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CARDIAC MARKERS
335
catheterization, must be employed to decide whether
these symptoms represent unstable angina or
coronary ischemia and whether a patient can safely
be discharged home.
References
Goldman L, Kirtane AJ. Triage of patients with acute 1
chest pain and possible cardiac ischemia: The elu-
sive search for diagnostic perfection. Ann Intern Med.
2003;139:987–995.
Giillum RF, Fortmann SP, Prineas RJ, Kottke TE. 2
International diagnostic criteria for acute myocardial
infarction and acute stroke. Am Heart J. 1984;108:
150–158.
Marsan RJ, Shaver KJ, Sease KL, et al. Evaluation of a 3
clinical decision rule for young adult patients with chest
pain. Acad Emerg Med. 2005:12(1):26–31.
The Joint European Society of Cardiology/American 4
College of Cardiology Committee. Myocardial infarction
redefi ned: A consensus document of the Joint European
Society of Cardiology/American College of Cardiology
Committee for the redefi nition of myocardial infarction.
Eur Heart J. 2000;21:1502–1513.
Hollander JE, Chang AM, Shofer FS, et al. Coronary 5
Computed Tomographic Angiography for Rapid Discharge
of Low-Risk Patients with Potential Acute Coronary
Syndromes. Ann Emerge Med. 2009;53:295–304.
Gulati M, Cooper-DeHoff RM, McClure C, et al. Adverse 6
cardiovascular outcomes in women with nonobstructive
coronary artery disease. Arch Intern Med. 2009;169:
843–850.
Thygesen, Alpert J, White HD, et al. Universal defi ni-7
tion of myocardial infarction. Eur Heart J. 2007;28:
2525–2538.
Brogan GX, Friedman S, McCuskey C, et al. Evaluation 8
of a new rapid quantitative immunoassay for serum
myoglobin versus CK-MB for ruling out acute myocar-
dial infarction in the emergency department. Ann Emerg
Med. 1994;24:665–671.
Schulz O, Kirpal K, Stein J, et al. Importance of low con-9
centrations of cardiac troponins. Clin Chem. 2006;52:
1614–1615.
Jaffe AS. Chasing troponin: How low can you go if you can 10
see the rise? J Am Coll Cardiol. 2001;48:1763–1764.
Newby KL, Storrow AB, Gibler BW, et al. Bedside mul-11
timarker testing for risk stratifi cation in chest pain units:
The Chest Pain Evaluation by Creatinine Kinase-MB,
Myoglobin and Troponin I (Checkmate) Study.
Circulation. 2001;103(14):1832–1837.
Anderson JL, Adams CD, Antman EM, et al. ACC/AHA 12
2007 guidelines for the management of patients with
characteristics, they should undergo further testing
before discharge in order to answer the remaining
questions.
24
Summary
In the current practice environment, missing an MI
or ischemia is not an option. Fortunately, a struc-
tured approach, using the currently available tech-
nology, provides a safety net for the patient and
the physician, as long as entry into the structured
diagnostic scheme is kept wide with respect to symp-
toms. This wide entry and use of a protocol approach
overcomes the demonstrably fallible judgment
of physicians.
1
Clearly, risk factors were not useful in assessing the
patient discussed in the case above. The physicians
caring for her did think enough of her symptoms,
despite a “negative” catheterization only 18 months
prior, to order an EKG and a marker. Ordering a
marker is a manifestation of attempting to answer the
question “Does this patient have an MI?”, and that
question can only be answered by serial troponins. If
the answer to that question is no, then the remaining
questions (Does this pain represent unstable angina?
Does this symptom represent coronary ischemia?
Can I safely send this patient home?) must still be
answered.
The diagnosis of unstable angina is purely clini-
cal, combining patient’s history, serial EKGs, and
the patient’s course in the ED. The search for isch-
emic disease with stress testing or a CT scan should
be done promptly (general agreement is within
72 hours), and can be done as an outpatient if the
patient is given a scheduled test time before leaving,
and is thought to be reliable with respect to keeping
the appointment. Otherwise, the patient should be
kept for further testing to detect ischemia or struc-
tural vascular disease.
Section IV: Decision making
Ordering a marker may only answer the question •
“Does this patient have an MI?”
The only cardiac markers that can rule out MI are •
serial troponins.
Other criteria, such as clinical presentation, •
past medical history, stress testing, or cardiac
CHAPTER 23
336
Siegel AJ, Sholar M, Yang J, et al. Elevated serum cardiac 18
markers in asymptomatic marathon runners after com-
petition: Is the myocardium stunned? Cardiology. 1997;
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kinetics of cardiac troponin T and I and N-terminal
pro brain natriuretic peptide in marathon runners. Clin
Chem. 2003;49(5):831–832.
