Resting energy expenditure in chronic cardiac failure

Abstract

1. Resting energy expenditure has previously been shown to be elevated in the acute phase of heart failure, but the situation in the compensated state of chronic cardiac failure is unclear. Resting energy expenditure was assessed in 14 patients with stable chronic cardiac failure and 14 matched control subjects by using indirect calorimetry. 2. Resting energy expenditure was significantly elevated in the patients with chronic cardiac failure (112.6 ± 18.1 versus 87.1 ± 12.2 kJ day−1 kg−1 total body weight, P < 0.0002; mean ± sd) as were resting O2 consumption (3.88 ± 0.64 versus 3.00 ± 0.43 ml min−1 kg−1, P < 0.0002), ventilation (164 ± 40.3 versus 104 ± 16.2 ml min−1 kg−1, P < 0.0001) and heart rate (85.8 ± 16.9 versus 66.6 ± 6.9 beats/min, P < 0.001). Both the resting plasma concentration of noradrenaline (4.48 ± 1.52 versus 2.28 ± 0.96 nmol/l, P < 0.0001) and the serum concentration of free fatty acids (0.78 ± 0.21 versus 0.57 ± 0.27 mmol/l, P < 0.03) were greater in the patients with chronic cardiac failure. Analysis of covariance indicated that most of the difference in resting energy expenditure could be accounted for by the elevated ventilation in the patients with chronic cardiac failure. Arm muscle area, an index of wasting, was lower in the patients with chronic cardiac failure (39.1 ± 13.1 versus 50.5 ± 9.4 cm2, P < 0.02) and resting energy expenditure was found to account for some of this difference. 3. We conclude that an elevated basal metabolism occurs in chronic cardiac failure. It is associated with excess ventilation, and could be an aetiological factor in the development of cardiac cachexia.