FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Equine veterinary journal2026; doi: 10.1002/evj.70286

First experience with radiofrequency catheter ablation in horses with recurrent, persistent naturally occurring atrial fibrillation.

Abstract: Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial fibrillation (AF) in horses. Objective: Isolation of myocardial sleeves in the caudal vena cava or pulmonary veins might reduce the risk for AF recurrence. Methods: Case series. Methods: Records from seven horses with persistent, recurrent, naturally-occurring AF that were treated with three-dimensional electro-anatomical mapping and radiofrequency catheter ablation (RFCA) in order to reduce recurrence risk were reviewed. Mapping of the caudal vena cava was performed in all horses, while the pulmonary vein ostia I and IV were mapped in two horses and pulmonary vein ostia II and III in one horse. Arrhythmogenic substrate was subsequently isolated by point-by-point RFCA. Results: Mapping identified arrhythmogenic substrates in the caudal vena cava (n = 6), ostium II (n = 1) and ostium IV (n = 2), which were isolated as confirmed by entrance and/or exit block. Five cases recurred (after 2 days, and 6, 11, 11 and 30 months). The horse that relapsed after 6 months underwent a second procedure to isolate ostium III, but the arrhythmia recurred 4 months later. To date, two of seven horses remain in sinus rhythm with a follow-up of 14 and 47 months. Conclusions: Small number of horses and limited follow-up. Conclusions: Arrhythmogenic substrate was identified in the caudal vena cava and pulmonary veins in horses with recurrent AF. Two of seven horses remain in sinus rhythm 14-47 months after RFCA. This study does not allow to demonstrate the benefit of ablation. Catheter ablation in horses to reduce AF recurrence risk remains challenging at this point and more research is needed to identify AF triggers and improve ablation technique.
© 2026 EVJ Ltd.
Get Full Text
Publication Date: 2026-07-24 PubMed ID: 42499210DOI: 10.1002/evj.70286Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study explored the use of radiofrequency catheter ablation (RFCA) to treat recurrent atrial fibrillation (AF) in horses by targeting specific heart areas responsible for sustaining arrhythmia.
  • The research investigated whether isolating myocardial sleeves in the caudal vena cava and pulmonary veins could reduce AF recurrence in affected horses.

Background

  • Atrial fibrillation (AF) is a common cardiac arrhythmia in horses characterized by irregular and often rapid heart rhythms.
  • Myocardial sleeves—extensions of heart muscle tissue—located around the caudal vena cava and pulmonary veins are known to contribute to AF initiation and maintenance.
  • In human and veterinary medicine, isolating these arrhythmogenic substrates using catheter ablation has shown promise in treating AF.

Study Objective

  • To identify arrhythmogenic substrates in horses with recurrent and persistent naturally-occurring AF and assess the feasibility of RFCA in isolating those substrates.
  • To evaluate whether this intervention could reduce the risk of AF recurrence over time.

Methods

  • Study Design: Retrospective case series analysis of seven horses with persistent, recurrent AF.
  • Intervention: Three-dimensional electro-anatomical mapping was performed to locate arrhythmogenic myocardial sleeves in the caudal vena cava and pulmonary vein ostia:
    • All seven horses had the caudal vena cava mapped.
    • Three horses had pulmonary vein ostia mapped (ostium I and IV in two horses, ostium II and III in one horse).
  • RFCA was applied point-by-point to isolate identified arrhythmogenic areas.
  • Isolation success was confirmed by observing entrance and/or exit blocks, indicating electrical disconnection of the target tissue.

Results

  • Arrhythmogenic substrates were identified predominantly in the caudal vena cava (6/7 horses).
  • Additional substrates were found at pulmonary vein ostium II (1 horse) and ostium IV (2 horses).
  • Post-ablation outcomes:
    • Five horses experienced recurrence of AF at varying intervals: 2 days, 6 months, 11 months (two cases), and 30 months.
    • One horse with recurrence at 6 months underwent a second ablation targeting ostium III, but AF recurred 4 months later.
    • Two horses maintained normal sinus rhythm with follow-up durations of 14 and 47 months.