Nagurney J, Brown D, Chae C, et al. The sensitiv-20
ity of cardiac markers stratifi ed by symptom duration.
J Emerg Med. 2005;29:409–415.
Farkouh ME, Smars PA, Reeder GS, et al. A clinical trial 21
of a chest-pain observation unit for patients with unsta-
ble angina. N Engl J Med. 1998:339:1882–1888.
Reichlin T, Hochholzer W, Bassetti S, et al. Early diag-22
nosis of myocardial infarction with sensitive cardiac tro-
ponin assays. N Engl J Med. 2009;361(9):858–867.
Keller T, Zeller T, Peetz D, et al. Sensitive troponin I assay 23
in early diagnosis of acute myocardial infarction. N Engl J
Med. 2009;361(9):868–877.
Morrow DA. Clinical application of sensitive troponin 24
assays. N Engl J Med. 2009;361(9):913–915.
unstable angina/non ST-elevation myocardial infarction: A
report of the ACC/AHA Task Force on practice guidelines.
Circulation. 2007;116(7):e148–e304.
Storrow AB, Lindsell CJ, Han JH, et al. Discordant cardiac 13
biomarkers: Frequency and outcomes in emergency depart-
ment patients with chest pain. Ann Emerg Med. 2006;48:
660–665.
Lim W, Qushmaq I, Devereaus PJ, et al. Elevated cardiac 14
troponin measurements in critically ill patients. Arch Intern
Med. 2006;166:2446–2454.
Alcalai R, Planer D, Afsin C, et al. Acute coronary syn-15
drome versus nonspecifi c troponin elevation: Clinical
predictors and survival analysis. Arch Intern Med. 2007;
167(3):276–281.
Aviles RJ, Askari AT, Lindah B, et al. Troponin T lev-16
els in patients with acute coronary syndromes, with or
without renal dysfunction. N Engl J Med. 2002;346:
2047–2052.
Kontos MD, Garg R, Anderson FP, et al. Outcomes 17
in patients admitted for chest pain with renal failure
and troponin I elevations. Am Heart J. 2005;150(4):
674–680.
Cardiovascular Problems in Emergency Medicine: A discussion-based review, First Edition.
Edited by Shamai A. Grossman and Peter Rosen.
© 2011 John Wiley & Sons, Ltd. Published 2011 by John Wiley & Sons, Ltd.
Jefferson Williams
1
& Shamai Grossman
2
1
EMS Fellow and Clinical Instructor, University of North Carolina Department of
Emergency Medicine, Chapel Hill, North Carolina, USA
2
Director, Cardiac Emergency Center and Clinical Decision Unit, Beth Israel Deaconess
Medical Center, Assistant Professor of Medicine Harvard Medical School, Boston,
Massachusetts, USA
24
A 49-year-old woman presented to the emergency
department (ED) on a Friday evening asking to be
evaluated for her recent chest discomfort. She stated
that over the past few months, she had been under
greater stress at work as a business executive, and
had been rushing out the door to catch the early
commuter train. Over the prior several weeks, she
had occasionally felt a burning sensation in her chest
while she was walking quickly, or jogging to catch
the train. She had also been skipping breakfast and
drinking more coffee, and initially attributed the chest
burning to worsening of her known gastroesophageal
refl ux disease. She reported having to run to catch the
train 2 days in a row, and on both days, she had severe
chest burning that was associated with shortness of
breath, which only resolved after 10–15 minutes of
rest while sitting on the train. She was concerned
about her heart, as her father died of a myocardial
infarction at age 69.
In the ED, the patient was not currently complaining
of any discomfort. She described the episodes of chest
discomfort as epigastric and substernal burning, occa-
sionally radiating as a sharp pain to her throat when
severe, exacerbated by exercise and lasting 20–30
minutes, then relieved by rest. She had a past medical
history of esophageal refl ux, and has been told that
she has a “minor valve problem” in her heart. The
cholesterol level was “borderline” at her last primary
care visit 1 year ago. She occasionally drank wine with
dinner. She took no medications other than omepra-
zole. She neither smoked nor used illicit drugs. She
was otherwise healthy.
The physical examination was notable for a BMI of
29. The vital signs were: resting heart rate 93 beats
per minute, blood pressure 141/92 mmHg, respira-
tory rate 16 breaths per minute, and oxygen satura-
tion 95%. There was a faintly audible mid-systolic
click on cardiac auscultation. The remainder of the
physical examination was unremarkable. A resting
EKG demonstrated ST depression of 1 mm in lead
III, T-wave fl attening in leads III and aVF, and fl ipped
T-waves in V1 and V2, with no prior tracing available
for comparison. The ED physician was appropriately
concerned regarding possible angina, and observed the
patient for two sets of cardiac enzymes, which were
normal, and serial EKGs, which were unchanged.
