Full text of DOI:10.1111/j.1553-2712.2001.tb01290.x

196
STRESS ECHOCARDIOGRAPHY
Buchsbaum et al. • EXERCISE STRESS ECHOCARDIOGRAPHY
mission to short-stay units and/or
the use of stress electrocardiogra-
phy, computed tomography, nuclear
BRIEF REPORTS
Emergency Department Evaluation of Chest
Pain Using Exercise Stress Echocardiography
perfusion imaging, or dobutamine
echocardiography in the ED.8–13 Few
studies have examined exercise
stress echocardiography (ESE) in
this arena especially in a non-uni-
versity setting. We conducted this
study to determine whether ESE
could be used to further support the
safe discharge of these low-risk pa-
tients.
M
ICHAEL S. BUCHSBAUM, MD, ERIK S. MARSHALL, MD,
RIAN J. LEVINE, MD, MARTIN A. BENNETT, MD,
NGELA ABATINO, RN, ROBERT E. O’CONNOR, MD, MPH,
EIL B. JASANI, MD
B
A
DIS
N
Abstract. Objective: Patients with a low risk of coronary artery dis-
ease (CAD) presenting to the emergency department (ED) with chest
pain pose a diagnostic dilemma because a small percentage will suffer
an acute myocardial infarction (MI) and sudden death. The authors
conducted this study to determine whether exercise stress echocardi-
ography (ESE) could be used to further support the safe discharge of
these low-risk patients. Methods: A convenience sample of patients
Ն30 years of age without a prior cardiac history who presented to an
academic community hospital with chest pain, normal initial creatine
kinase, and electrocardiography without ischemic changes underwent
ESE within 6 Ϯ 1.7 hours (mean Ϯ SD). Abnormal ESE was defined
as regional wall motion abnormality at rest or after exercise. The ED
disposition and three- and six-month follow-up for cardiac events were
recorded. This was a prospective observational cohort study. Results:
Of a total of 149 eligible patients, 145 completed the study. The mean
age (ϮSD) was 47 Ϯ 9 years; 56% were male. No adverse events were
noted during ESE. Seven patients (5%) had abnormal ESE (2 with
rest wall motion abnormalities and 5 with exercise-induced wall mo-
tion abnormalities). Five of the seven underwent cardiac catheteriza-
tion; three had CAD. All patients received telephone follow-up at three
months and six months. Of the 138 patients with a normal ESE, all
were free of cardiac events at three months. One patient had a non-
Q-wave MI at six months (negative predictive value = 99.3%, 95% CI
= 97.8% to 100%). Conclusions: Exercise stress echocardiography can
be used to evaluate low-risk chest pain patients in the ED. Patients
with a normal ESE may be considered for discharge with minimal risk
of sequelae. Key words: chest pain; exercise stress echocardiography;
emergency department; coronary artery disease; discharge; follow-up.
ACADEMIC EMERGENCY MEDICINE 2001; 8:196–199
M
ETHODS
Study Design. This was a pro-
spective observational cohort study
of patients who received ESE as part
of a protocol designed by the depart-
ments of emergency medicine and
cardiology. The protocol was de-
signed to identify patients with low
risk for coronary artery disease
(CAD) who could perform ESE for
evaluation of coronary ischemia
(Fig. 1). The study was reviewed and
approved by the institutional review
board.
Study Setting and Popula-
tion. The study was performed at
a community teaching hospital with
an annual ED census of 80,000 pa-
tients. Low-risk patients Ն30 years
of age qualified for this protocol if
they presented to the ED for chest
pain with some characteristics sug-
gestive of angina. For the purpose of
this study, patients were considered
low risk if they had a normal crea-
tine kinase–MB (CK-MB) isoen-
zyme, a normal or nondiagnostic
electrocardiogram (ECG), and had
no prior history of cardiac disease.
Patients did not have to have chest
pain on arrival to the ED to be en-
rolled in the study.
Patients who needed sublingual
nitroglycerin to relieve their pain re-
quired a second negative set of CK-
MB levels six hours after the initial
set. Patients were enrolled at the
discretion of the emergency physi-
cian (EP) and represented a conven-
ience sample. The study was con-
ducted during the normal operating
hours of the noninvasive laboratory
at our hospital (Monday through
Friday, 6 AM to 6 PM). The study pe-
riod was between March 1998 and
Chest pain is one of the most com- ment (ED) and accounts for an
estimated 5 million visits annually.1
mon complaints among patients pre-
senting to the emergency depart-
More than half of these patients are
admitted to the hospital, with an an-
nual cost of 10 billion dollars, al-
though most are ultimately found to
have non-cardiac chest pain.2–4
However, approximately 2% of
acute myocardial infarctions (MIs)
and 2% of unstable angina go undi-
agnosed in the ED, and these cases
result in some of the largest mone-
tary damages awarded in ED mal-
practice litigation.4–7 Though no one
factor seems to explain this, differ-
ent ED strategies have been evalu-
ated to identify these patients.
