Peer-reviewed veterinary case report
How flecainide works for atrial fibrillation in horses over time
By Carstensen, Helena et al.·Published in Journal of veterinary internal medicine·2018·Department of Veterinary Clinical Sciences·View original on PubMed →
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Original publication title: Time-dependent antiarrhythmic effects of flecainide on induced atrial fibrillation in horses.
- Species:
- horse
Plain-English summary
A group of nine Standardbred mares with induced atrial fibrillation (AF) were treated with a medication called flecainide to see how well it could restore normal heart rhythm. The results showed that all the mares returned to a normal heart rhythm within a few days of treatment, but the effectiveness decreased the longer the AF lasted. By day 55, only a couple of the mares responded to the treatment. While flecainide was generally effective for short-term AF, it can cause serious side effects, including abnormal heart rhythms and even cardiac arrest in one horse. Therefore, it should be used carefully under veterinary supervision.
People also search for: horse atrial fibrillation treatment · flecainide for horses · horse heart rhythm problems
Abstract
BACKGROUND: Pharmacological treatment of atrial fibrillation (AF) in horses can be challenging because of low efficacy and adverse effects. Flecainide has been tested with variable efficacy. OBJECTIVE: To test whether the efficacy of flecainide is dependent on AF duration. ANIMALS: Nine Standardbred mares. METHODS: Factorial study design. All horses were instrumented with a pacemaker and assigned to a control or an AF group. On day 0, all horses were in sinus rhythm and received 2 mg/kg flecainide IV. Atrial fibrillation subsequently was induced in the AF group by pacemaker stimulation. On days 3, 9, 27, and 55, flecainide was administered to all horses, regardless of heart rhythm. RESULTS: All horses in AF cardioverted to sinus rhythm on days 3 and 9. On day 27, 5/6 horses cardioverted, whereas only 2/6 cardioverted on day 55. The time from the start of flecainide infusion to cardioversion (range, 3-185 min, log transformed) showed linear correlation with the cumulative duration of AF (r = .80, P < .0001). Flecainide induced abnormal QRS complexes in 4/6 AF horses and 1/3 controls. A positive correlation was found between heart rate before flecainide infusion and number of abnormal QRS complexes (0.14, P < .05). One horse suffered from cardiac arrest and died after flecainide infusion. CONCLUSIONS AND CLINICAL IMPORTANCE: Flecainide is effective for cardioversion of short-term induced AF, but the effect decreases with AF duration. Controlling heart rate may minimize adverse effects caused by flecainide, but the drug should be used with great caution.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/30133839/