When there is less than 1 mm of ST depression, can you make the diagnosis of posterior OMI?

DiscussionApproximately 10% of OMIs will involve the posterior wall, most of which also have concomitant involvement of the lateral and/or inferior walls (though usually not meeting STEMI criteria). Isolated posterior OMI, however, manifests as STD without associated STE since the subepicardial myocardial ischemia that would normally generate STE on overlying leads is occurring in the opposing or negative vector compared to the recording ECG leads. The majority of isolated posterior OMIs will be due to occlusion of the LCX, RCA, or a variety of their posterior branches.The 4th Universal Definition of Myocardial Infarction defines posterior OMI as STE greater than or equal to 0.5 mm in leads V7-V9 (posterior leads) and only mentions STD in V1-V3 as potentially indicating LCX OMI, though it refers to these findings as " nonspecific. " Posterior leads, however, will not always demonstrate STE of even 0.5 mm even with clear evidence of OMI in standard ECG configuration, since more lung tissue separates the heart from the posterior ECG leads and air is a poor conductor of electricity. It is not surprising, then, that isolated posterior OMIs are often missed and associated with worse outcomes.Teaching Points - Isolated posterior OMI may manifest as STD maximal in leads V1-V4.That STD may be less than 1 mm. Remember that the vast majority of individuals have normal, baseline, non-ischemic STE in V2 and V3 (hence the STEMI " criteria " require 1.5 - 2.5 mm for diagnosis). T...

Source: Dr. Smith's ECG Blog - February 27, 2021 Category: Cardiology Authors: Pendell Source Type: blogs