Quantification of myocardial blood flow and flow reserve in children with a history of Kawasaki disease and normal coronary arteries using positron emission tomography

Objectives. The purpose of this investigation was to determine whether myocardial blood flow and flow reserve, based on quantitative measurements derived from positron emission tomographic (PET) imaging, would be globally impaired in children with a previous history of Kawasaki disease and normal epicardial coronary arteries. Background. Kawasaki disease is an acute inflammatory process of the arterial walls that results in panvasculitis in early childhood. Children with a history of Kawasaki disease and normal epicardial coronary arteries were previously considered to have normal coronary flow reserve. However, recent studies have reported exercise-induced regional perfusion abnormalities on single photon positron emission tomographic (SPECT) imaging. Methods. We assessed myocardial blood flow and flow reserve at rest and during adenosine stress with nitrogen-13 ammonia and PET in 10 children with a history of Kawasaki disease and in 10 healthy young adult volunteers. All children had acute Kawasaki disease 4 to 15 years before the PET study. None of the children had epicardial coronary artery abnormalities at the acute stage of the disease or during follow-up, as assessed by echocardiography. Results. Rest blood flows normalized to the rate-pressure product, an index of cardiac work, were similar in both the patients with Kawasaki disease and healthy adult volunteers (82 +/- 14 vs. 77 +/- 16 ml/100 g per min [mean +/- SD], p = NS). However, hyperemic blood flows were significantly lower in the patients with Kawasaki disease than in the control subjects (263 +/- 64 vs. 340 +/- 57 ml/100 g per min, p = 0.01), As a result, estimates of myocardial flow reserve were lower in the patients with Kawasaki disease than in the healthy young adult volunteers (3.2 +/- 0.7 vs. 4.6 +/- 0.9, p = 0.003). In addition, total coronary resistance was higher in the patients with Kawasaki disease than in the healthy adult volunteers (33 +/- vs. 24 +/- 5 mm Hg/ml per g per min, p = 0.04). Quantitative analysis of perfusion images demonstrated no evidence of regional perfusion abnormalities. Conclusions. Children with a previous history of Kawasaki disease and normal epicardial coronary arteries exhibit normal rest myocardial blood flows but reduced hyperemic flows and flow reserve. The abnormal hyperemic blood hows and how reserve suggest an impaired vasodilatory capacity, possibly due to residual damage of the coronary microcirculation.