Monthly 12 Lead Review 

September 1, 2017

Case Information:

A 62 year old male called Paramedics for chest pain. The patient complains of chest discomfort and denies any SOB.

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 Medic and a 12 lead ECG is obtained.

Skin is flushed, warm, and diaphoretic.

Vital signs are assessed.

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

Early inferior STEMI:

  • Hyperacute (peaked) T waves in II, III and aVF with relative loss of R wave height.
  • Early ST elevation and Q-wave formation in lead III.
  • Reciprocal ST depression and T wave inversion in aVL.
  • ST elevation in lead III > lead II suggests an RCA occlusion; the subtle ST elevation in V4R would be consistent with this.

Note how the ST segment morphology in aVL is an exact mirror image of lead III. This reciprocal change occurs because these two leads are approximately opposite to one another (150 degrees apart). 

The concept of reciprocal change can be further highlighted by taking lead aVL and inverting it… see how the ST morphology now looks identical to lead III.



Hospital Feedback:

We can post any hospital feedback that was sent to QAQI about this case.



Clinical PEARLS:

  • Inferior MIs account for 40-50% of all myocardial infarctions.
  • Generally have a more favourable prognosis than anterior myocardial infarction (in-hospital mortality only 2-9%), however certain factors indicate a worse outcome.
  • Up to 40% of patients with an inferior STEMI will have a concomitant right ventricular infarction. These patients may develop severe hypotension in response to nitrates and generally have a worse prognosis.
  • Up to 20% of patients with inferior STEMI will develop significant bradycardia due to second- or third-degree AV block. These patients have an increased in-hospital mortality (>20%).
  • Inferior STEMI may also be associated with posterior infarction, which confers a worse prognosis due to increased area of myocardium at risk.


If you have any questions please feel free to contact Dr. Wendell or an Instructor for EMS Training,

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