Provocative testing for low-risk chest pain patients, must we continue?
Provocative testing for low-risk chest pain patients, must we continue?
James Booth 0 1
J. Jeremy Thomas 0
0 Reprint requests: J. Jeremy Thomas, MD, UAB Health System , Birmingham, AL , USA
1 Emergency Medicine, UAB Health System , Birmingham, AL , USA
Between 6 and 10 million patients are brought to
US emergency departments with chest pain annually,
accounting for 5 to 10% of all ED visits.1,2 A subset of
these patients will have acute coronary syndrome (ACS)
including an acute myocardial infarction (MI). Missing
an acute MI is a significant risk of morbidity for patients
and risk of litigation for emergency physicians. While a
historical miss rate of 2% to 4% is commonly quoted,
more recent data suggest that current diagnostic
strategies reduce this miss rate below 1%.3-5 While this
reduction in missed MIs is desirable, it comes at the cost
of increased rates of hospital admissions for chest pain
‘‘rule outs’’ and additional diagnostic tests, accruing
more than $3 billion in annual hospital costs in the US
and subjecting many patients to testing that may not be
A subset of patients with ‘‘low-risk’’ or
‘‘moderaterisk’’ chest pain, as determined by risk assessment tools
or physician clinical judgment, are often admitted to
hospital observation units and subjected to additional
non-invasive cardiac testing, such as a stress test or
coronary computed tomographic angiogram (CCTA).
This practice is supported by the 2014 ACC/AHA
guidelines that recommend non-invasive cardiac testing
within 72 hours of presentation in patients with negative
cardiac markers and non-ischemic ECGs.8 In general,
patients with negative stress tests or negative CCTAs are
discharged home while patients with positive tests have
subsequent cardiology consultations to determine next
steps including possible invasive cardiac catheterization.
The HEART score is a risk stratification tool used
with increasing popularity in the emergency department
(ED) setting for patients with chest pain. The score has
been shown to reliably stratify patients with possible
ACS into low, moderate, and high-risk categories based
on 5 elements (history, ECG, age, risk factors, and
troponin). Patients with HEART scores less than 4 and
negative troponins may be discharged from the
emergency department with a low \ 1% rate of major
adverse cardiac event (MACE) in the 90 days following
ED evaluation. The reliability, ease of use, and
efficiency of the HEART score has led to an increasing
number of hospitals integrating the score into
standardized chest pain protocols for their emergency
departments. The use of the HEART score has been
shown to decrease the number of patients admitted to
hospitals for chest pain and thereby subsequently
decrease the utilization of non-invasive cardiac testing,
such as stress tests, to further risk stratify patients.
In this issue of the Journal, Krishnan et al9 publish
results from a retrospective analysis of 292 emergency
department patients with chest pain. These patients were
deemed low risk and subsequently placed in an
observation unit to receive additional non-invasive cardiac
testing. 69% of the patients underwent pharmacologic or
exercise stress tests with myocardial perfusion imaging
(MPI) while the remainder underwent exercise stress
tests without imaging. 33 patients (11.3%) had positive
stress tests for ischemia. 50% of these 33 patients had a
prior history of MI, percutaneous coronary intervention
(PCI), or coronary artery bypass graph (CABG). Of
these patients with positive stress tests, 12 underwent
subsequent diagnostic cardiac catheterization and only 4
of these patients (1.4% of the total 292 patients) had
revascularization with possible mortality benefit.
While the results published by Krishnan et al are
retrospective and limited to a single center, they add to a
growing body of recent literature that suggests that
cardiac stress tests are overutilized in emergency
department patients admitted (or even discharged with
expedited provocative testing as an outpatient) for
lowrisk chest pain.7,10-13 As one example, a recent large
retrospective analysis by Sandhu et al looked at an
insurance claims database of over 900,000 ED chest
pain patients with initial negative workups. The results
showed no significant reduction in subsequent
admissions for acute MIs in patients who underwent
noninvasive cardiac testing for further risk stratification.
Another recent study by Reinhardt et al13 looked at
1,000 ED chest pain patients across 9 hospitals with
initial negative workups for ischemia who were
randomized to non-invasive cardiac testing vs clinical
evaluation alone. The results showed that non-invasive
testing led to longer lengths of stay (LOS), greater costs,
more downstream testing, and more radiation exposure
without improvement in clinical outcomes.
In addition to the majority of stress tests being
negative for ischemia, the data from Krishnan et al also
show that the majority of studied patients with positive
stress tests did not undergo revascularization therapy. 21
of the 33 patients (63.6%) with positive stress tests were
discharged without cardiac catheterization during their
hospital stay. 13 were directly discharged from the
observation unit with cardiology follow-up and 8
patients underwent further non-invasive tests such as
CCTA, repeat stress test, or transthoracic
echocardiogram (TTE). The decision to proceed with cardiac
catheterization was made by the consulting cardiologist
without a standardized decision rule but mostly based
upon the size of the ischemic area noted on the MPI.
An unfortunate limitation to the Krishnan et al
analysis is the lack of standardization for determining
the patient’s risk of ACS. The emergency physicians at
the time deemed the patients to be ‘‘low-risk’’ yet not
low-enough-risk to be sent home directly from the
emergency department without further non-invasive
cardiac testing. Use of the HEART score could have
potentially resulted in a percentage of the 292 patients
being discharged directly from the emergency
department without undergoing further stress testing.
Unfortunately, limitations in the patient documentation
prevent a retrospective application of the HEART to this
The general approach to emergency department
patients with chest pain has been evolving over recent
years with the increasing use of the HEART score and
high-sensitivity troponins. Despite the 2014 ACC/AHA
guidelines, more ‘‘low-risk’’ patients are being
discharged directly from emergency departments without
undergoing further non-invasive cardiac testing (in the
inpatient, observation, or expedited outpatient setting).
The analysis by Krishnan et al and other similar studies
now raise questions regarding the best approach to
patients who are deemed ‘‘moderate-risk’’ (HEART
scores of 4-6) or ‘‘high-risk’’ (HEART scores [ 6) and
whether these patient populations benefit from
undergoing non-invasive cardiac testing in the acute setting.
As Krishnan et al identify in their results, 50% of the
patients who had positive stress tests had prior histories
of CAD. Future directions for research may include a
prospective randomized clinical trial of early
non-invasive testing and the utilization of the HEART score and
prior history of CAD to help guide a more targeted
higher-yield patient population.
In the setting of ongoing national health care
reform, universal emphasis on healthcare cost savings
and quality improvement, as well as the desire to
standardize practice based on evidence-based medicine—the
current universal practice of liberal provocative testing
will likely come under intense scrutiny in the near
future. Provocative testing is time consuming,
expensive, and often difficult to coordinate rapidly as an
outpatient from the ED setting. These issues often lead
to unnecessary observation stays and admissions to the
hospital that have shown no benefit to these low-risk
patients, but create significant cost and resource
utilization. With the growing body of evidence showing a
lack of benefit (in mortality or MACE) to low-risk ED
chest pain patients that undergo provocative testing in
the setting of a negative ED evaluation for ACS, we
anticipate (and hope) that future revisions of the ACC/
AHA guidelines will soften the recommendation for
provocative testing within 72 hours of ED evaluation for
this patient population.
James Booth and J. Jeremy Thomas declare that they
have no conflict of interest to disclose.
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