Short-term (90 min) diagnostic performance for acute non-ST segment elevation myocardial infarction and 30-day
Donald H Schreiber1, Chioma Agbo, Alan H B Wu
1Division of Emergency Medicine, Stanford University School of Medicine, Stanford, CA 94305-2200, United States. donalds@stanford.edu
Insights
The high-sensitivity troponin I (hs-cTnI) assay identifies more acute myocardial infarction (AMI) cases and enables faster rule-out in emergency departments. This advanced assay also detects more patients at risk for adverse cardiac events within 30 days.
Area of Science:
- Cardiology
- Clinical Chemistry
- Emergency Medicine
Background:
- Acute coronary syndrome (ACS) diagnosis relies heavily on troponin levels.
- Traditional troponin I (cTnI) assays have limitations in sensitivity and speed.
- High-sensitivity troponin I (hs-cTnI) assays offer potential improvements in early ACS detection.
Purpose of the Study:
- To evaluate a third-generation high-sensitivity troponin I (hs-cTnI) assay.
- To compare its diagnostic performance against a contemporary cTnI assay.
- To assess hs-cTnI for diagnosing acute myocardial infarction (AMI) and predicting 30-day adverse cardiac events (ACE).
Main Methods:
- Remnant samples from emergency department (ED) patients with suspected ACS were analyzed.
- Baseline and 90-minute blood samples were tested using both cTnI and hs-cTnI assays.
- Sensitivity, specificity, and predictive values for AMI and 30-day ACE were compared.
Main Results:
- The hs-cTnI assay demonstrated higher sensitivity for AMI at presentation (83.3% vs. 75%) and 90 minutes (100% vs. 77.7%).
- Using a 30% increase (Δ30%) criteria improved hs-cTnI specificity to 94.5% without compromising sensitivity.
- The hs-cTnI assay identified over three times more AMI cases and detected more patients at risk for 30-day ACE.
Conclusions:
- The hs-cTnI assay facilitates a 90-minute rule-out for AMI.
- The Δ30% criteria enhance the specificity of hs-cTnI in diagnosing AMI.
- hs-cTnI assay improves the detection of AMI and patients at risk for adverse cardiac events.
Objectives:
We evaluated a third-generation high sensitivity "guidelines acceptable" troponin I assay (hs-cTnI) against a contemporary "clinically usable" troponin assay (cTnI).
Design And Methods:
Remnant samples of undifferentiated emergency department (ED) patients with suspected acute coronary syndrome were enrolled. Baseline and 90-minute samples were analyzed for cTnI and hs-cTnI. Sensitivity, specificity, positive and negative predictive values for AMI and 30-day adverse cardiac events (ACE) were compared.
Results:
Of 486 ED patients, there were 465 patients who had blood remaining at the presentation for the hs-cTnI assays, with 12 AMIs. At presentation, the clinical sensitivity and specificity for AMI was 75% and 97% for cTnI and 83.3 and 82.1% for hs-cTnI. There were 407 patients who had paired baseline and 90-minute blood samples for cTnI and hs-cTnI including 9 of the 12 AMI patients. The sensitivity and specificity was 77.7% and 96.5% for cTnI and 100% and 81.9% for hs-cTnI at 90 min. A Δ change of 30% increase from baseline to 90 min improved the specificity to 94.5% (95% CI 92%-96%) without lowering the sensitivity. When AMI was defined as a Δ30% change of hs-cTnI at t=0 and 90 min and one hs-cTnI result >99th percentile cutoff, more than 3 times as many patients met the diagnostic criteria for AMI compared to results from the normal sensitive troponin assay; 28 (6.9%) for hs-cTnI vs. 9 (2.2%) with cTnI. There were 37 in-hospital or 30-day events, producing an OR of 3.03, 95% CI: 0.86-9.59 for cTnI, and 2.54, 95% CI: 1.27-5.10 for hs-cTnI, which detected 11 more cases.
Conclusions:
The hs-cTnI assay achieved a 90-minute rule out for AMI and detected more 3 times as many AMI cases. The specificity increased with the Δ30% criteria. The hs-cTnI assay also detected more cases of patient at risk for adverse cardiac events at 30 days.
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