Muscle strength in relation to disease severity in patients with congestive heart failure

Abstract

Objective: Indices of exercise capacity such as peak oxygen uptake (VO2peak) and muscle strength are important in association with reduced mortality. The present study compared differences in VO2peak and muscle strength indices (grip strength and knee extensor and flexor muscle strength) with disease severity and investigated the relation of these variables in congestive heart failure (CHF) patients.

Design: The study comprised 102 patients with stable CHF (93 men, age 61.4 +/- 10.2 yrs) with left ventricular ejection fraction (LVEF) <40% by echocardiography. We used New York Heart Association (NYHA) functional class to index disease severity. VO2peak, grip strength, knee extensor, and flexor muscle strength were determined. Patients were divided into three groups by NYHA class: class I (n = 39), class II (n = 49), and class III (n = 14).

Results: Age, sex, and LVEF did not differ according to NYHA class. VO2peak and all muscle strength indices decreased with increases in NYHA class (P < 0.05). VO2peak correlated positively with all muscle strengths (P < 0.05). Stepwise linear regression analysis revealed that grip and knee extensor strength were important in predicting VO2peak.

Conclusions: Exercise capacity and disease severity in CHF patients may be influenced not only by lower-limb but also upper-limb muscle strength.