When two Z-scores meet-analysis of exercise capacity of children and adolescents with Kawasaki disease by a new Z-score model of coronary artery and a new Z-score evaluating peak oxygen consumption

Background Coronary artery (CA) Z-score system is widely used to define CA aneurysm (CAA). Children and adolescents after acute stage of Kawasaki disease (KD-CA) have a higher risk of developing CAAs if their CA Z-score >= 2.5. Z-score system of peak oxygen consumption (Peak VO2 Z-score) allows comparisons across ages and sex, regardless of body size and puberty. We aimed to compare the exercise capacity (EC) indicated by peak VO2 Z-score during cardiopulmonary exercise testing (CPET) directly between KD-CA with different CA Z-score.Methods KD-CA after acute stage who received CPET in the last 5 years were retrospectively recruited. CA Z-score was based on Lambda-Mu-Sigma method. Max-Z was the maximum CA Z-score of different CAs. KD children with Max-Z < 2.5 and >= 2.5 were defined as KD-1 and KD-2 groups, respectively. Peak VO2 Z-score was calculated using the equation established based on Hong Kong Chinese children and adolescent database.Results One hundred two KD-CA were recruited (mean age: 11.71 +/- 2.57 years). The mean percent of measured peak VO2 to predicted value (peak PD%) was 90.11 +/- 13.33. All basic characteristics and baseline pulmonary function indices were comparable between KD-1 (n = 87) and KD-2 (n = 15). KD-1 had significantly higher peak VO2 Z-score (p = .025), peak PD% (p = .008), peak metabolic equivalent (p = .027), and peak rate pressure product (p = .036) than KD-2.Conclusions KD-CA had slightly reduced EC than healthy peers. KD-CA with Max-Z >= 2.5 had significantly lower peak EC than those < 2.5. Max-Z is potentially useful follow-up indicator after acute stage of KD.

Automated summary

The study compared the exercise capacity as indicated by peak VO2 Z-score during CPET between KD-CA patients with different CA Z-scores. The results showed that KD-CA patients had slightly reduced exercise capacity compared to healthy peers, and KD-CA patients with CA Z-score >= 2.5 had significantly lower peak exercise capacity than those with CA Z-score <2.5. Max-Z could potentially serve as a useful follow-up indicator after the acute stage of KD.