Repolarization abnormalities in children with a structurally normal heart and ventricular ectopy

Prognostic Significance of QT Interval Dispersion in the Response to Intravenous Immunoglobulin Therapy in Kawasaki Disease

BACKGROUND

Kawasaki disease (KD) is classified as a systemic vasculitis syndrome and QT interval dispersion (QTD) has been associated with cardiac involvement and disease activity in patients with cardiovasculitis. We examined whether baseline QTD could predict a response to intravenous immunoglobulin (IVIG) in KD.Methods and Results:QTD was recorded in 86 patients with KD before IVIG, who were separated into IVIG responders (R group; n=62) and nonresponders (N group; n=24). The association between baseline QTD and response to IVIG was investigated, and the predictive response value was compared with conventional risk scores from Gunma and Kurume universities. Baseline-corrected QTDs with Bazett's (QTbcD) and Fridericia's (QTfcD) formulae were significantly increased in the N group (R group vs. N group: 31.6 [28.3, 44.0] ms vs. 66.6 [50.5, 76.3] ms and 27.4 [25.2, 39.1] ms vs. 55.2 [42.4, 66.3] ms, respectively, both P<0.001). Multiple logistic regression analysis revealed QTfcD as an independent predictor of a response to IVIG after adjustment for conventional scores (odds ratio: 1.133, 95% confidence interval: 1.061-1.210, P<0.001). Moreover, QTfcD provided incremental predictive value for IVIG nonresponders over Gunma score (increment in global χ²=25.46, P<0.001).

CONCLUSIONS

QTD was significantly associated with a response to IVIG in KD patients and may represent a useful identifier of IVIG nonresponders with high risk of coronary aneurysm.

Ventricular repolarisation during exercise challenge occurring late after Kawasaki disease

Exercise testing can highlight repolarisation abnormalities in adults with coronary artery disease. Late after Kawasaki disease (KD), increased QT dispersion (QTd) has been reported on resting ECG in children, but there are no reported studies of QTd during exercise. Our objective was to determine the pattern of QTd response to exercise testing in children late after KD. Twenty-five KD patients without coronary complications, 28 with coronary dilation, and 18 with severe complications were compared with 28 controls. KD patients were 11.6 ± 3.0 years old versus 12.8 ± 2.9 for controls [p = not significant (NS)], and these patients were studied 7.5 ± 3.4 years after the onset of the disease. QT was measured from the onset of QRS to the apex (QTa) and the end (QTe) of T wave. Resting QTd was significantly increased in KD subjects (p < 0.05). The proportion of abnormal QTd was evenly distributed across the three KD groups (29-36%; p = NS). QTd response to exercise was significantly altered in KD, irrespective of resting QTd or coronary sequelae. Abnormal resting- and exercise-induced repolarisation are detectible after KD irrespective of the severity of coronary sequelae.

Increased pretransplant QT dispersion as a risk factor for the development of cardiac complications during and after preparative conditioning for pediatric allogeneic hematopoietic stem cell transplantation

Although cardiac complications are some of the most serious complications of HSCT for leukemia, it is difficult to predict them. QTD has been reported as a predictor of heart failure and fatal arrhythmia in adults. The purpose of this study is to examine whether QTD predicts cardiac complications in pediatric HSCT. Eighteen patients (mean age, 6.9 yr; 11 ALL and seven AML) underwent high-dose cyclophosphamide treatment and total body irradiation as preparative conditioning for HSCT. QTD, QTcD, echocardiographic functional parameters, and cumulative anthracycline dose were evaluated. We compared these values between patients with and without cardiac complications. Among 18 patients, seven patients experienced cardiac complications (heart failure in four, arrhythmia in three). There were significant differences in QTD (43.7 ms in patients with cardiac complications vs. 30.2 ms in patients without the complications, p = 0.019) and QTcD (55.3 vs. 36.9 ms, p = 0.003) between the two groups. On the other hand, the cumulative dose of anthracycline and echocardiographic parameters were not significantly different between the two groups. Increases in QTD and QTcD during the pretreatment period may be risk factors for the development of cardiac complications during and after conditioning for pediatric HSCT.