Mild troponin elevation in patients admitted to the emergency department with atrial fibrillation: 30-day post-discharge prognostic significance

João Augusto, Miguel Borges Santos, David Roque, Daniel Faria, Joana Urzal, José Morais, Victor Gil, Carlos Morais

Patients with atrial fibrillation (AF) often undergo troponin (Tn) testing in the emergency department (ED), but the clinical significance of mildly elevated values remains unclear. We evaluated short-term 30-day post-discharge outcomes in AF patients according to troponin levels. Out of 2181 AF patients evaluated in the ED (June 2014 to June 2015), we included consecutive admitted patients. Patients were grouped into those with normal Tn values (≤ 0.05 ng/mL), mild elevations (> 0.05-0.5 ng/mL, 10× URL) and marked elevations (> 0.5 ng/mL). Outcomes included acute coronary syndrome (ACS), revascularization, all-cause mortality and combined end point; the secondary outcome was ischemic stroke. A total of 348 patients (90.9%) had Tn testing, which was associated with longer in-hospital stay (median 2.04 vs. 0.74 days in unmeasured Tn, p = 0.014); 37.1% did not have clinical suspicion of ACS. Mild Tn elevation occurred in 19.0% and 6.3% had markedly elevated values. Compared to normal values, mild elevations had higher absolute incidence, without statistical significance, of ACS (1.5 vs. 0.0%, p = 0.202), revascularization (1.5 vs. 0.0%, p = 0.202), all-cause mortality (12.1 vs. 6.9%, p = 0.200), combined end point (13.3 vs. 6.9%, p = 0.084) or ischemic stroke (4.5 vs. 2.3%, p = 0.394). Tn testing is routine in admitted AF patients, even without suspicion of ACS, and is associated with prolonged stay. Mild Tn elevation is associated with a nonsignificant trend toward higher adverse events. Larger-scale studies are needed to evaluate the cost-effectiveness of Tn testing for prognosis in admitted AF patients, as this prolongs stay and has unclear impact on patient management.