TRUST: A novel diagnostic protocol to identify patients suitable for discharge after a single high-sensitivity troponin

@EddCarlton, Heart 2015, Online First  Feb 17, doi:10.1136/heartjnl-2014-307288

Clinical Question

• In patients with suspected acute coronary syndrome (ACS) does a novel accelerated diagnostic protocol (ADP) identify low risk patients suitable for discharge after a single high-sensitivity troponin T (hs-cTnT)?

Design

• Prospective observational study
• Consecutive patients
• Blinding of medical staff to initial hs-cTnT result
• Emergency physician staff completed ADP

Setting

• Single emergency department, UK
• July 2012 – August 2013

Population

• Inclusion criteria
  • Adult patients with ≥5 minutes of chest pain suggestive of ACS
  • Attending physician determined inpatient evaluation was required
• Exclusion criteria included
  • ECG changes
  • STEMI, LBBB not known to be old, ST depression ≥1mm, T wave inversion consistent with presence of ischaemia, arrhythmias
  • Age ≥80
  • Atypical symptoms in absence of chest discomfort
  • Clear non-ACS cause for chest pain found at presentation
  • Renal failure requiring dialysis

964 patients recruited, 4 patients lost to follow up

Test of Interest

• TRUST (Triage Rule-out Using high-Sensitivity Troponin) Accelerated Diagnostic Protocol
  • Considered low risk if all of the following
    • Modified-Goldman score of 0 or 1
      • 1 point for each variable present
      • Typical new onset chest pain at rest
      • Pain the same as previous MI
      • Pain not relieved by GTN within 15 minutes
      • Pain lasts >60 minutes
      • Pain occurring with increasing frequency
      • BP <100mmHg
      • Acute shortness of breath
      • Pain within 6 weeks of MI/revascularisation
    • Non-ischaemic ECG
    • Hs-cTnT <14ng/L at presentation
  • Blood taken for hs-cTnT at a median of 2 hours 55 minutes after chest pain onset

Gold Standard Investigation

• Risk assessment by ED staff using modified Goldman risk score
• Hs-cTnT at 6 hours after presentation
• Follow-up at least 6 months after attendance by independent review of hospital records, GP records and national clinical records search

5th generation ELECSYS hs-cTnT assay used for both test of interest and gold standard
For all patients

• Myocardial infarction (MI) diagnosed according to Third Universal Definition of MI
• Adjudication of primary outcome carried out by two local cardiologists who were blinded to m-Goldman score but not to serial hs-cTnT results

Outcome

• Primary outcome: diagnostic accuracy of ADP for fatal or non-fatal MI within 30 days (including index visit)
  • ADP identified 39.8% of patients at low risk of primary outcome
  • 8.3% of all patients had MI within 30 days
  • ADP 98.8% (95% CI 92.5-99.9) sensitive for ruling out MI
  • Single patient had false negative test
    • 78 year old female had initial hs-cTnT of 13 that rose to 20. Patient managed medically and had no further complications
• Secondary outcomes:
  • Diagnostic accuracy of ADP for Major adverse cardiac events (MACE) within 30 days
    • Death due to ischaemic heart disease, cardiac arrest, urgent revascularisation, cardiogenic shock, ventricular arrhythmia, high-degree atrioventricular block needing intervention, acute myocardial infarction
    • 10.1% of all patients had MACE within 30 days
    • ADP 99% (95% C.I. 93.7-99.9) sensitive for ruling out MACE
  • Diagnostic accuracy of using a single initial hs-cTnT of <5ng/L (did not include risk assessment i.e. modified Goldman score)
    • For fatal or non-fatal MI within 30 days
      • Sensitivity 100% (95% C.I. 94.3-100)
    • For MACE
      • Sensitivity 96.8% (90.6-99.2)
      • 3 false negatives, all aged in their 40’s and required urgent revascularisation. Two patients with severe left anterior descending artery disease and one patient with severe right coronary artery disease

Authors’ Conclusions

• The accelerated diagnostic protocol has the potential to allow early discharge in 40% of patients with suspected ACS

Strengths

• Prospective
• Appropriate inclusion + exclusion criteria leading to appropriate study population
• Blinding of medical staff to initial hs-cTnT result
• All patients received gold standard test
• Minimal loss to follow up

Weaknesses

• Single centre
• Exclusion of patients >80 years limits external validity
• With moderate numbers of patients included, the 95% confidence intervals for the primary outcome are wider than we would hope for (95% CI 92.5-99.9)

Of note, patients had initial hs-cTnT at nearly 3 hours after chest pain onset (shortly after they arrived in the Emergency Department). The ADP may therefore not apply to patients who present earlier