NICE advises routine high sensitivity troponin tests to rule out MI
BMJ 2016; 355 doi: https://doi.org/10.1136/bmj.i6503 (Published 02 December 2016) Cite this as: BMJ 2016;355:i6503All rapid responses
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Whilst I agree that novel approaches are needed to aid emergency physicians to safely discharge individuals who may be at risk of acute myocardial injury (AMI), the underlying research must be evaluated carefully. This is because most patients who were selected in the trials had only minimal underlying cardiovascular risk factors. Therefore, the results of these trials are being extrapolated to guide us on moderate to high risk individuals without a large evidence base to support this.
We know that elevated highly specific levels of troponin will be present in many individuals with moderate to high risk who are not having an AMI. A prominent example is in patients with chronic kidney disease requiring dialysis, who are mostly excluded in the studies. It is currently recommended in these subgroups that baseline troponin levels should be measured then compared against a second measurement. However, in order to detect AMI hyper-acutely the gold standard would be to have a national pre-existing baseline of highly sensitive troponin levels in different high risk subgroups. This would also be dependent on the laboratory assays being comparable on a national level, which is not available at present.
Ultimately whilst I welcome the important steps we are taking to aid early exclusion of AMI, it must be clear that troponin testing strategies in moderate-high risk subgroups needs further research to guide our national policies.
References
1.National Institute for Health and Care Excellence. Chest pain of recent onset: assessment and diagnosis (clinical guideline CG95). Updated Nov 2016. https://www.nice.org.uk/guidance/cg95.
2.National Institute for Health and Care Excellence. Myocardial infarction (acute): Early rule out using high-sensitivity troponin tests (Elecsys Troponin T high-sensitive, ARCHIITECT STAT High sensitive Troponin-I and AccuTnl+3 assays) Updated Oct 2016 https://www.nice.org.uk/guidance/dg15
3.Kmietowicz Z. Level of troponin needed to rule out MI in patients with chest pain is identified. BMJ2015;351:h5389. doi:10.1136/bmj.h5389 pmid:26449247.
4.Shah ASV, Anand A, Sandoval Y, et al. High sensitivity cardiac troponin I at presentation in patients with suspected acute coronary syndrome: a cohort study. Lancet2015; http://dx.doi.org/10.1016/S0140-6736(15)00391-8.
5.Cullen L, Parsonage W, Than M. Myocardial infarction: rapid ruling out in the emergency room. Lancet2015; http://dx.doi.org/10.1016/S0140-6736(15)00449-3.
6.Parikh RH, Seliger SL, deFilippi CR. Use and interpretation of high sensitivity cardiac troponins in patients with chronic kidney disease with and without acute myocardial infarction Clin Biochem. 2015 Mar;48(4-5):247-53; doi: 10.1016/j.clinbiochem.2015.01.004
Competing interests: No competing interests
Re: NICE advises routine high sensitivity troponin tests to rule out MI: thought through use for the GP please.
NICE’s advice may be good for the clinic but it is not for the GP. Chest pain is a common complaint in general practice and reason for consultation. Depending on the studies, only 3% (1) has an acute coronary syndrome. A study in general practice (2) came to the conclusion that a prediction rule based exclusively on symptoms and signs (with five determinants namely age/sex, known clinical vascular disease, patient assumes pain is of cardiac origin, pain worse during exercise and pain not reproducible by palpation) can help to rule out coronary artery disease in the majority of patients presenting with chest pain in a primary care setting.
Because primary care physicians work in a low-prevalence setting, with a cut-off score of 1 or 2 in the aforementioned study, 474/485 patients were true negative, which means that only 2% of patients presenting with chest pain would initially be classified wrongly as negative. In most of the cases, troponin use is not necessary.
What is the place for troponin testing? Sometimes forgotten, it can be a rapid rule in a patient with a low pretest probability but with a very suspected story e.g. a young female or a rapid rule out in a patient with an atypical story where there is no need for urgent referral.
Otherwise, a negative result may result in a claim when the patient (as happened in our region) ultimately had a thoracic aortic aneurysm. And if an acute coronary syndrome is suspected, it is better to refer the patient to the hospital as an emergency and then there is no time to lose with troponin testing.
1. Bösner S, Becker A, Haasenritter J, et al. Chest pain in primary care: epidemiology and pre-work-up probabilities. Eur J Gen Pract. 2009;15:141-6. doi: 10.3109/13814780903329528.
2. Bösner S, Haasenritter J, Becker A et al. Ruling out coronary artery disease in primary care: development and validation of a simple prediction rule. CMAJ. 2010 Sep 7;182:1295-300. doi: 10.1503/cmaj.100212.
Competing interests: No competing interests