Prehospital Blood Collection for High Sensitivity Cardiac Troponin Measurement in Patients with Acute Chest Pain
Michael W Supples1, Anna C Snavely1,2, Molly R Ehrig2
1Department of Emergency Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina.
Insights
Prehospital high-sensitivity cardiac troponin I (hs-cTnI) measurements, alone or with machine learning, can safely rule out myocardial infarction (MI) in emergency patients. Further trials are needed to confirm these findings in larger populations.
Area of Science:
- Cardiology
- Emergency Medicine
- Biomarkers
Background:
- High-sensitivity cardiac troponin (hs-cTn) assays are crucial for diagnosing myocardial infarction (MI) in emergency departments (EDs).
- Prehospital hs-cTn measurement offers potential for earlier MI rule-out, improving patient management.
- The Myocardial Ischemic Injury Index (MI³), a machine learning algorithm, aids in MI risk stratification.
Purpose of the Study:
- To evaluate the performance of prehospital hs-cTnI measurements for ruling out index MI.
- To assess the utility of serial hs-cTnI measurements (prehospital and ED arrival) combined with the MI³ algorithm.
- To determine the efficacy and negative predictive value (NPV) of different prehospital hs-cTnI strategies for MI rule-out.
Main Methods:
- A pilot prospective observational cohort study involving adult emergency medical services (EMS) patients with acute chest pain.
- Prehospital and ED arrival blood samples were collected for hs-cTnI measurement.
- Evaluated strategies included single prehospital hs-cTnI, serial hs-cTnI changes, and MI³ incorporating prehospital and/or arrival hs-cTnI.
Main Results:
- A very-low prehospital hs-cTnI (≤2.7 ng/L) demonstrated 100% NPV for index MI, ruling out 46.7% of patients.
- Serial hs-cTnI measurements (delta ≤3) achieved 97.7% NPV and ruled out 84.3% of patients.
- The MI³ algorithm with prehospital and arrival hs-cTnI showed 100% NPV, ruling out 70.6% of patients.
Conclusions:
- Prehospital hs-cTnI measurement alone and MI³ incorporating serial hs-cTnI are promising strategies for safely ruling out MI.
- These prehospital approaches can identify a significant proportion of patients eligible for early discharge.
- Larger trials are warranted to further validate these findings and their clinical utility.
Objectives:
High sensitivity cardiac troponin (hs-cTn) measures are used in the emergency department (ED) to evaluate patients with acute chest pain. Prehospital hs-cTn measurement could facilitate earlier rule-out of myocardial infarction (MI). The objective of this study is to assess the performance of prehospital blood draw for hs-cTnI measure alone, in combination with hs-cTnI measured at ED arrival, and incorporating the Myocardial Ischemic Injury Index (MI3) machine learning algorithm to rule-out index MI.
Methods:
We conducted a pilot prospective observational cohort study among adult emergency medical services (EMS) patients with acute, non-traumatic chest pain. Two third-service EMS agencies and two tertiary care EDs in North Carolina participated. Demographics and initial ECG findings were collected. Blood was obtained prehospital and on ED arrival for hs-cTnI measurement. The clinical outcome was adjudicated index visit MI. Efficacy (percentage of patients with index MI ruled-out) and negative predictive value (NPV) for index MI were determined for the following strategies: (1) a very-low single prehospital hs-cTnI, (2) serial hs-cTnI change (delta) at the prehospital and arrival timepoints, (3) MI3 incorporating prehospital hs-cTnI alone, and (4) MI3 incorporating prehospital and arrival hs-cTnI.
Results:
Of the 75 patients enrolled, 53.3% (40/75) were women, 32.0% (24/75) were Black patients, and the mean age was 62.2 ± 15.7 years. Index MI occurred in 8.0% (6/75). Prehospital hs-cTnI below the limit of quantification (≤2.7 ng/L) had an efficacy of 46.7% (35/75) with an NPV of 100% (95%CI 90.0%-100%) for index MI. A prehospital and arrival hs-cTnI delta ≤3 had an efficacy of 84.3% (43/51) with an NPV of 97.7% (95%CI 87.7-99.9%) for index MI. The standard low-risk MI3 threshold <1.6 with a single prehospital hs-cTnI had an efficacy and NPV for index MI of 76.0% (57/75) and 96.5% (95%CI 87.9-99.6), respectively. Finally, the standard low-risk MI3 threshold incorporating both prehospital and arrival hs-cTnI had an efficacy of 70.6% (36/51) and NPV of 100% (95%CI 90.3-100%) for index MI.
Conclusions:
Strategies using prehospital blood for hs-cTnI measurement alone and MI3 with prehospital and arrival hs-cTnI safely identified a large percentage of patients for rule-out, warranting further investigation in a larger trial.
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