The
n e w e ng l a n d j o u r na l
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m e dic i n e
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Coronary CT Angiography for Acute Chest Pain
Rita F. Redberg, M.D.
Each year, more than 6 million people in the
United States go to emergency departments because of acute chest pain. Some of them have
coronary artery disease, but most have diseases
that are unrelated to the heart or they have no
discernible physiological conditions. The vast
majority will undergo various diagnostic tests,
and many will be held for observation and may
be admitted to the hospital. This approach, however, is guaranteed to lead to unnecessary stays
in the emergency department and to overtreatment. More disturbingly, it is unclear whether
this approach actually results in better outcomes
than a more conservative one.
In this issue of the Journal, Hoffmann et al.1
describe an important comparative-effectiveness
study of two diagnostic strategies for patients
presenting to the emergency department with
chest pain. They investigate the effect of using
coronary computed tomographic angiography
(CCTA) to evaluate patients with symptoms suggestive of acute coronary syndromes to determine whether CCTA can safely reduce the time
such patients spend in the hospital. In their
study, Rule Out Myocardial Infarction Using
Computer Assisted Tomography II (ROMICATII), 1000 such patients were randomly assigned
to either CCTA or standard diagnostic procedures, which were performed at the discretion
of the physicians in the emergency department.
The authors found that the length of stay in
the hospital in the CCTA group was 7.6 hours
shorter than the length of stay in the standardevaluation group, and a follow-up evaluation 28
days later showed no overlooked cases of acute
coronary syndromes in either group — a fact
consistent with the low-to-intermediate-risk status of the study patients. They also found that
the CCTA group incurred only slightly higher
n engl j med 367;4
costs, as compared with the standard-evaluation
group. The authors’ findings build on similar
data from another study by Litt et al.2 that also
randomly assigned patients with suspected
acute coronary syndromes to CCTA or traditional care.
Both studies confirm the somewhat unremarkable fact that CCTA provides faster diagnostic
results than standard evaluation (which meant
some type of stress test in 74% of the patients
in the study by Hoffmann et al. and 64% of the
patients in the study by Litt et al.). It should be
noted that ROMICAT-II enrolled patients only
during “weekday daytime hours” at sites where
a “dedicated accelerated diagnostic protocol” was
performed; the costs (and wait time) increase
when any service is provided on nights and
weekends. Although shorter lengths of stay in
the hospital are highly desirable, especially from
the patient’s point of view, the ROMICAT-II study
reveals a deeper flaw in the approach to chest
pain in the emergency department.
The underlying assumption of the studies by
Hoffmann et al. and Litt et al. is that some diagnostic test must be performed before discharging these low-to-intermediate-risk patients
from the emergency department. This assumption is unproven and probably unwarranted. The
rationale for any test, as compared with no testing, should be that it will lead to an improved
outcome, and here there is no evidence that the
tests performed led to improved outcomes. Indeed, event rates for major adverse cardiac
events among all patients in the studies by
Hoffmann et al. and Litt et al. (whether the patients underwent CCTA, stress testing, or no
testing at all) were so low — less than 1% had a
myocardial infarction and no patients died —
that it is impossible to know whether the CCTA
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375
editorial
groups received any benefit whatsoever. These
very low event rates were observed in other similar studies.3,4 Moreover, in light of the certainty
that the patients in the CCTA group were exposed to substantial doses of radiation (from
both CCTA and nuclear stress tests) and were at
risk for nephrotoxicity and adverse reactions
from the CCTA contrast dye, clinicians may legitimately ask whether the tests did more harm
than good.
Patients who have normal electrocardiographic (ECG) findings and negative troponin
levels constitute a group at low risk for cardiac
events, and multiple studies show no evidence
that any additional testing further reduces that
risk. In the study by Litt et al., the average age
of the patients was 49 years, and 51% of the
patients in the CCTA group and 56% of the patients in the traditional-care group were women.
