The accuracy of respiratory muscle strength in identifying systolic dysfunction in patients with Chagas cardiomyopathy

Purpose To verify the accuracy of respiratory muscle strength in identifying systolic dysfunction in patients with Chagas cardiomyopathy (ChC), and to validate optimal cutoff points based on respiratory muscle strength.Methods First, 72 patients with ChC were enrolled and underwent echocardiography and assessment of respiratory muscle strength by manovacuometry. Inspiratory and expiratory muscle strength was defined by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), respectively. Systolic dysfunction was defined by left ventricular ejection fraction (LVEF) values below 52% (for men) or 54% (for women). Then, the validation of the cutoff points was verified by the percentage of true and false positives in another 30 ChC patients.Results The MIP showed adequate accuracy (p = 0.004) in identifying patients with systolic dysfunction (AUC = 0.73). The MEP did not show satisfactory accuracy in identifying those patients. The optimal MIP cutoff point to identify systolic dysfunction in ChC was ≤62 cmH2O, with a positive predictive value of 87%. In the validation analysis, MIP values below 62 cmH2O were able to identify 77% of patients with systolic dysfunction.Conclusion MIP has potential value in identifying systolic dysfunction in patients with ChC. This finding may aid in screening and risk stratification when echocardiography is not available.