Fatores determinantes da capacidade funcional na insuficiência cardíaca de etiologia chagásica e não chagásica

Abstract

INTRODUCTION: Heart failure (HF) is a growing public health problem in Brazil and in the world, being characterized by early signs of dyspnea, fatigue and significant limitation to physical efforts. The cardiac mechanisms involved in the reduction of exercise capacity are controversial. In the population with non-chagasic HF (NCH-HF), previous studies suggest that cardiac function, especially left ventricular ejection fraction (LVEF), does not show relevant association with functional status. However, given the peculiarities of HF of Chagas Disease etiology (CH-HF), recent studies suggest that the determining factors for the functional capacity of these subjects may involve cardiac function and morphology. OBJECTIVE: To identify the determinants of functional capacity in HF of Chagas and non-Chagas etiology. METHODS: Observational study involving 178 patients with HF who underwent clinical examination, cardiopulmonary exercise testing (CPET) and echocardiogram as part of the standard clinical evaluation. The sample was divided into Chagas HF (CH-HF, n=101) and non-Chagas (NCH-HF=77). Correlation analysis and multivariate linear regression were performed to identify independent predictors associated with VO2peak in the different groups. According to the predictors found, the prediction formula for the estimated VO2 was elaborated. The significance level of 5%. RESULTS: There were no statistical differences between the groups in terms of age (56.2±13.4 vs 55.1±11.7 years, p=0.58) and gender proportion (56 (55.4) vs 45 (44.5), p=0.69).When compared to the NCH-HF group, the CH-HF group had a lower BMI (25.7±4.6 vs 29.5±5 Kg/m, p< 0.001), higher VO2peak (16.8±6.1 vs 13.8±4.3ml/Kg/min, p<0.001) and left ventricular ejection fraction (LVEF, 42.6±18 vs 28.9±9.7%, p<0.001). Regarding the NYHA functional classification, the CH-HF group presented class I (40%), II (30%), III (28%) and IV (3%). The NCH-HF group presented class III (38%), II (30%) and I (9%), with no subjects in class IV. There were no statistical differences in terms of age (p=0.58) and in the proportion between men and women (p=0.69). In the CH-HF group, VO2peak was significantly correlated with age, male gender, functional class (NYHA-FC), LVEF, left atrial (LA) diameter, LV diastolic diameter, LV mass index, and E wave (p<0.05). In the multivariate analysis of this group, only age, male gender, LVEF and E wave remained associated with VO2peak with adjusted R2= 0.67, p<0.0001. In the NCH-HF group, VO2peak was associated with age, gender, NYHA-FC and LA diameter. In the multivariate analysis, only male gender, NYHA-FC and LA diameter remained associated with VO2peak (adjusted R2= 0.27, p<0.0001). In patients who were able to assess pulmonary artery systolic pressure (PASP) and tricuspid annular plane systolic excursion (TAPSE), a significant correlation between VO2peak and PASP was observed in the CH-HF group (r=0.60, p <0.001) while VO2peak was correlated with TAPSE (r=0.57, p=0.02) in the NCH-HF group. CONCLUSION: In patients with HF from Chagas etiology, gender, LV systolic and diastolic function, as well as pulmonary hypertension predict functional capacity. Conversely, in patients with HF from other etiology, sex, NYHA-FC, left atrial diameter and right ventricular systolic function seem to have a lesser impact on functional capacity.