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Am Fam Physician. 2018;97(6):410

Clinical Question

Is a cardiac troponin I concentration of less than 5 ng per L (.005 mcg per L) at presentation useful in identifying adults with potential acute coronary syndrome at low risk of myocardial infarction or cardiac death?

Bottom Line

A cardiac troponin I concentration of less than 5 ng per L in adults who present with potential acute coronary syndrome has a negative predictive value (NPV) of at least 99.9% for cardiac death at 30 days and at one year. (Level of Evidence = 1a–)

Synopsis

These investigators thoroughly searched Medline, Embase, the Cochrane Register, and the Web of Science without language restrictions for prospective studies that evaluated the accuracy of measured high-sensitivity cardiac troponin I in identifying adults with suspected acute coronary syndrome who are at risk of myocardial infarction or cardiac death. Two independent investigators assessed individual studies for inclusion criteria and methodologic quality using a standard risk-of-bias scoring tool. Disagreements were resolved by consensus agreement with a third reviewer. Patients with ST-segment elevation or myocardial infarction, and those who presented in cardiac arrest, were excluded. A total of 36 articles (N = 22,457 adults with suspected acute coronary syndrome) reporting observations from 19 individual cohorts met the inclusion criteria. The assessed risk of bias was low to moderate in eight of the 19 cohorts and high in the remaining 11 cohorts.

High-sensitivity cardiac troponin I concentrations were less than 5 ng per L at presentation in 11,012 patients (49%), with an NPV of 99.5% (95% confidence interval, 99.3% to 99.6%) for missed myocardial infarctions at 30 days, with no cardiac deaths at 30 days (NPV = 100%). The NPV for cardiac death at one year was 99.9% (95% confidence interval, 99.7% to 99.9%). In subgroup analysis, the NPV was lower in patients with myocardial ischemia on the initial electrocardiogram, those who presented within two hours of symptom onset, those 65 years or older, and those with a history of ischemic heart disease.

Study design: Systematic review

Funding source: Foundation

Setting: Various (meta-analysis)

Reference: ChapmanARLeeKKMcAllisterDAet alAssociation of high-sensitivity cardiac troponin I concentration with cardiac outcomes in patients with suspected acute coronary syndrome. JAMA2017;318(19):1913–1924.

POEMs (patient-oriented evidence that matters) are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, see http://www.essentialevidenceplus.com. Copyright Wiley-Blackwell. Used with permission.

For definitions of levels of evidence used in POEMs, see http://www.essentialevidenceplus.com/product/ebm_loe.cfm?show=oxford.

To subscribe to a free podcast of these and other POEMs that appear in AFP, search in iTunes for “POEM of the Week” or go to http://goo.gl/3niWXb.

This series is coordinated by Sumi Sexton, MD, editor-in-chief.

A collection of POEMs published in AFP is available at https://www.aafp.org/afp/poems.

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