Access this new clinical calculator
February 1, 1998 less than 1 minute read
Access this new clinical calculator
A clinical prediction tool that uses EKG to rule in acute myocardial infarction (AMI) in patients with left bundle-branch block (LBBB) is posted on the Internet.
An EKG is generally not useful in making a diagnosis of AMI in LBBB because the condition obscures findings. A newly developed calculator helps speed evaluation in this confounding situation with greater than 90% specificity and 36% to 78% sensitivity, allowing for more effective use of coronary reperfusion therapies.
For more information, access the following page on the Internet: http://www.medscape. com/Home/MedPulse/112697.html#20. There are three choices regarding ST-segment elevation. Click the appropriate box, and then click on "Calculate."
Two researchers looked at an analysis of GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) data and found that this EKG criteria were of independent value in predicting AMI in the presence of LBBB:
• ST-segment elevation>=1 mm and is concordant with QRS axis.
• ST-segment depression>=1 mm in lead V1, V2, V3.1
• ST-segment elevation>=5 mm and is discordant with QRS axis.
Their algorithm assigns a point score to each positive finding on the basis of its odds ratio and uses the combined score to determine the likelihood of AMI.
Reference
1. Sgarbossa EB, Pinski SL, Barbagelata A, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. N Engl J Med 1996; 334:481-487. t
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