From the Departments of Emergency
Medicine (MSB, BJL, MAB, REO, NBJ)
and Cardiology (ESM, AD), Christiana
Care Health Services, Newark, DE.
Received June 15, 2000; revision received
September 18, 2000; accepted September
27, 2000. Presented at the SAEM annual
meeting, Boston, MA, May 1999.
Address for correspondence and reprints:
Neil B. Jasani, MD, Department of
Emergency Medicine, Christiana Care
Health Services, 4755 Ogletown-Stanton
Road, P.O. Box 6001, Newark, DE 19718.
Fax: 302-733-4383; e-mail: njasani@
christianacare.org
These strategies have included ad- March 1999.

ACADEMIC EMERGENCY MEDICINE • February 2001, Volume 8, Number 2
197
Study Protocol. Exercise stress
echocardiography consisted of
a
resting two-dimensional echocardi-
ogram using commercially available
equipment (Hewlett-Packard, Sonos
2000 or 5500, Malvern, PA). This
was followed by a period of treadmill
exercise using the Bruce protocol.14
Target heart rate was defined as
85% of the age-predicted maximal
heart rate. Failure to reach target
heart rate was not an exclusionary
criterion so long as normal hyper-
dynamic wall motion was observed
during the study. If the resting im-
ages revealed segmental wall motion
abnormalities, exercise testing was
not performed and the patient was
referred for admission. Stress echo-
cardiographic images were obtained
immediately after exercise and were
completed within 1 minute. Images
were digitized online and compared
side by side with resting images in a
quad screen format. An ESE was
considered abnormal if new wall mo-
tion abnormalities were observed on
the post-exercise images.
A 12-lead electrocardiogram was
obtained at baseline and every min-
ute during exercise with continuous
monitoring of leads II, V1, and V5.
The exercise electrocardiogram was
considered abnormal if Ն1 mm of ST
depression was observed at 80 ms
from the J point. All tests were per-
formed and interpreted by one of six
cardiologists experienced with ESE.
All readers had to successfully pass
an examination of 30 ESE stud-
ies given by the director of the ESE
laboratory. Inter-reader reliability
was not tested.
Figure 1. Chest pain protocol. ECG = electrocardiography; CPK-MB = cre-
atine phosphokinase–MB.
tients with abnormal echocardi-
ograms at rest or following exercise
were recommended for admission.
Patients with submaximal tests (un-
able to exercise more than 3 minutes
of the Bruce protocol) or those with
inadequate echocardiographic im-
ages were recommended for admis-
sion. Final disposition of the patient
Data Analysis. Patients were
considered ‘‘true negative’’ if their
ESE was normal and they reported
no cardiac events at follow-up. Pa-
tients were identified as ‘‘true posi-
tive’’ if they had an abnormal ESE
and had either a clinical event or a
cardiac catheterization that demon-
strated a coronary stenosis of Ն50%
was at the discretion of the emer- in the same anatomic distribution.
The predictive value for ESE was
calculated.
gency physician.
Patient follow-up was obtained
by telephone interview at three and
six months after discharge. Clinical
cardiac events were defined as MI,
cardiac death, or need for cardiac re-
vascularization with either angio-
plasty or coronary bypass. All events
RESULTS
One hundred forty-nine consecutive
patients were enrolled. Three pa-
tients were excluded from analysis
due to submaximal or nondiagnostic
tests and were recommended for ad-
Patients with normal ESE were were confirmed by review of medical
recommended for discharge. Pa- records.
Figure 2. Patient distribution. ESE = exercise stress echocardiography; MI = myocardial infarction; CAD = coro-
nary artery disease.

198
STRESS ECHOCARDIOGRAPHY
Buchsbaum et al. • EXERCISE STRESS ECHOCARDIOGRAPHY
T
ABLE 1. Patient Risk Factors
low-up. The negative predictive sitive than the initial electrocardio-
value for ESE was 99.3% (95% CI = gram for detecting cardiac events
97.8% to 100%).
Number of
(91% vs 40%).15 Studies have also
Risk Factors
Patients (%)
shown that patients with acute
chest pain who have resting wall
motion abnormalities are at much
higher risk for cardiac events than
those who do not.11,15 In our study
only two patients had this finding.
