Chest pain: cardiac troponin T could help diagnose MI.

Clinical bottom line (level 1b)

Patients with a suspected myocardial infarction who had a positive cardiac troponin T test were more likely to have one, especially within four hours of onset of pain, but it was not diagnostic.
A negative cardiac troponin T test alone did not safely exclude an MI.

Antman et al: Journal of the American Medical Association 1995; 273 (16): 1279-1282

Expires July 2003

The study

Setting: coronary care unit, university hospital, USA

100 patients (aged ?, ?% male) with a clinical history suspicious of acute MI

Excluded if

insufficient blood samples at presentation for measurement of CK, CK-MB and cardiac troponin
history of MI within last two weeks
thrombolysis or PTCA of infarct-related vessel

Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:

history of ischaemic discomfort and at least one of:
- pathological Q-waves or symmetrically inverted T-waves on ECG
- CK>upper limit of normal; CK-MB:CK ratio >2.5%; and serial specimens demonstrated a rise and fall
- CK-MB >twice upper limit of normal, with CK-MB:CK ratio >2.5%; and serial specimens demonstrated a rise and fall
- histological evidence of acute MI on autopsy

Diagnostic test: cardiac troponin T bedside rapid immunoassay: read after 20 minutes

The evidence

pre-test probability of MI: 34%, (95% CI: 25% to 43%)

diagnostic test	MI	no MI	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
0 to 4 hours from onset of chest pain	7	9	14 (1.9 to 100)	88%	0.58 (0.38 to 0.90)	23%
>4 hours from onset	15	3	7.1 (2.8 to 18)	79%	0.19 (0.067 to 0.53)	9%
0 to >8 hours from onset	22	12	8.5 (3.6 to 21)	81%	0.38 (0.24 to 0.61)	16%
total	34	64

Comments

The study was too small to provide more detailed information on test characteristic adjusted for duration of pain prior to presentation.
Troponin T has been shown to provide prognostic information in patients with chest pain, but has not clearly been shown to be a better test than CK-MB for diagnosing MI.
This particular test kit has advantages of use outside traditional laboratory settings, making it useful for small medical facilities

Citation

Antman EM, Grudzien C, Sacks DB: Evaluation of a rapid bedside assay for detection of serum cardiac troponin T. Journal of the American Medical Association 1995; 273 (16): 1279-1282

Search Terms: troponin in Cochrane
Contributor: Chris Ball and Clare Wotton, July 2000
Reviewer: Dwight Peretz

_{Clinical Question.}