CTCA shows promise in reducing length of stay and costs for ED chest pain patients, but more research is needed. While CTCA is highly sensitive for detecting CAD, it may overestimate lesion severity and has radiation risks. Current evidence does not clearly support CTCA as a routine test for ED chest pain patients without known CAD who have normal ECG and biomarkers. CTCA may be useful in select subgroups, but how to define these subgroups is unclear.

1. Anne-Maree Kelly
Director, Joseph Epstein Centre for Emergency Medicine
Research@Western Health, Melbourne
@kellyam_jec

2.  This presentation may be reproduced in part or
whole for education purposes on the condition that
each reproduced slide contains the following:
‘Reproduced with permission of Professor Anne-
Maree Kelly, Joseph Epstein Centre for Emergency
Medicine Research @Western Health, Melbourne,
Australia’

3.  Support for this meeting and advisory boards from Astra Zeneca
 Travel support to speak at a conference (on blood gases) by Radiometer
 Advisory board membership MSD
 No relationships with cardiac diagnostic or imaging companies
 Co-author of NHF guidelines for the management of ACS and addenda
 Editorial boards of:
◦ Annals of Emergency Medicine
◦ Emergency Medicine Australasia
◦ Hong Kong Journal of Emergency Medicine

4.  To explore the role of CTCA in ED chest pain patients,
with a focus on those that ‘rule out’ for ACS
 To compare the cost-benefit of a CTCA compared to
alternatives
 To provoke debate about the rational place of CTCA in
ED chest pain work-up!

5. From Schussler JM. Cardiac computed tomography:Emergeing
cardiac devices and technology. Asian Hospital and Healthcare
Management.
http://www.asianhhm.com/diagnostics/cardiac_computed_tomograph
y.htm
• Non-invasive
• Nice pictures
• Can ‘see’ if there are lesions
or not

6. Three recent studies have suggested that CTCA for ED chest pain
patients:
• Reduces ED length of stay
• Reduces admissions
• Negative scans have good prognostic performance
• Maybe more ‘accurate’ in identification of CAD than alternatives
ROMICAT II
ACRIN-PA
CT-STAT

7. ACRIN-PA ROMICAT II
 50% reduction in
admissions (23% vs. 50%)
 25% reduction in LOS (18
hours vs. 25 hours)
 67% reduction in median
LOS (9 hours vs. 27 hours)
 19% reduction in ED costs
Litt HI et al. N Engl J Med 2012; 366:1393-403. Hoffmann U et al. NEJM 2012; 367:299-308

8. CT-STAT
 54% reduction in time to
diagnosis (3 hours vs 6
hours)
 38% reduction in costs
Goldstein et al. J Am Coll Cardiol 2011;58:1414-22

9.  In Victoria, estimated 37,500 patients undergo ACS rule out in
ED annually
 The ‘rule in’ rate for ACS is ~15-20%
◦ Depends how you count
 About 30-32,000 have ACS ruled out and (according to ACS
guidelines) need a further assessment strategy to rule out
clinically significant CAD
Based on Dept Health Victoria data and estimates of chest pain
presentations by Goodacre (UK): Goodacre et al. Heart. 2005; 91: 229–230.

10.  Highly variable
 Options
◦ Exercise test
◦ Nuclear medicine studies
◦ CTCA
◦ GP or cardiologist can decide!
◦ Nothing (active choice)

11. TIMI score Demographics
 0 33%
 1 18%
 2 18%
 3 11%
 4 11%
 5+ ~9%
 Male =60%
 Average age=62
 Known CAD = 33%
Based on data from cohort study @ WH
2009

12.  Is CTCA sensitive for the detection of CAD?
 Is CTCA suitable for the patient cohort in question?
 Does negative CTCA have good prognostic performance for
future ACS events?
 Does CTCA improve outcomes for patients?
 How does CTCA perform in comparison to alternative
investigation strategies?
 Which patients should have this test rather than an
alternative?

