Inspiratory muscle weakness in patients with Chagas heart disease: Echocardiographic and functional predictors

Background

Patients with Chagas heart disease (CHD) usually present progressive fatigue and dyspnea. The inspiratory muscle weakness (IMW) may be a marker of exercise intolerance during disease progression. However, the factors related to IMW in CHD patients still remain unknown.

Methods

Forty-eight CHD patients aged 56.4 (53.3–59.5) years were selected and underwent respiratory muscle strength, echocardiography, Cardiopulmonary Exercise Testing and International Physical Activity Questionnaire (IPAQ). The sample was stratified according to the percentage (%) of maximum inspiratory pressure (MIP) achieved in preserved muscle strength (MIP > 70%) or IMW (MIP ≤ 70%). Chi-square and Poisson regression analysis was performed to verify the predictors of IMW.

Results

The %MIP predicted correlated with left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVDd) and minute ventilation-carbon dioxide production slope (VE/VCO₂ slope). Significant differences in the IPAQ scores (p = 0.036), LVEF (p = 0.020) and VE/VCO₂ slope (p = 0.008) were found between groups with preserved inspiratory muscle strength and with IMW. In multivariate analysis, sedentary patients and those with reduced LVEF and impaired VE/VCO₂ slope had 6.3, 5.5 and 1.2-fold increased risk for IMW, respectively.

Conclusion

The sedentary lifestyle, reduced LVEF and impaired VE/VCO₂ slope showed to be independent predictors of IMW, probably by the association between these variables and the presence of inflammation in CHD patients. The detection of IMW may be helpful in identifying patients at high risk based on echocardiographic and functional aspects without much operating costs.