RESUMO
BACKGROUND: Myocardial dysfunction that complicates the initial stages of chronic kidney disease (CKD) has not been yet fully characterized in young patients. We aimed to assess the clinical usefulness of myocardial performance index obtained by pulsed-wave Doppler method (PWD-MPI) in predicting early disturbances of global left ventricular (LV) function in children with CKD stages 2-4. In addition, we evaluated the clinical utility of tissue Doppler imaging (TDI) as a tool for calculating MPI in comparison with the conventional method. METHODS: Standard echocardiography was performed in 34 patients aged 3-18 years and for 35 age-matched healthy control subjects. PWD-MPI was calculated from Doppler spectra of mitral inflow and LV outflow. To obtain TDI-MPI, time intervals were measured from mitral annulus. RESULTS: The mean values of both PWD-MPI and TDI-MPI of the patients were significantly different from those of the control subjects. Using receiver operating characteristics curve analysis, TDI-MPI yielded a better predictive discrimination for separating patients with versus those without myocardial dysfunction than PWD-MPI. Using a PWD-MPI >0.36 as the cutoff value, myocardial dysfunction was found with a sensitivity of 64.7% and specificity of 97%. The sensitivity and specificity of TDI-MPI >0.34 in identification of LV dysfunction were 91% and 82%, respectively. TDI-MPI was correlated with that measured by PWD (P < 0.004, r = 0.57). CONCLUSIONS: Subtle abnormalities of LV function develop early when renal insufficiency is mild to moderate. MPI, measuring by PWD and TDI, are appropriate indicators of overall LV function in young patients with CKD.