Atrial premature depolarisations five days post electrical cardioversion are related to atrial fibrillation recurrence risk in horses.

Abstract

BACKGROUND: The number of atrial premature depolarisations (APDs) is a known risk factor for atrial fibrillation (AF) recurrence in humans. OBJECTIVES: To evaluate if the number of APDs over a 24-h period 5&#xa0;days post cardioversion predicts AF recurrence within 1&#xa0;year in horses, taking the multifactorial nature of AF into account. STUDY DESIGN: Retrospective case series. METHODS: Eighty horses met these inclusion criteria: first AF episode, no AF recurrence within 5&#xa0;days post cardioversion, cardioversion by transvenous electrical cardioversion (TVEC), 24-h ECG recording and echocardiographic examination 5&#xa0;days post cardioversion, no antiarrhythmic treatment during the ECG recording and follow-up of minimum 1&#xa0;year. To compare the APD burden between the recurrence and non-recurrence group a Mann-Whitney U test was used. A multivariable survival model was built to identify additional risk factors for AF recurrence. RESULTS: The patient population mainly consisted of Warmbloods (93%). Twenty-six horses (33%) experienced AF recurrence within 1&#xa0;year. The number of APDs (median [range]) was significantly higher (P&#xa0;=&#xa0;0.01) in the recurrence group (15 [1-152]) compared with the non-recurrence group (7 [0-304]). In the multivariable survival model, APDs&#xa0;&#x2265;25/24&#xa0;h (hazard ratio [HR] 2.9, 95% confidence interval [CI] 1.2-6.8, P&#xa0;=&#xa0;0.02), mitral regurgitation (HR 8.6, 95% CI 2.6-28.9, P<0.001), left atrial active fractional area change &#x2264;9.6% (HR 2.6, 95% CI 1.0-6.5, P&#xa0;=&#xa0;0.04) and lower body weight (HR 0.99, 95% CI 0.98-0.99, P&#xa0;=&#xa0;0.001) were significantly associated with AF recurrence. MAIN LIMITATIONS: This study did not evaluate early AF recurrence within 5&#xa0;days. The results cannot necessarily be extrapolated to other treatment methods, as only horses converted by TVEC were included. CONCLUSIONS: The APD burden 5&#xa0;days post cardioversion could be a useful predictive value for AF recurrence within 1&#xa0;year in horses. However, other factors such as mitral regurgitation and atrial contractile function must also be taken into account.