CE ARTICLE
DIFFERENTIATING BETWEEN LVH
AND STEMI
Differentiating bet ween LVH and
STEMI can be difficult. A true STEMI
will have reciprocal ECG changes, while
ST-segment elevation secondary to LVH
will not.
As detailed in the ECG criteria
ab ove, LV H usually present s with
ST-segment elevation in the anterior
leads. Therefore, ST-segment eleva-
tion in the inferior, lateral, right-sided or
posterior leads should be considered a
STEMI. The true difficulty lies in differen-
tiating an anterior MI from LVH. A group
out of University of California-Davis has
put together an algorithm to better
predict which ST-segment elevation in
LVH is a true STEMI.
16
This algorithm has
not yet been validated, and the authors
acknowledge it "may augment interpre-
tation" but is by no means definitive.
The authors found that measuring the
relative amount of ST-segment eleva-
tion was more sensitive and specific
for STEMI than measuring the absolute
ST-segment elevation. To determine
the relative ST-segment elevation, it is
normalized against the difference of
the preceding R- and S-waves to give
a percentage (%STE). In this calcula-
tion, %STE = (height of T-P segment to
J-point)/(height of R-wave minus depth
of S-wave).
The authors found that legitimate
STEMIs had a greater percent STE versus
false STEMIs in LVH. If the percent STE
was less than 25%, a STEMI could be
ruled out. If the percent STE was greater
than 25%, the sensitivity and specificity
for legitimate STEMI were 77% and
91%, respectively.
The steps involved in using the algo -
rithm are as follows:
1. Are the ST elevations in leads
V1–V3? If yes, go to step 2. If they're
in other leads, it's a STEMI.
2. Is the %STE greater than 25%? If
no, it's not a STEMI. If yes, go to step 3.
3. Are there more than three leads
with ST elevation? If yes, it's a STEMI.
If no, go to step 4.
4. Are the T-wave inversions present
in V1–V3? If yes, it's a STEMI. If no, it's
not a STEMI.
Using these criteria, the patient in
our case does not meet the criteria for
STEMI. Her ST-segment elevation can
be considered normal with her LVH. In
addition, while she has weakness and
dizziness, and as an elderly diabetic
female we would expect her to present
with atypical chest pain with AMI, her
histor y and clinical exam strongly
suggest that she may be dehydrated
from long hours working in a warm
environment.
TREATMENT
In the absence of true STEMI, there
is no treatment for the ECG manifesta-
tions of LVH. Treatment of the patient in
this case should focus on her weakness
and dizziness, and these complaints
warrant ALS -level care. Administer
ox ygen if necessar y via the appro -
priate device and flow rate to maintain
an oxygen saturation of at least 94%,
obtain intravenous access, and a fluid
challenge could be administered in an
attempt to increase her blood pressure.
Place the patient on a cardiac monitor
and obtain serial 12-lead ECGs en route
to the emergency department, just to
be certain the ST-segment elevation is
not evolving or that reciprocal changes
don't emerge, both of which would indi-
cate an evolving STEMI.
Conclusion
Hopefully, this month's CE article
reinforc ed the message from last
month: STEMI imitators can be readily
identified with a good understanding
of the HPI, a thorough clinical exam
and an understanding of the ECG
patterns typical for the imitators. If a
patient presents with a suspected STEMI
imitator, if there is any change in their
symptoms or there are persistent clin-
ical symptoms suggestive of AMI in the
presence of a suspected STEMI imitator,
perform serial ECGs. If you find your-
self wanting to identify a 12-lead ECG
pattern as a STEMI imitator, continue
to reevaluate and perform serial ECGs!
When in doubt, always err on the side
of caution: Call it a STEMI and treat it
as such.
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Scott R. Snyder, BS, NREMT-P, is full-time faculty at
the Public Safety Training Center in the Emergency
Care Program at Santa Rosa Junior College, CA.
He is also a paramedic with AMR: Sonoma Life
Support in Santa Rosa, CA. E-mail scottrsnyder@
me.com.
Sean M. Kivlehan, MD, MPH, NREMT-P, is an
emergency medicine resident at the University of
California, San Francisco. E-mail sean.kivlehan@
gmail.com.
Kevin T. Collopy, BA, FP-C, CCEMT-P, NREMT-P,
WEMT, is performance improvement coordinator
for VitaLink/AirLink in Wilmington, NC, and a lead
instructor for Wilderness Medical Associates. E-mail
kcollopy@colgatealumni.org.
EMSWORLD.com | DECEMBER 2014 95