Table of Contents
ISRN Cardiology
Volume 2011 (2011), Article ID 364728, 7 pages
http://dx.doi.org/10.5402/2011/364728
Research Article

Can We Exclude the Diagnosis of Non-ST Segment Myocardial Infarction on the Basis of a Single Troponin I and a Symptom Duration ≥8 Hours?

Department of Emergency Medicine, Alameda County Medical Center, Highland Hospital, Oakland, CA 94602-1018, USA

Received 13 February 2011; Accepted 17 March 2011

Academic Editor: A. D. Szekely

Copyright © 2011 Jeremy S. Lynn et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. The use of a single troponin measurement to exclude the diagnosis of non-ST segment myocardial infarction (NSTEMI) in patients that present with ischemic symptom duration ≥8 hours is sometimes used in the Emergency Department. Study Objective. To describe the characteristics of patients with initial nondiagnostic troponin values who develop a positive troponin while in the Emergency Department and to evaluate whether NSTEMI can be excluded using symptom duration ≥8 hours and initial troponin I. Methods. Retrospective chart review of patients evaluated for NSTEMI in the Emergency Department. Results. 4,510 patients had at least two troponin I values obtained during the two-year study period. 115 (2.5%) of these patients had an initially nondiagnostic (<0.6 ng/mL) and subsequent positive (≥0.6 ng/mL) troponin I result. Twenty-five (22%) of the 115 had duration of symptoms ≥8 hours. Of these 25 patients, 18 had an intermediate first troponin value (i.e., >0.06 ng/mL, but <0.6 ng/mL). Only two of the remaining seven patients had a final primary diagnosis of NSTEMI. Conclusion. The use of a negative initial troponin I together with a symptom onset of ≥8 hours defines a population with a very low incidence of a hospital diagnosis of NSTEMI.