Differences in skeletal muscle between men and women with chronic heart failure

Men with chronic heart failure (CHF) have alterations in their skeletal muscle that are partially responsible for a decreased exercise tolerance. The purpose of this study was to investigate whether skeletal muscle alterations in women with CHF are similar to those observed in men and if these alterations are related to exercise intolerance. Twenty-five men and thirteen women with CHF performed a maximal exercise test for evaluation of peak oxygen consumption ((V) over dotO(2)) and resting left ventricular ejection fraction, after which a biopsy of the vastus lateralis was performed. Twenty-one normal subjects (11 women, 10 men) were also studied. The relationship between muscle markers and peak (V) over dotO(2) was consistent for CHF men and women. When controlling for gender, analysis showed that oxidative enzymes and capillary density are the best predictors of peak (V) over dotO(2). These results indicate that aerobically matched CHF men and women have no differences in skeletal muscle biochemistry and histology. However, when CHF groups were separated by peak exercise capacity of 4.5 metabolic equivalents (METs), CHF men with peak (V) over dotO(2) >4.5 METs had increased citrate synthase and 8-hydroxyacyl-CoA dehydrogenase compared with CHF men with peak (V) over dotO(2) <4.5 METs. CHF men with a lower peak ire, had increased capillary density compared with men with higher peak (V) over dotO(2). These observations were not reproduced in CHF women. This suggests that differences may exist in how skeletal muscle adapts to decreasing peak (V) over dotO(2) in patients with CHF.