A standard exercise treadmill EKG stress was ordered,
as that was the only stress test available on the weekend.
During the stress test, the patient exercised for 6.5
minutes under a standard Bruce protocol, at which
time she stopped due to fatigue and leg cramping.
The maximal heart rate during the test was 140 beats
per minute, just under 85% of predicted. She did not
complain of any chest burning or abnormal shortness
of breath, and the EKG showed ST depressions of
CHAPTER 24
evidence may require a stress test, or even a cardiac
catheterization, as I don’t think there are any good
descriptions that patients can use that tell you that
they have refl ux and not ACS. Often patients will say
they have “indigestion,” yet rule in for ACS.
PR: A generic error in emergency medicine is to
assume a patient has a diagnosis that can’t be proved
or disproved in the ED, and refl ux is one of them.
Many of our colleagues use the diagnosis of “refl ux”
because it requires much less workup, and enables
a rapid discharge of the patient. However, I too,
do not believe this diagnosis can be made based on
history alone. Do you think that there’s any utility
in ordering a plain chest X-ray study to look for a
hiatal hernia as evidence that the patient has refl ux
disease?
Dr William Brady: In the common undefi ned ED chest
pain patient, a chest X-ray study can be helpful in pro-
viding alternative diagnoses, including the occasional
hiatal hernia or other esophageal pathology, but there
still may be coexisting ischemic heart disease. This is
similar to obtaining a plain abdominal fi lm to demon-
strate constipation as the cause of abdominal pain. I
would be very wary of this practice.
PR: President Eisenhower, when he had his fi rst heart
attack in offi ce, was treated for 3 days for indiges-
tion! Our patient has a history not only of refl ux dis-
ease, but also has a history of a minor valve problem,
and a click on examination. We know that fl oppy
mitral valves can be associated not only with pain
that sounds like angina, but can also evolve into other
cardiac problems. How helpful is it that you hear the
click, and that she has had this diagnosis in the past,
or is this another confounder?
Dr David Brown: I believe the possible diagnosis
of mitral valve prolapse to be another confounder
here. Although patients with mitral valve prolapse
may have chest pain syndromes not related to other
cardiovascular disease, I would not rely on that as
the diagnosis, particularly in a patient for whom you
don’t have defi nitive prior evaluation data to confi rm
that diagnosis. Given that there is so much overlap
between ACS and all these other conditions, I believe
these patients must have a period of evaluation in an
ED or an ED-based observation area, and have some
kind of provocative testing before it’s safe to send
them home.
1.5 mm in lead III and avF and fl ipped T waves in V1–V3.
The patient had symptoms concerning for angina,
and a borderline or indeterminate exercise tolerance
test without imaging. It was Saturday morning, and
the patient wanted to go home.
Dr Peter Rosen: Does this patient’s BMI suggest that
she’s in the obese range?
Dr Shamai Grossman: Yes, it does.
PR: This is a very common history, a very common
kind of patient to see in the ED, where we have to
start by trying to distinguish between gastrointesti-
nal and cardiac disease. Here we have a patient who
could easily have both. And what are our obligations?
Do you have any clues for separating out these two
histories: the pain that she has now on exertion when
going to the train, and the pain that she has had in the
past thought to be esophageal refl ux?
Dr Amal Mattu: It’s interesting you pointed out that
she actually may have both. There’s a study that was
done a few years ago that suggests that patients with
underlying cardiac disease have a higher prevalence
of underlying refl ux disease as well.
1
Acute coro-
nary syndrome (ACS) and refl ux may then tend to
coexist more often than they exist individually. The
cardiology literature going back to the 1950s and
1960s has indicated that there is a “gastro-cardiac
refl ex” in which acute episodes of refl ux can induce
some cardiac ischemia on an EKG and cardiographic
monitoring.
2
This makes distinguishing between the
ACS and refl ux very diffi cult. One must also keep in
mind that refl ux is the most common misdiagnosis in
malpractice cases for a missed myocardial infarction
(MI), hence physicians have to be extremely careful
when discharging a patient with a diagnosis of refl ux
without fully considering the possibility that maybe
they’re missing an ACS. Unfortunately, I don’t think
there are reliable ways to tell the difference, and that’s
why we make the mistake so often in assuming the
benign diagnosis. Therefore, in emergency medicine
we must always fi rst consider the worst case scenario,
and assume it’s ACS initially to be prudent. If we can
acquire some negative evidence that it is not ACS, then
we can conclude the problem is refl ux. That negative
STRESS TESTING
the endocardium, thus, wall motion abnormalities are
easier to detect.
SG: I believe that although contrast may make identify-
ing regional wall motion abnormalities easier, I am not
convinced that it would adequately enable emergency
physicians to become as facile as they are in using bed-
side ultrasound for abnormalities such as trauma and
central line placement. I hope I am proven wrong.
