II. Background

  1. Introduced in United States in 2013, and adaptation is increasing at U.S. hospitals as of 2020
  2. Both High Sensitivity Troponin I and Troponin T Assays are available in U.S.

III. Efficacy: Where negative hs-cTnT <3 ng/L

IV. Advantages

  1. Highly sensitive assays are 1,000 to 10,000 more sensitive than older assays (measured in pg/ml instead of ng/ml)
  2. Test Sensitivity is considerably better (97% sensitive) with high sensitivity assays (fewer False Negatives, NPV 99.1%)
  3. Less imprecision at discriminatory values (i.e. abnormal values are highly reproducible on repeat measurement)
  4. Abnormal rise is detected more quickly than with older assays
  5. Time to run high sensitivity assay is shorter

V. Disadvantages

  1. Significantly worse Test Specificity than with older assays (with significantly higher False Positive Rate)
    1. See Troponin for False Positive causes
    2. hs-Troponin Is detectable in 50% of healthy patients
    3. hs-Troponin Is positive in 2% of normal patients (>99th percentile)

VI. Labs: hs-Troponin I

  1. Female: <55 ng/L
  2. Male: <80 ng/L

VII. Protocol: hs-Troponin I (on Emergency Department arrival)

  1. Normal: <3 ng/L (undetectable)
    1. Excludes ACS if >3 hours from onset of symptoms (if HEART Score <=3, negative acute EKG changes)
    2. Repeat at 2 hours if <3 hours of symptoms or as dictated by other findings (e.g. EKG, risks)
  2. Intermediate: 3 to 119 ng/L (indication for repeat testing)
    1. Repeat hs-Troponin at 2 hours after first
      1. Positive for ACS if increased >20 ng/L over first value (or >120 ng/L)
    2. Disposition
      1. Close outpatient follow-up for possible stress testing OR
      2. Continued observation with possible stress testing, third hs-Troponin, cardiology Consultation
        1. Third hs-Troponin Increased >20% over first Troponin Is concerning for ACS
  3. Positive: >120 ng/L
    1. Treat as Acute Coronary Syndrome
  4. References
    1. (2021) H-Health Fairview High Sensitivity Troponin I Protocol

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