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Journal of molecular and cellular cardiology plus2025; 12; 100452; doi: 10.1016/j.jmccpl.2025.100452

Performance horses as a model for exercise-associated cardiac arrhythmias and sudden cardiac death.

Abstract: This paper reviews the myocardial substrate of horses relative to that of humans and discusses the utility of performance horses as a model of exercise-associated cardiac arrhythmias and sudden cardiac death in athletes. The coronary circulation is similar between the species while coronary artery anomalies and myocardial bridging appear to only be associated with athletic mortality in human athletes and not in performance horses. There are subtle differences in the histology of the sinus and atrioventricular nodes, of unknown clinical significance, while the His bundle is more highly innervated in horses. The equine Purkinje network is much more extensive, contributing to a difference in the mean electrical axis between horses and humans. Differences in ion channel expression have been reported, although they are poorly characterized, and are of unknown clinical significance. However, horses may be a particularly good model to investigate the function of Kv1.5 due to its spontaneous ventricular expression, which is lacking in human ventricles. Similarities in cardiac structure, coronary vasculature, and ability to exercise at high levels makes performance horses a good model to investigate exercise-associated cardiac arrhythmias and sudden cardiac death in athletes. However, differences in myocardial substrate should be taken into consideration when designing studies and interpreting results.
Crown Copyright © 2025 Published by Elsevier Ltd.
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Publication Date: 2025-05-09 PubMed ID: 40475708PubMed Central: PMC12137179DOI: 10.1016/j.jmccpl.2025.100452Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article investigates the use of performance horses as a model to study exercise-related heart rhythm abnormalities and sudden cardiac deaths in athletes. The study underscores their anatomical similarities with human athletes, corroborated by subtle differences in the structure of heart tissues, ion channel expressions, myocardial substrates, and the nature of arrhythmic risk under strenuous physical activity.

Anatomical Comparisons

  • The article emphasizes the similarities in cardiac structure and coronary vasculature between horses and humans. The coronary circulation patterns are somewhat parallel between the two, providing a reliable comparison foundation.
  • However, the study notes differences such as coronary artery anomalies and myocardial bridging which are linked to mortalities in human athletes but not in performance horses.

Heart Tissue and Ion Channels

  • There exist subtle variations in the histology of the sinus and atrioventricular nodes between the two species. The study flags these as areas of unknown clinical significance, calling for further investigation.
  • It is noteworthy that the His bundle in the cardiac system is more highly innervated in horses, highlighting a crucial difference.
  • The equine Purkinje network, responsible for impulse conduction in the heart, is more extensive than in humans.
  • Furthermore, the mean electrical axis, indicating the general direction of the heart’s electrical drive differs between the two.
  • The ion channel expressions that regulate the flow of ions across the cell membranes, though poorly characterized, show variances.
  • Intriguingly, the Kv1.5 ion channel expression in horses’ ventricles, which is absent in humans’, presents horses as a valuable model for understanding its function.

Myocardial Substrate

  • The differences in myocardial substrate – the muscle tissue in the heart that contributes to contractions and relaxation during the cardiac cycle – is another area that needs to be taken into account when designing studies and interpreting results.

Conclusion

  • In the end, the study brings to the surface that despite their differences, the similarities in heart structure, coronary vasculature, and the ability to undertake strenuous exercise positions performance horses as a useful model to understand exercise-linked cardiac arrhythmias and sudden cardiac death in human athletes.

Cite This Article

APA
Avison A, Physick-Sheard PW, Pyle WG. (2025). Performance horses as a model for exercise-associated cardiac arrhythmias and sudden cardiac death. J Mol Cell Cardiol Plus, 12, 100452. https://doi.org/10.1016/j.jmccpl.2025.100452

Publication

Journal of molecular and cellular cardiology plus
ISSN: 2772-9761
NlmUniqueID: 9918470779706676
Country: England
Language: English
Volume: 12
Pages: 100452
PII: 100452

Researcher Affiliations

Avison, Amanda
  • Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.
Physick-Sheard, Peter W
  • Department of Population Medicine, Ontario Veterinary College, University of Guelph, Canada.
Pyle, W Glen
  • IMPART Team Canada, Dalhousie Medicine, Dalhousie University, Canada.
  • Women's Health Research Institute, BC Women's Hospital + Health Centre, Canada.

Conflict of Interest Statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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