Heart failure associated with chronic Chagas cardiomyopathy increases the risk of impaired lung function and reduced submaximal functional capacity

•Heart failure of Chagas cardiomyopathy can lead to a decline in lung function.•The 6MST is a promising tool for assess submaximal capacity in heart failure.•Lung function assessment is necessary to support exercise prescription. With the evolution of chronic Chagas cardiomyopathy (CC) and the progression towards heart failure (HF), patients may show a decline in inspiratory muscle strength, lung function, and functional capacity. We compared respiratory function and submaximal functional capacity in patients with CC with versus without HF. This observational, cross-sectional study was carried out with CC patients divided into CCG, a group without HF (n = 28), and HFG, a group with HF (n = 27). Spirometry (percent predicted forced vital capacity (ppFVC), forced expiratory volume in one second of FVC (ppFEV1), forced expiratory flow between 25 % and 75 % of FVC (ppFEF25–75%), and maximum voluntary ventilation (ppMVV)) and submaximal functional capacity (six-minute step test: 6MST) were evaluated. Mann-Whitney (comparison of pulmonary function and functional capacity between groups) and linear regression (association between the presence of HF and other variables) were performed. We included 55 participants, with median age of 67 years (56.25–71.75) and 54.55 % males. Dyslipidemia was the most recurrent comorbidity (49.09 %). HFG presented lower ppFVC (P = 0.000), ppFEV1 (P = 0.011), ppFEF25–75% (P = 0.017), and ppMVV (P = 0.003) than the CCG. The ppFVC (B = -18.95; P = 0.000), ppFEV1 (B = -16.29; P = 0.021), ppFEF25–75% (B = -19.57; P = 0.014), ppMVV (B = -16.59; P = 0.003), and 6MST (B = -17.13; P = 0.034) were negatively associated with the presence of HF. Our data suggest that impaired lung function, compatible with a restrictive pulmonary pattern, is present among adults with CC and HF.