Sustained atrial tachycardia in horses and treatment by transvenous electrical cardioversion.
Authors: Van Steenkiste G, De Clercq D, Vera L, Decloedt A, van Loon G
Journal: Equine veterinary journal
Summary
# Sustained Atrial Tachycardia and Transvenous Electrical Cardioversion in Horses Focal atrial tachycardia and macroreentrant atrial tachycardia (atrial flutter) remain poorly characterised conditions in equine practice, with limited guidance on diagnosis and treatment approaches. Van Steenkiste and colleagues examined seven horses treated with biphasic transvenous electrical cardioversion (TVEC), analysing surface and intra-atrial electrocardiography alongside tissue Doppler imaging (TDI) to assess treatment efficacy and atrial recovery. All seven horses converted to sinus rhythm immediately following the first TVEC procedure, with TDI demonstrating atrial contractile function recovery comparable to horses treated for atrial fibrillation; however, one horse developed atrial fibrillation within 24 hours post-treatment and another experienced recurrence at 8 years, whilst the remaining five maintained sinus rhythm for 9 months to 5 years. TDI proved valuable as a non-invasive method for measuring atrial cycle length and monitoring functional recovery, though the authors acknowledge that without invasive electrophysiology studies, distinguishing between focal atrial tachycardia and atrial flutter remains speculative. These findings suggest TVEC offers a high success rate for converting atrial tachycardias and may warrant consideration for horses presenting with these arrhythmias, though the small case series and variable long-term prognosis indicate that further research is needed to refine patient selection and predict recurrence risk.
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Practical Takeaways
- •TVEC is highly effective for converting sustained atrial tachycardia to sinus rhythm in horses, with 100% success rate in this series at initial treatment
- •Recurrence is possible but uncommon in the medium to long term; one horse had early recurrence (<24 h) requiring close monitoring post-procedure
- •Tissue Doppler imaging provides a non-invasive method to monitor atrial function recovery after cardioversion without requiring invasive electrophysiology studies
Key Findings
- •All seven horses with sustained atrial tachycardia converted to sinus rhythm during the first transvenous electrical cardioversion (TVEC) procedure
- •Tissue Doppler imaging showed atrial contractile function recovery after TVEC similar to cases treated for atrial fibrillation
- •Five of seven cases remained in sinus rhythm at 9 months to 5 years follow-up; one case developed atrial fibrillation 1 day post-treatment and another showed recurrence 8 years later
- •Mean bias between atrial cycle length measured from right atrial intra-atrial electrogram and tissue Doppler imaging ranged between -2 and 3 ms across sampled regions