Improved Assessment of Chest pain Trial (IMPACT): assessing patients with possible acute coronary syndromes

Louise Cullen, Jaimi H Greenslade, Tracey Hawkins, Chris Hammett, Shanen O'Kane, Kimberley Ryan, Kate Parker, Jessica Schluter, Emily Dalton, Anthony FT Brown, Martin Than, W Frank Peacock, Allan Jaffe, Peter K O'Rourke and William A Parsonage
Med J Aust 2017; 207 (5): 195-200. || doi: 10.5694/mja16.01351


Objective: To examine the safety and efficacy of the Improved Assessment of Chest pain Trial (IMPACT) protocol, a strategy for accelerated assessment of patients presenting to emergency departments (EDs) with chest pain.

Design, setting and participants: IMPACT was an intervention trial at a single tertiary referral hospital (Royal Brisbane and Women’s Hospital) during February 2011 – March 2014. 1366 prospectively recruited patients presenting to the ED with symptoms of suspected acute coronary syndrome (ACS) were stratified into groups at low, intermediate or high risk of an ACS.

Intervention: High risk patients were treated according to NHFA/CSANZ guidelines. Low and intermediate risk patients underwent troponin testing (sensitive assay) 0 and 2 hours after presentation. Intermediate risk patients underwent objective testing after the second troponin test; low risk patients were discharged without further objective testing.

Main outcome measures: The primary outcome was an ACS within 30 days of presentation. Secondary outcomes were ED and hospital lengths of stay (LOS).

Results: The IMPACT protocol stratified 244 (17.9%) patients to low risk, 789 (57.7%) to intermediate risk, and 333 (24.4%) to high risk categories. The overall 30-day ACS rate was 6.6%, but there were no ACS events in the low risk group, and 14 (1.8%) in the intermediate risk group. The median hospital LOS was 5.1 hours (IQR, 4.2–5.6 h) for low risk and 7.7 hours (IQR, 6.1–21 h) for intermediate risk patients.

Conclusions: The IMPACT protocol safely and efficiently allowed a large proportion of patients presenting to EDs with chest pain to undergo accelerated assessment for risk of an ACS.

Clinical trial registration: Australian New Zealand Clinical Trials Registry ACTRN12611000206921.

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  • Louise Cullen1,2,3
  • Jaimi H Greenslade2,3
  • Tracey Hawkins2
  • Chris Hammett2
  • Shanen O'Kane2
  • Kimberley Ryan2
  • Kate Parker2
  • Jessica Schluter2
  • Emily Dalton2
  • Anthony FT Brown2,3
  • Martin Than4,5
  • W Frank Peacock6
  • Allan Jaffe7
  • Peter K O'Rourke8
  • William A Parsonage1,2

  • 1 Queensland University of Technology, Brisbane, QLD
  • 2 Royal Brisbane and Women's Hospital, Brisbane, QLD
  • 3 The University of Queensland, Brisbane, QLD
  • 4 Christchurch Hospital, Christchurch, New Zealand
  • 5 University of Otago, Christchurch, New Zealand
  • 6 Baylor College of Medicine, Houston, TX, United States of America
  • 7 Mayo Clinic, Rochester, MN, United States of America
  • 8 Queensland Institute of Medical Research, Brisbane, QLD


We thank Adrian Barnett for his statistical advice, and the Australian Institute of Health and Welfare for providing mortality data. The Emergency Medicine Foundation funded the study, but played no further role.

