Abstract 13852: Key Value of Inspiratory Muscle Performance and Training in a Home-Based Program to Improve Functional Capacity in Older Heart Failure Patients

Abstract

Introduction: Patients with heart failure (HF) often have reduced exercise tolerance. Exercise training has putative value but is often limited by poor adherence or the effects of frailty. Baseline inspiratory muscle performance (IMP) may predict exercise limitation, and inspiratory muscle training (IMT) may have important clinical benefit, including offsetting the metaboreflex which may improve functional capacity by reducing sympathetic peripheral vasoconstriction induced by respiratory fatigue. We hypothesize that low IMP is an important predictor of exercise performance in older adults with HF and that IMT may be an effective home-based training program. Methods: Thirty-four male patients with HF (age and left ventricular ejection fraction of 69±7 years and 37±11%, respectively) were randomized into IMT (n=11) or aerobic and/or strength training (AST; n=23) for a 12-week home-based program. IMT was performed progressively from 50-85% of maximal inspiratory pressure (MIP) with the PrO 2 device (Smithfield, RI) which tracked data and adherence for comparison to AST regimens of cycle ergometry/walking and strength training individually advanced to achieve moderate to high intensities. Study endpoints included MIP, peak oxygen uptake (VO 2 ), 6-minute walk distance (6MWD), 30-second sit-to-stand (STS), grip strength, and leg strength (endurance, 1-rep max, and power). Results: IMT was well-tolerated with greater adherence (92±10% vs 79±34%) and a significantly greater MIP rise (25.3±25.0% vs 3.6±11.0%, p<0.05). Baseline MIP greater than the median of 66 cmH 2 O across all exercise forms (n=18) was associated with significantly greater baseline and post-intervention peak VO 2 (16.4±5.0 vs 12.9±3.9 and 17.5±5.3 vs 13.4±3.1, p<0.05) and was significantly correlated positively to change in 6MWD, STS, grip strength, and leg strength (r=0.352-0.504, p<0.05). Conclusion: Home-based IMT significantly improved IMP and greater baseline IMP was associated with greater cardiorespiratory fitness, functional capacity, and trainability in older HF patients due likely to metaboreflex attenuation and greater adherence. Further study is needed to assess IMP and IMT performed alone or combined with AST regimens to address the growing HF population.