Evaluation of myocardial ischemia in Kawasaki disease by dobutamine stress signal-averaged ventricular late potentials.

OBJECTIVE: To determine the possibility of diagnosing myocardial ischemia from signal-averaged electrocardiographic late potentials (LPs) in patients with Kawasaki disease. METHODS: Dobutamine stress LPs were obtained in 85 children with a history of Kawasaki disease (48 without coronary artery lesions, 19 with coronary artery lesions without myocardial ischemia, and 18 with myocardial ischemia). The infusion of dobutamine was started at 5 micrograms/kg/min, increased to 30 micrograms/kg/min. The presence of LPs was determined by the filtered QRS duration, the root mean square voltage during the last 40 ms, and the duration of the signal under 40 microV. RESULTS: Among the children without coronary lesions, LPs were detected in 4.2% at rest and in 2.1% with dobutamine stress. Among the group with coronary lesions but without ischemia, LPs were found in 5.3% at rest and in 5.3% with stress. In the group with ischemia, LPs were present in 44.4% at rest and in 77.8% with stress. The sensitivity for myocardial ischemia was 72.7% at rest and 87.5% with stress (p < 0.05), and the specificity was 86.5% at rest and 94.2% with stress. CONCLUSION: LPs associated with dobutamine stress testing are useful for identifying myocardial ischemia in children with Kawasaki disease, especially in those who cannot tolerate testing involving physical exercise.

Evaluation of myocardial ischemia and infarction by signal-averaged electrocardiographic late potentials in children with Kawasaki disease.

We investigated myocardial ischemia and old myocardial infarction noninvasively using signal-averaged electrocardiographic late potentials (LPs) in patients with Kawasaki disease. Patients were divided into 4 groups: a noncoronary artery lesion group (n=136), a coronary artery lesion group (without myocardial ischemia and an old myocardial infarction; n=33), an ischemia group (n=16), and an old myocardial infarction group (n=13). Grouping was based on exercise thallium-201 myocardial scintigraphy, thallium-201 myocardial scintigraphy, exercise electrocardiography, coronary angiography, left ventriculography, and echocardiography. Signal-averaged electrocardiograms were recorded using a high-resolution system. Values of filtered QRS duration (f-QRSd), root-mean-square voltage, and duration of low-amplitude signal were judged using our own body surface area-related criteria (n=205) to determine positive rates of LPs and sensitivities and specificities to ischemia and infarction. These data were also interpreted using published criteria for adults and compared with those interpreted by our criteria. Positive rates by our criteria were 0% in the noncoronary artery lesion group, 9.1% in the coronary lesion group, 56.3% in the ischemia group, and 69.2% in the old myocardial infarction group. However, using the criteria for adults, these values were 0%, 3.0%, 25%, and 46.2%, respectively. Sensitivities to ischemia and infarction using our criteria were significantly higher (56.3% and 69.2%) than those using the criteria for adults (p < 0.05). Moreover, specificities to ischemia and infarction were very high (93.4% and 93.5%, respectively) using our criteria, and there were no significant differences from specificities using the criteria for adults. Also, we examined the reproducibility of values of LPs and LP parameters. The values of filtered QRS duration showed a high reproducibility in both LP-positive and -negative groups, followed by low-amplitude signal and then root-mean-square voltage. The results of LP presence or absence showed 100% reproducibility for both the LP-positive and -negative groups, supporting the utility of LPs for clinical applications. Thus, LPs provide useful information in a noninvasive manner for clarifying ischemia and infarction in patients with Kawasaki disease.

Silent myocardial ischemia in Kawasaki disease: evaluation of percutaneous transluminal coronary angioplasty by dobutamine stress testing.

BACKGROUND: Myocardial ischemia and myocardial infarction are the most serious complications of coronary artery lesions in children with Kawasaki disease (KD). Therefore, early detection and treatment of myocardial ischemia in patients with KD is essential. We studied the effectiveness of percutaneous transluminal coronary angioplasty (PTCA) in patients with silent myocardial ischemia detected by dobutamine stress 99mTc myocardial scintigraphy (TMS), body surface mapping (BMS), and signal-averaged ECG late potentials (ELP). METHODS AND RESULTS: Eight of 76 asymptomatic patients with a coronary stenosis >25% and a positive dobutamine stress test were considered to have silent myocardial ischemia. All eight patients had >95% stenoses demonstrated by coronary angiography (CAG) just before PTCA. After PTCA, CAG showed that all of the coronary artery stenoses had been reduced to <50%. Additionally, intravascular ultrasonography (IVUS) performed in five patients before and after PTCA demonstrated adequate dilation of the coronary stenosis after PTCA. All eight patients underwent dobutamine stress TMS, BMS, and ELP 2 to 3 months after PTCA, which demonstrated no regions of myocardial ischemia. Approximately 6 months later, CAG was performed in all eight patients, and only one patient had developed restenosis. CONCLUSIONS: PTCA effectively dilates stenotic coronary arteries in children with KD. Moreover, dobutamine stress TMS, BMS, and ELP are useful for detecting silent myocardial ischemia and estimating the effectiveness of PTCA. Furthermore, IVUS is useful for evaluating the severity of coronary artery lesions before and after PTCA in patients with KD.