PR: In this case we have an abnormal EKG with
nothing to compare it to. How much trouble should
you go to in trying to fi nd another tracing? Do you
need to call other hospitals, or doctors’ offi ces? Are
you comfortable enough in your decision making that
in the absence of enzyme changes, it doesn’t really
matter what the prior EKG looked like?
DB: I would not go through a lot of trouble in this case
tracking down old EKGs if they were not readily avail-
able in my own healthcare system. These fi ndings aren’t
so worrisome to trigger a trip to the cardiac catheter-
ization laboratory or something along those lines. And
even if old EKGs were identical, it wouldn’t reassure me
enough to allow immediate discharge from the ED.
PR: This is the patient who is the curse of emergency
medicine. We all agree that this patient needs investi-
gation for an ischemic cardiac syndrome, but I doubt
that any of us agree about what that investigation
should be. Moreover, if we ask 100 cardiologists,
we’d get 100 different answers depending on the time
of the day, and whether or not they were responsible
for doing the work. I doubt any cardiologist would
take this patient to the catheterization laboratory. I
think some cardiologists might admit the patient in
order to obtain the next study, but there are many
cardiologists who wouldn’t even do that. Do you have
any advice from your own institutions and your own
cardiologists as to what the emergency physician can
hope for next in the evaluation of this patient?
AM: That’s a tough question. I think at our institution
this patient would at the very least get a stress test, if
not go directly to the catheterization laboratory, given
that she has an abnormal EKG at rest, and a concern-
ing story for what could be called true unstable angina
with exertional chest pressure, even if it also sounds
like refl ux. I think most cardiologists would agree that
this history is consistent with unstable angina, and she
has a baseline abnormal EKG. Alternatively, the next
PR: Along with an investigation of a potential isch-
emic coronary syndrome, would you send blood cul-
tures and order an echocardiogram to be sure this
isn’t new-onset endocarditis?
WB: If there was some point in the history that would
make me think of endocarditis, such as IV drug
abuse, bacteremia, or ongoing subacute symptoma-
tology like weakness, malaise, fever, a generic feeling
of being unwell, or stigmata of embolization, I might
explore it. Reading this story, I would not suspect
endocarditis, so I would not pursue this diagnosis in
this particular patient.
PR: Isn’t endocarditis associated with mitral valve
prolapse?
WB: Only if there is associated valvular dysfunction.
Without other symptoms in the information we are
given, I wouldn’t explore it.
PR: Our European colleagues often do echocardiog-
raphy on patients as part of their ischemic evaluation,
as well as for other reasons. Is that a test that you
think might have some utility in separating the gastro-
intestinal from the cardiac pathology?
SG: Sabia studied the utility of echocardiography to
discern ischemic chest discomfort from nonischemic
chest discomfort, and fi nds echocardiography to be
a highly sensitive tool.
3
If a patient were to have a
regional wall motion abnormality that disappears
when the symptoms go away, that would be a very
useful test to help discern whether this is ischemic
symptomatology or nonischemic symptomatology.
The problem with using echocardiography routinely in
the ED is that it’s operator dependent. In order to ade-
quately identify a regional wall motion abnormality,
one needs to be technically very adept at performing
echocardiography and at reading echocardiography.
Echocardiography could potentially be very useful
if we were all expert sonographers with vast expertise
in identifying a regional wall motion abnormality. For
valvular heart disease, one would also need expertise
to utilize echocardiography.
WB: What about contrast echocardiography? My
understanding is that although detecting wall motion
abnormality is a diffi cult call to make for anyone,
and clearly expertise is needed to make that call, with
contrast echocardiography it’s much easier to identify
CHAPTER 24
already put this off for a probably excessively long
period of time. She’s going to have in her mind that
she feels better, and the doctors let her go home, and
therefore she doesn’t need to follow up. I think we’ve
all seen people who were discharged with the hope of
near immediate follow up who end up back in the ED
sick, or worse yet, arrest outside the hospital.
PR: I would have a hard time getting this patient
admitted to a cardiologist in Jackson Hole, probably
in Tucson, and also probably in Boston. I think that
they might be willing to hold the patient in the ED to
do a stress test, but I don’t think they would be willing
to put the patient in the hospital to obtain an exercise
test or an imaging study.
SG: There are data that suggest that if a patient can go
6 minutes worth of exercise utilizing a standard Bruce
protocol, then regardless of the results of that stress
test the patient has an excellent prognosis, and should
able to go home. Some of our cardiologists would say,
“Well, the patient was able to do 6 and half minutes
worth of exercise, so it doesn’t matter what the stress
test shows. She is going to do fi ne, and you can send
her home. We’ll follow her up on Monday.”