13.  Depends on whether analysis is at patient level or segment level
◦ Patient level is of prime importance in the cohort of primary interest
 Simple answer is ‘YES’
 In a recent systematic review/ meta-analysis, CTCA had 94% (61-99%)
sensitivity and 87% (16-100%) specificity for CAD.
 Another meta-analysis of 64-slice +, reports sensitivity of 99% (95% CI 97-
99%)
 But about 9% of tests are non-diagnostic/ inconclusive
•Goodacre et al. Health Technol Assess 2013;17:1-188
•Mowatt et al. Technol Assess. 2008; 12:iii-iv, ix-143.

14.  The question being asked is “Is there CAD”?
 Just over 50% of the patient cohort is suitable for CTCA
 About 30-40% of patients already have known CAD
◦ Other investigation pathways more suitable in most
 Other ‘contra-indications’: 10-15%
◦ Metformin
◦ Inability to control rate adequately
◦ Renal failure
◦ Thyroid disease
◦ Irregular rhythms
Hamid S et al. Am J Emerg Med. 2010;28:494-8

15.  Safety
◦ Short term adverse events related to the scan are very rare
◦ Contrast allergy at expected rate (1/2,500-1/25,000)
◦ Adverse effects due to rate control-usually minor
◦ Radiation risk
 Feasibility
◦ Limited by access to scanner and availability of experienced readers
◦ ‘In hours’ only availability does not match ED 24/7 patient flow
◦ ‘Competition’ with other patients needing CT scan

16.  Simple answer is ‘YES’
 In meta-analysis:
 I death from 1334 patients
 No PCI, MI etc
 Rate = 0.07% (95% CI 0.01% to 0.4%)
Goodacre et al. Health Technol Assess 2013;17:1-188

17.  In meta-analysis:
 39 events in 332 cases
 12 MI
 Two thirds of events were revascularisations
 Rate 12% (95% CI 9-16%)
 Only one study was blinded to CTCA results:
◦ Showed CTCA results (presence of stenosis) was independently
associated with MACE (HR 17)
Goodacre et al. Health Technol Assess 2013;17:1-188. S
Schlett CA et al. JACC Cardiovasc Imaging. 2011;4: 481–491.

18.  Focus is the sub-population without known CAD
◦ 65-70% of cohort
◦ 19,500-22,500 patients annually in Victoria
 Available data suggests rate of undiagnosed CAD ~8-10%.
 It all depends on risk of adverse events (cardiac death, MI) vs.
cost
 NICE (UK) sets a willingness to pay threshold at $30,000 to
$45,000/ QALY

19.  CTCA asks “Is there plaque”?
 I am not sure that is the right question

20.  A. 5%
 B. 2%
 C. 1%
 D. 0.5%

21.  A. 5%
 B. 2%
 C. 1%
 D. 0.5%

22.  What is the risk of MACE in patients without
known CAD, with non-diagnostic ECG and normal
serial biomarkers in ED?
 A. 5%
 B. 2%
 C. 1%
 D. 0.5%
Fitzgerald P et al. Acad Emerg Med 2011;18:488–95.

23. Test Sensitivity NPV (MACE)
CTCA 94-99% >99%
MPS 87% 97.2%
Exercise ECG (EST) 20-30% As low as 86%
Conti et al. Nucl Med Commun 2011 32;1223

24.  Varying study design, populations and outcomes
studied
 In meta-analysis
 Rate of MACE for negative EST 0.7% (95% CI 0.5-
1.2%)
 But sensitivity questionable
◦ Some studies around 30% sensitivity for occlusive CAD
Goodacre et al. Health Technol Assess 2013;17:1-188. S
Schlett CA et al. JACC Cardiovasc Imaging. 2011;4:481–491.

25.  Not enough data in the specific population of interest
to draw conclusions

26.  Positive predictive value for CAD at segment level is
only moderate (78%)
◦ False positives: over-estimation of lesion severity in presence
of calcified plaques
 Scanning 15,000 patients in Victoria/year will pose
access issues for CT scanners!

27.  An ‘elephant in the room’
 Retrospectively gated protocols, risk estimated at:
◦ 0.11 to 0.13% for men
◦ 0.27-0.37% for women
 Prospectively gated protocols, risk estimated at:
◦ 0.014-0.017% for men
◦ 0.035-0.06% for women
 Risk is inversely related to age
 Significant ethnic variation
Huang et al. Br J Radiol. 2010;83(986):152-8.

