THE INCIDENCE OF UNSTABLE ANGINA IN PATIENTS WITH LOW HIGH-SENSITIVITY TROPONIN I VALUES: A SUBGROUP ANALYSIS OF THE RACE-IT TRIAL

Document Type

Conference Proceeding

Publication Date

4-1-2024

Publication Title

J Am Coll Cardiol

Abstract

Background We sought to identify the incidence of unstable angina in patients with low high-sensitivity cardiac troponin I (hs-cTnI) in Emergency Departments (EDs). Methods This was a preplanned secondary analysis of the Rapid Acute Coronary Syndrome Exclusion using high-sensitivity I cardiac Troponin (RACE-IT) stepped-wedge randomized trial, which compared two rule-out protocols (0/1-hour and 0/3-hour) for myocardial infarction (MI) in 9 EDs from 7/2020-3/2021. A hs-cTnI assay from Beckman Coulter was used (99th percentile 18 ng/L). In the accelerated protocol (AP), MI was excluded if hs-cTnI was <4 ng/L at presentation, or =4 ng/L at presentation with a 1-hour value <8 ng/L. Those that did not rule-out within 1 hour required a 3-hour hs-cTnI ≤18 ng/L to rule-out. In the standard care (SC), MI was excluded if hs-cTnI values were ≤18 ng/L at 0 and 3 hours. Patients were excluded if hs-cTnI was >18 ng/L within 3 hours of presentation. Unstable angina was adjudicated based on the ISCHEMIA trial definition, which required electrocardiographic changes or findings at coronary angiography (ruptured/ulcerated plaque or thrombus). Adjudication was performed by interventional cardiologists for patients undergoing coronary angiography, and by cardiology fellows in patients with hs-cTnI >18 ng/L >3 hours after presentation. Results Of the 32,608 patients in the trial, 58 patients (0.18%) met the definition of unstable angina (35 in the AP and 23 in the SC protocol). In the AP 12/35 (34.3%) patients with unstable angina had a presenting hs-cTnI <4 ng/L. In the AP, among patients who ruledout for MI within 1 hour, 13/10444 (0.12%) had unstable angina vs. 22/8659 (0.25%) among those who did not meet early rule-out criteria (adjusted odds ratio 0.73, 95% CI 0.33 - 1.60, p=0.43). Within 30 days there were 113 (0.35%) patients in the entire cohort who had a revascularization procedure and in the unstable angina group there were 38 (65.5%). Conclusion Unstable angina is rare in patients with a low hs-cTnI values at presentation to the ED and few receive revascularization procedures. However, of those ultimately diagnosed with unstable angina in the AP, a substantial portion had an extremely low hs-cTnI at presentation.

Volume

83

Issue

13

First Page

1268

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