Abstract 2341: Myocardial Ultrasound Tissue Characterisation in Children after Kawasaki disease

Abstract

Background: Reports of late follow-up of patients with Kawasaki Disease (KD), even with no epicardial coronary artery disease, have demonstrated abnormal vascular reactivity and myocardial perfusion. Left ventricular (LV) function is usually normal in KD patients during long-term follow-up. However, data regarding the myocardial properties of these children are lacking. Ultrasound tissue characterization (UTC), under some circumstances, appears to be predictive of subsequent development of myocardial dysfunction. Methods and Results: We performed UTC analysis in 22 asymptomatic KD patients, mean age 6.6±3.4 years, 17 males, with a mean follow-up of 4.8±3.4 years after the illness. Coronary aneurysms were present in 8 patients (mean age 7.8±5.3 years). Cyclic variation of integrated backscatter (cvIBS) and calibrated integrated backscatter (cIBS) were assessed in 16 LV myocardial segments. Tissue Doppler imaging (TDI) at the mitral annulus was performed to assess LV diastolic function. All UTC and TDI data were compared to 22 age-matched controls, mean age 6.6±3.4 years. All patients had normal LV systolic function and wall motion score index (WMSI) compared to controls (EF 60.3±4.0% vs 60.8±4.4%, p=0.64, WMSI 1 vs 1, p=NS respectively). Myocardial velocities in systole and diastole by TDI did not differ significantly between patients and controls. CvIBS and cIBS mean values showed significant differences, for all segments sampled, between patients and controls (7.8±0.8 dB vs 8.9±0.6 dB, p<0.001, and 28.6±3.2 dB vs 25.2±1.0 dB p< 0.001 respectively). Neither cvIBS nor cIBS differed significantly between patients with and without aneurysms (7.9±0.8 dB vs 7.8±0.8 dB, p=0.84, and 30.3±4.3 dB vs 27.7±2.3 dB, p=0.20 respectively). Conclusions: We detected widespread differences in myocardial physical properties between KD patients and controls late after the acute disease, despite normal LV function and independent of demonstrable coronary abnormalities. These differences could be related to cellular damage induced by occult myocardial ischemia or could represent abnormalities of small myocardial vessels. Further studies are needed to confirm these findings in a larger group of patients and to determine the clinical significance.