Transvenous electrical cardioversion of atrial fibrillation in horses: Horse and procedural factors correlated with success and recurrence.
Authors: Vernemmen Ingrid, Van Steenkiste Glenn, Dufourni Alexander, Decloedt Annelies, van Loon Gunther
Journal: Journal of veterinary internal medicine
Summary
# Transvenous Electrical Cardioversion for Equine Atrial Fibrillation: Key Prognostic Factors in Warmbloods Atrial fibrillation remains a significant arrhythmia in performance horses, with transvenous electrical cardioversion (TVEC) representing a primary treatment option, though most large-scale evidence has derived from Standardbred populations rather than sport horses. Vernemmen and colleagues retrospectively analysed 231 TVEC procedures in 199 horses (predominantly Warmbloods without severe structural cardiac disease) to identify horse and procedural factors influencing cardioversion success, energy requirements and arrhythmia recurrence. The procedure achieved a 94.4% success rate; however, recurrence occurred in nearly one-third of horses (31.9%), with mitral regurgitation and longer AF cycle length emerging as independent predictors of successful cardioversion, whilst stallions, those with prior AF episodes, increased body weight, tricuspid regurgitation and longer AF duration significantly increased both energy demands and recurrence risk. Catheter selection proved particularly influential—bipolar catheters required substantially less cumulative energy (≤600 J) compared to multipolar alternatives. For practitioners, these findings suggest that pre-procedure echocardiographic assessment, case selection based on sex and AF history, and choice of catheter technology should all inform both treatment recommendations and prognostic counselling, particularly in sport horse populations where recurrence carries substantial implications for athletic return.
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Practical Takeaways
- •TVEC offers high success rates for AF in horses, but consider echocardiographic findings (especially mitral regurgitation) when predicting outcomes and counseling owners on prognosis
- •Stallions with AF require closer monitoring post-cardioversion due to significantly elevated recurrence risk
- •Procedural factors like catheter type and body weight influence energy requirements—heavier horses and those requiring certain catheter types may need more energy delivery
Key Findings
- •Transvenous electrical cardioversion achieved 94.4% success rate in 231 procedures across 199 horses with atrial fibrillation
- •Mitral regurgitation and longer AF cycle length were independent determinants of cardioversion success
- •31.9% of horses experienced recurrence after successful first cardioversion (51/160 cases)
- •Stallions had 3-fold higher recurrence risk compared to other sexes, with mitral regurgitation and longer AF duration also increasing recurrence risk