28. ACRIN-PA
 50% reduction in
admissions (23% vs. 50%)
 25% reduction in LOS (18
hours vs. 25 hours)
 No patient with negative
CTCA had death, MI within
30 days
 Only 2/1357 (0.15%) of
patients not diagnosed with
MI at index visit had MI
within 30 days
 Trial conditions re CT
availability
 TIMI 0-2
◦ >85% TIMI 0 or 1
Litt HI et al. N Engl J Med 2012; 366:1393-403.

29. CT-STAT
 54% reduction in time to
diagnosis (3 hours vs. 6
hours)
 38% reduction in costs
 Only included ED costs
 Trial conditions re CT availability
 Highly selected cohort
 In CTCA cohort, 6 times greater
rate of additional non-invasive
tests after ED discharge
◦ Cost
◦ Radiation, etc
Goldstein et al. J Am Coll Cardiol 2011;58:1414-22

30. ROMICAT II
 67% reduction in median
LOS (9 hours vs. 27 hours)
 19% reduction in ED costs
 Eventual hospital costs actually
50% higher in CTCA group
 Higher rate of additional testing
(27% vs.12%)
 No difference in events
 Trial conditions re CT availability
 Selected population
◦ 40-74
◦ No AF or renal disease or BMI<40Hoffmann U et al. NEJM 2012; 367:299-308

31.  Data from administrative dataset
◦ Age 66+
◦ Non-emergent, non-invasive test for ?CAD
◦ No known CAD
 Compared CTCA vs. stress myocardial perfusion scan
 Results:
Outcome CTCA MPS
Cardiac catheter 23% 12%
PCI 7.8% 3.4%
CABG 3.7% 1.3%
All cause mortality 180
days
1.05% 1.28%
Hospitalization for MI 180
days
0.19% 0.43%
Schreibati et al. JAMA 2011; 306:2128-36

32.  1. That a test to rule out CAD before discharge is needed in ED
chest pain patients
◦ This is unproven!
◦ The rationale for any test (compared to no test) is that it improves
outcome
◦ Event rates are so low (<1%) in all arms that it is impossible to tell if
CTCA provided benefit
 2. All lesions found were cause of symptoms
◦ 5% rate of occlusive lesions found in screening of asymptomatic
patients
With risk of dye, radiation, extra tests etc. harm
is likely to seriously compete with any benefit!

33.  In Australia:
◦ ~75% of patients are discharged from ED/SSU
◦ Most do not have additional testing before discharge
◦ Median LOS of the order of 10 hours, depending on centre
and protocol
◦ LOS likely to reduce as accelerated diagnostic biomarker
pathways are validated

34.  SCCT/AHA/ACC:
◦ Symptomatic patients without known CAD with ‘intermediate’
pre-test probability
◦ Symptomatic patients without known CAD with ‘low’ pre-test
probability who cannot perform a functional test or with
equivocal functional test results
◦ Not suitable for high pre-test probability patientsdue to:
 High likelihood of plaques
 Limited spatial and temporal resolution
 These should have CA or functional test
Taylor AJ et al. J Am Coll Cardiol 2010:56:1864-94.

35.  CTCA is not indicated as a ‘routine’ test in ED patients
with chest pain without known CAD and with normal
biomarkers and ECG
 It may be useful in a subgroup based on risk, but how
this risk might be defined in unclear
 There is a reasonable case for no further testing in
significant proportion of ED chest pain patients who
have had ACS ruled out by ECG and biomarkers

36.  Comparison of DM, ‘metabolic syndrome’ and other (MPS
study)
 Metabolic syndrome defined as at least 3 of:
◦ Fasting glucose >110mg/dl
◦ High BP
◦ Low HDL
◦ High triglicerides
◦ High waist circumference
 Rate of MACE at 1 year
◦ DM 30%
◦ Metabolic syndrome 26%
◦ Others 15%
Conti et al. Nucl Med Commun 2008; 29:1106-12.
Could similar parameters
identify a subgroup of
patients who might benefit
from CTCA?