Insights into the pathogenesis of chronic heart failure: immune activation and cachexia

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Abstract
Body wasting, ie, cardiac cachexia, is a complication of chronic heart failure (CHF). The authors have suggested that cardiac cachexia should be diagnosed when nonedematous weight loss of more than 7.5% of the premorbid normal weight occurs over a time period of more than 6 months. In an unselected CHF outpatient population, 16% of patients were found to be cachectic. The cachectic state is predictive of poor survival independently of age, functional class, ejection fraction, and exercise capacity. Patients with cardiac cachexia suffer from a general loss of fat, lean, and bone tissue. Cachectic CHF patients are weaker and fatigue earlier. The pathophysiologic causes of body wasting in patients with CHF remain unclear, but initial studies have suggested that humoral neuroendocrine and immunologic abnormalities may be of importance. Cachectic CHF patients show increased plasma levels of catecholamines, cortisol, and aldosterone. Several studies have shown that cardiac cachexia is linked to increased plasma levels of tumor necrosis factor α. The degree of body wasting is strongly correlated with neurohormonal and immune abnormalities. Some investigators have suggested that endotoxin may be important in triggering immune activation in CHF patients. Available studies suggest that cardiac cachexia is a multifactorial neuroendocrine and immunologic disorder that carries a poor prognosis. A complex catabolic–anabolic imbalance in different body systems may cause body wasting in patients with CHF.