While one refused further testing,
the other had significant left main
CAD and required urgent coronary
artery bypass surgery.
The accuracy of ESE for diagnos-
ing CAD is similar to that of other
forms of imaged stress testing. The
positive predictive value of ESE is
75–90%, with a negative predictive
value of 80–90%. This discrimina-
tory power has compared favorably
with that of stress thallium imaging
in a recent meta-analysis.16 It also
appears to be more accurate than
standard stress electrocardiography
to detect CAD in women.17–20 Our
positive predictive value for ESE
was lower (43%) and may be related
to the fact that our population was
a relatively low-risk one. Addition-
ally, the studies were read in an un-
blinded fashion, which may have in-
troduced bias due to the tendency to
overdiagnose wall motion abnormal-
ities.
Patients exercised an average
(ϮSD) of 8.8 Ϯ 2.7 minutes, and 88%
achieved their target heart rate. Of
the 18 patients (12%) who did not
reach target heart rate, two had ab-
normal ESE studies and were ad-
mitted. Both underwent cardiac
catheterization and were found to
have CAD. The remaining 16 pa-
tients had a normal ESE and were
discharged. All 16 were free of car-
diac events at six-month follow-up.
For the purposes of the study, these
patients were not excluded from fi-
nal data analysis for ESE.
The average time (ϮSD) from in-
itial ED triage to discharge for pa-
tients with normal ESE was 8.3 Ϯ
3.0 hours. This was divided into 1.0
Ϯ 0.9 hours from triage to first phy-
sician evaluation, 5.0 Ϯ 0.8 hours
from first physician evaluation to
transporting the patient to the non-
invasive laboratory (6 Ϯ 1.7 hours
from ED presentation to ESE), and
2.3 Ϯ 0.9 hours to perform ESE and
discharge the patient. No patient
had an adverse event during exer-
cise testing.
Tobacco use
Family history
Hypertension
Hypercholesterolemia
Diabetes mellitus
75 (52%)
49 (34%)
38 (26%)
29 (20%)
4
(3%)
mission. One patient was lost to fol-
low-up. The remaining 145 patients
who completed three- and six-month
follow-up comprised the study pop-
ulation (Fig. 2). The mean age (ϮSD)
was 47 Ϯ 9 years; 56% were male.
Patient risk factors are summarized
in Table 1. The mean number of car-
diac risk factors (ϮSD) per patient
was 1.4 Ϯ 1.0.
Overall, seven patients had an
abnormal ESE, two patients with
resting wall motion abnormalities
and five patients with abnormal
post-exercise images. One patient
had marked hypokinesis of the in-
ferior, posterior, and lateral walls at
rest and went directly to cardiac
catheterization, which revealed a
significant left main stenosis. He
was referred for emergent bypass
surgery. Another patient with pos-
terior and apical hypokinesis at rest
refused admission but had no known
DISCUSSION
The negative predictive value
was very high at both three months
(100%) and six months (99.3%). Only
one patient with a negative ESE had
a cardiac event during the follow-up
period. He proved to have single-ves-
sel disease involving the left circum-
flex artery, which is difficult to de-
tect by ESE, and in general is
difficult to detect by any type of non-
invasive testing.
cardiac events at six-month follow- Disposition of low-risk patients with
up. Four of the five patients with ab- chest pain remains a diagnostic di-
normal exercise images underwent lemma for EPs. Routine history and
cardiac catheterization, which re- physical exam, electrocardiography,
vealed two true positives and two and cardiac enzyme levels help iden-
false positives. The remaining pa- tify patients with acute coronary
tient, who refused catheterization, syndromes. However, a small per-
was event-free at six-month follow- centage of serious cardiac disease is
up. The positive predictive value for still missed by these findings.6 Un-
ESE was 43%.
fortunately, missing this minority
Other studies have evaluated
stress echocardiography in the ED
and reported similar results. Trippi
et al. evaluated 163 low-risk ED pa-
tients presenting with chest pain
who underwent dobutamine echo-
cardiography. The negative predic-
tive value was 98.5%.12 In another
study by Stomel et al., only 11 of 455
patients followed for one year after
negative ESE in a chest pain center
had further evidence of CAD (nega-
tive predictive value = 97.6%).21 Co-
lon and colleagues followed 108 pa-
tients after ESE using a protocol
similar to ours and reported no car-
diac events (negative predictive
value = 100%).22
One hundred thirty-eight pa- may have serious consequences for
tients had a normal ESE. Only one both the patient and the EP.6,7 With
patient had a cardiac event during the diagnostic modalities currently
the follow-up period. This patient in use, it remains difficult to distin-
was a 39-year-old hypercholestero- guish between the minority of pa-
lemic man with atypical chest dis- tients with serious cardiac disease
comfort and a normal ESE who had from those with chest pain due to
a non-Q-wave MI six months after other etiologies.5 Many strategies
ED discharge. Cardiac catheteriza- have been evaluated to separate the
tion demonstrated an isolated left two groups, but none has been uni-
circumflex stenosis. Thirty-eight pa- versally accepted. In this study we
tients (26%) received sublingual ni- reviewed our experience at a large
troglycerin in the ED and required a community hospital with ESE.
