Effectiveness of practices for improving the diagnostic accuracy of Non ST Elevation Myocardial Infarction in the Emergency Department: A Laboratory Medicine Best Practices™ systematic review

Abstract

Objectives: This article is a systematic review of the effectiveness of four practices (assay selection, decision point cardiac troponin (cTn) threshold selection, serial testing, and point of care testing) for improving the diagnostic accuracy Non-ST-Segment Elevation Myocardial Infarction (NSTEMI) in the Emergency Department.

Design and methods: The CDC-funded Laboratory Medicine Best Practices (LMBP) Initiative systematic review method for quality improvement practices was used.

Results: The current ACC/AHA guidelines recommend using cardiac troponin assays with a 99th percentile upper reference limit (URL) diagnostic threshold to diagnose NSTEMI. The evidence in this systematic review indicates that contemporary sensitive cTn assays meet the assay profile requirements (sensitivity, specificity, PPV, and NPV) to more accurately diagnose NSTEMI than alternate tests. Additional biomarkers did not increase diagnostic effectiveness of cTn assays. Sensitivity, specificity, and NPV were consistently high and low PPV improved with serial sampling. Evidence for use of point of care cTn testing was insufficient to make recommendation, though some evidence suggests that use may result in reduction to patient length of stay and costs.

Conclusions: Based on the review of and the LMBP(TM) A-6 Method criteria, we recommend the use of cardiac troponin assays without additional biomarkers using the 99th percentile URL as the clinical diagnostic threshold for the diagnosis of NSTEMI. We recommend serial sampling with one sample at presentation and at least one additional second sample taken at least 6h later to identify a rise or fall in the troponin level. No recommendation is made either for or against the use of point of care tests.

Disclaimer: The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention/the Agency for Toxic Substances and Disease Registry (CDC/ATSDR).

Keywords: Acute coronary syndrome; Cardiac troponin; Myocardial infarction; Non-ST-segment elevation.

Figure 1

LMBP™ QI Analytical Framework: Cardiac Biomarkers

Figure 2

Systematic Review Flow Diagram

Figure 3

Cumulative Assay Specificity at 95% Sensitivity by Sampling Time

Figure 4

Serial Testing Evaluation of cTn Assays