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Three Part Question

In [patients with cardiac chest pain and a normal ECG] is [a troponin T measurement at 12 hours] sensitive enough to [rule out myocardial damage in the first 12 hours]?

Clinical Scenario

A 50 year old man attends the emergency department with a 12 hour history of chest pain that may be cardiac in origin. His ECG is normal. You want to rule out possible myocardial damage and wonder whether a single troponin T measurement taken at this time is sensitive enough to do this.

Search Strategy

Medline 1966-01/00 using the OVID interface.
({exp diagnosis OR diagnosis.mp} AND troponin$.mp) LIMIT to human AND english.

Search Outcome

590 papers found of which 581 were irrelevant or of insufficient quality. The remaining 9 papers are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Mair J et al, 1995, Austria	114 emergency department patients with chest pain	Diagnostic test study	AMI	Sensitivity 46% on admission	Only admitted patients. Troponin cut-off set at 0.032 ng/l
De Winter RJ et al, 1995, Netherlands	309 emergency department patients with chest pain	Diagnostic test study	AMI	Sensitivity 67% in patients with less than 75% chance of AMI	Unclear if gold standard blinded. Risk assessment was by clinical judgement. Patients with abnormal ECGs included
Tucker JF et al, 1997, USA	177 emergency department patients within 24h of onset of chest pain	Diagnostic test study	AMI	Sensitivity 33.3% at 1h Sensitivity 33.3% at 2h Sensitivity 59.3% at 6h Sensitivity 96.3% at 12-24h Specificity 86.7% at 12-24h	Only admitted patients.
REACTT investigators, 1997, USA	926 emergency department patients with chest pain Rapid bedside test vs laboratory test	Diagnostic test study	AMI	Sensitivity 19.6% vs 25% on admission Sensitivity 59% vs 69.6% at 3h Sensitivity 69.7% vs 79.8% at 6h	206 patients excluded due to lack of data. Discharged patients not followed up with same gold standard
Hamm CW et al, 1997, Germany	773 emergency department patients within 12h of onset of chest pain, with no ST elevation	Observational	Death or non-fatal AMI within 30 days	44% predicted on arrival 79% predicted after 4h	No indipendent gold standard applied to all patients. Inadequate follow up of discharged patients. Sensitivity could not be calculated
Moher ER et al, 1998, USA	100 patients with chest discomfort	Diagnostic test study	AMI	Sensitivity 90% at 4h	Cumulative sensitivities at 4h.
Sayre MR et al, 1998, USA	667 patients with chest pain	Diagnostic test study	AMI	Sensitivity 88% at 12h post admission Sensitivity 97% at 24h post admission	Only admitted patients studied.
Zimmerman J et al, 1999, USA	955 emergency department patients with chest pain	Diagnostic test study	AMI	Sensitivity 87% at 10h post onset
Johnson PA et al, 1999, USA	1477 emergency department patients with chest pain	Diagnostic test study	AMI in the 24h following presentation	Sensitivity 99% at 24h Specificity 86% at 24h	174 cases excluded

Comment(s)

No study has evaluated the point at which troponin T becomes sensitive enough to effectively rule-out acute myocardial infarction in emergency department patients. However no study has shown a high enough sensitivity (> 95%) to allow use as a SnNout at less than 12-24 hours.

Clinical Bottom Line

Troponin T is not sensitive enough to rule out myocardial damage in the first 12 hours after onset of chest pain.

References

1. Mair J, Smidt J, Lechleitner P at al. Rapid accurate diagnosis of acute myocardial infarction in patients with non-traumatic chest pain withn one hour of admission. Coronary Artery Dis 1995;6:539-45.
2. De Winter RJ, Koster RW, Sturk A at al. Value of myoglobin, troponin T and CK-MB mass in ruling out acute myocardial infarction in the emergency room. Circulation 1995;92:3401-7
3. Tucker JF, Collins RA, Anderson AJ at al. Early diagnostic efficiency of cardiac troponin I and troponin T for acute myocardial infarction. Acad Emerg Med 1997;4:13-21.
4. REACTT investigators study group. Evaluation of a bedside whole blood rapid troponin T assay in the Emergency Department. Rapid evaluation by assay of cardiac troponin T (REACTT). Acad Emerg Med 1997;4:1018-24.
5. Hamm CW, Goldman BU, Heeschen C at al. Emergency room triage of patients with acute chest pain by means of rapid testing for cardiac troponin T or I. New Engl J Med 1997;337:1648-53.
6. Moher ER 3rd, Ryan T, Segar DS at al. Clinical utility of troponin T levels and echocardiography in the Emergency Department. Am Heart J 1998;135:253-60.
7. Sayre MR, Kaufmann KH, Chen IW at al. Measurement of cardiac troponin T is an effective method for predicting complications among emergency department patients with chest pain. Ann Emerg Med 1998;31:539-49.
8. Zimmerman J, Fromm R, Meyer D at al. Diagnostic marker cooperative study for the diagnosis of myocardial infarction. Circulation 1999;99:1671-7.
9. Johnson PA, Goldmman L, Sacks DB at al. Cardiac troponin T as a marker for myocardial ischaemia in patients seen at the Emergency Department for acute chest pain. Am Heart J 1999;137:1137-44.