Utility of Serial Troponin Testing in Evaluation for Acute Coronary Syndrome

The high sensitivity troponin assay (hsTrop) has improved accuracy in evaluating emergency department (ED) patients for acute coronary syndrome (ACS). Often, a second troponin is obtained hours after the initial troponin to detect a delayed rise following a cardiac event; however, this practice originated before the hsTrop, and recent data suggests it has minimal diagnostic yield in low-risk HEART score patients. We evaluated the utility of a second hsTrop in assessing for ACS in patients with an initial normal hsTrop regardless of HEART score, and we investigated if symptom duration greater than 3 hours yielded a delayed rise in hsTrop leading to medical intervention.

We conducted a retrospective cohort study of all Veterans Affairs (VA) ED patients from 2021-2023 who had an initial normal hsTrop and a second hsTrop drawn during the same visit. We then quantified the cases with a 20% or greater increase in the second hsTrop and performed a manual chart review of those where the second hsTrop rose by 100% or more, assessing the duration of chest pain or other symptom(s) prior to ED arrival, EKG findings, and cardiac catheterization results. Descriptive statistics were performed.

There were 48,840 patients meeting inclusion criteria with an initial non-elevated hsTrop. Of these, 1,189 patients (2.4%) had a second hsTrop ≥ 20% compared to the first, and 730 patients (1.5%) had a second hsTrop ≥ 100% compared to the first. After excluding patients with second hsTrop ≥ 100% with unavailable EKGs (38), initial ST-elevation myocardial infarction EKGs (40), and those without a clearly documented time of symptom onset (105), there were 562 patients remaining. Of these, 161 (29%) had greater than 3 hours of symptoms prior to ED arrival; 35 of these patients received cardiac catheterizations with 15 undergoing subsequent angioplasties, and 3 were referred for coronary artery bypass grafting. These 35 patients undergoing cardiac medical interventions represent 0.07% of patients with an initial non-elevated hsTrop.

Serial hsTrop testing in 48,840 VA ED patients with a negative initial hsTrop did identify ACS in those with preliminary reassuring workups, but diagnostic yield was low. Most patients with a hsTrop increase ≥ 100% had less than 3 hours of symptoms prior to ED arrival; cases of troponin increases resulting in intervention in patients with longer duration of symptoms occurred rarely.