Prognostic implications of detectable cardiac troponin I below the 99th percentile in patients admitted to an emergency department without acute coronary syndrome.

Background: Detectable troponin below the 99th percentile may reflect an underlying cardiac abnormality which might entail prognostic consequences. This study aimed to investigate the prognosis of patients admitted to an emergency department (ED) with detectable troponin below the 99th percentile reference limit who did not present with an acute coronary syndrome (ACS).
Methods: We analysed the clinical data of all consecutive patients admitted to the ED during the years 2012 and 2013 in whom cardiac troponin was requested by the attending clinician (cTnI Ultra Siemens, Advia Centaur). Patients with troponin below the 99th percentile of the reference population (40 ng/L) and who did not have a diagnosis of ACS were selected, and their mortality was evaluated in a 2-year follow-up.
Results: A total of 2501 patients had a troponin level below the reference limit, with 43.9% of those showing detectable levels (>6 ng/L and <40 ng/L). Patients with detectable levels were elderly and had a higher prevalence of cardiovascular history and more comorbidities. The total mortality in the 2-year follow-up was 12.4% in patients with detectable troponin and 4.5% in patients with undetectable troponin (p<0.001). In the Cox multivariate regression analysis, the detectable troponin was an independent marker of mortality at 2 years (HR 1.62, 95% CI 1.07-2.45, p=0.021).
Conclusions: Detectable troponin I below the 99th percentile is associated with higher mortality risk at 2-year follow-up in patients admitted to the ED who did not present with ACS.