Validation and clinical application of implantable loop recorders for diagnosis of atrial fibrillation in horses.
Abstract: Paroxysmal atrial fibrillation (pAF) occurs sporadically and can impair athletic performance. Gold standard for diagnosis is surface electrocardiography (ECG), however, this requires AF to be sustained. Implantable loop recorders (ILRs) are routinely used for AF detection in human medicine. While ILR placement has been studied in horses, its AF detection performance is unknown. Objective: (I) Validation of ILRs for AF detection in horses. (II) Determining pAF incidence using ILRs and estimate the positive predictive value (PPV). Methods: (I) Experimental study; (II) Longitudinal observational study. Methods: (I) Implantation of ILRs in 15 horses with AF and 13 horses in sinus rhythm. Holter ECGs were recorded at: 1, 4, 8, 12 and 16 weeks of AF. The ILR ECGs were compared with surface ECGs to assess diagnostic sensitivity and specificity. (II) Eighty horses (43 Warmbloods, 37 Standardbreds) with ILRs were monitored for 367 days [IQR 208-621]. Results: (I) ILRs detected AF on all recording days, in horses with AF, with a sensitivity of 66.1% (95% CI: 65.8-66.5) and a specificity of 99.99% (95% CI: 99.97-99.99). The sensitivity remained consistent across all time points. (II) The incidence of pAF was 6.3% (5/80). In horses with pAF, the PPV ranged from 8% to 87%. Increased body condition score (BCS > 6/9) was associated with an increased number of false positive episodes (p = 0.005). Conclusions: (I) Horses were stabled during the ECG recordings, and AF was induced, rather than naturally occurring pAF. (II) Integrated algorithm in this ILR is optimised for AF detection in humans using remote monitors. Additionally, sensing is affected by motion artefacts. Conclusions: The ILR reliably detected AF in resting horses, particularly in horses with normal BCS (6/9). The ILR proved useful to detect pAF and is recommended alongside Holter monitoring for diagnostic workup of horses with suspected pAF. Unassigned: Paroxysmales Vorhofflimmern (pAF) tritt sporadisch auf und kann die athletische Leistungsfähigkeit beeinträchtigen. Goldstandard für die Diagnose ist die Oberflächen‐Elektrokardiographie (ECG), die jedoch ein anhaltendes Vorhofflimmern voraussetzt. Implantierbare Loop‐Recorder (ILRs) wurden in der Humanmedizin routinemäßig zur Erkennung von Vorhofflimmern (AF) eingesetzt. Während die Platzierung von ILRs bei Pferden untersucht wurde, ist deren Fähigkeit in der Erkennung von Vorhofflimmern unbekannt. ZIELSETZUNG: (I) Validierung von ILRs zur Erkennung von AF bei Pferden. (II) Bestimmung der pAF‐Inzidenz mit ILRs und Schätzung des positiven prädiktiven Werts (PPV). Methods: (I) Experimentelle Studie; (II) Längsschnittliche Beobachtungsstudie. Methods: (I) Implantation von ILRs bei 15 Pferden mit AF und 13 Pferden mit Sinusrhythmus. Holter‐ECGs wurden aufgezeichnet nach: 1 Woche, 4 Wochen, 8 Wochen, 12 Wochen und 16 Wochen mit AF. Die ILR‐ECGs wurden mit Oberflächen‐ECGs verglichen, um die diagnostische Sensitivität und Spezifität zu beurteilen. (II) Achtzig Pferde (43 Warmblüter, 37 Standardbreds) mit ILR wurden 367 Tage lang überwacht [IQR 208‐621]. ERGEBNISSE: (I) ILRs erkannten AF an allen Aufzeichnungstagen bei Pferden mit AF mit einer Sensitivität von 66.1% (95% CI: 65.8–66.5) und einer Spezifität von 99.99% (95% CI: 99.97–99.99). Die Sensitivität blieb über alle Zeitpunkte hinweg konstant. (II) Die Inzidenz von pAF betrug 6.3% (5/80). Bei Pferden mit pAF reichte der PPV von 8% bis 87%. Ein höherer Body Condition Score (BCS > 6/9) war mit einer höheren Anzahl falsch positive Episoden verbunden (P = 0.005). HAUPTEINSCHRÄNKUNGEN: (I) Pferde waren während der ECG‐Aufzeichnungen im Stall, und es handelte sich um induziertes AF und nicht um natürlich vorkommende pAF. (II) Der Integrierte Algorithmus der ILR ist für die Erkennung von AF bei Menschen mit Fernüberwachung optimiert. Außerdem wird die Erkennung durch Bewegungsartefakte beeinträchtigt. Unassigned: Mit den ILR wurde AF bei ruhenden Pferden zuverlässig erkannt, insbesondere bei Pferden mit normalem BCS (6/9). Der ILR erwies sich als nützlich für den Nachweis von pAF und wird neben der Holter‐Überwachung für die diagnostische Abklärung von Pferden mit Verdacht auf pAF empfohlen.