DB: I think that it depends on how you’re using the
stress test, and how you present it to the patient. If
we’re using it to diagnose coronary artery disease,
then we are using the test improperly. A nonimaging
stress test is not a good diagnostic test for coronary
artery disease. If we are using it to determine whether
the patient is safe to go home once she has ruled out
for an MI, and continue her activities of daily living
while undergoing a reasonably prompt outpatient
evaluation for a chest pain syndrome, then I think it
is appropriate to do what you just described. In my
institution, you would have three options with this
patient. She would never get admitted to the hospital,
and cardiology would never hear about her, unless
you decide to choose option three. In my mind, she
gets admitted to an observation unit, she gets ruled
out for an MI, she gets a stress test (which would
have the described equivocal results), and then you
either keep her to do a stress test with imaging (option
one), or (option two) you do a CT scan of her coro-
nary arteries to determine whether she has coronary
artery stenosis or not. She may be a great candidate
for that considering she is young, and doesn’t have
any previous diagnosis of coronary artery disease. If
best options would be to arrange very close follow up
or even transfer to another institution where the car-
diologists are more aggressive about their workups.
I wouldn’t feel comfortable discharging this patient
home even after an observation period unless I knew
that this patient was going be seen again in the next
day or two. Even that would not be ideal.
DB: Before a stress test, would this patient go for a
cardiac catheterization at your institution?
AM: At our institution, at the very least, she would get a
stress test, and there are some cardiologists who would
take her directly for catheterization given the abnormal
EKG, cardiac risk factors, and history of worsening
exertional symptoms over the past couple of weeks.
PR: Would they do the procedure at night? Or would
they admit her, and perform it the next day?
AM: If she’s asymptomatic and hemodynamically
stable, I don’t think any of them would perform the
procedure that night nor in the next few hours, even if
it was daytime. Nevertheless, I think that they would
be fairly aggressive with this patient (even though
there is no indication that she should be treated like
a ST-segment elevation myocardial infarction, and go
to the catheterization laboratory immediately).
WB: In someone who presents and remains symp-
tom free, doesn’t evolve the electrocardiogram, and
has two markers that are negative in sequential fash-
ion, I think you’ve clearly ruled out the presence of a
ST-segment elevation myocardial infarction, non-ST-
segment elevation myocardial infarction, and likely
a more severe form of unstable angina, but you still
haven’t answered the question: “Are there symptom-
atic obstructive coronary lesions present?” I would
admit her to an observation unit, and arrange an
exercise test. But an exercise stress test in this popula-
tion, particularly in a younger woman, may not be
revealing. Many hospitals will not have this resource
available on a Friday evening, and might not do any-
thing with these patients until Monday. This hospital
actually has the capability of stressing her, so that’s
what I would do. But, if you have a nondiagnostic
result, then I think you need to take the next couple
of steps, which would either be catheterization or a
nuclear study or exercise echocardiography. I would
be very uncomfortable discharging her. If you look
at this patient, she is a very busy woman, and she’s
STRESS TESTING
get the discomfort. But we have not answered the
question of, “Do we need to worry about this patient
to the point of pushing her toward coronary cath-
eterization?” I believe short of that, we are never
going to get a good answer for this patient. However,
I think the reality in most EDs in this country is that
this woman is not admissible. So what it really boils
down to in my mind is: if you can do an imaging study
or a CT scan and get more evidence for plaque-cor-
onary artery disease, you may have acquired enough
evidence to get her an elective coronary angiography.
If you can’t get either of those, then the best that you
can hope for is a cardiologist who will get her in
early in the next week.
AM: I wonder if the reason we tend to be more
aggressive is because our patients cannot get good
follow up. In some ways this may be a blessing in
disguise, because we tend to go ahead and try to get
the workup sooner rather than discharging them for a
72-hour follow up despite the ACC/AHA guidelines.
I wonder whether if in Boston there is a higher per-
centage of insured patients, and ironically, they end
up waiting longer for a defi nitive workup than our
uninsured patients.
DB: I would take the opposite approach. Let’s say you
catheterize this patient, and she has 60 or 70% lesion
in her right coronary artery. We have no idea whether
that is causing her symptoms or not, and in an aggres-
sive institution she’s going to get a stent placed, she is
going to be on clopidogrel for a year, and then she’s
going to be at risk for in-stent stenosis in 2 years, and
when and if that occurs, she will really need a proce-
dure. In a less aggressive institution she’s going to get
a functional study, either a stress ECHO or a stress
MIBI, in some reasonable time frame, either the next
day, or in 72 hours, or even in the next week, and then
if she has ischemia that’s documented in that region,
then proceeding with cardiac catheterization and
placing a stent makes sense to me. But the alternative
of catheterization based on a non-specifi c fi nding on
a nonimaging stress test, I think, puts large groups of
patients at risk for procedures they don’t need.