Conclusions and Implications

  • It is feasible to identify and isolate arrhythmogenic myocardial sleeves in horses using RFCA guided by electro-anatomical mapping.
  • The caudal vena cava and pulmonary veins represent potential targets for AF treatment in horses.
  • Despite procedural success in isolating substrates, recurrence rates remain high, suggesting current techniques are insufficient to fully prevent AF relapse.
  • The limited number of cases and follow-up duration restrict definitive conclusions about the efficacy of RFCA in reducing AF recurrence in horses.
  • RFCA for AF in horses is technically challenging and requires further research to better characterize arrhythmia triggers and improve ablation protocols for lasting success.

Significance for Veterinary Cardiology

  • This pioneering study offers initial insights into interventional electrophysiology treatments in large animal cardiology, particularly for equine AF.
  • It draws attention to the importance of myocardial sleeve anatomy in equine AF pathophysiology and highlights the potential for catheter-based therapies beyond traditional medical management.
  • Future advancements building on this work may improve long-term arrhythmia control, enhance horse performance, and reduce morbidity associated with persistent AF.

Cite This Article

APA
Buschmann E, Van Steenkiste G, Vernemmen I, Schauvliege S, Decloedt A, Duytschaever M, van Loon G. (2026). First experience with radiofrequency catheter ablation in horses with recurrent, persistent naturally occurring atrial fibrillation. Equine Vet J. https://doi.org/10.1002/evj.70286

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Buschmann, Eva
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Van Steenkiste, Glenn
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Vernemmen, Ingrid
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Schauvliege, Stijn
  • Department of Large Animal Surgery, Anaesthesia and Orthopaedics, Ghent University, Ghent, Belgium.
Decloedt, Annelies
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Duytschaever, Mattias
  • Department of Cardiology, AZ Sint-Jan, Bruges, Belgium.
van Loon, Gunther
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.

Grant Funding

  • 1S71521N / Fonds Wetenschappelijk Onderzoek
  • 1SE9122N / Fonds Wetenschappelijk Onderzoek
  • 01B05818 / Bijzonder Onderzoeksfonds UGent

