Asymptomatic left ventricular dysfunction 48 years after the onset in an adult patient with three-vessel giant aneurysms caused by Kawasaki disease

N-ammonia positron emission tomography findings revealed significant ischemia with a reduced left ventricular ejection fraction (LVEF). The coronary angiograms showed an almost complete occlusion of the right coronary artery (RCA) and localized stenosis of the left anterior descending artery (LAD). The fractional flow reserve (FFR) in the LAD was 0.75. After coronary artery bypass grafting of the RCA and LAD was performed, CLBBB and a low LVEF improved. Although the grafting to the RCA was patent, the graft to the LAD developed a string sign. The progression of localized stenosis in adults continues slowly more than 40 years after the onset of KD. The value of the FFR, which has localized stenosis with giant aneurysms, can be overestimated and should be further investigated. Learning objective: Asymptomatic left ventricular dysfunction with complete left bundle branch block due to a right coronary artery occlusion occurred in an adult patient more than 40 years after the onset of Kawasaki disease. They improved after coronary artery bypass grafting. The value of the flow fraction ratio for localized stenosis with giant aneurysms can be overestimated in this population. Coronary risk factors such as hypertension, dyslipidemia, and diabetes mellitus associated with aging must be avoided.