiovasc Dis. 1975 Jan-Feb;17(4):247-57.
Stein PD, Dalen JE, McIntyre KM, Sasahara AA, Wenger NK, Willis PW 3rd.
Electrocardiograms of 90 patients with arteriographically documented acute submassive or massive pulmonary embolism and no associated cardiac or pulmonary disease were studied. ... None of the patients had atrial flutter or atrial fibrillation, which appears to occur more typically in patients with pulmonary embolism who have preexistent cardiac disease.
Now, how did Martins & Reiss conclude from this that a-fib was a sign of PE??? Evaluation of the references of many studies claiming this association yields similar results: studies quoting reviews quoting studies that don't actually show such an association.
Quite to the contrary, legitimate, large-scale studies demonstrate no such association:Diagnostic value of the electrocardiogram in suspected pulmonary embolism.
Am J Cardiol. 2000 Oct 1;86(7):807-9, A10.
Rodger M, Makropoulos D, Turek M, Quevillon J, Raymond F, Rasuli P, Wells PS.
In this study of 212 patients with suspected PE, the association between a-fib and PE was P=0.403, i.e., not significant; not even close.
It would appear, then, that a-fib is not</I> a legitimate reason to go on a wild PE-hunt. On the other hand, there is good reason to believe that a-fib may in fact cause</I> PE, in the exact same way that it produces systemic embolism/stroke.