Evaluation of point-of-care test systems using the new definition of myocardial infarction Stefan Agewall, MD, PhD Department of Cardiology, Huddinge University Hospital, Karolinska Institute, Stockholm, Sweden Received 8 July 2002; received in revised form 18 October 2002; accepted 18 October 2002 Abstract Objectives: To examine the proportion of patients admitted to CCU because of chest pain with a negative quantitative troponin t-test (Cardiac reader; Roche), who despite the negative test, would fulfil the new myocardial infarction criteria. A second aim was to evaluate the clinical utility of troponin I. Design and methods: Troponin T (Cardiac reader; Roche) was measured 12 h after the last chest pain episode. If Troponin T was negative the subjects were included in the study. All included subjects were also examined with troponin I (Stratus CS; Dade Behring) and troponin T at the central laboratory (Elecsys 2010) at the same time. 187 patients were included. CKMB was also measured 6 h after the last chest pain (Stratus CS; Dade Behring). Results: Fifth teen patients (8.0%) fulfilled the criteria of myocardial infarction, despite a negative Troponin T (Cardiac reader; Roche). CKMB measures did not add useful diagnostic information. The sensitivity and specificity were 100% and 95.3%, respectively for troponin I, when 0.2 g/L was used as cut off level for myocardial infarction. Conclusion: In this low risk group, eight percent of the patients with a negative Troponin T (Cardiac reader; Roche) fulfilled the new criteria of myocardial infarction. Troponin I (Stratus CS; Dade Behring) appeared to be a reliable method in this group. © 2003 The Canadian Society of Clinical Chemists. All rights reserved. Keywords: Myocardial infarction; Definition; Troponin; CKMB 1. Introduction The cardiac-specific troponins are highly sensitive and specific markers of myocardial damage [1–2] and therefore cardiac troponins (I or T) are the preferred markers for the diagnosis of myocardial infarction [3]. The impact of laboratory information on the manage- ment of patients with chest pain has led to the development and definition of recommendations designed to reduce the therapeutic turnaround time, thus improving the medical outcome for patients. Because of the delay often associated with transport-related problems, the concept of point-of- care testing has been introduced for the measurement of cardiac markers [4 – 6] The most important potential advan- tages of bedside measurement of biochemical markers with the new assay and reader device in patients with chest pain are that the biochemical test result is immediately available at the hands of the responsible physician. These Point-of-Care test systems for determination of troponin T and I have been continuously developed during the last decade. Gradually the detection limit has been improved and cross-reactivity problems have also been re- duced by the selection of other cardiac-specific monoclonal antibodies [7]. Indeed it was recently reported that a multimarker Point- of-Care testing, identified positive patient earlier and pro- vided a better risk stratification for mortality than a local laboratory-based, single-marker approach did in chest pain units [5]. However, this study has been criticized, since old criteria of myocardial infarction were used [8]. In the new myocardial infarction criteria, an increased troponin value is defined as a measurement exceeding the 99 th percentile of a reference control group [3]. Therefore, the aim of this study was to examine the proportion of patients admitted to CCU because of chest pain with a negative quantitative troponin t-test (Cardiac Corresponding author. Tel.: +46-8-585-817-33; fax: +46-8-585-867- 10. E-mail address: stefan.agewall@cardiol.hs.sll.se (S. Agewall). Clinical Biochemistry 36 (2003) 27–30 0009-9120/03/$ – see front matter © 2003 The Canadian Society of Clinical Chemists. All rights reserved. doi:10.1016/S0009-9120(02)00417-4