Abstract
BACKGROUND: We implemented a hs-cTnI (high-sensitivity cardiac troponin I)-based algorithm for emergency department (ED) evaluation of possible non-ST-segment-elevation acute coronary syndrome within an integrated health system (Kaiser Permanente Northern California). METHODS: Retrospective study of adult (18+ years) ED encounters for chest pain/discomfort with hs-cTnI testing (Access hsTnI, Beckman) at 21 medical centers between January 1, 2023 and June 30, 2024, excluding ST-segment-elevation myocardial infarction. The primary outcome was 30-day myocardial infarction or death. Sensitivity, specificity, negative predictive value, positive predictive value, and likelihood ratios were reported, with subgroup analyses by age, sex, coronary artery disease, chronic kidney disease, and ED disposition. RESULTS: There were 104 025 encounters in the final cohort (median age 59 years, 45% male, 18% coronary artery disease, and 13% chronic kidney disease). The primary outcome occurred in 5.5% encounters. Rule-out criteria were present in 70% of encounters (sensitivity, 95.4% [95% CI, 94.8%-96.0%]; negative predictive value, 99.7% [95% CI, 99.6%-99.7%]; likelihood ratio, -0.05) and 7% of encounters met rule-in criteria (specificity, 96.7% [95% CI, 96.6-96.8%]; positive predictive value, 60.2% [95% CI, 59.3%-61.1%]; likelihood ratio, +24.4). In subgroup analyses, rule-out criteria negative predictive value was below 99% in stage 4+ chronic kidney disease (96.1% [95% CI, 94.6%-97.6%]) and ischemic coronary artery disease (98.6% [95% CI 98.3-98.9%]), though not among those selected for ED discharge (98.4% [95% CI, 96.7%-99.2%] and 99.1% [95% CI, 98.8%-99.4%], respectively). CONCLUSIONS: The Kaiser Permanente Northern California non-ST-elevation acute coronary syndrome evaluation algorithm demonstrated excellent overall performance. Negative predictive value was modestly diminished in ischemic coronary artery disease or advanced chronic kidney disease, but risk was largely mitigated by ED discharge disposition decisions.