Application of signal-averaged electrocardiogram to myocardial damage in the late stage of Kawasaki disease

IL-1-dependent electrophysiological changes and cardiac neural remodeling in a mouse model of Kawasaki disease vasculitis

Kawasaki disease (KD) is the leading cause of acquired heart disease in children. In addition to coronary artery abnormalities, aneurysms and myocarditis, acute KD is also associated with echocardiogram (ECG) abnormalities in 40-80% of patients. Here, we show that these ECG changes are recapitulated in the Lactobacillus casei cell wall extract (LCWE)-induced KD vasculitis mouse model. LCWE-injected mice developed elevated heart rate and decreased R wave amplitude, with significant differences in prolonged ventricular repolarization. LCWE-injected mice developed cardiac ganglion inflammation, that may affect the impulse-conducting system in the myocardium. Furthermore, serum nerve growth factor (NGF) was significantly elevated in LCWE-injected mice, similar to children with KD vasculitis, associated with increased neural remodeling of the myocardium. ECG abnormalities were prevented by blocking interleukin (IL)-1 signaling with anakinra, and the increase in serum NGF and cardiac neural remodeling were similarly blocked in Il1r1-/- mice and in wild-type mice treated with anakinra. Thus, similar to clinical KD, the LCWE-induced KD vasculitis mouse model also exhibits electrophysiological abnormalities and cardiac neuronal remodeling, and these changes can be prevented by blocking IL-1 signaling. These data support the acceleration of anti-IL-1 therapy trials to benefit KD patients.

Electrocardiographic Analysis of Repolarization Changes in South Indian Children with Kawasaki Disease after the Acute Phase of Illness

Background

Cardiac involvement in children with Kawasaki disease (KD) may present with repolarization abnormalities which are associated with increased risk of ventricular arrhythmias and sudden cardiac events.

Methods

Twenty children with history of KD without cardiac involvement in the acute phase were recruited along with age and sex-matched controls. Twelve-lead ECG was obtained from both groups using CARDIART 610T ECG system at 25 mm/sec and 50 mm/sec paper speed. ECG was repeated in 19 children in the study group after 9 ± 2 months. Measurements (QT dispersion (QTd), T-wave peak to end (Tp-Te) interval, and Tp-Te/QT ratio) were made using standard digital calipers. Statistical analysis was performed with student t-test and analysis of variance (ANOVA) using SSPS version 17.0.

Results

The mean value of QTd in the first ECG in cases was significantly high: 43.15 ± 14.13 versus 29.47 ± 8.637 in the controls (p = 0.001). The follow-up ECG in 19 cases showed a mean value of 46.26 ± 16.25 versus 43.89 + −14.53 at baseline (p = 0.440). QTd was increased in the follow-up ECG but was not statistically significant. There was no statistical significance seen in the Tp-Te interval and Tp-Te/Qt ratio as observed in Lead II and Lead V5.

Conclusion

Significant increase in the QTd in children with KD indicates repolarization changes in the myocardium even in the absence of clinical carditis. The persistence of this change on follow-up could indicate a possible increased risk for ventricular arrhythmia and warrants long term assessment of the cardiovascular status.

Mid-term Risk for Subclinical Atherosclerosis and Chronic Myocarditis in Children with Kawasaki Disease and Transient Coronary Abnormalities

There is evidence for premature atherosclerosis and systemic arterial stiffening during follow-up of children with Kawasaki disease (KD) and coronary artery abnormalities (CAA). Moreover, patients with KD may also have subclinical myocardial involvement and inhomogeneous ventricular repolarization. The inhomogeneous ventricular repolarization manifests as increased QT dispersion on electrocardiography. There is a paucity of studies in endothelial dysfunction and QT dispersion in children with KD and transient CAA. Twenty children with KD and transient CAA were studied at least 1 year after resolution of CAA. Mean follow-up period between KD onset and enrolment in the study was 53.7 months. Twenty age and sex-matched controls were enrolled. High-resolution B-mode ultrasonography was used to analyze brachial artery dilatation in response to reactive hyperemia (cases and controls) and sublingual nitroglycerine (cases only). Carotid artery intima-media thickness (cIMT) and stiffness index were calculated. The difference between maximum and minimum QTc intervals on 12 lead electrocardiogram was calculated as QTc dispersion (QTcd). No statistically significant difference was noted in percent flow-mediated dilatation of brachial arteries in response to reactive hyperemia between cases (13.31 ± 10.41%) and controls (12.86 ± 7.09%). Sublingual nitroglycerine-mediated dilatation in children with KD was 14.88 ± 12.03%. Mean cIMT was similar in cases (0.036 ± 0.015 cm) and controls (0.035 ± 0.076 cm; p = 0.791). No statistically significant difference between groups was observed in mean QTcd values (0.057 ± 0.018 s vs. 0.059 ± 0.015 s in controls, p = 0.785). No evidence of significant endothelial dysfunction or increased QT dispersion in patients with KD and transient coronary artery abnormalities was found in our cohort when studied at a mean follow-up of 53.7 months. This is reassuring, and indicates that risk of subclinical atherosclerosis and myocarditis in a subset of children with KD and transient coronary artery abnormalities is not significant.

