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Three Part Question

In [patients with chest pain and an ischaemic ECG] does [a negative troponin T/I result] rule out [the occurrence of adverse cardiac events in the ensuing month].

Clinical Scenario

A 62-year-old man presents to the emergency department with a 45-minute history of chest pain that is beginning to abate after aspirin and buccal nitrates in the ambulance. As he has a 1 mm ST depression in his anterior leads you give him low molecular-weight heparin and refer him to the medical team. While waiting to be transferred to the ward his 12-h troponin level is reported as negative; the medical senior house officer feels he is therefore fit for discharge. You disagree saying he remains high risk and needs further investigation and/or intervention. During the ensuing discussion you wonder if there is any evidence to back up your assertions

Search Strategy

Medline 1966 to January Week 2 2009 using the OVID interface:
[{exp TROPONIN C/OR exp TROPONIN T/OR exp TROPONIN/OR exp TROPONIN I/OR troponin.af} AND {exp DEATH/OR exp DEATH, SUDDEN, CARDIAC/OR exp PROGNOSIS/OR exp MORTALITY/OR exp Myocardial Infarction/OR death.af. OR mortality.af. OR prognos$.af. OR predict$.af. OR myocardial infarction.af. OR heart attack.af.} AND {("30" adj5 day).af. OR (thirty adj5 day).af. OR (one adj5 month).af. OR ("1" adj5 month).af.} AND {exp Electrocardiography/OR electrocardiogr$.af. OR ECG.af OR EKG.af}] LIMIT to human and English Language.

The Cochrane Library Issue 1 2009: [MeSH descriptor Chest Pain explode all trees] AND [MeSH descriptor Troponin explode all trees] AND [MeSH descriptor Prognosis explode all trees] 35 records 0 relevant.

Search Outcome

A total of 71 papers was found, of which three answered the three-part question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ohman ME et al. 1996 USA/Canada/Germany	855 patients with chest pain and abnormal ecgs as part of the GUSTO IIa study	Prospective diagnostic study	Adjusted relative value as predictors of 30 day mortality by CHI squared at 3DF	Trop T 9.2 ECG 11.5	Most trop T < 12 hours post pain. Patients divided into various treatments as substudy of PCRT on mortality prevention. Trop T cut off of 0.1 used. Large proprtion of patients with STEMI.
Wilcox G et al 2001 Melbourne	424 patients presenting to the ED with chest pain.	Prospective diagnostic study	Odds ratio on multivariate analysis (95% CI)	Trop I 0.6-2.0microg/l 2.2 (0.7-6.8) Ischamic ECG 1.3 (0.5-3.6)	Timing of trop I measurement not stated. Small numbers.
Alp et al 2001 UK	400 patients>30 yoa in CCU with chest pain	Prospective diagnostic	Death at 30 days	Tn I +ve 4%.(1-13%) Tn I-ve ECG ischaemic 2% (0-9%)	45/51 TnI +ve patients had ischaemic ECG. Small numbers. Trop I measured at 6 hours
			MI at 30 days	Tn I +ve 63% (48-75%) Tn I-ve ECG ischaemic 9% (3-19%)

Comment(s)

All the studies above have flaws in particular in the timing of troponin measurement. However all point to troponin rises and ischamic changes being independent predictors of mortality/MI in the next 30 days.

Clinical Bottom Line

Negative troponin does not make an ischaemic ECG low risk chest pain, however a combination of the two points to a very high risk group.

References

1. Ohman EM. Armstrong PW. Christenson RH. Granger CB. Katus HA. Hamm CW. O'Hanesian MA. Wagner GS. Kleiman NS. Harrell FE Jr. Califf RM. Topol EJ. Cardiac troponin T levels for risk stratification in acute myocardial ischemia. GUSTO IIA Investigators. New England Journal of Medicine. 335(18):1333-41, 1996 Oct 31
2. Wilcox G. Archer PD. Bailey M. Dziukas L. Lim CF. Schneider HG Measurement of cardiac troponin I levels in the emergency department: predictive value for cardiac and all-cause mortality Medical Journal of Australia. 174(4):170-3, 2001 Feb 19.
3. Alp NJ. Bell JA. Shahi M. A rapid troponin-I-based protocol for assessing acute chest pain QJM. 94(12):687-94, 2001 Dec.