An exercise tissue Doppler and strain rate imaging study of diastolic myocardial dysfunction after Kawasaki syndrome in childhood

OBJECTIVE: Myocardial dysfunction due to coronary arterial lesions is an important complication after Kawasaki syndrome in childhood. Tissue Doppler echocardiography, and strain rate imaging, have shown their value in detecting regional myocardial dysfunction in coronary arterial disease. We aimed to examine the diagnostic value of these methods in patients with coronary arterial lesions after Kawasaki syndrome. METHODS: We assessed regional myocardial function in 17 asymptomatic patients with coronary arterial lesions. Follow-up coronary angiographies were available in all cases. Tissue Doppler echocardiography, and strain rate imaging, were performed at rest and during bicycle exercise. Examination included peak systolic and diastolic velocities, peak systolic strain and strain rate. We enrolled 17 age- and gender-matched persons to serve as a control group. RESULTS: Segmental left ventricular longitudinal function did not significantly differ between the groups with respect to peak systolic velocity, strain, and strain rate. Diastolic abnormalities were identified in segments supplied by coronary arteries with stenotic lesions. Peak diastolic velocity decreased significantly during exercise in those areas, from 77 plus or minus 34 to 59 plus or minus 56 millimetres per second, p smaller than 0.05. Under exercise, a peak diastolic velocity value under 90 millimetres per second enabled us to identify coronary arterial stenosis with a sensitivity of 75 percent and specificity of 64 percent. CONCLUSIONS: After Kawasaki syndrome, diastolic impairment develops in segments supplied by stenotic coronary arteries before systolic dysfunction is detectable. Exercise tissue Doppler echocardiography has the potential to detect these subtle abnormalities, and help monitor progression of the disease.