Immune activation plays an important role in the progression of chronic heart failure (CHF). We sought to investigate whether different degrees of tumor necrosis factor-alpha (TNF-alpha) activation are associated with exercise intolerance, neurohormonal activation and alterations in muscle mass and function in patients with CHF without cardiac cachexia. Patients were divided into quartiles according to their TNF levels (first quartile: 0.98-4.90 pg/ml, second quartile: 5.00-6.60 pg/ml; third quartile 6.80-9.00 pg/ml; fourth quartile 9.80-32.00 pg/ml). Patients underwent cardiopulmonary exercise testing, quadriceps muscle strength test, quadriceps fatigue test, and assessment of thigh muscle and fat cross-sectional area (CSA) by computerized tomography scanning. Patients in the highest TNF quartile had the lowest peak oxygen consumption [13.1 (+/-4.1) ml/kg/min vs 18.1 (+/-5.3), 18.8 (+/-4.8) and 18.7 (+/-5.6) ml/kg/min, P<0.01] the greatest relation of ventilation and dioxide production (VE/VCO(2)) slope (P<0.05) and the most elevated catecholamine levels (P<0.05) compared to patients in the first three quartiles. Patients with the lowest TNF levels had preserved thigh muscle size and quadriceps strength. Strength/muscle CSA was similar in the four groups. Muscle strength during fatigue testing was significantly lower in the fourth quartile (P=0.01) compared with the other three groups. In CHF patients only the highest levels of TNF are associated with poor functional status and neurohormonal activation. This group of patients may represent the appropriate target population for TNF antagonism.
Copyright 2001 Academic Press.