EBQ:ADAPT Trial 2-Hour Troponin Rule Out

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Complete Journal Club Article
Than M.. "2-Hour accelerated diagnostic protocol to assess patients with chest pain symptoms using contemporary troponins as the only biomarker: the ADAPT trial". Journal of the American College of Cardiology. 2012. 59(23):2091-2098.
PubMed Full text PDF

Clinical Question

Can an accelerated diagnostic protocol (ADP) for chest pain be used to identify low-risk patients suitable for discharge with close followup?

Conclusion

An accelerated diagnostic protocol of 2 negative troponins, a TIMI score < 0 and no ischemic changes on ECG. can successfully identify low risk chest pain patients for discharge from the emergency department and decrease observational stay.

Major Points

  • The ADP relies on a combination of 2 negative troponins, a TIMI score < 0 and no ischemic changes on ECG.
  • The ADP successfully classifies patients as low risk and has a sensitivity of 99.7 for identifying patients who will have Major Adverse Cardiac Events (MACE)
  • Patients who are not low risk according to the ADP should continue to be managed with existing clinical care that involves extended observation or admission.
  • Patients with a negative troponin at 0 hours and 2 hrs, a TIMI<0 and no ischemic ECG changes can be discharged with close cardiac followup.

All parameters had to be negative for the ADP to be considered negative and for the patient to be identified as low-risk

  1. cTnI level at 0 and 2 h below institutional cutoff for an elevated troponin concentration
  2. No new ischemic changes on the initial ECG 3. TIMI score < 0

NSTEMI TIMI Score[1]

Used to estimate percent risk at 14 days of MI, or revascularization
  1. Age >65 yrs (1 point)
  2. Three or more risk factors for coronary artery disease: (1 point)
    • family history of coronary artery disease
    • hypertension
    • hypercholesterolaemia
    • diabetes
    • current smoker
  3. Use of aspirin in the past 7 days (1 point)
  4. Significant coronary stenosis (stenosis >50%) (1 point)
  5. Severe angina (e.g., >2 angina events in past 24 h or persisting discomfort) (1 point)
  6. ST-segment deviation of ≥0.05 mV on first ECG (1 point)
  7. Increased troponin and/or creatine kinase-MB blood tests (1 point)
TIMI Risks
points % risk of mortality, MI, or revascularization
0 5%
1 5%
2 8%
3 13%
4 20%
5 26%
6 41%

Design

  • Prospective observational validation study
  • The study population was from Brisbane, Australia and Christchurch, New Zealand. These patients were from 2 of the 14 sites participating in the ASPECT Trial.
  • Although using the same patients, the ADAPT trial was approved at the initiation of the ASPECT Trial.
  • Patients were enrolled consecutively between November 2007 and February 2011

Population

Inclusion Criteria

  • Age >18 years of age, with at least 5 min of symptoms consistent with ACS
  • The attending physician planned to perform serial cTn tests

Exclusion Criteria

  • ST-segment elevation myocardial infarction (STEMI)
  • Cause other than ACS for the symptoms (e.g., examination findings of varicella zoster)
  • Inability to provide informed consent
  • Staff considered recruitment to be inappropriate (e.g., receiving palliative treatment), transfer from another hospital, pregnancy, previous enrollment, or inability to be contacted after discharge.

Baseline Characteristics

  • Age: 60.4
  • Male: 60.0%
  • White Race: 90%
  • Risk Factors
    • HTN: 52.1%
    • DM: 14.4
    • Dyslipidemia: 51

Interventions

Patients were either stratified to the be negative or positive for the accelerated diagnostic protocol and were then followed for 30 days with major cardiac events recorded.

Outcomes

Primary Outcomes

  • No patients were lost at 30-day followup
  • 392 patients were classified as ADP negative and only 1 had a major cardiac event
    • This patient 12 hour after evaluation had an MI requiring stenting
Major Adverse Cardiac Events (MACE)
(n=350)
  1. Non–STEMI (273)
  2. STEMI (25)
  3. Emergency revascularization (26)
  4. Cardiovascular death (8)
  5. Ventricular arrhythmia (6)
  6. Cardiac arrest (3)
  7. Cardiogenic shock (4)
  8. High atrioventricular block (5)

Secondary Outcomes

  • Subgroup analysis classified the individual diagnostic parameters (TIMI score, ECG, and 2 sets of troponins) in various combinations identified in the following table.
  • TIMI score and ECG without troponins failed to identify 5 patients with major cardiac event

Subgroup Analysis

Diagnostic qualities to predict adverse major adverse cardiac events

Test Characteristic ECG Troponin Troponin & ECG TIMI & ECG ADP (ECG +TIMI + Troponin)
Sensitivity 24.5% 87.4% 89.1% 98.3% 99.7%
Specificity 88.5% 92.6% 82.6% 23.5% 23.4%
Negative Likelihood Ratio 0.85 0.14 0.13 0.07 0.01
Positive Likelihood Ratio 2.12 11.79 5.12 1.29 1.3

Criticisms and Further Discussion

  • The pretest probability for MACE was 15.3% which may differ for many readers depending on their patient population. Also this protocol has not been validated at any outside institution.
  • The study uses the used Troponin I (cTnI) not the high sensitivity version (hs-cTnI).[2] If using this troponin the study can directly apply to certain EDs. However if using the high sensitivity version then more positives are likely and the the patients with negative rapid diagnostics protocols will be less and admission rates may be higher
  • The TIMI score has questionable application to an acute ED population since it was developed for inpatients[3]
  • 74% of patients had a followup provocative study so this protocol should not be initiated if proper outpatient followup cannot be imitated[3]
  • With a high combined sensitivity it offers promise for ruling out MACE but the low specificity may actually result in too stringent a criteria with unnecessary chest pain admissions.

Funding

Christchurch Cardio-Endocrine Research Group and the Queensland Emergency Medicine Research Foundation with (20%) contributions from industry (Abbott and Alere). Drs. Than, Cullen, and Parsonage, and Prof. Richards and Prof. Peacock had paid travel, accommodations, consulting fees, and honoraria from Abbott.


Sources

  1. Antman, Elliot et al. The TIMI Risk Score for Unstable Angina/Non–ST Elevation MI A Method for Prognostication and Therapeutic Decision Making. JAMA. 2000;284(7):835-842. doi:10.1001/jama.284.7.835. PDF
  2. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3627711/
  3. 3.0 3.1 Hess, Erik et al. Evaluation of Patients With Possible Cardiac Chest Pain - A Way Out of the Jungle. J Am Coll Cardiol. 2012;59(23):2099-2100. doi:10.1016/j.jacc.2012.03.021 PDF