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Likelihood Ratio (LR) in Emergency Medicine

1/15/2013

Useless ECG?


Clinical Scenario

A 67 y/o man arrives to the ED by ambulance because of precordial pain since half an hour, during the transport, paramedics perform an ECG that shows a left bundle branch block (LBBB), that patient refers in his history.




They find it unuseful and so they do not transmit it to the cardiologist, is it correct?












Conclusion

When read with passion and deep attention ECG may tell us much more than what we believe, this passion made Sgarbossa find that some modifications are associated with AMI in patient with chest pain and previously known LBBB. As it shows in the images, the most significant is the presence of ST elevetion (STE) >1mm that is concordant with QRS in any derivation, followed by ST depression (STD) >1 mm in lead V1, V2, V3; the presence of this two signs increase significantly the likelihood of AMI.
On the other and the absence of any of the signs studied does not rule out AMI. 


Bibliography

S. Serge Barold et al
Electrocardiographic Diagnosis of Myocardial Infarction during Left Bundle Branch Block 
Cardiol Clin 24 (2006) 377–385 

Sgarbossa EB et al
Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle branch block. 
New Engl J Med 1996;334:481–7. 

McMahon R et al
Left bundle branch block without concordant ST changes is rarely associated with acute coronary occlusion.
Int J Cardiol. 2012 Apr 30. [Epub ahead of print]

http://lifeinthefastlane.com/ecg-library/basics/sgarbossa/

http://youtu.be/jGQajcVgYPM


Ilenia Spallino

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