What is most likely to happen in patients with advanced Kawasaki's disease without treatment?

In patients with advanced Kawasaki's disease that is left untreated, the most likely outcome is the development of coronary artery aneurysms. Kawasaki disease is a vasculitis that primarily affects children and can lead to inflammation of the coronary arteries. As the disease progresses, the resulting inflammation can cause damage to the arterial walls, leading to dilation and the formation of aneurysms.

This is particularly concerning because aneurysms in the coronary arteries can increase the risk of thrombosis, myocardial infarction, or ischemic heart disease in affected individuals later in life. The condition necessitates close monitoring and often treatment to mitigate these serious risks. In contrast, while other options may have some association with cardiac function, they are not direct outcomes of advanced Kawasaki disease. For instance, while reduced blood pressure might be seen in some cardiac conditions, it is not a hallmark of Kawasaki's disease complications. Similarly, heart chamber dilation and increased cardiac output are roles more commonly associated with chronic heart failure or volume overload situations, rather than specifically being a direct complication of Kawasaki disease itself.