© 2024 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
Publication Date: 2024-06-21 PubMed ID: 39031582PubMed Central: PMC11807927DOI: 10.1111/evj.14112Google Scholar: Lookup
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- Journal Article
- Validation Study
Summary
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This research validates the clinical use of implantable loop recorders (ILRs) to detect sporadic atrial fibrillation (AF) in horses, a condition which can impact their athletic performance. The use of ILR technology has proven effective for AF detection in humans, but its efficacy in horses had not been previously known.
Methodology of the Study
- The research was carried out in two phases: an experimental study and a longitudinal observational study.
- In the experimental study, ILRs were implanted in 15 horses with AF and an additional 13 horses which had a normal heart rhythm. Over 16 weeks, the heart patterns of these horses were recorded at several intervals (1, 4, 8, 12, and 16 weeks) to assess the diagnostic sensitivity and specificity of ILRs for AF detection in comparison with surface ECG
- In the longitudinal observational study, 80 horses (43 Warmbloods, 37 Standardbreds) were observed over a 367-day period. These horses were also fitted with ILRs to monitor their heart patterns.
Results of the Study
- From the experimental study, it was found that the implantable loop recorders could detect AF in all the recordings taken from the horses with AF. The sensitivity of the detection was 66.1%, and the specificity was 99.99%. These percentages remained consistent throughout the 16 weeks.
- From the observational study, it was determined that the incidence rate of sporadic atrial fibrillation was 6.3% (5 out of the 80 horses).
- It was also seen that horses with a higher body condition score (BCS > 6/9) were more likely to have a higher number of false positive results.
Conclusions of the Study
- The study concluded that ILRs are an effective tool to detect AF in resting horses, and its detection ability was particularly useful in horses with a normal BCS.
- The ILR was deemed to be particularly beneficial in detecting sporadic atrial fibrillation and is now recommended for use in combination with Holter monitoring in the diagnostic process for horses suspected of having sporadic AF.
- However, the study also indicated that the current ILR algorithm used for humans may not be as effective for horses due to the presence of motion artifacts. This is mentioned as a potential focus area for future research and development.
Limitations of the Study
- The horses in the study were stabled during the ECG recordings, so the AF detected was induced rather than naturally occurring.
- The algorithm in the ILR is optimized for AF detection in humans using remote monitors. Therefore, the detection in horses may be affected by motion artifacts.
Cite This Article
APA
Kjeldsen ST, Nissen SD, Christensen NC, Haugaard SL, Schneider MJ, Vinther Z, Sattler SM, Carstensen H, Jøns C, Hopster-Iversen C, Buhl R.
(2024).
Validation and clinical application of implantable loop recorders for diagnosis of atrial fibrillation in horses.
Equine Vet J, 57(2), 449-458.
https://doi.org/10.1111/evj.14112 Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Cardiology, Herlev and Gentofte University Hospital, Gentofte, Denmark.
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Cardiology, The Heart Centre, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
MeSH Terms
- Animals
- Horses
- Atrial Fibrillation / veterinary
- Atrial Fibrillation / diagnosis
- Horse Diseases / diagnosis
- Electrocardiography, Ambulatory / veterinary
- Electrocardiography, Ambulatory / instrumentation
- Electrocardiography, Ambulatory / methods
- Male
- Female
- Longitudinal Studies
- Sensitivity and Specificity
Grant Funding
- 1032-00053B / Independent Research Fund Denmark
- Hans Nielsen Foundation
Conflict of Interest Statement
Medtronic has generously sponsored the implantable loop recorders for the purpose of this study.
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