EVALUATION OF MYOCARDIAL-ISCHEMIA AND INFARCTION BY SIGNAL-AVERAGED ELECTROCARDIOGRAPHIC LATE POTENTIALS IN CHILDREN WITH KAWASAKI-DISEASE

We investigated myocardial ischemia and an old myocardial infarction n oninvasively using signal-averaged electrocardiographic late potential s (LPs) in patients with Kawasaki disease. Patients were divided into 4 groups: a noncoronary artery lesion group (n = 136), a coronary arte ry lesion group (without myocardial ischemia and on old myocardial inf arction; n = 33), an ischemia group (n = 16), and an old myocardial in farction group (n = 13). Grouping was based on exercise thallium-201 m yocardial scintigraphy, thallium-201 myocardial scintigraphy, exercise electrocardiography, coronary angiography, left ventriculography, and echocardiography. Signal-averaged electrocardiograms were recorded us ing 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 d etermine positive rates of LPs and sensitivities and specificities to ischemia and infarction. These data were also interpreted using publis hed criteria for adults and compared with those interpreted by our cri teria. Positive rates by our criteria were 0% in the noncoronary arter y lesion group, 9.1% in the coronary artery lesion group, 56.3% in the ischemia group, and 69.2% in the old myocardial infarction group. How ever, using the criteria for adults, these values were 0%, 3.0%, 25%, and 46.2%, respectively. Sensitivities to ischemia and infarction usin g our criteria were significantly higher (56.3% and 69.2%) than those using the criteria for adults (p < 0.05). Moreover, specificities to i schemia and infarction were very high (93.4% and 93.5%, respectively) using our criteria, and there were no significant differences from spe cificities using the criteria for adults. Also, we examined the reprod ucibility of values of LPs and LP parameters. The values of filtered Q RS duration showed a high reproducibility in both LP-positive and -neg ative groups, followed by low-amplitude signal and then root-mean-squa re voltage. The results of LP presence or absence showed 100% reproduc ibility for both the LP-positive and -negative groups, supporting the utility of LPs for clinical applications, Thus, LPs provide useful inf ormation in a noninvasive manner for clarifying ischemia and infarctio n in patients with Kawasaki disease.