Acute Cardiac Ischemia Time-Insensitive Predictive Instrument ACI-TIPI

Acute Cardiac Ischemia
Time-Insensitive Predictive Instrument
GE Medical Systems Information Technologies
(GEMS IT) went to the original inventor, the trial
coordinator, and a physician who participated
in the ACI-TIPI Trial for some expert discussion.
GE Medical Systems proudly incorporates
Marquette’s history in electrocardiography
to ensure the highest quality and accuracy.
Ask the Experts
Harry P. Selker, M.D.
Tom Aufderheide, M.D.
Joni Beshansky, R.N., M.P.H.
What gave you the initial idea for a predictive
instrument for acute cardiac ischemia?
As a clinician in the emergency department,
I well knew how hard it was, among the many patients
presenting with chest pain or other symptoms suggestive
of acute cardiac ischemia, to decide whom I should admit
and whom I could safely send home. I saw the idea of a predictive instrument that could give an independent objective
assessment of the patient’s true probability of truly having
acute ischemia (i.e., either acute myocardial infarction or
unstable angina pectoris, for which we hospitalize patients)
as being a potentially very helpful thing.
How does ACI-TIPI address the need for
“real-time”and retrospective interpretation
of data?
The ability to make a decision correctly
is important, and to make it quickly is also important.
So, we think that in general, when used in a real-time
clinical setting, ACI-TIPI may help the physician make
more informed decisions. And that’s very good. But, why
do we call it the “time-insensitive” predictive instrument
(TIPI)? Well, we made it so it would be “insensitive”
to when in time you use it, whether for real-time care or
if used later, retrospectively, after the fact to judge the
appropriateness and quality of care. This demonstrated
validity for both real-time and retrospective use is unique
to TIPIs, and has proven to be an attractive way to get all
members of the healthcare community to work together
to improve care.
The ACI-TIPI algorithm was developed by Harry P. Selker, MD, Chief
of Clinical Care Research and Director of the Center for Cardiovascular Health Services Research at New England Medical Center.
Dr. Selker is also Professor of Medicine at Tufts University. Dr. Selker
has pioneered research in hospitals and emergency departments to
develop methods to improve cardiac care, including development of
cardiac predictive instruments as decision aids such as ACI-TIPI.
ACI-TIPI underwent extensive clinical testing
in a federally-funded clinical trial led by
Dr. Selker that included 10,689 patients at
10 hospitals nationwide.
randomized study, the data demonstrated that ACI-TIPI
did improve triage decisions when it was available to the
clinician. In general, the physicians did not want to recognize that a computerized instrument was better than their
independent clinical judgment. However, when they realized
that ACI-TIPI information supplemented, not replaced,
physician judgement, and when they learned the results
of the study, physician opinion dramatically changed.
What about the effect of individual patient
circumstances? How did that impact your
findings with respect to ACI-TIPI?
DR. AUFDERHEIDE: ACI-TIPI doesn’t restrict the physician’s
Dr. Tom Aufderheide was one of the site co-investigators, at the
Medical College of Wisconsin, where he is Associate Professor
of Emergency Medicine. Dr. Aufderheide is board certified in
internal medicine and emergency medicine. He has published
extensively in the field of emergency cardiac care.
work-up or approach to patient care. Physicians can
implement a comprehensive or succinct evaluation, as
they feel appropriate for any individual patient. In addition,
they can incorporate the ACI-TIPI score into that clinical
decision-making process. ACI-TIPI, then, is applicable to
a wide range of patients and can be incorporated into
any approach to patient care that the physician feels is
appropriate for that individual.
The ACI-TIPI "score" reflects the percentage of probability that the patient has acute cardiac ischemia.
How should physicians interpret that score?
A good analogy for the score is the weather
report. It will tell you there’s a 30 per cent, 50 per cent,
or 90 per cent probability of rain, and that helps you make
a better decision. Of course, it depends on how the sky
looks and how far you’re walking – they affect your decision.
For example, if the weather forecaster says there’s only a
30 per cent chance of rain, but it’s raining cats and dogs
outside, you’ll carry an umbrella. It’s obvious. You don’t need
a weather forecast to help you. On the other hand, if it's
blue, sunny skies and they report a 20 or 30 per cent chance,
you probably won’t bring an umbrella. It’s when it’s overcast,
that the prediction is most useful. Well, it’s that way for a
patient, too, with the probability of acute ischemia. It’s for
the “overcast” patient that ACI-TIPI is most helpful in your
triage decision making.
How was the trial conducted?
This was a prospective, randomized,
controlled clinical trial. The ACI-TIPI was not available to
the treating clinician 50 percent of the time. The primary
study end point was accuracy of triage decisions with
and without the availability of ACI-TIPI.
Did you have any pre-conceived ideas about
ACI-TIPI before you participated in the study?
DR. AUFDERHEIDE: I always strive to maintain an open
mind until all of the data has been acquired and analyzed.
If there was any collective bias at our study site, it was
that ACI-TIPI would not significantly improve accuracy
of triage decisions.
What did you discover with regard to that
particular bias?
