Final answer:
The primary concern following Kawasaki disease is coronary aneurysm.
Step-by-step explanation:
The primary concern following Kawasaki disease is coronary aneurysm. Kawasaki disease is an acute febrile illness that predominantly affects children under the age of 5. It is characterized by inflammation of the blood vessels throughout the body, including the coronary arteries. If left untreated, Kawasaki disease can lead to the development of coronary aneurysms, which are abnormal dilations or bulges in the walls of the coronary arteries. These aneurysms pose a risk for blood clots and can potentially lead to heart attacks or other complications.