The Others
MK Strecker-McGraw, MD, FACEP
ACS Mimics: Non AMI
Causes of ST-Segment
Elevation
• ST segment elevation is important EKG
criterion for dx of AMI
• But, there are other conditions that can
cause elevation of the ST segments
• Clinical consequences of
misinterpretation can be deleterious
DDX ST Segment Elevation
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Acute Myocardial infarction
Acute pericarditis or
myocarditis
Brugada syndrome
Cardioversion
Early repolarization
Hyperkalemia
LBBB
Left ventricular aneurysm
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Left ventricular hypertrophy
Prinzmetal angina
Pulmonary embolism
Miscellaneous causes
Case 1
• 66 year old white male
• ST elevation MI 6 weeks ago
• calls EMS for SOB, diaphoresis
Left Ventricular Aneurysm
• persistence of ST-segment elevation for
4 weeks or more suggests a ventricular
aneurysm
• when no previous EKG is available,
presence of a QS wave in the setting of
ST segment elevation without T-wave
inversion is highly suggestive of an
aneurysm
• reciprocal changes in the inferior leads
are absent
• Focus on HPI
• Aneurysm should already have Q
waves
• No reciprocal changes
• Get old EKG’s
• Get serial EKG’s
• Need time and biomarkers/ECHO
Case 2
• 18 year old white male
• chest pain, SOB
Acute Pericarditis and
Myocarditis
• diffuse ST-segment elevations and PRsegment depressions
• ST segment has concave morphology
except aVR, which may be depressed
• when ST elevation in lead II is greater
in magnitude the the ST elevation in
lead III, acute pericarditis is the likely
diagnosis
Pericarditis/Myocardit
• a depressed ST is
segment in lead aVL
associated with an elevated ST
segment in lead III suggests infarction.
This relationship is not present in
pericarditis or early repolarization
• in the limb leads, significant elevations
> 5mm of the ST segment are
uncommon with pericarditis, if present,
suspect AMI
• junction of the QRS and ST segment (J
point) is clearly discernible
Case 3
• 88 year old female with chest pain for 2
hours
Left Bundle Branch Block
• LBBB septal depolarization is delayed
and proceeds abnormally from right to
left
• generate wide and primarily
monophasic complexes ORS complex >
0.12 sec
• a QS wave in V1 and a monophasic R
wave in V6
• large negative QRS complexes in lead
V1, V2 or V3 are only seen in a few
• key morphologic findings are a wide,
slurred R wave in the left-sided leads (
I, aVL, V5 and V6 as well as a QS or an
rS complex in the right precordial leads
( V1 and V2
• absence of customary q wave in lead
V6 so V6 only demonstrates an initial R
wave in uncomplicated LBBB
Case 4
• 40 year old female
• SOB, cough
• fat
Pulmonary Embolism
• most common EKG dysrhythmia with
PE is normal sinus, sinus tachycardia
is less common
• morphology shows ST segment
depression
• T wave inversions V1-V4 most common
• complete or incomplete RBBB
• S1Q3T3
• P pulmonale ( P wave amplitude > 2.5
mm in lead II)
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New T-wave inversions are very common
in cases of large PEs
• Especially common in anteroseptal leads
• Marriott and other others:
• Simultaneous TWIs in anteroseptal +
inferior leads is HIGHLY specific for acute
pulmonary hypertension (= PE)
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S1Q3T3 is a sign of acute cor pulmonale
Any cause of acute cor pulmonale (PE, PTX
bronchospasm, etc) can result in the S1Q3T3 finding
on the EKG
The ECG is often abnormal in PE, but findings are
not sensitive, not specific
Anterior T wave inversions? Consider the diagnosis
of massive or sub-massive PE.
The ECG is a poor diagnostic tool for PE. The
greatest utility of the ECG in the patient with
suspected PE is ruling out other potential lifethreatening diagnoses such as MI.
Case 5
• 45 yo male with hypertension
• short of breath, right sided chest pain
Left Ventricular Hypertrophy
• LVH is one of the most common causes
of ST segment elevation and is
frequently mistaken for AMI
• in LVH, ST segment and the T wave
deviate in the opposite direction from
the major QRS complex
• ST segment elevation has a concave
contour and is generally limited to leads
V1-V3
Left Ventricular Hypertrophy
• The deeper the S wave, the greater the
ST segment elevation
• fully developed LVH commonly shows
ST segment depression with T wave
inversion in leads I, aVL, V5 and V6
• ST segment depression is often
minimal and has a downsloping contour
(hockey stick)
Left Ventricular Hypertrophy
• T waves are not deep and are
asymetrically inverted ( slow downward
phase with fast upward wave)
• significant and/or horizontal ST
segment depressions and deep
symmetric inverted T waves are
atypical and should raise concern for an
ischemic process
• T wave inversions in leads other than
the lateral leads suggest myocardial
ischemia
Left Ventricular Hypertrophy
• Stand alone criteria: R > 11 in aVL
• Sokolow criteria: S V1 + R V5 or V6
>35
• Cornell criteria:
S V3 + R aVl > 28 mm men
S V3 + R aVL > 20 mm women
Case 6
• 38 yo diabetic female, on dialysis
• short of breath, vomiting
Hyperkalemia
• Hyperkalemia is defined as a serum K+
of > 5.5 mEq/L
• mild hyper-K= 5.5-6.5, moderate
hyperK+ =6.5-8 and severe K+>
8mEq/L
• The ST segment elevations associated
with hyperkalemia is uncommon and
can be diffuse or localized
• unlike typical plateau or upsloping ST
segment elevation, hyperkalemia often
Hyperkalemia
• hyperkalemia shortens repolarization
and the T waves become symmetrically
tall and peaked with pointed tips
• the base of the T wave narrows ,
shortening the QT interval ( k+>5.5)
• as K+ increases the QRS widens and
you can see ST elevation or depression
(K+>7)
• with further elevation you see flattening
or disappearance of P waves ( K+>8
mEq/L)
Hyperkalemia
• as QRS widens, it merges with the T
wave resulting in the sine wave pattern
Case 7
• 18 yo football player
• short of breath at halftime
• had a fight with girlfriend before
becoming short of breath
Early Repolarization
• ST segment elevation in the precordial
leads most commonly V2- V5
• amplitude ranges from 1-4 mm most
marked in V4 with concave upward
morphology
• notch at the J point and tall, upright T
waves
• no reciprocal changes
Early Repolarization
• can be seen in limb leads (inferior leads
II, III and aVF with the elevation in II >
III
• also find reciprocal ST segment
depression in aVR
• may find a short QT interval and high
QRS voltages
Case 8
• 17 yo male, syncope in the hall at
school
• no past medical history
Brugada Syndrome
• inherited arrhythmogenic disease
characterized by a right bundle branch
like pattern on the EKG
• associated with ST segment elevation
in leads V1 and V2, less commonly V3
• ST segment is typically downsloping
and followed by an inverted T wave
• associated with high incidence of
sudden death among previously healthy
individuals
Brugada Syndrome
• believed to be responsible for 4-12% of
all nonischemic SCD and for
approximately 20% of SCD in patients
with structurally normal hearts
• patients are predisposed to episodes of
ventricular tachycardia
Brugada
Syndrome
• 3 patterns associated with Brugada
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I: ST segment elevation is triangular (
coved or convex upward) and the T
waves can be inverted in leads V1 to V3
II: Downward displacement of the ST
segment lies between the two elevations
of the segment in leads V1 to V2 (
concave upward) but does not reach the
baseline
III: Downward displacement of the ST
segment lies between the 2 elevations of
the segment in leads V1-V3 and the
middle part of the ST segment touches