Question: Reviewing the STEMI bypass protocol I noticed that it requires 2mm of elevation in V1-V3 in two contiguous leads and 1mm of elevation in any other contiguous leads.
My question is then twofold:
1. What's different about V1-V3 that we require 2mm of elevation?
2. Why is V3 included in this since it is not anatomically contiguous with V1 or V2? Should then V4 not be included to give a "partner" to V3?
Thanks for your help!
The criteria for 2 mm of elevation in V1-V3 is derived by the Cardiac Care Network from evidence based guidelines including the American Heart Association and the European Society of Cardiology. There are actually a variety of different criteria for the degree of ST elevation depending on sex and age and lead. These criteria are there to reduce the false positive rate and to prevent people who dont have a STEMI from going to the PCI centre. To simplify, a decision was made to use 2mm of STE in V1-V3 in two contiguous leads, or 1mm of STE in any other contiguous lead for all ages and sex.
Traditionally, V1 and V2 are thought of as septal leads while V3 and V4 are thought of as anterior leads. However, a STEMI does not know about these anatomic divisions, and may actually be antero-septal, or involve even more myocardium. In those situations, V2 and V3 may actually be contiguous, since there is no real anatomic border between them. Therefore, the criteria that there needs to be at least 2 mm of ST elevation in V1-3 in two contiguous leads just means that either V1 and V2, or V2 and V3 have at least 2 mm of ST elevation.