The physiological significance of coronary aneurysms in Kawasaki disease

Aims: A coronary aneurysm is one of the most frequent complications of Kawasaki disease, and yet there is little information concerning the haemodynamic abnormality influenced by the existence of a coronary aneurysm. When blood flow passes through an aneurysm, the turbulence that then occurs means that part of the initial energy is lost, and that energy loss could cause a drop in pressure, such as when passing through a stenotic lesion. The aim of this study is to prove the hypothesis that a giant aneurysm haemodynamically acts in a manner similar to that of stenosis. Methods and results: The study population consisted of 47 patients with a simple coronary aneurysm after Kawasaki disease. Fractional flow reserve was measured in 32 coronary aneurysms. The fractional flow reserve in non-giant aneurysms was 0.95 +/- 0.03 and 0.90 +/- 0.03 in giant aneurysms (P=0.0004). Conclusions: The present data demonstrated that the coronary aneurysm could give rise to a small decline of pressure along the artery. Since no aneurysm demonstrated a fractional flow reserve under 0.75, a simple aneurysm would not cause coronary ischaemia by itself. However, it could trigger a coronary ischaemia in case of multiple coronary aneurysms and a coronary aneurysm with mild stenosis.