Chest discomfort and very subtle acute inferior STEMI

A 59 year old male presents to the fire station during a 12-lead ECG class (you can’t make this stuff up) and complains of chest discomfort.

He is anxious, appears acutely ill, and is rubbing his chest. He senses that “something is wrong.”

  • Onset: 30 minutes ago while patient was walking on the beach
  • Provoke: Nothing makes the discomfort better or worse
  • Quality: A “sort of pressure or ache”
  • Radiation: The pain does not radiate
  • Severity: 7/10.
  • Time: A similar episode occurred yesterday but resolved

The patient is placed in the back of the ambulance and undressed from the waist up. Lead placement is supervised by yours truly and is perfect.

Skin is flushed, warm, and diaphoretic.

Vital signs are assessed.

  • RR: 20
  • HR: 60
  • NIBP: 104/44
  • SpO2: 98% on room air

A 12 lead ECG is obtained.

TOMB072809AwmSinus bradycardia with a rate of 54. There is subtle downsloping of the ST-segment in lead aVL. There is a straightening of the ST-segments in leads III and aVF with slight terminal T-wave inversion in lead III. The R/S ratio in lead V2 is < 1 but it doesn’t feel quite right. There is a slight flattening of the ST-segment in lead V2.

As we have described on many occasions, a downsloping ST-segment in lead aVL is often an early sign of acute inferior STEMI! Although this ECG is suspicious it does not meet our prehospital Code STEMI criteria.

The patient was given aspirin. An IV was started, the patient received a 250 ml infusion of 0.9% normal saline, and a single sublingual nitroglycerin spray was administered.

On arrival in the Emergency Department the following 12-lead ECG was obtained.


Sinus rhythm with a rate of 66. Now there is ST-segment elevation in leads II, III, and aVF. Although the ST-segment elevation is minimal the QRS complexes are small (rule of proportionality). There is new ST-segment depression in leads V1 and V2. This ECG is diagnostic for acute inferior-posterior STEMI.

The patient was taken to the cardiac cath lab and was found to have 100% occlusion of the right coronary artery (RCA).

See also:

Importance of lead aVL in STEMI recognition

Cardiac cath lab activation for subtle acute inferior STEMI

Updated 02/23/2016


  • medicblog999 says:

    Well, I think its about time I started giving these a bash too!!Looking at the 12 Lead, I think that the patients inferior leads are starting to show a rise in the ST segment hinting towards a progressing infarct. Nothing definitive yet, but certainly reason to perform serial ECGs en route to wherever you are heading. There is also potentially the start of a reciprocal pattern in aVL.I could be looking a little too closely here, but I wonder if the ST segment in V5 and V6 are also starting on their way up as well. Possibly on their way to a infero-lateral?The only thing I would wonder about is the lack of hyper acute T waves if we are catching the MI so early on.Well, there you go. My ECG Geek status is on the line!!!Certainly one to keep an eye on.

  • Minimal elevation in lead III. Pathological Q in aVF.I'm thinking some hypokalemia though…

  • SoCal Medic says:

    I agree that there seems to be minor changes in III and aVF along with the possibility of the reciprocal in aVL. What I don't like is the poor R Wave progression through the V Leads. My gut says the QRS Complex looks weird (First thing my eyes went to), not sure why though.

  • medic1488 says:

    We could be seeing the development of an inferior/posterior MI or maybe just a normal variant for this patient. As already stated there appears to be some very minimal ST elev. in the inferior leads and depression in high lateral. In V2, although the R:S isnt technically increased yet it is getting close. T waves seem symetrical in several leads also (but to be honest I'm horrible at decidingon symmetry) As Adam noted, U wave that could mean some hypokalemia or may just be because of the bradycardia. Also some possible LAE from the P wave in V1. Overall, with how the patient is presenting regardless of what the 12 lead shows at this point they should be headed towards the cardiac center based on history.

  • SoCal Medic says:

    Agreed, I would want to take him to the hospital affiliated with his cardiologist, and if he is from out of town, suggest a cardiac care center because of the changes on his 12 Lead and presentation.

  • Shaggy says:

    It does look like there is potentially hypokalemia. Is there a history to suspect as much? Either way, what is most pressing to ME is the rising ST elevation in all the inferior leads and the reciprocal change in aVL, as already stated, and of course serial EKGs like I now do for most everyone I do EKGs on. Of course the patient will go to a hospital with PCI capabiiity, but the question is: Is this something that would warrant cath lab activation?

  • SoCal Medic says:

    Shaggy, here locally I would not get the "automatic" activation, as the computer did not give the Acute MI Suspected message. If the patient however, had a significant cardiac history, along with his current presentation, they may ask cardiology to come down during the day, but I doubt I would get the team in at night until serial ones showed evolving changes or the Physician saw the initial.

