Inspiratory Muscle Weakness is Associated With Exercise Intolerance in Patients With Heart Failure With Preserved Ejection Fraction: A Preliminary Study.
BACKGROUND
The relationship between inspiratory muscle weakness (IMW) and exercise intolerance in patients with heart failure with preserved ejection fraction (HFpEF) remains unestablished.


RESULTS
The present study enrolled 40 patients with HFpEF (EF ≥45%). IMW was defined as maximum inspiratory pressure <70% normal predicted values. The function of the diaphragm was assessed by means of ultrasound measurement of muscle thickening of the diaphragm. IMW was prevalent in 27.5% of patients. Patients with IMW had significantly lower vital capacity relative to normal predicted values (%VC), lower knee extensor muscle strength in relation to body weight (%KEMS), poorer nutritional status as assessed by means of the Geriatric Nutritional Risk Index, and shorter 6-minute walk distance (6MWD) compared with patients without IMW (all P < .05). Impaired diaphragm muscle thickening at end-inspiration (median value < 3.9 mm) was significantly associated with a high prevalence of IMW and reduced 6MWD (all P < .05). Subgroup analysis showed that IMW was accompanied by a further decrease in 6MWD in patients with restrictive pulmonary dysfunction (%VC <80%) or lower-limb muscle weakness (median %KEMS <30%; all P < .05).


CONCLUSIONS
IMW is associated with exercise intolerance in patients with HFpEF.
Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan.
Kensaku
K
Yamada
Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan. Electronic address: ykinugasa-circ@umin.ac.jp.
Yoshiharu
Y
Kinugasa
Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan.
Takeshi
T
Sota
Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan.
Mari
M
Miyagi
Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan.
Shinobu
S
Sugihara
Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan.
Masahiko
M
Kato
Division of Cardiovascular Medicine, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan.
Kazuhiro
K
Yamamoto
D000368:Aged; D000369:Aged, 80 and over; D003964:Diaphragm / Q000000981:diagnostic imaging / Q000503:physiopathology*; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology*; D009752:Nutritional Status; D012129:Respiratory Function Tests; D013318:Stroke Volume; D014463:Ultrasonography
Exercise intolerance; diaphragm; skeletal muscle