Influence of detomidine on atrial fibrillation cycle length measured by intracardiac electrogram recording and by colour tissue Doppler imaging in horses.
Authors: Decloedt A, de Clercq D, van der Vekens N, Verheyen T, Ven S, van Loon G
Journal: Equine veterinary journal
Summary
Atrial fibrillation (AF) in horses is characterised by progressive electrical remodelling of the atria, reflected in a shortening of the atrial fibrillation cycle length (AFCL), and measuring this parameter non-invasively would enhance clinical and research applications. Decloedt and colleagues compared AFCL measurements obtained via invasive intracardiac electrograms against non-invasive tissue Doppler imaging (TDI) in 33 AF episodes across 32 horses, assessing whether sedation with detomidine (7.5 µg/kg intravenously) affected these measurements prior to electrical cardioversion. Whilst detomidine produced a statistically significant but clinically minimal increase in AFCL of 4 milliseconds, sedation substantially improved the technical quality of TDI recordings and enabled measurement of more atrial fibrillatory cycles per cardiac cycle, with Bland-Altman analysis demonstrating acceptable agreement (bias −18 to +15 ms) between invasive and non-invasive methods. These findings validate non-invasive AFCL measurement via TDI as a reliable tool for monitoring atrial remodelling progression and evaluating anti-arrhythmic drug efficacy in clinical practice. For practitioners managing equine AF cases, this work supports the use of ultrasound-based AFCL assessment as a practical alternative to invasive electrography, particularly when mild sedation is employed to optimise image quality and repeatability.
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Practical Takeaways
- •Detomidine sedation facilitates noninvasive measurement of atrial fibrillation cycle length via tissue Doppler imaging, making it a useful clinical tool for equine AF assessment without requiring invasive electrogram recordings
- •The +4 ms increase in AFCL with sedation is clinically negligible and should not affect interpretation of results when monitoring AF progression or drug effects
- •Noninvasive AFCL measurement can be used in practice to track atrial electrical remodelling and evaluate responses to anti-arrhythmic therapy in horses with AF
Key Findings
- •Detomidine administration caused a small but statistically significant increase in atrial fibrillation cycle length of +4 ms
- •Sedation significantly improved the quality of atrial myocardial velocity curves and increased the number of AF cycles measurable per cardiac cycle using tissue Doppler imaging
- •Bland-Altman bias between invasive electrogram and noninvasive tissue Doppler imaging measurements ranged from -18 to +15 ms depending on atrial wall region
- •Noninvasive AFCL measurements with sedation provide reliable estimates of atrial fibrillatory rate and can assess atrial electrical remodelling