Prior to the end of the trial, we asked
our local physicians whether they thought the ACI-TIPI
helped their triage decisions. The consensus opinion of
the physicians was that ACI-TIPI did not improve their
clinical judgment. However, following completion of this
Is ACI-TIPI validated for various ethnic groups?
In that national trial, we had excellent ethnic
diversity, including Asian, Caucasian, Hispanic and Black
patients, and the results showed that ACI-TIPI was effective
across all those groups.
One of the variables that the ACI-TIPI algorithm
takes into account is whether the patient has
a chief or secondary complaint of chest pain.
How do you define "chest pain" for the purposes
of using ACI-TIPI?
The definition of “chest pain” is discomfort consistent with an anginal equivalent syndrome.
This could be any combination of pain, pressure, tightness,
squeezing or shortness of breath. The discomfort may be
located in the chest, upper abdomen, neck, jaw or left arm.
If the discomfort is the primary symptom that caused the
patient to seek medical attention, it is considered a chief
complaint. Otherwise, it is considered a secondary complaint. When using ACI-TIPI, it is important to adequately train
personnel to accurately assess whether the symptom complex potentially represents an anginal equivalent syndrome,
and whether it is a chief or secondary complaint. The treating physician, in my opinion, has the most information and
expertise to accurately make this judgement.
The Project Director for the national ACI-TIPI Trial,
Joni Beshansky, RN, MPH, has helped hospitals’ emergency
departments throughout the country institute use of ACI-TIPI.
She is a clinical researcher with Dr. Selker at the Center for
Cardiovascular Health Services Research at New England
Medical Center and is Assistant Professor of Medicine at
Tufts University School of Medicine.
users of ACI-TIPI might think
that for the ACI-TIPI chest pain question, the patient must
have chest pain at the time the electrocardiogram is
being done. That is not the case. We just need to know
whether chest pain was the primary symptom and the
main reason for coming to the emergency department.
The confusion might arise about the distinction between primary complaint and secondary complaint.
If the users aren’t sure, they should consider it “primary.”
This default will lead to a slightly higher number which
is safer than having a lower value. The fortunate thing
is that the most powerful variables for ACI-TIPI are the
data from the ECG. So chest pain is important, but the
ECG really tells the story.
Case 1:
41-Year-Old Male ACI-TIPI Score: 96%
DR. AUFDERHEIDE: For patients with obvious hyper-acute
ST segment elevation MI, the ACI-TIPI score may be less
frequently useful. The physician should immediately recognize the electrocardiographic diagnosis without assistance
from ACI-TIPI. Conversely, it may be immensely helpful
if the relatively obvious diagnosis remains unrecognized
until the high ACI-TIPI score causes the physician to more
carefully evaluate the ECG.
Case 2:
50-Year-Old Male ACI-TIPI Score: 25%
DR. AUFDERHEIDE: This example identifies that “gray”
area where ACI-TIPI demonstrates significant benefit.
Such patients are very difficult to evaluate, in part, because
of an abnormal, but non-diagnostic electrocardiogram.
An ACI-TIPI score in these circumstances can assist the
physician is making sound triage decisions.
Case 3:
50-Year-Old Male ACI-TIPI Score: 5%
DR. AUFDERHEIDE: One of the major benefits of ACI-TIPI
is independent confirmation of a low risk for ischemia. In fact,
use of ACI-TIPI, with physician interpretation, is associated
with reduced hospitalization among emergency department
patients without acute cardiac ischemia. ACI-TIPI can independently confirm the physician’s suspicion of low risk and
appropriately allow the non-ischemic patient to be safely
discharged home.
Do you think physicians will embrace ACI-TIPI?
Of the many different physicians to
whom I have presented, all were more than pleased to
use it once they understood the operational simplicity
of the software as implemented in the electrocardiograph.
They needed to understand that ACI-TIPI was not
telling them “what to do” with their patients, but that
it was simply another piece of information provided to
them to assist in their own decision-making process
DR. AUFDERHEIDE: I view ACI-TIPI as an effective, user-
friendly addition to the diagnostic evaluation of one of the
most difficult patient populations in emergency medicine.
If physicians can recognize this effective tool for what it is
(valuable supplemental information, not replacing physician
judgement), it is likely to be widely applied.
In summary, what are the most important benefits
of ACI-TIPI to the physician?
What are some specific situations where ACI-TIPI
would be particularly valuable?
DR. SELKER: The ACI-TIPI, along with physician interpretation,
has now been shown to improve the accuracy and speed
of emergency department triage. Also, it can act as part of
an emergency department risk-management error-reduction
program to help reduce the likelihood of patients being
mistakenly sent home with acute cardiac ischemia, which
of course, could also reduce malpractice costs. Finally,
because, as a “TIPI,” the ACI-TIPI is valid for both real-time
and retrospective use, it can promote the coming together
of clinicians, hospitals, and others in the healthcare system
to improve emergency cardiac care by their all using the
same, clinically valid, tool.
DR. AUFDERHEIDE: Another potential use of ACI-TIPI is in
determining eligibility for chest pain observation unit evaluation. Many chest pain observation units in the United States
target relatively low risk patients with a less than 15 percent
chance of ischemia. The ACI-TIPI risk stratifies patients with
chest pain and has the potential to assist emergency physicians in more appropriately utilizing chest pain observation
unit services.
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