Chest pain: troponin T may rule out MI.

Clinical bottom line (level 2b)

  1. Troponin T may help rule in myocardial infarction, but not safely exclude it in less than 24 hours.
Sayre et al: Annals of Emergency Medicine 1998; 31: 539-549
Expires July 2003

The study

Setting: emergency department, university hospital, USA

667 patients (aged range 22 to 93 years; mean 53, 52% female) chest pain or other symptoms consistent with acute ischaemic heart disease

Excluded if
  • <25 years
  • traumatic chest pain
  • unusable blood sample



    • Independent blinded reference standard, applied in all patients from a non-consecutive appropriate spectrum.
    Reference standard:
    • WHO criteria for MI (and 12-lead ECG or CK-MB positive; CK-MB positive if >7 ng/ml and CK-MB/CK >3)
    Diagnostic test: cardiac troponin T- positive if 0.2 or more mcg/l; if ECG indicating ischaemic disease: hourly for 9 hours, then at 12, 18, 24 hours: if ECG non-diagnostic at 3, 6, 9, 12, 24 hours
    • Patients were only enrolled between 8am and 11pm
    • Most patients had between one and four samples.
    • 88% followed for 60 days by telephone or hospital records.
    • The assay used in this investigation required 1 and a half hours to complete results

    The evidence


    differential diagnosis number of patients prevalence
    (95% CI)
    MI 34 5.1%
    (3.4% to 6.8%)
    unstable angina 82 12%
    (9.8% to 15%)
    congestive heart failure 40 6.0%
    (4.2% to 7.8%)
    cocaine-related chest pain 25 3.7%
    (2.3% to 5.2%)
    non-cardiac pain 484 73%
    (69% to 76%)
    unknown 2 0.3%
    (0.0% to 0.7%)


    diagnostic test MI no MI LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    troponin T test positive 0-3 hours after arrival 22 47 8.7
    (6.0 to 13)     		32% 0.38
    (0.24 to 0.60)     		2%
    troponin T test positive 0-6 hours after arrival 27 44 11
    (8.2 to 16)     		38% 0.22
    (0.11 to 0.43)     		1%
    troponin T test positive 0-9 hours after arrival 29 46 11
    (8.6 to 16)     		38% 0.16
    (0.071 to 0.36)     		1%
    troponin T test positive 0-12 after arrival 30 49 11
    (8.5 to 15)     		38% 0.13
    (0.051 to 0.32)     		1%
    troponin T test positive 0-24 hours after arrival 33 51 12
    (9.2 to 16)     		39% 0.032
    (0.0046 to 0.22)     		0%
    total 34 633

    Comments

    1. Low risk population for MI, and high number of cocaine users.
    2. No indication how long troponin done after onset of chest pain (more useful than arrival time in the emergency department).
    3. Patients had multiple tests- would fewer tests be as accurate?
    4. Troponin T has not been shown to be clearly better than CK-MB in other studies for diagnosing MI.

    Citation

    1. Sayre MR, et al: Measurement of cardiac troponin T is an effective method for predicting complications among emergency department patients with chest pain. Annals of Emergency Medicine 1998; 31: 539-549
    Contributor: Chris Ball and Bob Phillips, July 2000
    Reviewer: William Rhoton

    Clinical Question.
    Patient suspected MI, chest pain
    Intervention or Exposure troponin T levels
    Outcome confirmed MI