References

This article includes 59 references
  1. Decloedt A, Van Steenkiste G, Vera L. Atrial fibrillation in horses part 1: pathophysiology. Vet J 2020;263:105521.
  2. Reef VB, Bonagura J, Buhl R, McGurrin MKJ, Schwarzwald CC, van Loon G. Recommendations for Management of Equine Athletes with cardiovascular abnormalities. J Vet Intern Med 2014;28:749–761.
  3. van Loon G. Cardiac arrhythmias in horses. Vet Clin North Am Equine Pract 2019;35:85–102.
  4. Reef VB, Levitan CW, Spencer PA. Factors affecting prognosis and conversion in equine atrial fibrillation. J Vet Intern Med 1988;2:1–6.
  5. Takahashi Y, Ishikawa Y, Ohmura H. Treatment of recent‐onset atrial fibrillation with quinidine and flecainide in thoroughbred racehorses: 107 cases (1987–2014). J Am Vet Med Assoc 2018;252:1409–1414.
  6. Deem DA, Fregin GF. Atrial fibrillation in horses: a review of 106 clinical cases, with consideration of prevalence, clinical signs, and prognosis. J Am Vet Med Assoc 1982;180:261–265.
  7. Gehlen H, Stadler P. Atrial fibrillation in warmblood horses – echocardiography, therapy, prognosis and outcome in 72 cases. Pferdeheilkunde 2002;18:530–536.
  8. Van Steenkiste G, Carlson J, Decloedt A. Relationship between atrial fibrillatory rate based on analysis of a modified base‐apex surface electrocardiogram analysis and the results of transvenous electrical cardioversion in horses with spontaneous atrial fibrillation. J Vet Cardiol 2021;34:73–79.
  9. Decloedt A, de Clercq D, van der Vekens N, Verheyen T, van Loon G. Noninvasive determination of atrial fibrillation cycle length by atrial colour tissue Doppler imaging in horses. Equine Vet J 2014;46:174–179.
  10. McGurrin MK, Physick‐Sheard PW, Kenney DG. Transvenous electrical cardioversion of equine atrial fibrillation: patient factors and clinical results in 72 treatment episodes. J Vet Intern Med 2008;22:609–615.
  11. Vernemmen I, Van Steenkiste G, Dufourni A. Transvenous electrical cardioversion of atrial fibrillation in horses: horse and procedural factors correlated with success and recurrence. J Vet Intern Med 2022;36:758–769.
  12. Decloedt A, Van Steenkiste G, Vera L. Atrial fibrillation in horses part 2: diagnosis, treatment and prognosis. Vet J 2021;268:105594.
  13. Decloedt A, Schwarzwald CC, De Clercq D. Risk factors for recurrence of atrial fibrillation in horses after cardioversion to sinus rhythm. J Vet Intern Med 2015;29:946–953.
  14. Buschmann E, Van Steenkiste G, Boussy T. Three‐dimensional electro‐anatomical mapping and radiofrequency ablation as a novel treatment for atrioventricular accessory pathway in a horse: a case report. J Vet Intern Med 2023;37:728–734.
  15. Buschmann E, Van Steenkiste G, Vernemmen I. Lesion size index‐guided radiofrequency catheter ablation using an impedance‐based three‐dimensional mapping system to treat sustained atrial tachycardia in a horse. Equine Vet J 2025;57(4):1009–1016.
  16. Buschmann E, Van Steenkiste G, Vernemmen I. Caudal vena cava isolation using ablation index‐guided radiofrequency catheter ablation (CARTO™ 3) to treat sustained atrial tachycardia in horses. J Vet Intern Med 2025;39:e17251.
  17. Van Steenkiste G, Boussy T, Duytschaever M. Detection of the origin of atrial tachycardia by 3D electro‐anatomical mapping and treatment by radiofrequency catheter ablation in horses. J Vet Intern Med 2022;36:1481–1490.
  18. Buschmann E, Easton‐Jones C, Van Steenkiste G. Orthodromic atrioventricular reentry bradycardia and tachycardia caused by an accessory pathway in horses. J Vet Intern Med 2025;39:e70175.
  19. Buschmann E, Van Steenkiste G, Bulckens H. Three‐dimensional electro‐anatomical mapping of premature atrial complexes originating from the right atrial free wall and treatment by radiofrequency ablation in three horses. Equine Vet J 2026;58(4):1032–1040.
  20. Issa ZMJM, Zipes DP. Ablation energy sources. Clinical Arrhythmology and electrophysiology 3rd ed. Philadelphia, PA: Elsevier; 2019. p. 206–237.
  21. Hindricks G. 2020 ESC guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association of Cardio‐Thoracic Surgery (EACTS). Eur Heart J 2021;42:373–498.