SG: The literature bears this out somewhat. When
they looked at the number of cardiac procedures in
New England versus the rest of the United States,
they fi nd that the physicians in New England were
far more conservative in performing invasive cardiac
her coronary arteries are clean, then she can be dis-
charged quite safely. The third option is to send her
home with a scheduled stress test or arrange with her
cardiologist or internist to make sure they schedule
her a stress test with imaging on the next business
day. The ACC/AHA guidelines for patients like this
recommend provocative testing within 72 hours if the
patient is pain free. In my institution, the cardiologists
would not admit her from the observation unit after
this nondiagnostic treadmill test.
WB: I agree that it would be hard to get a cardiolo-
gist involved until she infarcted, and then we’re all
incorrect for having sent her home in the fi rst place.
Nevertheless, you really haven’t answered the ulti-
mate question as to whether this patient had cardiac
ischemia. You’ve demonstrated that she is stable with
a normal to near-normal electrocardiogram and two
negative markers. There are some data to suggest
that this person has a low negative 30-day event rate.
Should you really obtain an advanced imaging study,
like a stress test with a radionuclide, MIBI, or a stress
ECHO before she goes home, or can we be comfort-
able doing these tests within 72 hours?
DB: I would be comfortable waiting 72 hours because
I know I can personally schedule these tests for
Monday morning. I think if she has good follow up
with an internist or a cardiologist who can make sure
this happens, that would be perfectly reasonable. In
many institutions, if a patient had a nondiagnostic
stress test, that patient would automatically be rolled
over to a MIBI to get a better answer. But I think it’s
within the standard of care to allow her go home with
the understanding that we haven’t excluded coronary
artery disease, but we have given her the opportunity
to continue with her activities of daily living without
much risk while she completes this workup as an
outpatient.
PR: I am somewhat concerned about using a stress
test on an obese patient whose only exercise is catch-
ing a train. I would predict that we would not be
able to get a diagnostic treadmill test. In my mind,
the real problem here is not whether she is having an
MI; I think that we have successfully answered this
question. I also would say that we have successfully
answered that she’s not having truly unstable angina.
She almost falls into my defi nition of stable angina,
in that she has to do something unusual in order to
CHAPTER 24
WB: I think you have to put yourself in the position
of a small fi ve-bed ED where you don’t even have a
cardiologist, and they do stress tests Monday through
Friday during bankers’ hours; it is a very diffi cult sit-
uation for an emergency physician to be in.
DB: In a way that situation is almost easier. As an
emergency physician in that situation, you have to
admit the patient to the hospital. You can’t get the
stress test, you can’t keep her in the ED for 12 hours
to rule her out, and the patient can’t go home with-
out some sort of stress test. I think it’s harder if
you have some of the resources, but not all of the
resources. It’s harder if you get to the point where
this case ends, but you can’t obtain either a stress
imaging test or schedule one for the fi rst business
day after she goes home.
WB: That’s assuming that you can get a family prac-
titioner or internist to admit these patients to the
hospital. We have a number of small feeder hospitals
in the area that don’t want to take anything even
close to unstable angina, no matter how stable it
might be, so then you’re almost back in that same
position.
DB: This case is a perfect example of a case where I
believe the standard of care for our specialty is going
to change over the next few years. I think that she is
a great candidate for a coronary CT scan. There is
a large group of patients with no known coronary
artery disease, a story that is both typical and atypi-
cal, and an EKG that is nondiagnostic, who will have
a negative coronary CT angiography. The CT scan
can be done 24/7 and the images sent anywhere in
the world to be read by a competent radiologist. I
personally think that we are going to see a change in
practice over this next 3–5-year interval for patients
just like this.
PR: One last question based on the facts of this case
as presented. We have a patient who is going to move
on to another kind of imaging study, and we have a
weekend facing us. If you are working at an institu-
tion where the best you could arrange for this patient
is home with a 72-hour follow-up, is there any spe-
cial therapy that you would place the patient on while
she is awaiting the stress test: plavix, low-molecular
weight heparin, aspirin, or nothing?
DB: My vote would be for aspirin.
procedures, yet the outcomes in New England and
the rest of the United States were the same. So we
tend to do less, but our patients seem to do just
as well, or perhaps just as poorly. The literature
also suggests that with regards to stress testing, if
a patient gets a stress test as an outpatient, or if a
patient is scheduled for a stress test from the ED as
an outpatient, they tend to have poorer outcomes
when compared with patients who had their stress
tests done in the ED. This makes sense in a patient
population where most of those patients would not
be compliant with a previously outpatient scheduled
stress test that is easily scheduled. In Boston, our
patients are well connected with their insurers and
primary care physicians so that they will likely get
their stress test regardless of whether it is as an inpa-
tient, or in the ED, or shortly afterward as an out-
patient. I think this too might infl uence the outcome
in which the less aggressive physicians in Boston do
not have worse outcomes than anyone else anywhere
else in the country.
