Variabilidade interobservador e entre ciclos cardíacos na avaliação eletrocargiográfica de cães

Abstract

The electrocardiogram represents the graphic record of the phases of the cardiac cycle, indicating the depolarization and repolarization of the myocardium and is mainly used for the diagnosis of arrhythmias or conduction disorders. However, the reliability of the results can be influenced by the level of experience of the evaluators. Due to the possibility of variation in the results of the same electrocardiographic exam between cardiac cycles and between analyzers with different levels of experience, the study aimed to evaluate the interobserver and between cardiac cycles variability during the evaluation of electrocardiographic exams in dogs. The research was conducted retrospectively at the University Hospital Veterinary Unit Superintendence of the Federal University of Fronteira Sul, Campus Realeza – PR. For the electrocardiographic analysis, exams of 50 dogs were randomly selected, recorded in computerized files during the period from September 2018 to December 2019, regardless of breed, sex, age and weight. Recordings were performed by a multichannel computerized electrocardiograph, representing increased bipolar and unipolar leads, frequency, in beats per minute, and heart rate, wave measurements, in milliseconds and millivolts, and mean atrial and ventricular axes, were evaluated. Data were analyzed using the Shapiro-Wilk normality test, with parametric data analyzed by analysis of variance followed by Tukey's test and nonparametric data by the Kruskal-Wallis test, followed by the Dunn's test. As a last step, the data were submitted to the Kappa Coefficient of Concordance Test. Two hypotheses were investigated, namely that there is a difference between the measurement of one or the average of three cardiac cycles and that there is a difference between different levels of degrees of experience in the electrocardiographic assessment. Variability was evidenced in the interpretation of heart rhythms with disagreement by both low and intermediate level raters, difference in the maximum heart rate by the low level of experience rater who underestimated the values, obtaining a median of 105, while the high one level obtained a median of 122 (p=0.0100). Furthermore, there was an overestimation of the P wave duration by the low and intermediate level evaluators, who found medians of 52 and 51 respectively, while the high level had a median of 48 (p=0.0064). Regarding different cardiac cycles, there were no differences between the analysis of just one cycle in relation to three cycles or the average of three cycles, therefore, the assessment of a cardiac cycle can represent the mean of cardiac cycles in the electrocardiographic record of dogs. Through this study, it was possible to evidence the variability in the interpretation between evaluators with different levels of experience, especially in relation to the duration of the P wave, in which the evaluators overestimated the values and in relation to the degrees of agreement that did not represent the experience levels of the evaluators in the analysis of all variables, emphasizing the importance of training and routine electrocardiographic tests to avoid misinterpretation and analysis.