Autonomic function in Kawasaki disease with myocardial infarction: Usefulness of monitoring heart rate variability

BACKGROUND: Despite anticoagulant therapy, many patients with Kawasaki disease and giant coronary artery aneurysm develop myocardial infarction. These patients have a high risk of sudden death, but the etiology is not clear. We studied autonomic function and the possibility of malignant ventricular arrhythmia through heart rate variability. METHODS: We studied six Kawasaki disease patients with myocardial infarction and 16 normal controls. Heart rate variability was investigated using a 24 h electrocardiogram. We assessed the standard deviation from the mean of the normal R-R intervals (SDNN), the proportion of adjacent R-R intervals with a difference greater than 50 msec (pNN50) and the root-mean square of successive R-R differences as time-domain analysis (rMSSD). We assessed very low-frequency power, low-frequency power (LF), high-frequency power (HF) and the LF/HF ratio in frequency-domain analysis. RESULTS: There was no significant difference in SDNN, but there was a significant difference in pNN50 and rMSSD. Patients with Kawasaki disease showed lower HF and higher LF/HF than normal controls. CONCLUSION: Our findings suggest that patients with Kawasaki disease and myocardial infarction show decreased vagal activity, which could cause malignant arrhythmia.