Competing interests:

Louise Cullen has received grants from Beckman, Roche and Radiometer; grants, consultancy fees, and personal fees from Abbott Diagnostics; grants and consultancy fees from Siemens; and personal fees from Alere, AstraZeneca, and Novartis, all unrelated to this study. Chris Hammett has received personal fees from Astra Zeneca, Amgen, Bayer Healthcare, Boehringer Ingelheim, The Medicines Company and Medtronic, all unrelated to this study. Anthony Brown is a consultant for both Boehringer Ingelheim and Shire, and has been paid to provide expert medical testimony for the Queensland and New South Wales Coronial Services; he receives royalties from Taylor & Francis and Elsevier. Martin Than has received grants, personal fees and other funding from Abbott and Beckman, grants and personal fees from Alere, and personal fees from Roche, all unrelated to this study. Frank Peacock received unrelated grants from Abbott, Alere, Banyan, Cardiorentis, Janssen, Portola, Pfizer, Roche, The Medicines Company, and ZS Pharma; he is a consultant for Alere, Cardiorentis, Ischemia Care, Janssen, Phillips, Portola, Prevencio, The Medicines Company, and ZS Pharma, and has ownership interests in Comprehensive Research Associates and Emergencies in Medicine, all unrelated to this study. Allen Jaffe is a consultant for Abbott, Alere, Siemens, Diadexus, ET Healthcare, Novartis,, and Becton Dickinson. William Parsonage is a consultant for Hospira/Pfizer and has received personal fees from AstraZeneca and non-financial support from Bayer, all unrelated to this study.

