Ambulance UK April 2024

FEATURE
5 WAYS TO MISS AN ACUTE
MYOCARDIAL INFARCTION
Jerry W. Jones, MD FACEP FAAEM
1. You stop looking too soon!
If you were at home with your 2½ year old son or grandson and
you suddenly noticed that he wasn’t in the room with you, you
would go looking for him. Let’s say your home has ten rooms. You
check eight rooms, but he isn’t in any of them. Would you stop
looking for him and just assume he’s OK because he wasn’t in any
of those rooms? Of course not! But that’s what too many people
do when they order a 12-lead ECG for a patient with suspicious
chest pain. They fail to “look in all the rooms.” They all too often
take the advice of colleagues who say, “Well, if it’s not on the 12-
lead ECG, you’re probably not going to find it in any of the other
leads!” (I once overheard a resident tell a medical student this!)
Probably? Think about that word for a moment – probably. It’s a
word you use when you don’t know the answer to a question.
If the patient is having chest pain consistent with an acute
coronary syndrome and the initial 12-lead ECG is non-diagnostic
– look in the posterior leads and the right-sided leads. It is NOT
necessary to have an inferior MI for there to be an inferobasal
(formerly posterior) infarction OR a right ventricular
infarction. An occlusion of the left circumflex artery can easily
cause an inferobasal infarction without an inferior infarction. And
did you know that isolated right ventricular infarctions (without
a concurrent inferior infarction) can occur in up to 5% of ALL
myocardial infarctions?
I can remember a number of times when, as the attending
physician coming on-duty in the emergency department, the offgoing
doctor would tell me about a patient with chest pain who
was having a non-STEMI waiting for a CCU bed. The ECG showed
no changes. The ECG? Singular? The first thing I did was to order
a second ECG which occasionally resulted in my alerting the cath
lab immediately.
Bottom Line: If the first ECG is non-diagnostic, yet you are still
suspicious of an acute MI – repeat the 12-lead ECG every 20
minutes for at least 3 times!
3. Adhering to the STEMI paradigm.
OK… this one is a bit controversial because not everyone has
accepted the Occlusion Myocardial Infarction (OMI) concept
(but I certainly do!).
If you aren’t familiar with OMI, it’s an approach to diagnosing
acute myocardial infarctions by looking for evidence of acute
coronary occlusion rather than an arbitrary, fixed deviation of
the ST segment. Adhering to a fixed measurement to decide if a
patient gets emergent reperfusion or medical management has
one major flaw – you’re going to miss an unacceptable number
of complete or near-complete acute coronary occlusions with
transmural ischemia (25 – 30%) which would definitely benefit from
emergent reperfusion.
resulting in STE in Leads I and aVL which oppose simultaneous
STE in Leads II, III and aVF). And that does NOT include all the
ECGs that do have ST elevation but don’t quite meet the STEMI
criteria and which are neither repeated nor pursued any further
after being diagnosed as “non-STEMIs.”
Bottom Line: If you are not familiar with all these ECG
presentations, you’d better look them up! Better yet, enroll
in The Masterclass in Advanced Electrocardiography
(https://medicusofhouston.com).
5. Depending on the ECG machine
interpretation.
I really don’t have much to say here but I will be brutally blunt: if
part of your job involves ordering ECGs on acutely ill patients and
making medical decisions based on those ECGs, and your ECG
interpretation skills are so poor that you must depend completely
on the ECG machine interpretation, you should find someone with
better skills to see those patients.
Bottom Line: If you are making immediate medical
management decisions based on the ECGs that you are
ordering, you must be able to read those ECGs with a high
level of skill and confidence. If you are depending on the ECG
machine interpretation to direct your management of the
patient, you are betting the patient’s LIFE on a machine that is
notorious for giving incorrect interpretations!
FEATURE
I teach ADVANCED electrocardiography because when a patient’s
LIFE is in YOUR hands, introductory knowledge is simply not enough!
Come join us and be a PARTICIPANT… never just an audience!
WEBSITE: https://medicusofhouston.com
EMAIL: jwjmd@medicusofhouston.com
WHY NOT WRITE FOR US?
Bottom Line: If the initial 12-lead ECG is non-diagnostic,
keep looking using posterior and right-sided leads.
2. Once again, you stopped too soon!
Returning to our allegory of the missing toddler, let’s say you
check the remaining two rooms and you still don’t find him. Some
rooms have more than one door by which one can enter or leave.
The GOOD news: By abiding by the OMI concept, you will miss
fewer acute myocardial infarctions!
The “SO-SO” news: There are no specific algorithms or criteria
to guide you. You are going to have to depend on more advanced
ECG interpretation skills than you did by simply following a “cookbook”
method of diagnosis.
Ambulance UK welcomes the submission of
clinical papers and case reports or news that
you feel will be of interest to your colleagues.
AMBULANCE UK – APRIL
He could have gone out one door as you were entering the other.
And children that age love to hide, so you need to go back through
some of those rooms and look more thoroughly rather than
just glancing.
But too many healthcare providers managing patients with very
credible chest pain don’t take that “second look in all the rooms.”
The repolarization changes indicating acute ischemia (ST elevation)
may not show up immediately and it is not too unusual for a patient
who is indeed having an acute MI to have an initial ECG that shows
nothing – even to an experienced electrocardiographer. It’s also
possible that the reciprocal change may appear before the primary
change of acute ischemia! What IS unusual, however, is for NO
Bottom Line: You are going to need advanced ECG
interpretation skills.
4. Thinking that ST elevation is the only way
to diagnose an acute MI!
There are a number of acute myocardial infarctions that don’t
always manifest with ST elevation: Wellens Syndrome, De Winter
T waves, acute inferobasal (formerly “posterior”) infarctions,
right ventricular infarctions, some proximal occlusions of the left
circumflex artery (resulting in STE in Leads I and aVL which oppose
simultaneous STE in Leads II, III and aVF) and some proximal
Material submitted will be seen by those working within the public and private
sector of the Ambulance Service, Air Ambulance Operators, BASICS Doctors etc.
All submissions should be forwarded to
If you have any queries please contact the publisher Terry Gardner via:
info@mediapublishingcompany.com
info@mediapublishingcompany.com
AMBULANCE UK – APRIL
signs of an acute MI to appear at all during the next hour or two.
occlusions of a “wraparound” left anterior descending artery (also
6
7
For further recruitment vacancies visit: www.ambulanceukonline.com
For further recruitment vacancies visit: www.ambulanceukonline.com