In the study by Hoffmann et al., the average age
was 54 years, and 47% were women. On the basis of age, sex, and history of chest pain alone,
the pretest probability is generally not high for
coronary artery disease in patients with these
demographic characteristics.5 Furthermore, the
risk of cancer from radiation is higher in younger age groups and among women. In the study
by Hoffmann et al., the radiation burden was
clinically significant in the standard-evaluation
group (4.7±8.4 mSv) and nearly tripled in the
CCTA group (13.9±10.4 mSv). Exposures of
10 mSv have been projected to lead to 1 death
from cancer per 2000 persons.6 Equally alarming, the testing may lead to an increased risk of
breast cancer among these patients, many of
whom are middle-aged women. A report from
the Institute of Medicine showed that medical
imaging is a leading environmental cause of
breast cancer, more than any suspected toxins.7
The decision regarding the need for diagnostic testing in these patients usually can be safely
deferred to outpatient follow-up within a few
weeks after the visit to the emergency department. The vast majority of patients have no cardiac causes for their chest pain, and many need
no further testing. An acute coronary syndrome
was a discharge diagnosis in less than 10% of
the patients in the ROMICAT-II study. Patients
in the CCTA group in both studies underwent
more tests, received more radiation, and had
more interventions than the standard-evaluation
group. The increased likelihood of downstream
testing after CCTA, which can lead to serious
376
n engl j med 367;4
complications, cautions against choosing this
test as the initial strategy.8
The studies by Hoffmann et al. and Litt et al.
showed that (assuming that a radiology department can read the computed tomographic [CT]
scans promptly) it is faster to obtain a cardiac
CT scan than a stress test. Of course, it is even
faster to discharge these patients without any
additional diagnostic test after determining that
their ECG findings and troponin levels are normal. Thus, with no evidence of benefit and definite risks, routine testing in the emergency department of patients with a low-to-intermediate
risk of acute coronary syndromes should be
avoided.
In short, the question is not which test leads
to faster discharge of patients from the emergency department, but whether a test is needed
at all. The Choosing Wisely campaign reminds
physicians to order testing only when the benefits will exceed the risks.9 I believe judicious
clinical follow-up is safer and in the best interests of the majority of these patients.
Disclosure forms provided by the author are available with the
full text of this article at NEJM.org.
From the Division of Cardiology, University of California, San
Francisco, San Francisco.
1. Hoffmann U, Truong QA, Schoenfeld DA, et al. Coronary
CT angiography versus standard evaluation in acute chest pain.
N Engl J Med 2012;367:299-308.
2. Litt HI, Gatsonis C, Snyder B, et al. CT angiography for safe
discharge of patients with possible acute coronary syndromes.
N Engl J Med 2012;366:1393-403.
3. Body R, Carley S, McDowell G, et al. Rapid exclusion of acute
myocardial infarction in patients with undetectable troponin using a high-sensitivity assay. J Am Coll Cardiol 2011;58:1332-9.
4. Goldstein JA, Chinnaiyan KM, Abidov A, et al. The CT-STAT
(Coronary Computed Tomographic Angiography for Systematic
Triage of Acute Chest Pain Patients to Treatment) trial. J Am Coll
Cardiol 2011;58:1414-22.
5. Diamond GA, Forrester JS. Analysis of probability as an aid
in the clinical diagnosis of coronary-artery disease. N Engl J
Med 1979;300:1350-8.
6. Berrington de González A, Mahesh M, Kim KP, et al. Projected cancer risks from computed tomographic scans performed in the United States in 2007. Arch Intern Med
2009;169:2071-7.
7. Smith-Bindman R. Environmental causes of breast cancer
and radiation from medical imaging: findings from the Institute
of Medicine report. Arch Intern Med 2012 June 11 (Epub ahead
of print).
8. Becker MC, Galla JM, Nissen SE. Left main trunk coronary
artery dissection as a consequence of inaccurate coronary computed tomographic angiography. Arch Intern Med 2011;171:698701.
9. Qaseem A, Alguire P, Dallas P, et al. Appropriate use of
screening and diagnostic tests to foster high-value, cost-conscious care. Ann Intern Med 2012;156:147-9.
DOI: 10.1056/NEJMe1206040
Copyright © 2012 Massachusetts Medical Society.
nejm.org
july 26, 2012
The New England Journal of Medicine
Downloaded from nejm.org at LINKOPING UNIVERSITY on August 15, 2013. For personal use only. No other uses without permission.
Copyright © 2012 Massachusetts Medical Society. All rights reserved.