Correlation between Macruz Index and left atrial enlargement in dogs with myxomatous mitral valve disease

The Macruz Index is a simple electrocardiographic methodology indicated in the evaluation of possible left atrial remodeling in human medicine. In dogs, the main cause of left atrial remodeling is mitral valve myxomatous degeneration, a degenerative valvulopathy with high occurrence in the routine of the veterinary clinic. Thus, the objective was to determine the values of the Macruz Index and correlate them with the echocardiographic variable left atrium/aorta ratio in dogs with valvulopathy. For this, 11 healthy dogs, male and female, aged between 2 and 8 years, weighing up to 10 kg were selected; together with 60 dogs with mitral valve myxomatous degeneration, small breed and ages 7 to 17 years, which were subdivided into groups according to the class of congestive heart failure - B1 (n=20), B2 (n=20) and C (n=20). All dogs in the present study underwent clinical cardiological, electrocardiographic and echocardiographic evaluation in order to obtain the values of the Macruz Index and the left atrium/aorta ratio. The results showed a significant difference (p<0.05) between the values of the Macruz Index of healthy dogs compared to the groups of dogs with the studied valvular disease (class B2 and C1). However, its correlation with the values of the left atrium/aorta ratio obtained in dogs with mitral valve myxomatous degeneration according to the congestive heart failure classes was low, positive and not statistically significant. Thus, we can conclude that the Macruz Index suggests left atrial remodeling in dogs with mitral valve myxomatous degeneration compared to healthy dogs. However, it does not correlate or evidence progressive left atrial remodeling between classes of congestive heart failure.