Discussion

Complications of Kawasaki disease range from asymptomatic coronary artery dilatation to large coronary artery aneurysms. These are prone for thrombosis with resultant myocardial infarction and sudden death.^{Reference Newburger, Takahashi and Gerber1} Treatment with intravenous immunoglobulins has resulted in significant decline in its incidence. Myocarditis, pericarditis, and valvular regurgitations culminating in heart failure are also reported sequalae.

Aneurysms occur mostly during the initial phase and predominantly involve the proximal segments of the coronary arteries. Approximately 50% of the aneurysms regress within 5 years of disease onset.^{Reference Gersony2} These aneurysms also develop stenosis over the course. Chronic endothelial shear stress at the site of aneurysm will trigger the transformation of smooth muscle cells to myofibroblasts.^{Reference Tsuda, Kamiya and Ono3,Reference Suzuki, Miyagawa-Tomita and Komatsu4} This causes arterial narrowing.

As per guidelines, all patients diagnosed with Kawasaki disease should undergo serial echocardiography on diagnosis, at 2 and 6 weeks after the onset of the disease. Those with evolving coronary artery abnormalities should undergo echocardiography twice/week until the lesions have stopped progressing.^{Reference Dallaire and Dahdah5} Children may not exhibit typical features of myocardial ischemia. Hence, they should be carefully monitored and thromboprophylaxis should be judiciously administered. Those with giant aneurysms (>8 mm) should be subjected to coronary angiography to identify stenotic lesions. An extensive collateral supply to distal part of right coronary artery in our patient was probably due to chronic stenosis and occlusion.

Flow stasis in large aneurysms forms the pathophysiological basis of thrombus formation, and hence oral anticoagulation with warfarin should be given to patients with giant aneurysms. Revascularisation is not indicated in an acute phase of the illness. Aneurysms usually do not rupture and surgical plication of the aneurysm has not been fruitful and has even caused catastrophic complications and death. Revascularisation is indicated in the chronic phase if there are symptoms of ischemia or if more than 10% of left ventricular myocardium is ischemic. Coronary artery bypass grafting appears to be superior to percutaneous coronary intervention.^{Reference McCrindle, Rowley and Newburger6} Long-term outcome of coronary artery bypass grafting in Kawasaki disease is not known.^{Reference Holve, Patel and Chau7} As our patient was asymptomatic without left ventricular dysfunction, we decided to treat him conservatively with warfarin and aspirin.

This report shows different morphological spectrums of Kawasaki disease in different coronary arteries in the same patient. This report emphasises the fact that all patients of Kawasaki disease with large aneurysms should be meticulously maintained on aspirin and anticoagulation to prevent myocardial ischemia. Aneurysms are prone for thrombosis due to shear endothelial stress. Acute thrombotic occlusion results in myocardial infarction and rarely sudden cardiac death.