  22. Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M, Quiniou G. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659–666.
  23. Ibrahim L, Buschmann E, van Loon G. Morphological evidence of a potential arrhythmogenic substrate in the caudal and cranial vena cava in horses. Equine Vet J 2024;57:256–264.
  24. Kjeldsen ST, Nissen SD, Saljic A, Hesselkilde EM, Carstensen H, Sattler SM. Structural and electro‐anatomical characterization of the equine pulmonary veins: implications for atrial fibrillation. J Vet Cardiol 2024;52:1–13.
  25. Vandecasteele T, Van den Broeck W, Tay H. 3D reconstruction of the porcine and equine pulmonary veins, supplemented with the identification of telocytes in the horse. Anat Histol Embryol 2018;47:145–152.
  26. Linz D, Hesselkilde E, Kutieleh R, Jespersen T, Buhl R, Sanders P. Pulmonary vein firing initiating atrial fibrillation in the horse: oversized dimensions but similar mechanisms. J Cardiovasc Electrophysiol 2020;31:1211–1212.
  27. Buschmann E, Van Steenkiste G, Duytschaever M. Successful caudal vena cava and pulmonary vein isolation in healthy horses using 3D electro‐anatomical mapping and a contact force‐guided ablation system. Equine Vet J 2023;56:1068–1076.
  28. Paulussen E, Van Steenkiste G, Hermans BM. Einthoven's triangle adapted for horses: proposal for the Delta configuration. J Vet Intern Med 2024;38:2698–2706.
  29. Verheyen T, Decloedt A, De Clercq D. Electrocardiography in horses – part 1: how to make a good recording. Vlaams Diergen Tijds 2010;79:331–336.
  30. Van Steenkiste G, Paulussen E, Decloedt A. Vectorcardiography in healthy horses can be obtained from 2 sequentially recorded electrocardiograms using a standard, dual‐channel recorder (Televet100). In: ECEIM 2022, Rome, Italy. 2022.
  31. van Loon G, Decloedt A. Arrhythmias and abnormalities of the cardiac conduction system in athletic horses. In: Hinchcliff K, Kaneps A, Geor R, van Erck‐Westergem E, editors. Equine sports medicine and surgery. 3rd ed. Missouri: Elsevier; 2024. p. 831–865.
  32. Van Steenkiste G, Delhaas T, Hermans B. An exploratory study on Vectorcardiographic identification of the site of origin of focally induced premature Depolarizations in horses, Part I: The Atria. Animals (Basel) 2022;12:549.
  33. Vernemmen I, Buschmann E, Demeyere M, Verhaeghe LM, van Steenkiste G, Decloedt A. Feasibility of transthoracic echocardiographic guidance for multi‐catheter electrophysiological mapping studies in horses. J Vet Intern Med 2024;38:2686–2697.
  34. Vernemmen I, Buschmann E, Van Steenkiste G. Intracardiac ultrasound‐guided transseptal puncture in horses: outcome, follow‐up and peri‐operative anticogulant treatment. J Vet Intern Med 2024;38:2707–2717.
  35. Vernemmen I, Van Steenkiste G, Buschmann E. Atrial fibrillation is significantly slower near the caudal vena cava compared to the right atrium in horses. In: Veterinary Cardiovascular Society, Autumn meeting, Warwick, United Kingdom. 2023.
  36. Sim I, Bishop M, O'Neill M. Left atrial voltage mapping: defining and targeting the atrial fibrillation substrate. J Interv Card Electrophysiol 2019;56:213–227.
  37. Miyamoto K, Tsuchiya T, Narita S, Yamaguchi T, Nagamoto Y, Ando SI. Bipolar electrogram amplitudes in the left atrium are related to local conduction velocity in patients with atrial fibrillation. Europace 2009;11:1597–1605.
  38. Kovacs S, Racz B, Sotonyi P, Bakos Z. Morphological and histological investigation of the conduction system in the equine atrial muscle sleeve of pulmonary veins. Equine Vet J 2024;56:1059–1067.
  39. Chen JY, Wu HI, Chang KC. Pulmonary vein volume and myocardial sleeve extension estimated by 3D computed tomography and voltage mapping predict arrhythmogenic triggers of paroxysmal atrial fibrillation. J Interv Card Electrophysiol 2021;62:177–185.
  40. Buschmann E, Van Steenkiste G, Vernemmen I. Multiple catheter recording in horses to investigate atrial depolarization pattern during sinus rhythm and induced premature atrial complexes. J Vet Intern Med 2025;39:e70218.
