Kawasaki disease (KD) is an acute, self-limiting, febrile illness that occurs predominantly in children with pathology demonstrating vasculitis of small and medium size blood vessels with a predilection for coronary arteries [
Myocardial damage results in altered electrical potential distributions and repolarization changes manifesting as prolonged Qt dispersion and electrophysiological changes in T-waves [
T peak is a marker of epicardial repolarization while T end is believed to represent completion of repolarization of the mid-myocardial cells. The interval between T peak and T end provides a measure of transmural dispersion of repolarization which can be used as a tool for detection of life threatening arrhythmias [
Only a few studies have demonstrated these repolarization changes after the acute phase of illness. The long term impact on myocardial electrical stability after KD is not well understood especially in children with no cardiac involvement during the acute phase. So a prospective cohort study was conducted on 20 children with history of KD for the analysis of repolarization changes on ECG.
A hospital-based prospective study was conducted at a tertiary care centre between October 2014 and September 2016. Children with history of KD diagnosed at least 3 months prior were included in the study. Patients who fulfilled the inclusion criteria were recruited into the study after getting clearance from the institutional ethics committee. Informed consent was obtained from either of the parents of the child and a semistructured proforma was prepared to record all data.
A 12-lead ECG was obtained from each subject after a period of 5 minutes of rest using CARDIART 6108T ECG system at 25 mm/sec and 50 mm/sec paper speed. Measurements were made manually using STANDARD DIGITAL CALIPERS (AEROSPACE, China). The following variables were measured using the calipers Qt dispersion (QTd): defined as the difference between maximum and minimum QT interval of a 12-lead ECG. T peak to T end (Tpe) interval: the peak of the T-wave as defined as a point of highest amplitude of the T-wave deflection and the end as a point where the tangent on descending limb of T-wave intersects the isoelectric line. T peak to T end/QT(Tpe/QT) ratio.
ECGs with low amplitude or unreliable T-waves and U waves were excluded from analysis. The mean QTd were calculated from all the 12 leads in the study group and compared with the control group. Tpe and Tpe/QT ratio were measured in one of the limb leads (II) and chest leads (V5) and the mean calculated values were compared between the groups.
Blood pressure was recorded for all the children included in the study using a standard mercury sphygmomanometer with appropriate cuff size. A repeat ECG was obtained from the study group after a period of
ECG was interpreted with the guidance of a cardiologist with fellowship in cardiac electrophysiology and a 2D ECHO was performed on all children with history of KD by the same cardiologist to look for coronary artery abnormalities. Out of the 696 leads obtained, 71 leads had to be excluded from analysis because of the poor T-wave formation and presence of U waves.
Collected data were analyzed using statistical package for social sciences (SPSS) version 17.0. The data was presented as mean and standard deviations. Statistical analysis for difference in mean value was performed using student
In children with history of Kawasaki disease, QT dispersion is significantly increased compared to the control group. The mean value of QTd in the first ECG in children with KD was
The follow-up ECG also showed similar result with a mean value of
Comparison of mean QTd in children with KD with controls
Comparison of mean in children with KD with follow-up ECG
Comparison of mean T peak to T end interval (Lead II)
Comparison of mean T peak to T end interval (Lead V5)
Comparison of mean T peak to T end/QT (Lead II)
Comparison of mean T peak to T end/QT (Lead V5)
There was no statistical significance observed in the Tp-Te interval in cases when compared to controls, Lead II (
Kawasaki disease (KD) is an acute, self-limiting, febrile illness that occurs predominantly in children with pathology demonstrating vasculitis of small and medium size blood vessels with a predilection for coronary arteries. It is complicated by either clinical or subclinical myocarditis in the acute stage and can lead to histological changes of the myocardium such as interstitial fibrosis.
We attempted to study the hypothesis that, in children with KD without overt coronary artery involvement, myocardial abnormalities may persist even after acute phase which is reflected on surface ECG as repolarization changes. The study was conducted on 20 children with history of typical KD without coronary artery involvement in the acute phase and treated with 2 g/kg of IVIG within 10 days of onset of illness (diagnosed based on American Heart Association (AHA) criteria) and an equal number of age and sex-matched controls.
QT interval dispersion (QTd) represents a general abnormality in repolarization. Increased QT dispersion has been demonstrated in various cardiac diseases. Data obtained from almost 7000 patients with cardiac disorders like myocardial infarction, cardiomyopathies, and long QT syndrome have shown that there is definite evidence of increased QT dispersion in these cardiac disorders [
Our study showed significant difference in the QT dispersion in children with KD when compared to the control group. The follow-up ECG which was done
In the year 1999, a study was conducted by Osada et al. [
Three years later Dahdah et al. [
In 2008, Ghelani et al. [
Similarly, in 2014, Gupta et al. conducted a study on a cohort including 30 children with history of KD and measured QTd. Though it was not the main objective of the study they have concluded that study population showed increased QTd when compared to the control group.
Recently a study conducted by Parihar et al. [
Apart from QT dispersion, we have also studied the ventricular repolarization changes, namely, T peak to T end interval and T peak to T end/QT ratio. These variables have been used extensively in predicting the arrhythmic risk in various cardiac disorders like myocardial infarction, hypertrophic cardiomyopathy, and pulmonary embolism (PE) [
Evidence supporting these parameters as a prognostic tool in forecasting the risk of arrhythmias have been provided under congenital and acquired long Qt, hypertrophic cardiomyopathy, and Brugada syndrome [
In a study done by Abdullah Icli et al. [
The ratio between the Tpe interval and QT interval (Tpe/QT) has been proposed as a noninvasive marker of arrhythmic risk along with Tpe interval, while QT interval and Tpe interval vary with various body sizes Tpe/QT remains relatively constant. It was also reported to be stable with varied heart rates [
There is evidence of repolarization changes in the myocardium in children with history of KD without cardiac involvement in acute stage even after treatment with IVIG/Aspirin in recommended doses. This cohort may be at risk of developing long term complications like arrhythmias. This cohort requires long term assessment and follow-up to identify the risk of myocardial dysfunction. Further studies are warranted on a larger sample size to identify the significance of these repolarization parameters in forecasting the arrhythmic risk.
The data used to support the findings of this study are available from the corresponding author upon request.
An earlier version of this work was presented at Indian Rheumatology Association Conference “IRACON” 2016.
The authors declare that there are no conflicts of interest regarding the publication of this paper.