Inspiratory muscle weakness in cardiovascular diseases: Implications for cardiac rehabilitation

Exercise limitation is a cardinalmanifestation of many cardiovascular diseases (CVD) and is associated with poor prognosis. It is increasingly well understood that exercise-based cardiac rehabilitation (CR) is an intervention that portends favorable clinical outcomes, including improvements in exercise capacity. The etiology of exercise limitation in CVD ismultifactorial but is typically governed by terminal sensations of pain, fatigue, and/or breathlessness. A known but perhaps underestimated complication of CVD that contributes to breathlessness and exercise intolerance in such patients is inspiratory muscle dysfunction. For example, inspiratory muscle dysfunction, which encompasses a loss in muscle mass and/or pressure generating capacity, occurs in up to similar to 40% of patients with chronic heart failure and is associatedwith breathlessness, exertional intolerance, and worse survival in this patient population. In this review, we define inspiratory muscle weakness, detail its prevalence in a range of CVDs, and discuss how inspiratory weakness impacts physiological function and clinical outcomes in patients with CVD often referred to CR. We also evaluate the available evidence addressing the effects of exercise-based CR with and without concurrent specific inspiratory muscle training (IMT) on inspiratory muscle function, general physiological function, and clinical outcomes in patients with CVD. Finally, we consider whether the assessment of global respiratory muscle function should become standard as part of the patient intake assessment for phase II CR programs, giving practical guidance on the implementation of such measures as well as IMT as part of phase II CR. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Exercise limitation is a common manifestation of cardiovascular diseases and can be improved through exercise-based cardiac rehabilitation. Inspiratory muscle dysfunction is a underestimated complication of cardiovascular diseases that contributes to breathlessness and exercise intolerance. This review explores the prevalence of inspiratory muscle weakness, its impact on physiological function and clinical outcomes, and evaluates the effects of exercise-based cardiac rehabilitation on inspiratory muscle function in patients with cardiovascular diseases. The assessment of global respiratory muscle function and implementation of inspiratory muscle training are recommended for phase II cardiac rehabilitation programs.