Avaliação da prevalência de potenciais tardios identificados no eletrocardiograma de alta resolução em pacientes com doença de Chagas

Abstract

The World Health Organization estimates 8 million people infected worldwide; an estimated 10,000 deaths per year from clinical complications related to Chagas´ disease. Approximately 30% of the cases have evolved to cardiac form; the main clinical presentations are ventricular arrhythmia, heart failure and sudden death. Objective: Taking into account the importance of ventricular arrhythmias as predictors of sudden death, this study aims at evaluating the association between the late potentials identified in Signal-Averaged Electrocardiogram with the presence of non-sustained ventricular tachycardia in 24-Holter monitoring, reduced left ventricular ejection fraction or with other prognostic variables in Chagas' disease. Casuistic and Method: Cross-sectional retrospective study by means of medical chart analysis of chagasic patients who performed DMS® Holter in the sector of graphic methods of Hospital de Base between the periods of September/2012 and December/2015, whose Holter recording presented the module of research of late potentials through the Signal-Averaged Electrocardiogram. The patients were divided into two groups for comparison based on the late potential variable (present or absent). The Chi-Square test was used for comparisons between noncontinuous variables and the T test of independent samples for comparisons between the means of two groups for continuous variables. In the continuous variables that have not presented normal distribution, the Mann-Whitney test was used for comparison between the median of the two groups. The variables that presented association with the late potential variable in the univariate analysis with a p-value of ≤ 0.05 were entered the Binary Logistic Regression model, using the "forward" method for the selection of stepwise variables in which the variables are inserted sequentially in the model. The significance level considered was p ≤ 0.05. The IBM SPSS Statistics software was used for statistical analysis. Results: Considering the inclusion and exclusion criteria, 49 patients were selected for the sample. In the univariate analyses, the variables right branch block, left atrium diameter, left ventricular systolic diameter and left ventricular ejection fraction were predictors of late potentials (p-value ≤ 0.05). These variables were included in the Binary Logistic Regression model using the "forward" method, remaining the right branch block and left atrium diameter variables as independent predictors of the presence of late potential. Conclusion: In the present study there was no association of the presence of late potential in the signal-averaged electrocardiogram with the presence of ventricular arrhythmia in the Holter 24 hours or reduced left ventricle ejection fraction.