The Role of Inspiratory Muscle Strength in Functional Capacity and Left Atrial Strain in Patients With Heart Failure With Mildly Reduced and Preserved Ejection Fraction

OBJECTIVES: This study aimed to explore the correlation among inspiratory muscle strength, left atrial strain reservoir (LAsr), and functional capacity in patients with heart failure with preserved and mildly reduced ejection fractions (HFpEF and HFmrEF). METHODS: ), six-minute walk distance (6MWD), and LAsr. RESULTS: (β = 0.07, 95% CI: 0.02-0.14, p = 0.044) and 6MWD (β = 1.14, 95% CI: 0.04-2.23, p = 0.043). While univariate analysis showed a meaningful correlation between MIP and LArs (r = 0.364, p = 0.021), this was not notable in the multivariable model (β = 0.09, 95% CI: -0.05-0.24, p = 0.181). CONCLUSIONS: MIP is a significant predictor of exercise capacity in HFpEF and HFmrEF; however, its relationship with LAsr was influenced by confounding factors. It is essential to address inspiratory muscle weakness for effective management of patients with HFpEF and HFmrEF. TRIAL REGISTRATION: This trial was registered in the Thai Clinical Trials Registry (https://www.thaiclinicaltrials.org/) under the trial ID TCTR20231121001.