Kawasaki disease can affect the heart by causing the following complications:
- Coronary artery aneurysms
- Leakage of valves (often mitral valve regurgitation)
- Accumulation of fluid around the heart (pericardial effusion)
In as many as 15 percent to 25 percent of children with Kawasaki disease, the heart is affected. Aneurysms of the coronary arteries (the blood vessels that supply oxygen to the heart itself) are the most important complication of Kawasaki disease.
In general, if coronary artery changes have not occurred by six weeks after the onset of the illness, the risk of developing the changes is very low.
Depending on the size of the aneurysm, the coronary changes can resolve, remain unchanged, or progress. Patients with large aneurysms are at risk for developing coronary artery clots or stenoses (narrowing) as the aneurysms heal.
It has been reported that in 50 percent of the patients with small coronary aneurysms, the changes resolve during the first year after the illness. Unfortunately, physicians cannot predict which course a patient will take.
What if coronary artery changes occur?
If your child has coronary artery changes, they will require continued cardiology follow-up. Due to the vessel wall irregularity, a coronary artery aneurysm can become a site of blood clot formation. If a large enough blood clot forms, it can cause obstruction to blood flow, and the heart tissue becomes deprived of needed oxygen, and in rare cases, could lead to a heart attack.
Depending upon the size and number of the coronary aneurysms, your child may need to be on medication to prevent blood clotting. If the aneurysms are small and few, the medication will usually be only aspirin taken once a day. If the aneurysms are large (termed "giant aneurysms"), a "blood thinner" such as Coumadin (warfarin) is used.
Children with giant coronary aneurysms will need periodic cardiac catheterization to assess the size of the vessels. Periodic stress / exercise tests are used to assess the heart's ability to obtain adequate oxygen during exertion.
Children with larger coronary artery aneurysms or abnormal stress / exercise tests may require restriction from certain physical activities.