24-Hour Kinetics of Cardiac Troponin-T Using a "High-Sensitivity" Assay in Thoroughbred Chuckwagon Racing Geldings...

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.