  • Tom B says:

    You guys are sharp! @medicblog999 I think your ECG Geek status is intact! Solid observations. I especially like that you noticed the downsloping ST segment in lead aVL and the flat ST segment in lead I.@Adam I agree there is minimal elevation in lead III. Is there a pathological Q wave in aVF? Hard to tell with such an isoelectric complex! @SoCal (Christopher) Nice catch with regard to the R wave progression! That's an important piece of the puzzle in this case.@medic1488 The R:S ratio in lead V2 is definitely a clue. You also mentioned bradycardia. What is the most common arrhythmia in acute inferior STEMI? @Shaggy As suspicious as this ECG is, I would not pull the trigger on the cath lab yet, simply because it does not meet the AHA's STEMI criteria! On the other hand, I would still try to divert the patient to a hospital with a cardiac cath lab.I think we're all agreed that we'd be watching this patient carefully and perform serial ECGs!I'll be posting a follow-up ECG taken in the hospital later today if I can locate my thumb drive.Tom

  • SoCal Medic says:

    22 minutes. Nice evolution of changes though. What was the patient outcome at the ED?

  • Tom B says:

    The patient was (eventually) sent to the cath lab. 100% occlusion of the RCA.Tom

  • Looks like I got here too late. How come you're all hiding this from me? You especially Mark!I don't like the way III is going and the R wave progression caught my eye as well.Even if this machine says *NORMAL EKG* I'm lighting it up to a lab facility. Luckily I have many of them.HM

  • Tom B says:

    @THM Better late than never! :)Let's summarize the findings that suggested acute inferior STEMI in the first ECG (albeit subltely).1.) It was sinus bradycardia.2.) There was a loss of upward concavity and ever-so-slight ST-elevation in leads III and aVF.3.) There was a downsloping ST segment in lead aVL and a flattening of the ST-segments in leads I and right precordial leads.4.) There was an apparent increase in R wave amplitude in lead V2, enough to disturb normal R-wave progression.Taken in isolation, any of these findings might not be particularly relevant. But, like Tomas Garcia MD is fond of saying of any ECG abnormality, "consider the company it keeps." The ECG taken in the emergency department should have removed all doubt, although the patient still sat in the ED for an hour before being sent to the cardiac cath lab. In fairness to the ED physician on duty, later ECGs looked more like the first.However, the cardiologist did discover 100% occlusion of the RCA. I even asked him if the RCA was small and non-dominant, and he said no, that it was normal sized. I asked if he could explain why this particular inferior STEMI was so subtle. He said it was an interesting question, but he didn't know the answer. People are just different.I can see where the first ECG looked a bit like hyokalemia (especially the first complex in lead V1). On the other hand, the QTc was only 417 ms. Once again, consider the "company it keeps" and factor in the history and clinical presentation. Good thought, though! Thanks for playing!Tom

  • mariam says:

    inferior wall MI !!

  • saif says:

    i think its inf. MI with possibility of post. MI since v1 ,v2 showing st depreesion

  • AzAm says:

    Guys why dont you make this so complex? Even the house officer can make the diagnosis of Infero posterior STEMI at first glance on this ECG..

  • Tom B says:

    I don’t believe that’s true. The first ECG is suspicious but not a slam dunk, and no one is making it complex. Quite the reverse. It’s the constellation of minor abnormalities that is significant for the first ECG.

  • Zeeshan says:

    TRUE acute STEMI Infero post MI

  • Noman Adel says:

    ACS(infro-posterior MI)

  • On The Road says:

    Tom, your 12 lead traces are always so much cleaner than those my colleagues and I manage to get at work. Is there any chance you could outline how you go about performing a 12-lead in order to minimise interference and artefact?

  • cancer_g says:

    inferoposterior STEMI

  • Troy says:

    STD in aVL with STE in II, III, and aVF. Although its not the criteria of 1mm, using the rule of proportionality it fits an injury pattern BUT I cannot activate the cath lab due to no 1mm of elevation

  • Bertie says:

    Was totally stuck until I read this, now back up and runnnig.

  • Pete says:

    on the road make sure the ecg is set to 40hz not 150hz Phillips mrx anyways

  • William Dillon says:

    Subtle inferior ST elevation. Important to note the mild terminal T wave inversion in 3 and subtle ST depression in AvL.  Does not meet criteria for lytics or activation of the cath lab.  Although with the history and this ECG I would take for urgent cath and likely find a high grade RCA lesion.

  • Ernie says:

    I agreed that this paints a picture of a right sided event. The ST segments in V1 and V2 certainly suggest a posterior event as well. I would flip the ECG around and hold it up to the light and get a look that the posterior elevations as well. This patient needs to go to PCI center. Ernie 🙂

  • Unni says:

    First ECG guide towards inferior MI,rule of proportionality down sloping ST segment in avL support it. Second ecg shows concordant ST depression in lead v2 – inferio posterior STEMI

  • Craig Barraclough says:

    Great car demonstrating the development of STEMI changes and commentary regarding serial ECG showing initial ECG. Keep up the great work.

  • Stuart Henderson says:

    Looks like a developing inferior infarction. With the patient, diaphorectic and feeling like crap, it would be well worth doing rV4 lead to exclude right ventricular invovement

  • Alexandra says:

    did anyone check aVR?

  • Alexandra says:

    sorry V4R

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