RESUMO
AIMS: Right ventricular (RV) dysfunction is an important factor on effort tolerance in cardiopulmonary diseases. Nevertheless, the role of RV function in predicting exercise capacity in patients with Chagas disease has not been reported. This study aims to evaluate whether RV function assessed by tissue Doppler can predict functional capacity in patients with Chagas heart disease. METHODS AND RESULTS: We evaluated 65 patients (48.6 +/- 9.1 years, 60% men) with Chagas heart disease. Standard and tissue Doppler echocardiography were performed before maximal exercise testing. Tissue Doppler imaging (TDI) was used to measure RV peak annular systolic and diastolic velocities. Exercise testing was performed using a standard Bruce protocol. Linear regression analysis was used to determine multivariate peak oxygen consumption (VO(2)) predictors. All patients were in NYHA functional class I or II. Mean peak VO(2) was 32.4 +/- 10.2 mL/kg/min and mean LV ejection fraction was 43 +/- 11%. There was correlation between TDI RV peak systolic velocity and LV ejection fraction (r = 0.5; P < 0.001). In a multivariate analysis, after adjustment for age and gender, RV function emerged as an independent predictor of functional capacity, as demonstrated in the model: peak VO(2) (r = 0.71) was: 42.22-(9.77 x female gender)-(0.29 x age) + (1.54 x RV systolic velocity). CONCLUSION: In this cross-sectional study, RV function was an important, independent determinant of exercise capacity in patients with Chagas heart disease. TDI RV systolic annular velocity was most closely associated with peak VO(2), regardless of the influence of age, gender, and other echocardiographic parameters.