Biopsy-proven myocardial sequels in Kawasaki disease with giant coronary aneurysms

BACKGROUND

Although most Kawasaki disease with giant coronary aneurysms is asymptomatic, conventional investigations might not identify previous lesions, or all Kawasaki disease with giant aneurysms at risk of future myocardial lesions. We evaluated the long-term histopathology of the myocardium, especially of intramural small vessels in asymptomatic Kawasaki disease with giant aneurysms.

METHOD

The initial study comprised 16 consecutive Kawasaki patients - male-to-female ratio was 12:4 - aged from 2 to 12 years, and in the subsequent study, the same patients were aged from 4.9 to 16 years. Endomyocardial biopsies were histopathologically evaluated. Microangiopathies, mitochondrial abnormalities, and loss or disarray of myofibrils were compared by electron microscopy.

RESULTS

The incidence of histopathological abnormalities such as degeneration, hypertrophy, and inflammatory cell infiltration was quite high in the initial study, and inflammatory cell infiltration, interstitial fibrosis, and disarray were very noticeable at follow-up biopsies. The area of fibrous tissue was significantly higher in patients administered with intravenous immunoglobulin at follow-up biopsies. Electron microscopy showed microangiopathies including microthrombi within intramural small vessels in some patients at follow-up biopsies. The sites of the coronary aneurysms did not seem to have an impact on the biopsy findings, suggesting that the underlying pathophysiology is related to the original disease process.

CONCLUSIONS

Whether the abnormalities were due to direct myocardial injury, chronic ischaemia, repeated small-vessel thrombosis, or other problems associated only with biopsies, is difficult to determine. However, this subgroup had residual abnormal lesions in the myocardium. Follow-up should be more aggressive in this group of patients to identify myocardial damage that could be asymptomatic.

QT interval dispersion in North Indian children with Kawasaki disease without overt coronary artery abnormalities

Increased QT interval dispersion has been associated with an increased risk for ventricular arrhythmias and sudden cardiac events. We examined the QT interval dispersion in 20 North Indian children with Kawasaki disease (KD) with no coronary artery abnormalities on echocardiography compared the same with matched controls. The study population consisted of 20 children in convalescent phase of KD and 20 age and sex-matched healthy controls. Intervals were measured with the use of a digital caliper with least count of 0.01 mm by a single blinded observer. The QTc dispersion was calculated as the difference between the maximum and minimum corrected QT intervals in 12 and 8 leads (i.e. the 6 precordial leads, the shortest extremity lead, and the median of the 5 other extremity leads). Of the 480 leads obtained (12 per subject), 36 were excluded from analysis (15 because of poor T wave formation and 11 because of presence of U waves). Children with KD had significantly higher QTc dispersion in 12 lead (67.08 ± 17.72 ms compared to 47.63 ± 16.48 ms in controls P ≤ 0.001) as well as 8 lead (60.51 ± 18.54 ms compared to 42.92 ± 18.03 ms in controls P ≤ 0.001) analysis. There was no correlation between delay in IVIG therapy and QT interval dispersion. In conclusion, QT interval dispersion is significantly increased in North Indian children with KD. The dispersion is indicative of inhomogenous ventricular repolarization and may represent increased risk for developing ventricular arrhythmia in this population.

Natriuretic peptide as an adjunctive diagnostic test in the acute phase of Kawasaki disease

Coronary arteritis rather than myocardial involvement is typically emphasized in Kawasaki disease (KD). Moreover, the criteria and the usual biological markers oversee the importance of cardiac-specific markers in diagnosing this disease. We sought to study the clinical usefulness of measuring B-type natriuretic peptide (BNP) and its N-terminal moiety (NT-proBNP) at the onset of KD. Our objective was to evaluate blood concentrations of BNP and NT-proBNP during the acute and subacute phases of KD. We conducted a prospective study comparing newly diagnosed KD patients to non-KD febrile controls. Blood specimens were collected at presentation, 6-12 h after intravenous immunoglobulin (IVIG) therapy, 1-2 weeks later, and 2-3 months later, or only upon reenrollment for controls. Forty-there KD and 19 control patients were enrolled consecutively. The mean age was 47.1 +/- 34.3 and 62.2 +/- 44.9 months, respectively (p = NS). Pre-IVIG NT-proBNP levels were significantly higher in KD patients than in controls (923.6 +/- 1361.7 vs. 186.2 +/- 198.0 ng/L; p < 0.001), with no statistical difference for BNP (141.9 +/- 227.5 vs. 59.9 +/- 72.4 ng/L; p = 0.112). In conclusion, our data indicate that NT-proBNP is a better marker of myocardial involvement in acute KD than BNP, particularly in cases with incomplete diagnostic criteria, and suggest that it may be a valid adjunctive diagnostic method to support the diagnosis of KD.