CARDIOLOGY
AFib Rate Could Offer Non-Invasive Predictor of Recurrent Arrythmia By Adam Marcus convert to sinus rhythm, and these Noninvasive cardiac testing can horses had higher AFR than did accurately predict which horses the horses that responded successare likely to experience relapses of fully to the drug (383 vs. 351 fpm; atrial fibrillation (AFib) after treatP<0.01), according to the researchment for the arrhythmia, researchers. All but 1 horse that underwent ers found. TVEC successfully achieved norAs with humans, AFib is prevamal sinus rhythm. lent in equids—particularly larger Over the next 6 months, 12% of breeds—affecting as many as 2.5% horses given quinidine, and 34% of of animals, depending on the those that received TVEC, experibreed, and can significantly imenced recurrent atrial fibrillation. pair exercise tolerance. Although Although AFR did not appear to —Dr. Rikke Buhl (above) treatment with drugs and devices predict risk of recurrence in horses can correct the abnormal heart treated with quinidine, the marker rhythm, relapse is common, ocwas strongly associated with relapse curring in as many as about 40% of cases. Predicting in the animals that underwent TVEC, the researchers rewhich animals are most at risk of relapse could help ported. In this group, an AFR above 380 fpm was linked clinicians better manage atrial fibrillation, according with a 2.4-fold greater likelihood of recurrence (95% to Rikke Buhl, DVM, PhD, a professor in the Departconfidence interval 1.2–4.8; P=0.01), they found. ment of Veterinary Clinical Sciences at the University “Horses with high AFR had a higher risk of getof Copenhagen, in Denmark, and the first author of the ting AF again after a successful cardioversion to new study. sinus rhythm,” Dr. Buhl told Modern Equine Vet. One method for predicting relapse that has gained “Therefore, it seems that high AFR had a poor progrecent attention is the atrial fibrillation rate (AFR), nosis for keeping the heart in normal sinus rhythm. which is obtained by surface electrocardiography This can be helpful for the practicing vet as they can (ECG). AFR is thought to reflect electrical remodeling add this value to the other clinical parameters that in the heart. The higher rate of fibrillations per minassist in prognostication.” ute—expressed as the number of waves per minute The researchers noted that the TVEC group in(fpm)—the greater the remodeling. cluded more older, and especially Warmblood animals, For the new study, Dr. Buhl and her colleagues at which are known to be more prone to recurrent AFib institutions in the United States, Europe and Dubai and a higher prevalence of mitral regurgitation. “These sought to learn if AFR could be used to predict relapse factors may increase the complexity of AF and the atria of AFib in 195 horses. Of those, 74 received nasogasbecomes more remodeled. Whether this remodeling tric administration of the drug quinidine, a standard occurred before AF or as a consequence of AF is diftherapy for AFib, and 121 received an intervention ficult to answer,” Dr. Buhl said. called transvenous electrical cardioversion (TVEC), an At the moment, she added, ECG analysis occurs invasive procedure in which 2 catheters are introduced post-processing, but in the future the technology may through a vein in the neck and positioned in the heart, evolve to calculate AFR instantaneously. “That would and the organ is pulsed with electricity until normal siprovide the clinician with information that can assist nus rhythm returns. not only in treatment selection, but also for prognostiOf the animals treated with quinidine, 10 did not cation of the risk of AF recurrence,” she said. MeV
AFib is prevalent in equids.
For more information: Buhl R, Hesselkilde EM, Carstensen H, et al. Atrial fibrillatory rate as predictor of recurrence of atrial fibrillation in horses treated medically or with electrical cardioversion. Equine Vet J. 2021 Dec. 27. https://doi.org/10.1111/evj.13551 https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.13551 14
Issue 3/2022 | ModernEquineVet.com
