DispersÃo do intervalo QT na cardite reumÃtica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Despite the French term "acute joint rheumatism" emphasizing the involvement of the joints, it is heart attacks that are the major cause of morbidity and mortality in rheumatic disease. Rheumatic carditis, the only manifestation of the disease that can be lethal in its acute phase and produce permanent sequelae, continues to be quite prevalent in economically less favored countries. The electrocardiogram is a valid method for the clinical diagnosis of cardiac involvement in rheumatic disease. The electrocardiographic findings are many during the course of the disease, but they are not always sufficient for enabling the cardiac component to be recognized. The interest in seeking fresh, more sensitive and specific data by electrocardiography is thus understandable. The dispersion of the QT interval, a likely measurement of the low homogeneity of ventricular repolarization, defined as the difference between the largest and the smallest QT intervals in the twelve leads, has been investigated in a number of studies. The increased dispersion of the QT interval appears to have a major prognostic significance and has proved to be an independent predictor of mortality in patients with acute myocardial infarct and cardiac insufficiency. Up to now, there do not seem to be any studies correlating the dispersion of the QT interval with the presence of rheumatic carditis. In Brazil, especially in the poorer regions, rheumatic disease still represents a public health problem, so the search for new indices of diagnosis, severity and prognosis of the disease is particularly relevant. In the present study a comparison was made of the electrocardiographic features, in particular, the dispersion of the QT interval, in patients with and without rheumatic carditis hospitalized for an initial heart attack at the Federal University of Pernambuco Hospital and the Mother and Child Institute of Pernambuco. Sixty-six children, half of whom had rheumatic carditis, were evaluated from July to December 2003. The children with carditis met the following criteria for inclusion in the study: acute rheumatic carditis according to the Jones criteria and suffering their first attack of carditis.The electrocardiogram was done on the first day of their hospital sojourn. Children on medication and with metabolic disturbances that could alter the dispersion of the QT interval were excluded from the study. In the control group, children suffering from any heart condition were also excluded. The mean age and gender distribution were similar in the two groups studied. The valvular disease most frequently found in the children with carditis was isolated mitral insufficiency and almost half were suffering from cardiac insufficiency. As regards severity, as the two hospitals taking part in the study are reference centers, 66.7% of the cases were classified as moderate or serious. Even with QTc values significantly higher than in the control group (p<0.01), the QTc was normal in 84.4% of the patients with carditis. The dispersion of the QT interval was significantly greater in the group with carditis than in the control group (p<0.0001). No statistical significance was found when an attempt was made to correlate the QT interval dispersion values with the variables cardiothoracic index, severity of the carditis, type of valvular condition encountered and QTc. In accordance with the results, the dispersion of the QT interval appears to have a high specificity and positive predictive value for the presence of carditis. Prospective and controlled studies with a larger number of cases are required to confirm the present findings

ASSUNTO(S)

eletro cardiograma â dispersÃo do intervalo qt medicina cardiologia âcardite reumÃtica

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