Sumeshni Jairam, MBChB, Emergency Registrar; Peter Jones, MBChB, MSc, Emergency Medicine Specialist and Director of Emergency Research; Luay Samaraie, MBChB, Cardiology Registrar; Alexei Chataline, MBChB, Senior Cardiology Registrar; James Davidson, MBChB, MRCPath, Chemical Pathologist; Ralph Stewart, MBChB, MD, Cardiologist.
Clinical diagnosis and outcomes for Troponin T ‘positive’ patients assessed by a high sensitivity compared with a 4th generation assay
Article first published online: 23 JUN 2011
© 2011 The Authors. EMA © 2011 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine
Emergency Medicine Australasia
Volume 23, Issue 4, pages 490–501, August 2011
How to Cite
Jairam, S., Jones, P., Samaraie, L., Chataline, A., Davidson, J. and Stewart, R. (2011), Clinical diagnosis and outcomes for Troponin T ‘positive’ patients assessed by a high sensitivity compared with a 4th generation assay. Emergency Medicine Australasia, 23: 490–501. doi: 10.1111/j.1742-6723.2011.01446.x
Presentations of this Study: Oral presentations: LS at the Cardiac Society of Australia and New Zealand Annual Scientific Meeting, June 2010, SJ at the Peripheral Hospitals Spring Seminar on Emergency Medicine, September 2010. Poster presentations: PJ at the Australasian College for Emergency Medicine Annual Scientific Meeting and the Auckland City Hospital Celebration of Research Week, both November 2010.
- Issue published online: 8 AUG 2011
- Article first published online: 23 JUN 2011
- Accepted 29 March 2011
- diagnostic test;
- myocardial infarction;
Background: High sensitivity troponin T (hsTnT) detects lower levels of troponin T with greater precision than the 4th generation (cTnT) assay. However, the clinical implications of this are uncertain.
Objectives: Primary: Describe the proportion of patients who test ‘positive’ with hsTnT but negative with cTnT. Secondary: Determine proportion in each group with an adverse event (representation, AMI or died) within 90 days of the index test.
Method: 161 patients samples were tested with cTnT and hsTNT assays. McNemar's test was used to compare paired samples. Electronic medical records were reviewed, with discharge diagnosis and 90 day outcomes determined blind to hsTnT results. Patients were then classified as ‘TnT negative’ (hsTnT was <0.014 mcg/mL), ‘new positive’ (hsTnT was ≥0.014 mcg/mL and cTnT <0.03 mcg/mL) and ‘TnT positive’ (cTNT was ≥0.03 mcg/mL).
Results: Positive results more than doubled with the hsTnT assay (50% vs 22%, P < 0.001). 81 patients were ‘TnT negative’, 44 were ‘new positive’ and 36 ‘cTnT positive’. The discharge diagnosis for ‘new positives’ was AMI in 4 (9%), other cardiac in 13 (30%) and non-cardiac in 27 (61%). At 90 days adverse events occurred in 30%, 54% and 50% of the groups respectively. There were no late cases of AMI or cardiovascular death in ‘new positive’ patients.
Conclusion: Many patients with diagnoses other than AMI will have hsTNT above the reference level. Indiscriminate testing with hsTnT might lead to more patients requiring serial troponin testing and/or invasive further tests, which will have process and resource implications for EDs and health services.