Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.
Authors: Lotstra R J, van den Broek J, Power T, Marr C M, Wijnberg I D
Journal: Equine veterinary journal
Summary
# Editorial Summary Atrial fibrillation remains a frequently encountered arrhythmia in equine practice, yet evidence regarding optimal medical management—particularly in Warmblood populations where arrhythmia duration is often undocumented—remains limited. Researchers from Utrecht University and Rossdales Equine Hospital conducted a retrospective analysis of 51 horses (predominantly Warmbloods and Thoroughbreds, mean age 8.8 years) treated with quinidine sulphate, with 18 receiving the additional benefit of digoxin co-therapy, to identify factors predicting successful cardioversion to sinus rhythm. Eighty per cent of horses converted successfully; notably, the addition of digoxin to quinidine sulphate emerged as the only statistically significant predictor of conversion success, with an odds ratio of 12.4, regardless of breed or (in most cases) known duration of fibrillation. This finding has direct clinical relevance: whilst the retrospective nature introduces inherent bias and baseline arrhythmia duration was unknown in the majority of cases, the data suggest that dual-drug therapy warrants consideration as a first-line approach rather than sequential treatment escalation. For practitioners managing equine atrial fibrillation, this evidence supports earlier adoption of digoxin alongside quinidine to optimise the likelihood of restoring sinus rhythm, though individualised assessment of cardiac function and drug interactions remains essential.
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Practical Takeaways
- •Consider adding digoxin to quinidine sulfate treatment for atrial fibrillation, as combination therapy significantly improved conversion rates to normal rhythm
- •Expect approximately 80% success rate with quinidine-based treatment in equine AF cases, even when exact duration of arrhythmia is unknown
- •Breed does not appear to influence treatment response to digoxin and quinidine combination therapy for atrial fibrillation
Key Findings
- •80% of horses treated with quinidine sulfate converted to sinus rhythm
- •Combination therapy with digoxin and quinidine sulfate was associated with successful cardioversion (odds ratio 12.4; 95% CI 2.61-91.85)
- •Digoxin combination therapy improved conversion rates regardless of breed despite unknown AF duration in most horses
- •Study included 49 horses (29 Warmbloods, 20 Thoroughbreds, 1 Anglo-Arabian) with mean age 8.8 years