Impact of cardiac structure and function on exercise intolerance in Chagas cardiomyopathy: Insights from CPET and echocardiography

Introduction: Chronic Chagas cardiomyopathy (CCC), the most severe clinical condition of Chagas disease, often leads to a reduction in functional capacity and the appearance of symptoms such as fatigue and dyspnea on exertion. However, its determinant factors remain unclear. We aimed to evaluate the peak oxygen consumption (VO2peak) in patients with CCC and identify its determining factors. Methods: An observational study with 97 CCC patients was conducted. Patients underwent clinical examination, cardiopulmonary exercise test (CPET), and echocardiography as part of the standard clinical evaluation. Multivariate linear regression was used to identify independent clinical and echocardiographic predictors of VO2peak and percentage of predicted VO2. Results: Mean age of study patients was 55.9 +/- 13.4 years, median left ventricle ejection fraction (LVEF) was 40 (26-61.5) % and median VO2peak was 16.1 (12.1-20.8) ml/Kg/min. 36 patients presented preserved LVEF and 61 presented reduced LVEF. There were significant differences in almost all CPET variables (p < 0.05) between these two groups. VO2peak was associated with age, male sex, NYHA functional class, LVEF, left atrium diameter, LV diastolic diameter, E wave, LV mass index, and pulmonary artery systolic pressure (PASP). Age, male sex, LVEF, and E wave remained independently associated with VO2peak in the multivariate analysis (R-2 = 0.69), furthermore, only LVEF and E wave were associated with the predicted VO2 percentage (R-2 = 0.53). Conclusion: In patients with CCC, disease severity, male sex, LV systolic and diastolic function influence the functional capacity.