CT coronary angiography in ED chest pain patients

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CT coronary angiography is the new kid on the block for assessing emergency department patients with chest pain. How accurate is it? What are the down sides? How useful is it? Which patients is it …

CT coronary angiography is the new kid on the block for assessing emergency department patients with chest pain. How accurate is it? What are the down sides? How useful is it? Which patients is it suitable for? This presentation attempts to answer these questions in light of current evidence.

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  • 1. Anne-Maree KellyDirector, Joseph Epstein Centre for Emergency MedicineResearch@Western Health, Melbourne@kellyam_jec
  • 2.  This presentation may be reproduced in part orwhole for education purposes on the condition thateach reproduced slide contains the following:‘Reproduced with permission of Professor Anne-Maree Kelly, Joseph Epstein Centre for EmergencyMedicine 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 toalternatives To provoke debate about the rational place of CTCA inED chest pain work-up!
  • 5. From Schussler JM. Cardiac computed tomography:Emergeingcardiac devices and technology. Asian Hospital and HealthcareManagement.http://www.asianhhm.com/diagnostics/cardiac_computed_tomography.htm• Non-invasive• Nice pictures• Can ‘see’ if there are lesionsor not
  • 6. Three recent studies have suggested that CTCA for ED chest painpatients:• Reduces ED length of stay• Reduces admissions• Negative scans have good prognostic performance• Maybe more ‘accurate’ in identification of CAD than alternativesROMICAT IIACRIN-PACT-STAT
  • 7. ACRIN-PA ROMICAT II 50% reduction inadmissions (23% vs. 50%) 25% reduction in LOS (18hours vs. 25 hours) 67% reduction in medianLOS (9 hours vs. 27 hours) 19% reduction in ED costsLitt 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 todiagnosis (3 hours vs 6hours) 38% reduction in costsGoldstein et al. J Am Coll Cardiol 2011;58:1414-22
  • 9.  In Victoria, estimated 37,500 patients undergo ACS rule out inED 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 ACSguidelines) need a further assessment strategy to rule outclinically significant CADBased on Dept Health Victoria data and estimates of chest painpresentations 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 @ WH2009
  • 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 forfuture ACS events? Does CTCA improve outcomes for patients? How does CTCA perform in comparison to alternativeinvestigation strategies? Which patients should have this test rather than analternative?
  • 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 rhythmsHamid 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 independentlyassociated with MACE (HR 17)Goodacre et al. Health Technol Assess 2013;17:1-188. SSchlett 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 withoutknown CAD, with non-diagnostic ECG and normalserial 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 outcomesstudied 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 CADGoodacre et al. Health Technol Assess 2013;17:1-188. SSchlett CA et al. JACC Cardiovasc Imaging. 2011;4:481–491.
  • 25.  Not enough data in the specific population of interestto draw conclusions
  • 26.  Positive predictive value for CAD at segment level isonly moderate (78%)◦ False positives: over-estimation of lesion severity in presenceof calcified plaques Scanning 15,000 patients in Victoria/year will poseaccess 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 variationHuang et al. Br J Radiol. 2010;83(986):152-8.
  • 28. ACRIN-PA 50% reduction inadmissions (23% vs. 50%) 25% reduction in LOS (18hours vs. 25 hours) No patient with negativeCTCA had death, MI within30 days Only 2/1357 (0.15%) ofpatients not diagnosed withMI at index visit had MIwithin 30 days Trial conditions re CTavailability TIMI 0-2◦ >85% TIMI 0 or 1Litt HI et al. N Engl J Med 2012; 366:1393-403.
  • 29. CT-STAT 54% reduction in time todiagnosis (3 hours vs. 6hours) 38% reduction in costs Only included ED costs Trial conditions re CT availability Highly selected cohort In CTCA cohort, 6 times greaterrate of additional non-invasivetests after ED discharge◦ Cost◦ Radiation, etcGoldstein et al. J Am Coll Cardiol 2011;58:1414-22
  • 30. ROMICAT II 67% reduction in medianLOS (9 hours vs. 27 hours) 19% reduction in ED costs Eventual hospital costs actually50% 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 MPSCardiac catheter 23% 12%PCI 7.8% 3.4%CABG 3.7% 1.3%All cause mortality 180days1.05% 1.28%Hospitalization for MI 180days0.19% 0.43%Schreibati et al. JAMA 2011; 306:2128-36
  • 32.  1. That a test to rule out CAD before discharge is needed in EDchest pain patients◦ This is unproven!◦ The rationale for any test (compared to no test) is that it improvesoutcome◦ Event rates are so low (<1%) in all arms that it is impossible to tell ifCTCA provided benefit 2. All lesions found were cause of symptoms◦ 5% rate of occlusive lesions found in screening of asymptomaticpatientsWith risk of dye, radiation, extra tests etc. harmis 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 centreand protocol◦ LOS likely to reduce as accelerated diagnostic biomarkerpathways are validated
  • 34.  SCCT/AHA/ACC:◦ Symptomatic patients without known CAD with ‘intermediate’pre-test probability◦ Symptomatic patients without known CAD with ‘low’ pre-testprobability who cannot perform a functional test or withequivocal 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 testTaylor AJ et al. J Am Coll Cardiol 2010:56:1864-94.
  • 35.  CTCA is not indicated as a ‘routine’ test in ED patientswith chest pain without known CAD and with normalbiomarkers and ECG It may be useful in a subgroup based on risk, but howthis risk might be defined in unclear There is a reasonable case for no further testing insignificant proportion of ED chest pain patients whohave had ACS ruled out by ECG and biomarkers
  • 36.  Comparison of DM, ‘metabolic syndrome’ and other (MPSstudy) 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 parametersidentify a subgroup ofpatients who might benefitfrom CTCA?