Editorâs note: We asked columnist Tom Bouthillet to pick a winner to this monthâs challenge and he wrote: âWinner of July 2011 EMS 12-Lead ECG Challenge is paramedictroy with honorable mention to codestemi for bringing up the EMRAP podcast on the topic and mrtomsr for his well thought-out comment. Itâs always hard to single out one comment above the others but paramedictroy picked up on the relevant ECG features of the case, considered the possibility of a high risk lesion in the LMCA but also realizes this pattern could also be due to 3-vessel disease and that the patient might also require CABG. Read their diagnoses in the comment block.
Havenât read the initial case presentation? Read: ECG Challenge: Just a little depression
Letâs take another look at the patientâs 12-lead ECG.
Now with the computerized interpretation.
This 12-lead ECG shows lots of ST-depression and looks particularly bad in lead II.
Hereâs lead II âflipped.â
When lead II is âflippedâ it looks like a STEMI. Whenever I see ST-depression like this it makes me very suspicious that Iâm dealing with something serious.
Now that weâve identified some scary looking ST-depression on the ECG we should go hunting for ST-elevation.
You should always think reciprocal changes first and ischemia second!
Do we see any ST-elevation on this ECG? At first it doesnât seem like it but in fact two leads show ST-elevation: aVR and V1. Remember lead aVR? The forgotten lead that serves no apparent purpose? When you have ST-elevation in lead aVR and widespread ST-depression thereâs an excellent chance the patient is suffering from a high-risk coronary lesion.
This pattern is often cited as being specific for left main coronary occlusion. However, others argue that patients with left main coronary occlusion die very quickly and this pattern really signifies widespread subendocardial ischemia.
Widespread subendocardial ischemia could be caused by an occlusion of the left main coronary artery (LMCA) but it could also be caused by an occlusion of the proximal left anterior descending artery (LAD) or â3-vessel diseaseâ â coronary artery disease in the three main epicardial coronary arteries â the right coronary artery (RCA), the left anterior descending (LAD) and the circumflex artery (LCX).
Rokos et al. recently published an article in the American Heart Journal entitled Appropriate Cardiac Cath Lab activation: Optimizing electrocardiogram interpretation and clinical decision-making for acute ST-elevation myocardial infarction that proposes several additions to the ACC/AHA STEMI guidelines.1
They argue that several different ECG patterns should be considered âSTEMI equivalentsâ even though they donât meet the conventional STEMI criterion of 2 mm of ST-elevation in two or more contiguous leads. One of the STEMI equivalents they list is ST-depression â„ 1 mm in 6 or more leads with ST-elevation in lead aVR â„ V1.
So, would it be appropriate to call a âSTEMI Alertâ based on this ECG? In my opinion, yes! When you have clinical correlation an ECG like this one should be considered a STEMI until proven otherwise. That means either bypassing the local non-PCI hospital for a hospital with a cath lab and open heart surgery or a pre-alert so the hospital knows that you are in-bound with a high risk patient. Many will end up receiving coronary artery bypass.
References:
1) Rokos IC, French WJ, Mattu A, Nichol G, Farkouh ME, Reiffel J, Stone GW (December 2010). âAppropriate Cardiac Cath Lab activation: Optimizing electrocardiogram interpretation and clinical decision-making for acute ST-elevation myocardial infarctionâ. Am Heart J 160 (6): 995â1003.e8
