High sensitivity troponin: Does the 50% delta change alter clinical outcomes in chest pain presentations to the emergency room?

Background: The National Heart Foundation (NHF) and Cardiac Society of Australia and New Zealand (CSANZ) Acute Coronary Syndrome (ACS) guidelines recommend the use of a high sensitivity troponin assay (hsTrop) in the assessment of patients presenting with ACS. A troponin delta of 50% compared with the previously recommended 20% is advocated by the guidelines to aid in the clinical diagnosis of ACS. We sought to determine the clinical impact of the updated recommendation to use 50% troponin delta for patients presenting with chest pain to the emergency department.

Method: We retrospectively collected data for all patients >18 years presenting with chest or abdominal pain with a hsTrop test performed between January-June 2012. Patients with a STEMI, lacked serial hsTrop, were on dialysis or had trauma-related pain were excluded.

Results: Of the 1054 eligible patients, 422 (40%) with serial hsTrop had at least one abnormal troponin (>14 ng/ml). 73 (6.9%) fell within 20-50%. Twenty-seven had clinical or ECG evidence suggestive of ACS and were referred for further cardiac investigations. Of the remainder, five patients were medically managed for ACS, 38 patients with non-cardiac chest pain had no further tests. At 1 year follow-up, of the patients that did not undergo further investigations, 6 patients represented with ACS; there was no cardiac mortality.

Conclusion: Our data showed a number of patients that would be potentially missed with the implementation of a 50% troponin. However, this loss of sensitivity was mitigated by the use of clinical acumen.