Risk Factors for Atrial Fibrillation in the Dog: A Systematic Review

Simple Summary Atrial fibrillation (AF) is the most common supraventricular arrhythmia in dogs and can lead to a severe decline in the cardiac function. In the last decade, an increased burden of clinical articles has been published that evaluated different aspects of AF in dogs with cardiac disease, particularly in animals affected by myxomatous mitral valve disease (MMVD) and dilated cardiomyopathy (DCM). In this study, we aimed to determine the risk factors for AF in the dog. Therefore, we performed a comprehensive systematic review and critical evaluation of the veterinary literature that reports the risk factors for the development of AF in the dog following the Prisma 2020 guidelines. High bodyweight and left atrial enlargement emerged as predominant risk factors for AF development in dogs with cardiac diseases. Importantly, distinct risk factors for AF were identified between dogs with MMVD and those with DCM (e.g., presence of congestive heart failure in dogs with MMVD but not in those with DCM), highlighting the nuanced nature of AF etiology in different canine cardiac conditions. Furthermore, significant differences in risk factors were observed between dogs and humans. In particular, advanced age and male sex are not reliable indicators of an increased risk of AF in dogs. Abstract Different risk factors for atrial fibrillation (AF) development have been identified in numerous studies on humans, but this information is less clearly available on the dog. The aim of this systematic review is to determine the risk factors for AF in the dog. Following the PRISMA 2020 guidelines, we conducted a comprehensive search using the Web of Science and Scopus databases for articles reporting on cases of spontaneously occurring AF in dogs. The level of evidence was assessed using the Evidence Quality Grading System of the National Institute of Health. One thousand forty-three studies were initially identified, and twenty of them were included in this systematic review involving 2,359,275 dogs, of which 4807 showed spontaneously occurring AF. Genetics, for the Irish Wolfhound, increased body weight, and left atrial enlargement were the main risk factors for the development of AF in dogs with different cardiac diseases, particularly myxomatous mitral valve disease (MMVD) and dilated cardiomyopathy (DCM). However, some differences were found between these two cardiac diseases regarding additional risk factors. In particular, the presence of congestive heart failure and echocardiographic evidence of increased left atrial pressure or the presence of right atrial enlargement emerged as risk factors in dogs with MMVD or DCM, respectively. Furthermore, significant differences in risk factors were observed between dogs and humans. In particular, advanced age and male sex are not reliable indicators of an increased risk of AF in dogs.