Clinical significance of initial troponin I in the grey zone in emergency department chest pain patients: a retrospective pilot study

AIM: 'Normal' range for cardiac troponin I (TnI) has changed with more sensitive tests, but the validity of low-level elevations is contentious. We aimed to describe the characteristics and outcome of patients with an initial TnI level 1-5 times the upper limit of normal. METHODS: Retrospective study of patients assessed for ACS with initial TnI level between 0.05-0.19 ng/ml. Data collected included demographics, clinical data, TnI levels and outcome. Primary outcome was the proportion of patients who had a serial TnI rise consistent with ACS. RESULTS: 72 patients were studied; median age 71, median TIMI score 3, 66.7% male. 35 patients (48.6%) had a TnI rise consistent with ACS. CONCLUSION: Approximately half of patients with initial TnI between 0.05-0.19 ng/ml had a TnI rise consistent with ACS. An initial TnI in this range is not, of itself, indicative of ACS. Clinical decision-making should be guided by clinical features and serial TnI measurement.