Abstract
BackgroundAtrial fibrillatory cycle length has been considered one of the indices of atrial electrical remodelling during atrial fibrillation (AF), which can be assessed from surface ECG by computer-assisted calculation of atrial fibrillatory rate (AFR). Horses have been suggested as a bona fide model for AF studies since horses too, develop lone AF, however data on AF characteristics in horses are extremely sparse and non-invasive characterization of AF complexity using surface ECG processing has not been reported.AimThe aim was to study characteristics of induced AF and its modification by flecainide.MethodsThe study group consisted on 3 horses with spontaneous persistent AF and 13 with pace-induced AF. Seven horses were treated with saline (control) and eight with flecainide (2 mg/kg). ECGs were analysed using spatiotemporal cancellation of QRST complexes and calculation of AFR from the residual atrial signal.ResultsAt AF onset, AFR was 295 ± 52 fibrillations per minute (fpm) in the horses with induced AF treated with flecainide, 269 ± 36 fpm in the control group (ns), and 364 ± 26 fpm in the horses with spontaneous persistent AF (P < 0.05 compared to the control group). Flecainide caused a decrease in AFR in all animals and restored sinus rhythm in the animals with induced AF. In the control animals, AFR increased from 269 ± 36 fpm to a plateau of 313 ± 14 fpm before decreasing to 288 ± 28 fpm during the last 10% of the AF episodes preceding spontaneous conversion (P < 0.05).ConclusionAFR in horses with induced AF resembles AFR in humans with paroxysmal AF. Flecainide caused a rapid decrease in AFR in all horses, further supporting the method to be a non-invasive technique to study the effect of antiarrhythmic compounds.
Highlights
Atrial fibrillatory cycle length has been considered one of the indices of atrial electrical remodelling during atrial fibrillation (AF), which can be assessed from surface ECG by computer-assisted calculation of atrial fibrillatory rate (AFR)
Flecainide caused a rapid decrease in AFR in all horses, further supporting the method to be a non-invasive technique to study the effect of antiarrhythmic compounds
AFR significantly increased in all horses from the 10th percentile (299 ± 10 fpm) to the 45-55th percentile (313 ± 14 fpm; P < 0.05)
Summary
Atrial fibrillatory cycle length has been considered one of the indices of atrial electrical remodelling during atrial fibrillation (AF), which can be assessed from surface ECG by computer-assisted calculation of atrial fibrillatory rate (AFR). Horses have been suggested as a bona fide model for AF studies since horses too, develop lone AF, data on AF characteristics in horses are extremely sparse and non-invasive characterization of AF complexity using surface ECG processing has not been reported. [9] AFR has been reported to decrease after flecainide treatment [3], but whether non-invasive AFR assessment is suitable for monitoring drug effects in horses (based on the processing of surface electrocardiogram (ECG) recordings) is yet to be studied A study by Ohmura et al [7] describes flecainide to be safe and efficient in restoring sinus rhythm in an experimental setting, whereas a Belgian group reported disappointing efficacy [8] and fatal side effects. [9] AFR has been reported to decrease after flecainide treatment [3], but whether non-invasive AFR assessment is suitable for monitoring drug effects in horses (based on the processing of surface electrocardiogram (ECG) recordings) is yet to be studied
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