Atrial Fibrillation Cycle Length and Atrial Size in Horses with and without Recurrence of Atrial Fibrillation after Electrical Cardioversion

Abstract

BackgroundAtrial fibrillation (AF) cycle length (CL) and atrial size have been used in humans to characterize electrical and structural remodeling to predict outcome of cardioversion of AF and risk for AF recurrence (rAF).HypothesisAtrial fibrillation cycle length can be determined in horses with AF, and AFCL and atrial size are related to risk for rAF.AnimalsEighteen horses with naturally occurring AF that were successfully converted to sinus rhythm (SR) by transvenous electrical cardioversion (TVEC).MethodsProspective study. Horses with severe valvular regurgitation, left atrial enlargement, or that required sedation for catheter placement were excluded. In all horses intra‐atrial electrograms were recorded and estimated AF duration and echocardiographic parameters were determined before TVEC. The follow‐up time was 1 year after TVEC.ResultsAtrial fibrillation cycle length could be determined in all horses. The AFCL and the shortest 5th percentile (p5) AFCL in horses with rAF (n = 6 or 33%) were (mean ± SD) 157 ± 28 and 134 ± 24 milliseconds, respectively, and in those maintaining SR (n = 12 or 67%) 166 ± 13 and 141 ± 13 milliseconds, respectively. Significant parameters to predict rAF were (1) the ratios of the p5AFCL to the left atrium (LA) sizes corrected to the size of aorta (AO) and (2) LA sizes corrected to the size of AO.Conclusions and Clinical ImportanceBefore TVEC, assessment of LA size and atrial electrophysiologic characteristics might help to identify horses at increased risk for AF recurrence.

Reversed patent ductus arteriosus and multiple congenital malformations in an 8‐day‐old Arabo‐Friesian foal

“…The left atrium (LA) to aortic root (Ao) ratio in our foal was increased to 2.42 (reference value in adult horses: 1.04 ± 0.12; De Clercq et al . ), which confirmed left atrial dilation. Increases in left atrial volume and pressure may result in lung oedema.…”

Pharmacokinetics and electrophysiological effects of sotalol hydrochloride in horses

“…AF induces electrical remodelling leading to AF stabilisation, both in human subjects and in horses [13,31]. However, if sotalol is to be used to suppress arrhythmias or to prevent AF recurrence, its effects might be different compared with healthy animals.…”

Atrial Fibrillation: Mechanisms, Therapeutics, and Future Directions

“…Reentrant circuits form more readily with larger atrial size, potentially due to the additional area available for rotor formation as demonstrated in computer modeling studies (278). Animal models (50, 123, 165), as well as clinical data support this idea (51,95,153). Atrial size may also indirectly affect tissue properties, since it can be a sign of increased atrial stretch, which is generally associated with increased tissue remodeling in the atria (108).…”