Atrial Conduction Times Change with Progression of Mitral Valve Disease in Dogs
Abstract
This study evaluated electrocardiographic and echocardiographic indices of atrial conduction and electromechanical activation in dogs with myxomatous mitral valve disease and in healthy dogs, and assessed their association with disease stage, cardiac remodeling, heart failure, and supraventricular arrhythmias. A total of 139 small-breed dogs (<15 kg) were included (42 healthy, 50 stage B1, 19 stage B2, and 28 stage C). Atrial electromechanical intervals were measured using tissue Doppler imaging at the lateral mitral, septal mitral, and tricuspid annuli, and electrocardiographic indices including P-wave duration and P-wave dispersion were assessed. Receiver-operating characteristic analysis was performed to evaluate the discriminatory performance of atrial conduction markers. Several electrocardiographic and echocardiographic indices increased across disease stages, with more pronounced differences observed in dogs with advanced disease. A broad range of parameters was associated with cardiac remodeling and heart failure, including P-wave duration across multiple leads and tissue Doppler-derived indices. Among these, P-wave dispersion, septal electromechanical delay (S-PAp), and P-wave duration in selected leads (e.g., lead II and aVF) showed consistent discriminatory performance across outcomes. Dogs with supraventricular arrhythmias showed increased atrial conduction times compared with dogs in sinus rhythm, particularly in electrocardiographic indices and septal electromechanical measurements. Electrocardiographic and echocardiographic indices of atrial conduction provide complementary, non-invasive information on atrial remodeling and electrophysiological alterations in dogs with myxomatous mitral valve disease. In addition, this study establishes reference values for multiple tissue Doppler-derived atrial conduction indices in healthy and myxomatous mitral valve disease–affected dogs. Cite this article as: Vila, B. C. P., & Sousa, M. G. (2026). Atrial conduction times change with progression of mitral valve disease in dogs. Acta Veterinaria Eurasia, 52, 0115, doi: 10.5152/actavet.2026.26115.