I have heard many times in the past this awful statement: “Why shouldI do a 12-lead, he has a paced rhythmand thus I can’t see an MI”. Well that is very inaccurate. We can use Sgarbossacriteria for determining MI in the presence of LBBBor paced rhythm.
The criteria (Sgarbossa) that can be used in case of a LBBBand suspicion of infarction are:
- ST elevation > 1mmin leads with a positive QRScomplex (concordance in ST deviation) (score 5)
- ST depression > 1 mm in V1-V3(concordance in ST deviation) (score 3)
- ST elevation > 5 mm in leads with a negative QRScomplex (inappropriate discordance in ST deviation) (score 2). This criteriais sensitive, but not specific for ischemia in LBBB. It is however associated with a worse prognosis, when present in LBBBduring ischemia.
At a score-sum of 3, these criteria have a specificity of 90% for detecting a myocardial infarction
I understand that this holds very little weight as medics in the field, but knowledge is power and when teaching a 12 lead class this should be mandatory instruction. Here are some links to some videos that illustrate this.