Yet there is another problem with taking many of
the patients directly for catheterization. The literature
also suggests that patients with angina have the same
mortality rates when maximized on medical therapy
when compared to invasive therapy.
PR: I have some problem with that data; mortality
may not be the most appropriate endpoint, as I don’t
think medical therapy will permit the same magnitude
of physical activities. To my mind it is a life quality
question, not just a mortality question.
PR: If you were talking to a rural Virginia physician
about this patient, would you accept her in-transfer
on a Friday or Saturday, or would you just make an
arrangement for her to come up on Monday?
WB: I wouldn’t accept her in-transfer to the ED. If
the transferring physician had concerns, and wanted
the patient admitted to the hospital, I would refer
that to the cardiologist. The initial ED evaluation
process has been taken care of, and all I could offer
is a parking spot waiting for her to be evaluated in
some further fashion.
PR: Unfortunately, many of our emergency medi-
cine colleagues are faced with this transfer decision
because they can’t get cardiologists to accept patients
like this, and more unfortunately, sometimes they just
arrive at your door.
STRESS TESTING
actually have coronary heart disease or an acute cor-
onary syndrome represents a serious challenge to the
emergency physician. Although the rates of missed diag-
noses of acute cardiac ischemia in the ED are low and
are improving, a missed diagnosis may be associated
with increased morbidity and mortality.
7
On the other
hand, the evaluation of patients for possible myocardial
ischemia represents a signifi cant fi nancial burden to the
healthcare system.
5,9
The development of rapid, cost-
effective, and accurate strategies for risk stratifi cation
and diagnosis of patients presenting with chest pain and
associated symptoms remains an important goal.
What is the role of cardiac stress testing in these
patients? The key questions for the emergency phy-
sician are to determine who requires cardiac testing,
which testing modality should be used, and what
should be done with the results of the test.
Initial workup
Once an emergency physician determines that a patient
is hemodynamically stable, and does not require imme-
diate intervention or resuscitation, a detailed history
begins the evaluation for possible coronary artery
disease. The patient in this case illustrates a com-
mon scenario: the patient presents symptom-free and
hemodynamically stable with an unremarkable physi-
cal examination, has a normal or nonspecifi c EKG,
and has a normal initial laboratory profi le. In these
patients, suspicion for an acute ischemic coronary
syndrome (ACS) may be based solely on the history.
The patients whose history is concerning for possible
myocardial ischemia, but whose initial evaluation is
otherwise normal, represent a diagnostic challenge,
and are the patients who should undergo extended
observation and timely cardiac stress testing.
10,11
Etiology and differential diagnosis
The differential diagnosis for chest pain is broad. Many
potential non-ACS cardiovascular etiologies must be
considered, as well as musculoskeletal, gastrointestinal,
and respiratory disorders.
12
Features of the initial evalu-
ation and the clinical history of a patient lead the ED
physician to establish the likelihood, or pretest probabil-
ity, of each disease process in the differential diagnosis.
The concept of pretest probability is an initial estimate
of the likelihood that a patient has a given disease.
AM: My vote would be for aspirin, and a prescription
for nitroglycerin with the instructions to return if she
needs to take a couple.
AM: In conclusion, the standard of care is not deter-
mined by the four or fi ve of us at major centers, but
rather by what resources people have where they are.
Patients need to understand that we’re not going to
be right every time. The standard of care means to be
reasonable and prudent, but not necessarily ideal. The
standard in hospitals with fi ve-bed ERs may be very
different, and perhaps discharging this patient is their
standard. Patients need to be reasonable and under-
stand that in this scenario, their doctor maybe doing
the best this weekend that he can.
PR: What we’re trying to do here is not defi ne a legal
standard of care, which after all is what a prudent phy-
sician in the same circumstances would do. What we’re
trying to do is medically defi ne what is safe for the
patient in most cases. Obviously, there are going to be
outliers, and we’ll have been wrong. But, for the most
part, with the workup that we’ve described, it is safe to
discharge this patient even if it is suboptimal compared
to what we can achieve at a more aggressive tertiary
care center. Nevertheless, I don’t believe that what we
are advising people to do here is unsafe for the patient.
Case resolution
The patient was admitted to the hospital and had
myocardial perfusion testing before and after exer-
cise, which was normal. At 6-month follow up, the
patient had been taking a proton pump inhibitor daily
and was symptom free.
Background
Chest pain and related symptoms constitute the second
most common reason (behind abdominal pain) for ED
visits in the United States, with approximately 6 million
visits annually, or 5% of all ED visits.
