Utility of serial conventional troponin testing for emergency department patients stratified by HEART score and symptom timing.

Background: The HEART score for risk stratifying chest pain patients in the emergency department (ED) has been widely adopted in clinical practice, but is often employed with nonconformant serial troponin measurements.

Objective: The primary objective of this study was to examine the utility of obtaining a second conventional 3-h troponin I (TnI) level in ED patients presenting with potential acute coronary syndrome (ACS), stratified by HEART score and duration of symptoms.

Methods: This was a retrospective cohort study of consecutive adult ED patients with a complete HEART score. We assessed the utility of repeat TnI measurement by examining the positivity rate of ΔTnI = [Second TnI] - [Initial TnI] stratified by HEART score and time elapsed since onset or resolution of symptoms. Major adverse cardiac events (MACE) within 6 weeks of index visit were assessed.

Results: A total of 944 patients were included with 433 (45.9%) assigned a low risk HEART score 0-3. Of the 268 (61.9%) low risk HEART score patients receiving a second TnI, only 3 (1.1%, [0.2-3.2%]) resulted in a positive ΔTnI, one of which occurred in the setting of an elevated initial TnI. Overall, patients presenting within 3 h of symptoms were more likely to experience positive ΔTnI, index MACE and MACE at 6 weeks compared to patients presenting ≥3 h since symptoms onset/resolution and patients with unknown timing of symptoms (15.9% vs 11.0% vs 10.3%, p < 0.001; 10.0% vs 5.3% vs 4.6%, p = 0.021; 12.7% vs 6.6% vs 6.4%, p = 0.047).

Conclusion: Our data suggest serial measurement of conventional troponin provides limited added benefit in low risk HEART score patients, regardless of duration and timing of symptoms. Conversely, serial troponin measurement may confer utility in moderate/high risk HEART score patients, particularly those presenting within 3 h of symptoms.