  41. Erhard N, Mauer T, Ouyang FF, Sciacca V, Rillig A, Reissmann B. Mechanisms of late arrhythmia recurrence after initially successful pulmonary vein isolation in patients with atrial fibrillation. Pace 2023;46:161–168.
  42. Sundaram S, Choe W, Jordan JR, Boorman C, Mullins N, Davies A. Two year, single center clinical outcome after catheter ablation for paroxysmal atrial fibrillation guided by lesion index. J Atr Fibrillation 2018;11:1760.
  43. De Mattia L, Crosato M, Indiani S. Prospective evaluation of lesion index‐guided pulmonary vein isolation technique in patients with paroxysmal atrial fibrillation: 1‐year follow‐up. J Atr Fibrillation 2018;10:1858.
  44. Das M, Loveday JJ, Wynn GJ. Ablation index, a novel marker of ablation lesion quality: prediction of pulmonary vein reconnection at repeat electrophysiology study and regional differences in target values. Europace 2017;19:775–783.
  45. Hussein A, Das M, Chaturvedi V. Prospective use of ablation index targets improves clinical outcomes following ablation for atrial fibrillation. J Cardiovasc Electrophysiol 2017;28:1037–1047.
  46. Ioannou A, Papageorgiou N, Lim WY, Wongwarawipat T, Hunter RJ, Dhillon G. Efficacy and safety of ablation index‐guided catheter ablation for atrial fibrillation: an updated meta‐analysis. Europace 2020;22:1659–1671.
  47. Phlips T, Taghji P, El Haddad M. Improving procedural and one‐year outcome after contact force‐guided pulmonary vein isolation: the role of interlesion distance, ablation index, and contact force variability in the ‘CLOSE’‐protocol. Europace 2018;20:F419–F427.
  48. Andrade JG. Cryoballoon ablation for pulmonary vein isolation. J Cardiovasc Electrophysiol 2020;31:2128–2135.
  49. Bradley CJ, Haines DE. Pulsed field ablation for pulmonary vein isolation in the treatment of atrial fibrillation. J Cardiovasc Electrophysiol 2020;31:2136–2147.
  50. Schipper JH, Steven D, Lüker J. Comparison of pulsed field ablation and cryoballoon ablation for pulmonary vein isolation. J Cardiovasc Electrophysiol 2023;34:2019–2026.
  51. Woermann J, Schipper JH, Lueker J. Comparison of pulsed‐field ablation versus very high power short duration‐ablation for pulmonary vein isolation. J Cardiovasc Electrophysiol 2023;34:2417–2424.
  52. Chun KRJ, Miklavcic D, Vlachos K. State‐of‐the‐art pulsed field ablation for cardiac arrhythmias: ongoing evolution and future perspective. Europace 2024;26:euae134.
  53. Boersma L. New energy sources and technologies for atrial fibrillation catheter ablation. Europace 2022;24:44–51.
  54. Joshi S, Choi AD, Kamath GS, Raiszadeh F, Marrero D, Badheka APURVA. Prevalence, predictors, and prognosis of atrial fibrillation early after pulmonary vein isolation: findings from 3 months of continuous automatic ECG loop recordings. J Cardiovasc Electrophysiol 2009;20:1089–1094.
  55. Bordignon S, Barra S, Providencia R, de Asmundis C, Marijon E, Farkowski MM. The blanking period after atrial fibrillation ablation: an European heart rhythm association survey on contemporary definition and management. Europace 2022;24:1684–1690.
  56. Muller J, Nentwich K, Berkovitz A, Sonne K, Kozlova O, Barth S. Recurrent atrial fibrillation ablation after initial successful pulmonary vein isolation. J Clin Med 2023;12:7177.
  57. Hesselkilde EZ, Carstensen H, Flethoj M. Longitudinal study of electrical, functional and structural remodelling in an equine model of atrial fibrillation. BMC Cardiovasc Disord 2019;19:1–12.
  58. Oral H, Knight BP, Özaydin M, Tada H, Chugh A, Hassan S. Clinical significance of early recurrences of atrial fibrillation after pulmonary vein isolation. J Am Coll Cardiol 2002;40:100–104.
  59. Chew DS, Black‐Maier E, Loring Z, Noseworthy PA, Packer DL, Exner DV. Diagnosis‐to‐ablation time and recurrence of atrial fibrillation following catheter ablation a systematic review and meta‐analysis of observational studies. Circ Arrhythm Electrophysiol 2020;13:e008128.

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 106,532 horse owners like you who receive our email updates on horse health and nutrition.