4
Nevertheless,
over half of these patients do not have a cardiac cause
for their symptoms.
5–7
Yet, heart disease remains the
leading cause of death in the United States.
8
Determining which ED patients presenting with
symptoms concerning for possible myocardial ischemia
CHAPTER 24
evaluation. For example, a 25-year-old nonsmoking
female patient with intermittent sharp chest pain last-
ing seconds, whose pretest probability for signifi cant
coronary artery disease is likely less than 5%, would
not warrant further evaluation with cardiac stress
testing.
13,16
A positive fi nding on a cardiac stress test
in this patient is likely to be a false positive given the
low probability for coronary ischemic disease as well
as the imperfect sensitivity and specifi city of diagnos-
tic testing.
13,16,17
Similarly, a 65-year-old male smoker
with substernal aching radiating to the left arm lasting
for 30 minutes after exercise (typical angina, with pre-
test probability likely greater than 90%) should also
not undergo stress testing for the purpose of diagnos-
ing suspected coronary artery disease.
13,16
A negative
fi nding on this patient’s exercise stress test is likely to
be a false negative, and would not lower the posttest
probability to a degree that would reassure the physi-
cian that coronary artery disease is absent. Cardiac
stress testing is most useful for the patients who,
based on clinical history and pretest probability, are
at intermediate risk for coronary artery disease (e.g., a
middle-aged person with atypical angina).
11,17,18
Testing
Once a cardiac stress test is indicated, the physician
must decide which test to choose. If the patient can-
not or does not adequately complete the appropriate
protocol, the results of the test may not be interpre-
table. In general, three options are available: standard
exercise radionuclide exercise EKG testing, exercise
echocardiography, and myocardial perfusion testing.
Pharmacologic stress may also be available for patients
unable to physically exercise. Each testing modality
has advantages and disadvantages, as well as differ-
ences in sensitivity, specifi city, and cost effectiveness.
Exercise EKG testing, typically on a treadmill, has
been extensively studied, and is generally reported to
have a sensitivity of around 70% and specifi city of
around 80%, with broad variability across studies.
6,18–20
It is the least expensive, and possibly the most cost-
effective method, of cardiac stress testing, and is widely
available.
6
However, this modality has a lower sensitiv-
ity than stress imaging tests (see below). Another disad-
vantage, given that test results rely on EKG changes, is
that nonspecifi c abnormalities on the resting EKG (i.e.,
ST depression at baseline or left bundle branch block)
may render the test uninterpretable.
19,20
After further evaluation and subsequent testing is
performed, the resulting likelihood of disease is the
posttest probability, which the physician uses to make
decisions regarding therapy and disposition. Pretest
probability is combined with test characteristics such as
sensitivity and specifi city, and the results of a given test,
to determine the posttest probability that a patient has
a given disease. For example, a patient who describes
chest pain of sudden onset that is sharp, pleuritic, and
associated with shortness of breath may have an inter-
mediate pretest probability of pneumothorax. If a sub-
sequent CT scan, which is highly sensitive and specifi c
for pneumothorax, shows fi ndings concerning for pneu-
mothorax, then the patient’s posttest probability for the
disease has increased substantially, and should lead the
physician to treat the patient for pneumothorax.
In cases of suspected coronary heart disease such as
the present one, patient-specifi c features of the clini-
cal history create the pretest probability of coronary
heart disease or ACS. This pretest probability guides
the physician in choosing the next step in evalua-
tion, with the understanding that no test is perfectly
sensitive and specifi c. For example, a patient with a
very high pretest probability of ACS should undergo
extensive and perhaps invasive evaluation for ACS,
while a patient with very low pretest probability for
ACS may not require any further testing.
The medical literature has extensively reviewed the
concept of estimating the pretest probability of coro-
nary heart disease.
13–16
Historical factors (“cardiac risk
factors”) that can assist in determining pretest prob-
ability include age, gender, smoking, diabetes, hyper-
tension, and hypercholesterolemia. One of the most
important historical factors is the character of the
patient’s symptoms.
12,16
Classic cardiac chest pain may
be defi ned as substernal in location with the three fol-
lowing characteristics: of a typical quality and duration,
incited by physical or emotional stress, and relieved by
rest or nitroglycerin. Atypical angina may have two of
the three characteristics, and noncardiac chest pain may
have one or none. The diffi culty is that the description
of the pain is not constant between patients, and is often
hard for the patient to describe. Often, the closest gen-
eralization is the pain makes the patient restless. While
the patient often cannot exactly describe the pain, it can
be severe, is usually something the patient wants to be
rid of, and not something they stoically tolerate.
Once a patient’s pretest probability is estimated,
the physician must decide upon the next step in