Validation of High-Sensitivity Troponin I in a 2-h Diagnostic Strategy to Assess 30-Day Outcomes in Emergency-Department Patients With Possible Acute Coronary Syndrome
What is the validity of a new high-sensitivity troponin I (hs-TnI) assay in assessing patients who present to the emergency department with chest pain?
This study evaluated two prospective cohorts of patients in the emergency department with acute coronary syndrome (ACS) in an accelerated diagnostic pathway integrating 0- and 2-hour hs-TnI results, Thrombolysis In Myocardial Infarction (TIMI) risk scores, and electrocardiography. Strategies to identify low-risk patients incorporated TIMI risk scores = 0 or ≤1. The primary endpoint was a major adverse cardiac event (MACE) within 30 days.
In the primary cohort, 1,635 patients were recruited and had 30-day follow-up. A total of 247 patients (15.1%) had a MACE. The finding of no ischemic electrocardiogram and hs-TnI ≤26.2 ng/L with the TIMI = 0 and TIMI ≤1 pathways, respectively, classified 19.6% (320) and 41.5% (678) of these patients as low risk; 0% (0) and 0.8% (2) had a MACE, respectively. In the secondary cohort, 909 patients were recruited. A total of 156 patients (17.2%) had a MACE. The TIMI = 0 and TIMI ≤1 pathways classified 25.3% (230) and 38.6% (351), respectively, of these patients as low risk; 0% (0) and 0.8% (1) had a MACE, respectively. Sensitivity, specificity, and negative predictive value for TIMI = 0 in the primary cohort were 100% (95% confidence interval [CI], 98.5-100), 23.1% (20.9-25.3), and 100% (98.8-100), respectively. Sensitivity, specificity, and negative predictive value for TIMI ≤1 in the primary cohort were 99.2 (95% CI, 97.1-99.8), 48.7 (95% CI, 46.1-51.3), and 99.7 (95% CI, 98.9-99.9), respectively. Sensitivity, specificity, and negative value for TIMI ≤1 in the secondary cohort were 99.4% (95% CI, 96.5-100), 46.5% (95% CI, 42.9-50.1), and 99.7% (95% CI, 98.4-100), respectively.
The authors concluded that an early-discharge strategy using an hs-TnI assay and TIMI score ≤1 had similar safety as previously reported, with the potential to decrease the observation periods and admissions.
In this study, the strategy using TIMI = 0 classified similar numbers of patients as low risk as previously reported using currently available troponin assays, while maintaining a sensitivity of >99%. The strategy incorporating a TIMI risk score ≤1 doubled the proportion of patients in the emergency department who are classified as low risk while maintaining >99% sensitivity and negative predictive value for adverse events in both cohorts. This finding suggests that approximately 40% of patients presenting to emergency departments with possible cardiac chest pain could rapidly and safely progress to early discharge for outpatient management. This has the potential to have a considerable impact on reducing hospital admission rates and emergency department overcrowding.
Keywords: Myocardial Infarction, Acute Coronary Syndrome, Follow-Up Studies, Biological Markers, Chest Pain, Troponin I, Troponin T, Emergency Service, Hospital, Electrocardiography, Troponin
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