  • 1. Bhuiya FA, Pitts SR, McCaig LF. Emergency department visits for chest pain and abdominal pain: United States, 1999–2008. NCHS Data Brief 2010; 43: 1-8.
  • 2. Chew DP, Scott IA, Cullen L, et al; NHFA/CSANZ ACS Guideline 2016 Executive Working Group. National Heart Foundation of Australia & Cardiac Society of Australia and New Zealand: Australian clinical guidelines for the management of acute coronary syndromes 2016. Heart Lung Circ 2016; 25: 895-951.
  • 3. Than M, Cullen L, Aldous S, et al. 2-Hour accelerated diagnostic protocol to assess patients with chest pain symptoms using contemporary troponins as the only biomarker: the ADAPT trial. J Am Coll Cardiol 2012; 59: 2091-2098.
  • 4. Body R, Carley S, McDowell G, et al. The Manchester Acute Coronary Syndromes (MACS) decision rule for suspected cardiac chest pain: derivation and external validation. Heart 2014; 100: 1462-1468.
  • 5. Carlton EW, Cullen L, Than M, et al. A novel diagnostic protocol to identify patients suitable for discharge after a single high-sensitivity troponin. Heart 2015; 101: 1041-1046.
  • 6. Mueller C, Giannitsis E, Christ M, et al. Multicenter evaluation of a 0-hour/1-hour algorithm in the diagnosis of myocardial infarction with high-sensitivity cardiac troponin T. Ann Emerg Med 2016; 68: 76-87.
  • 7. Chew DP, Scott IA, Cullen L, et al. National Heart Foundation of Australia and Cardiac Society of Australia and New Zealand: Australian clinical guidelines for the management of acute coronary syndromes 2016. Med J Aust 2016; 205: 128-133. <MJA full text>
  • 8. Roffi M, Patrono C, Collet JP, et al; Task Force for the Management of Acute Coronary Syndromes in Patients Presenting without Persistent ST-Segment Elevation of the European Society of Cardiology (ESC). 2015 ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation. Eur Heart J 2016; 37: 267-315.
  • 9. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014; 64: e139-e228.
  • 10. Greenslade JH, Parsonage W, Ho A, et al. Utility of routine exercise stress testing among intermediate risk chest pain patients attending an emergency department. Heart Lung Circ 2015; 24: 879-884.
  • 11. Hermann LK, Newman DH, Pleasant WA, et al. Yield of routine provocative cardiac testing among patients in an emergency department-based chest pain unit. JAMA Intern Med 2013; 173: 1128-1133.
  • 12. Luepker RV. Case definitions for acute coronary heart disease in epidemiology and clinical research studies. A statement from the AHA Council on Epidemiology and Prevention; AHA Statistics Committee; World Heart Federation Council on Epidemiology and Prevention; the European Society of Cardiology Working Group on Epidemiology and Prevention; Centers for Disease Control and Prevention; and the National Heart, Lung, and Blood Institute. Circulation 2003; 108: 2543-2549.
  • 13. Aroney C, Aylward P, Kelly AM. National Heart Foundation of Australia and Cardiac Society of Australia and New Zealand Guidelines for the management of acute coronary syndromes. Med J Aust 2006; 184 (8 Suppl): S1-S32. <MJA full text>
  • 14. Cullen L, Than M, Brown AF, et al. Comprehensive standardized data definitions for acute coronary syndrome research in emergency departments in Australasia. Emerg Med Australas 2010; 22: 35-55.
  • 15. International Federation of Clinical Chemistry and Laboratory Medicine. Analytical characteristics of commercial cardiac troponin I and T assays declared by the manufacturer. Nov 2014. (accessed June 2017).
  • 16. Thygesen K, Alpert JS, Jaffe AS, et al. Third universal definition of myocardial infarction. Circulation 2012; 126: 2020-2035.
  • 17. Backus BE, Six AJ, Kelder JC, et al. A prospective validation of the HEART score for chest pain patients at the emergency department. Int J Cardiol 2013; 168: 2153-2158.
  • 18. Than M, Pickering J, Aldous SJ, et al. effectiveness of EDACS versus ADAPT accelerated diagnostic pathways for chest pain: a pragmatic randomized controlled trial embedded within practice. Ann Emerg Med 2016; 68: 93-102.
  • 19. Body R, Cook G, Burrows G, et al. Can emergency physicians “rule in” and “rule out” acute myocardial infarction with clinical judgement? Emerg Med J 2014; 31: 872-876.
  • 20. Hulten E, Pickett C, Bittencourt MS, et al. Outcomes after coronary computed tomography angiography in the emergency department: a systematic review and meta-analysis of randomized, controlled trials. J Am Coll Card 2013; 6: 880-892.
  • 21. Than M, Herbert M, Flaws D, et al. What is an acceptable risk of major adverse cardiac event in chest pain patients soon after discharge from the emergency department? A clinical survey. Int J Cardiol 2013; 166: 752-754.
  • 22. Cheng Q, Greenslade J, Parsonage WA, et al. Change to costs and lengths of stay in the emergency department and the Brisbane protocol: an observational study. BMJ Open 2016; 6: e009746.
  • 23. George T, Ashover S, Cullen L, et al. Introduction of an accelerated diagnostic protocol in the assessment of emergency department patients with possible acute coronary syndrome: The Nambour Short Low-Intermediate Chest pain project. Emerg Med Australas 2013; 25: 340-344.
  • 24. Mahler SA, Riley RF, Hiestand BC, et al. The HEART Pathway randomized trial: identifying emergency department patients with acute chest pain for early discharge. Circ Cardiovasc Qual Outcomes 2015; 8: 195-203.
  • 25. Mahler SA, Riley RF, Russell GB, et al. Adherence to an accelerated diagnostic protocol for chest pain: secondary analysis of the HEART Pathway randomized trial. Acad Emerg Med 2016; 23: 70-77.
  • 26. Backus BE, Six AJ, Kelder JC, et al. Chest pain in the emergency room: a multicenter validation of the HEART Score. Crit Pathw Cardiol 2010; 9: 164-169.
  • 27. Cullen L, Greenslade J, Merollini K, et al. Cost and outcomes of assessing patients with chest pain in an Australian emergency department. Med J Aust 2015; 202: 427-432. <MJA full text>
  • 28. Reichlin T, Twerenbold R, Maushart C, et al. Risk stratification in patients with unstable angina using absolute serial changes of 3 high-sensitive troponin assays. Am Heart J 2013; 165: 371-378.e3.
  • 29. Cullen L, Greenslade J, Hammett CJ, et al. Comparison of three risk stratification rules for predicting patients with acute coronary syndrome presenting to an Australian emergency department. Heart Lung Circ 2013; 22: 844-851.
  • 30. Amsterdam EA, Kirk JD, Diercks D, et al. Exercise testing in chest pain units: rationale, implementation, and results. Cardiol Clin 2005; 23: 503-516.


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