Than: A 2-hour diagnostic protocol for possible cardiac chest pain in the emergency department

Than, JAMA Internal Medicine. 2014,174(1):51-58

Clinical Question

  • In patients with suspected acute coronary syndrome does a rapid diagnostic pathway allow early discharge from hospital without more adverse effects when compared with a conventional diagnostic assessment and discharge plan?


  • Randomised controlled trial
  • Computer generated
  • Block Randomisation
  • Blinding of personnel determining results of primary outcome


  • Single centre, Emergency Department, New Zealand
  • October 2010 – July 2012


  • Inclusion: Adult patients with possible cardiac chest pain whose physician planned further observation/troponin testing
  • Exclusion: STEMI, other clear cause for chest pain, chest pain >12 hours, persisting chest pain, pregnancy
  • 3594 assessed for eligibility of whom 544 randomised


  • Low risk patients with a modified TIMI score of 0, and no new ischaemic ECG changes, underwent the rapid diagnostic pathway with a repeat Troponin 2 hours after the initial test.
    • If repeat Troponin test normal then patient discharged with outpatient stress test within 72 hours
  • If TIMI score >0 or new ischaemic ECG changes, then investigated in standard fashion

(Journal watch – accessed 30th May 2014)


  • Repeat Troponin I assay at 6-12 hours
    • Follow up investigations at discretion of treating clinician

All Troponin tests were ARCHITECT Troponin I assay in both intervention and control group. This is not a high sensitivity troponin.


  • Primary outcome: discharge within 6 hours of arrival and without a subsequent major adverse cardiac event (MACE) within 30 days.
    • MACE:
      • death (unless clearly non-cardiac)
      • cardiac arrest
      • emergency re-vascularisation
      • cardiogenic shock
      • ventricular arrhythmia or high degree atrioventricular block requiring intervention
      • acute MI
    • Significantly more patients were successfully discharged within 6 hours in the intervention group (19.3%) vs. the control group (11%). Difference 8.3% (95% C.I. 1.8-14, P=0.009)
  • Secondary outcome: Patients who had a MACE during follow-up (not including initial hospital visit)
    • 0.4% in intervention group vs. 0.0% in control group

Authors’ Conclusions

  • The rapid diagnostic pathway is an effective and practical strategy to improve early discharge rates for some patients with chest pain


  • Randomised controlled trial
  • Blinding of staff determining primary outcome


  • Not powered to compare rates of MACE between intervention and control groups
  • Only 52 patients underwent the rapid diagnostic pathway.
  • Patients in the intervention and control group treated differently with regard to the follow up investigations that were arranged.
  • All patients that were discharged early had an outpatient stress test within 72 hours. This will limit the external validity of this trial as a number of institutions will not be able to provide this service.
  • Single centre
  • Only recruited between 0800 – 2200. If people who present at night are different in anyway then this trial may lack external validity.

The Bottom Line

  • A rapid diagnostic pathway for patients with suspected cardiac chest pain allowed earlier discharge of some low risk patients. However, further work is necessary before we can tell if this is a safe strategy, and therefore currently this strategy cannot be recommended.


abstract / doi: 10.1001/jamainternmed.2013.11362

Editorial, Commentaries or Blogs

  • None


Summary author: @DavidSlessor
Summary date: 11 May 2014
Peer-review editor: @stevemathieu75

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