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

Study Questions:

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?

Methods:

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.

Results:

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.

Conclusions:

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.

Perspective:

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.

Clinical Topics: Acute Coronary Syndromes, ACS and Cardiac Biomarkers

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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