second set of negative CK-MB prior
Stress echocardiography is at-
to ESE. Ninety-five percent of these tractive for several reasons. It al-
patients (36 of 38) who required sub- lows for the identification of resting
lingual nitroglycerin in the ED were wall motion abnormalities, which
free of known CAD at six-month fol- have been reported to be more sen-
One of the advantages of ESE is

ACADEMIC EMERGENCY MEDICINE • February 2001, Volume 8, Number 2
199
al. Use of electron-beam computed to-
mography in the evaluation of chest pain
patients in the emergency department.
Ann Emerg Med. 1999; 33:15–21.
11. Kontos MC, Arrowood JA, Jesse R,
et al. Comparison between 2-dimen-
sional echocardiography and myocardial
perfusion imaging in the emergency de-
partment in-patients with possible myo-
cardial ischemia. Am Heart J. 1998; 136:
that the results are immediately not able to compare ESE with the
available. This allows for prompt standard treatment for a similar
disposition by the EP. While the group of low-risk patients with chest
time to discharge was just over eight pain. Future studies should be
hours, it took only two hours to per- larger and conducted in a prospec-
form the ESE and discharge the pa- tive, randomized fashion. They
tient. Some of the delay prior to should include clinical outcome data
transport to the noninvasive lab was as well as information on cost and
because 26% of our patients re- patient satisfaction vs routine hos- 724–33.
12. Trippi JA, Lee KS, Kopp G, et al. Do-
quired a second set of negative CK- pital admission.
MB levels prior to ESE.
butamine stress tele-echocardiography
for evaluation of emergency department
patients with chest pain. J Am Coll Car-
diol. 1997; 30:627–32.
A final advantage of ESE is
C
ONCLUSIONS
cost.23,24 While costs and reimburse-
ments vary widely depending on lo-
cation, in general ESE is relatively
inexpensive. At our institution ESE
is about half the cost of thallium im-
aging.
13. Hilton TX, Thompson RC, Williams
HJ, et al. Technetium-99m sestamibi
myocardial perfusion imaging in the
emergency room evaluation of chest
pain. J Am Coll Cardiol. 1994; 23:1016–
22.
14. Fletcher GF, Balady G, Froelicher
VF, et al. Exercise standards: a state-
ment for healthcare professionals from
the American Heart Association. Circu-
lation. 1995; 91:580–97.
15. Kontos MC, Arrowood JA, Paulsen
WH, Nixon JV. Early echocardiography
can predict cardiac events in emergency
department patients with chest pain.
Ann Emerg Med. 1998; 31:550–7.
16. Fleischmann KE, Hunink MG,
Kuntz KM, Douglas PS. Exercise echo-
cardiography or exercise SPECT imag-
ing? A meta-analysis of diagnostic test
performance. JAMA. 1998; 280:913–20.
17. Tong, AT, Douglas PS. Stress echo-
cardiography in women. Cardiol Clin
North Am. 1999; 17:573–82.
18. Marshall ES, Bowens CA, Spector L.
Exercise stress echocardiography; an al-
ternative to perfusion imaging. Del Med
J. 1997; 69:291–4.
19. Marwick TH, Anderson T, Williams
MJ, et al. Exercise echocardiography is
an accurate and cost-efficient technique
for detection of coronary artery disease
in women. J Am Coll Cardiol. 1995; 26:
335–41.
20. Lewis JF, Lin L, McGorray S, et al.
Dobutamine stress echocardiography in
women with chest pain. J Am Coll Car-
diol. 1999; 33:1462–8.
21. Stomel R, Grant R, Eagle KA. Les-
sons learned from a community hospital
chest pain center. Am J Cardiol. 1999;
83:1033–7.
In a large community hospital, ESE
can be useful in determining dispo-
sition of low-risk patients presenting
with chest pain. Those patients with
a normal ESE may be considered for
discharge from the ED with minimal
risk of sequelae.
There are disadvantages to ESE
that must be considered. First, some
patients have poor echocardio-
graphic windows and are not candi-
dates for this approach. Second,
ESE in its present form is a subjec-
tive test and dependent on the ex-
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