Premature depolarisations in horses competing in United States Eventing Association and Fédération Equestre Internationale-sanctioned 3-day events.
Authors: Durando Mary M, Slack Joann, Birks Eric, Belcher Carolyn, Kohn Catherine
Journal: Equine veterinary journal
Summary
# Editorial Summary Concerns about injuries and sudden cardiac death during cross-country eventing have prompted closer investigation of rhythm disturbances in competition horses. Durando and colleagues conducted continuous electrocardiographic monitoring on 75 event horses before, during and immediately after cross-country phases at USEA and FEI competitions, using logistic regression to identify risk factors associated with premature depolarisations (PDs)—irregular heartbeats arising from ectopic foci rather than normal conduction pathways. Over half the cohort (56%) exhibited PDs during cross-country, with horses competing at upper levels showing 17.5 times greater odds of developing PDs than lower-level competitors; furthermore, time spent with heart rates exceeding 199 bpm correlated significantly with more complex arrhythmias (triplets, salvos and tachyarrhythmias), whilst arrhythmias present at rest predicted arrhythmia recurrence during early recovery. For practitioners, these findings suggest that upper-level event horses warrant particular cardiac scrutiny, and that controlling exercise intensity—particularly duration above 199 bpm—may help mitigate complex arrhythmias during demanding cross-country efforts. Pre-competition baseline ECGs identifying resting rhythm disturbances could flag higher-risk individuals likely to experience arrhythmias in recovery, supporting more targeted monitoring and potentially safer competition decisions.
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Practical Takeaways
- •High prevalence of cardiac arrhythmias (56%) in event horses during cross-country competition suggests baseline ECG screening and cardiac monitoring may be warranted for competition horses
- •Upper-level event horses face substantially increased arrhythmia risk; veterinarians should consider pre-competition cardiac assessment for advanced competitors
- •Horses exhibiting arrhythmias at rest require careful monitoring during recovery periods post-competition, as resting arrhythmias predict continued arrhythmias during recovery
Key Findings
- •Premature depolarisations were identified in 42/75 horses (56%) during cross-country eventing competition
- •Horses competing in upper divisions had 17.5 times higher odds of premature depolarisations compared to lower divisions (p=0.006)
- •Time spent at heart rates greater than 199 BPM was associated with more complex arrhythmias including triplets, salvos and tachyarrhythmias (p=0.005)
- •Presence of arrhythmias at rest was associated with 3.5 times higher odds of arrhythmias during early recovery period (p=0.03)