Atrial premature depolarisations five days post electrical cardioversion are related to atrial fibrillation recurrence risk in horses.
Authors: Vernemmen I, De Clercq D, Decloedt A, Vera L, Van Steenkiste G, van Loon G
Journal: Equine veterinary journal
Summary
# Atrial Premature Depolarisations and Atrial Fibrillation Recurrence in Horses Atrial fibrillation (AF) remains a significant arrhythmia in equine practice, but predicting which horses will experience recurrence after successful electrical cardioversion has proved challenging. This retrospective analysis of 80 horses (predominantly Warmbloods) evaluated whether the frequency of atrial premature depolarisations (APDs) detected on 24-hour Holter monitoring five days post-transvenous electrical cardioversion could identify animals at higher risk of AF recurrence within one year. A quarter of the study population (26 horses, 33%) experienced recurrence, and those with ≥25 APDs per 24 hours showed nearly threefold increased hazard for relapse (HR 2.9), alongside independently significant contributors including mitral regurgitation (HR 8.6), reduced left atrial contractile function (LA active fractional area change ≤9.6%), and lower bodyweight. Beyond the APD burden itself, this finding underscores that AF recurrence is multifactorial—clinicians should interpret Holter recordings five days post-cardioversion as part of a broader echocardiographic and clinical assessment rather than in isolation. For practices employing transvenous cardioversion, this protocol offers a practical window to stratify recurrence risk and inform prognosis discussions with owners, though these predictive parameters require validation across alternative treatment modalities before broader application.
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Practical Takeaways
- •24-hour ECG at 5 days post-cardioversion can help identify horses at higher risk of AF recurrence; those with ≥25 APDs/24h warrant closer monitoring and consideration of additional preventive measures
- •Structural cardiac changes (mitral regurgitation and atrial dysfunction) are stronger predictors of recurrence than APD burden alone, so echocardiographic assessment remains essential in post-cardioversion management
- •Smaller horses and those with valvular disease have elevated recurrence risk and may benefit from more aggressive management strategies or closer follow-up intervals
Key Findings
- •APD burden ≥25/24h was significantly associated with AF recurrence (HR 2.9, P=0.02) in horses 5 days post cardioversion
- •AF recurrence occurred in 33% (26/80) of horses within 1 year post transvenous electrical cardioversion
- •Median APD count was significantly higher in recurrence group (15 vs 7, P=0.01) compared to non-recurrence group
- •Mitral regurgitation (HR 8.6, P<0.001), reduced left atrial contractility (HR 2.6, P=0.04), and lower body weight were independent risk factors for AF recurrence