Myocardial strain and strain rate in Kawasaki disease

Abstract

We sought to determine whether velocity vector imaging (VVI)-derived left ventricular (LV) myocardial deformation indices could detect subtle myocardial abnormalities in acute Kawasaki disease (KD). The study cohort of children with KD was divided by coronary artery dilation (CAD, Z-score >2.5) and/or uncomplicated vs. treatment-resistant (persistent/recrudescent fever) cases and compared with age-matched controls. Peak systolic LV myocardial strain (ε) and strain rate (SR) were obtained using VVI on pre-treatment echocardiograms. Comparisons were made between controls and (i) the entire KD group, (ii) KD group subdivided by CAD, and (iii) KD group subdivided by treatment resistance. The KD group consisted of 32 children (66% male, 24 ± 20 months). Of these, 17 had CAD and 14 had resistant KD. The control group consisted of 22 children (55% male, 20 ± 17 months). Routine echo indices of LV systolic function were normal for both groups. Compared with controls, KD patients had lower global longitudinal ε (-15.29 vs. -12.94, P = 0.04) and SR (-1.12 vs. -0.87, P = 0.003). On subgroup analysis compared with controls, KD patients with CAD (n = 17) had lower longitudinal ε (-15.29 vs. -11.87, P = 0.02) and SR (-1.12 vs. -0.86, P = 0.005). Subdivided by treatment resistance, compared with controls, those with resistant KD had lower longitudinal ε (-15.29 vs. -11.8, P = 0.01) and SR (-1.12 vs. -0.82, P = 0.003). Despite normal LV systolic function by routine echocardiographic measurements, KD patients have reduced longitudinal LV ε and SR, which may be more sensitive indicators of myocardial inflammation and may provide supportive criteria to avoid delayed diagnosis of KD.