Descriptive Values and Diagnostic Utility of a 13-Lead Electrocardiographic System in Healthy Cats and Cats with Cardiac or Non-Cardiac Disease

Surface electrocardiogram including peripheral limb and precordial leads has shown clinical utility in humans and dogs, but it is rarely employed in cats. This prospective single-center study aimed to evaluate a 13-lead electrocardiographic system including six peripheral limb and seven precordial leads in a group of healthy cats and cats with cardiac and non-cardiac diseases. To obtain 13 leads, after two minutes of simultaneous recording of the first 12 leads, one lead was moved in another position, and two additional minutes were recorded. The aim was to report descriptive values for several electrocardiographic variables from healthy cats and to test the exploratory diagnostic value to identify diseased status. A total of 125 cats with sinus rhythm were enrolled and grouped as healthy (H, n = 40), cardiac disease (CaD, n = 57) or non-cardiac disease without cardiac involvement (NCD, n = 28). Diagnostic work-up included echocardiography for every cat and different additional diagnostic tests based on the clinical need. Cats were mildly restrained in right lateral recumbency, and peripheral limb and precordial leads were positioned according to an adjusted Wilson system. In total 141 electrocardiographic variables were measured by one operator blinded to group allocation. Descriptive values were obtained from the H group. P wave amplitude was generally higher in peripheral limb leads compared to precordial leads. Thirty-five variables differed between H and CaD on pairwise comparison, while no variable differed between H and NCD. On multivariable logistic regression analysis, R wave amplitude in lead II, aVL, and V6, P wave amplitude in V8, and age were useful in identifying cardiac disease in this cohort. The same variables, without age but including R wave amplitude in V8, were also able to discriminate between H cats and cats with hypertrophic cardiomyopathy phenotype. In our population of cats with sinus rhythm, 13-lead electrocardiogram allowed differentiating H cats from those with CaD and with hypertrophic cardiomyopathy but not from cats with NCD. Descriptive values are provided for different variables.