24-Hour Kinetics of Cardiac Troponin-T Using a "High-Sensitivity" Assay in Thoroughbred Chuckwagon Racing Geldings
E Shields1, I Seiden-Long2, S Massie1
1Faculty of Veterinary Medicine (UCVM), University of Calgary, Calgary, Alberta, Canada.
Insights
Cardiac troponin-T (cTnT) levels increase in racing Thoroughbreds for 2-6 hours post-race, peaking at 3 hours. These cTnT concentrations return to baseline within 12-24 hours, aiding clinical assessment.
Area of Science:
- Equine cardiology
- Biomarker kinetics
- Exercise physiology
Background:
- High-sensitivity cardiac troponin-T (hscTnT) assay is validated for horses, serving as a specific biomarker for myocardial damage.
- Postexercise release kinetics of cardiac troponin-T (cTnT) using the hscTnT assay in horses remain to be established.
Purpose of the Study:
- Determine cTnT release kinetics in racing Thoroughbreds after high-intensity exercise.
- Investigate the influence of age on pre- and postrace cTnT concentrations.
- Establish sampling guidelines for clinicians assessing postexercise horses.
Main Methods:
- Prospective, observational study involving 38 Thoroughbred geldings (aged 5-16 years).
- Blood samples collected pre-race and at 2, 3, 4, 6, 12, and 24 hours post-race.
- Fifth-generation hscTnT assay used for plasma analysis; biochemistry assessed for rhabdomyolysis, renal failure, and dehydration.
Main Results:
- Significant postexercise increases in cTnT observed, with a median peak of 8.0 ng/L at 3 hours post-race.
- Peak postexercise cTnT concentrations remained below the 99th percentile upper reference limit (23.2 ng/L) between 2-6 hours post-race.
- cTnT concentrations returned to baseline by 12-24 hours; no correlation found between cTnT and age.
Conclusions:
- In racing Thoroughbreds, cTnT concentrations are elevated 2-6 hours post-race and normalize by 12-24 hours, remaining below 23.2 ng/L.
- These findings establish crucial guidelines for the clinical application of the hscTnT assay in exercising horses.
- The study provides a temporal profile for cTnT release, aiding in the interpretation of myocardial damage markers in equine athletes.
Background:
A "high-sensitivity" cardiac troponin-T (hscTnT) assay recently has been validated for use in horses and is a specific biomarker of myocardial damage. Postexercise release kinetics of cTnT utilizing the hscTnT assay have yet to be established in horses.
Objectives:
To determine: (1) cTnT release kinetics in racing Thoroughbreds after a high-intensity 5/8th mile Chuckwagon race; (2) the effects of age on pre- and postrace cTnT concentrations; and (3) sampling guidelines for clinicians evaluating horses presenting after exercise.
Animals:
Samples were obtained from 38 Thoroughbred geldings aged 5-16 years before racing and immediately, 2, 3, 4, 6, 12, and 24 hour postrace.
Methods:
Prospective, observational study with convenience sampling. A fifth-generation hscTnT assay was used for plasma sample analysis, and concentrations were compared at all time-points. Correlations were determined between cTnT concentrations and age. Biochemistry analysis was performed to assess rhabdomyolysis, renal failure, and exercise-induced dehydration.
Results:
All horses with measureable cTnT concentrations had significant postexercise increases in cTnT with a median peak (8.0 ng/L) at 3-hour postrace. All horses had peak postexercise cTnT concentrations 2- to 6-hour postrace ≤ the 99th percentile upper reference limit of 23.2 ng/L, after which all cTnT concentrations decreased until returning to baseline by 12-24 hours. There was no correlation over time between cTnT concentrations and age.
Conclusions And Clinical Importance:
In racing Thoroughbreds completing short-duration, high-intensity Chuckwagon races, cTnT concentrations are expected to be increased 2- to 6-hour postrace and to decrease by 12-24 hours while remaining ≤23.2 ng/L throughout. This study contributes to establishing guidelines for clinical use of the hscTnT assay in exercising horses.
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