Evaluation of assays for troponin I in healthy horses and horses with cardiac disease.
Authors: Van Der Vekens N, Decloedt A, Sys S, Ven S, De Clercq D, van Loon G
Journal: Veterinary journal (London, England : 1997)
Summary
Cardiac troponin I (cTnI) serves as a valuable serum marker for identifying myocardial injury in horses, yet the clinical utility of different commercially available assays remains unclear owing to variations in analytical performance. Van Der Vekens and colleagues compared two cTnI assays using sera from 23 clinically healthy horses and 72 horses with confirmed cardiac disease, with assay 1 demonstrating a lower limit of detection (0.03 ng/mL) compared to assay 2 (0.01 ng/mL). Whilst both assays showed significantly elevated cTnI in diseased horses relative to controls (assay 1: median 0.11 ng/mL versus <0.03 ng/mL; assay 2: median 0.02 ng/mL versus <0.01 ng/mL; both P<0.05), substantial mean differences between assays precluded direct comparability of results and risked misinterpretation in clinical settings. Only assay 1 yielded a statistically robust cut-off value (0.035 ng/mL) for cardiac disease detection with clinically acceptable sensitivity (70%) and specificity (91%), whereas assay 2 failed to establish a significant discriminatory threshold. For equine practitioners using cTnI as a diagnostic aid, this research underscores the critical importance of understanding which assay platform has been employed and establishing laboratory-specific reference intervals rather than applying universal cut-off values across different analytical systems.
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Practical Takeaways
- •When assessing horses for cardiac disease, verify which cTnI assay your laboratory uses—assay 1 provides superior diagnostic performance (70% sensitivity, 91% specificity) with a clear cut-off value of 0.035 ng/mL
- •Different troponin assays cannot be used interchangeably; results from assay 2 were less clinically useful, so standardization on assay 1 is recommended for consistent disease detection
- •Troponin I elevation (>0.035 ng/mL with assay 1) is a reliable indicator of myocardial damage in horses and supports cardiac disease diagnosis when clinical signs are present
Key Findings
- •Assay 1 (LOD 0.03 ng/mL) showed significantly higher median cTnI values in cardiac disease horses (0.11 ng/mL) compared to healthy horses (<0.03 ng/mL, P<0.001)
- •Assay 2 (LOD 0.01 ng/mL) detected lower median cTnI in cardiac disease (0.02 ng/mL) versus healthy horses (<0.01 ng/mL, P=0.044) with less clinical discrimination
- •Assay 1 achieved optimal clinical cut-off of 0.035 ng/mL with 70% sensitivity and 91% specificity for cardiac disease detection, whereas assay 2 could not establish a significant cut-off
- •Large mean differences existed between the two assays despite significant correlation, potentially affecting clinical interpretation of results