Kawasaki disease can affect the heart by causing the following complications:
- Coronary artery aneurysms (or ballooning of the arteries)
- Leakage of valves (often mitral valve regurgitation)
- Build-up of fluid around the heart (pericardial effusion)
Kawasaki disease is the leading cause of acquired heart disease in children. In as many as 25 percent of children with Kawasaki disease, the heart becomes affected without proper treatment. Aneurysms of the coronary arteries, the blood vessels that supply oxygen to the heart itself, are the most important complication of Kawasaki disease. With appropriate and timely treatment, the risk of coronary artery involvement decreases to around 5 percent.
In general, if coronary artery changes have not occurred by six to eight weeks after the onset of the illness, the risk of developing these changes is very low.
If a coronary aneurysm develops, the presence of long-term coronary artery changes depends on the size of the aneurysm – the coronary artery changes can resolve, remain unchanged, or progress. Patients with large aneurysms are at risk for developing coronary artery clots or stenosis (narrowing) as the aneurysms heal.
It has been reported that in half of the patients with small coronary aneurysms, the changes resolve during the first year following the illness. Unfortunately, doctors cannot predict which course a patient will take.
Regardless of coronary artery involvement, your child will need to see a pediatric cardiologist through childhood and often into adulthood. Cincinnati Children’s Heart Institute has a Coronary Artery Clinic that specializes in this patient population.
What if coronary artery changes occur?
Due to the vessel wall irregularity, a coronary artery aneurysm can become a site of blood clot. If a large enough blood clot forms, it can block the 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 medicine to prevent blood clotting. If the aneurysms are small and few, the medicine 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 check the size of the vessels. Periodic stress / exercise tests are used to check the heart’s ability to get enough oxygen during exertion.
Children with larger coronary artery aneurysms or abnormal stress / exercise tests may have restrictions from certain physical activities.