The impact of cachexia on cardiorespiratory reflex control in chronic heart failure

Background The mechanism of persistent neurohormonal and cardiorespiratory reflex abnormalities in chronic heart failure remain unclear. Also, why chr onic heart failure patients who develop cachexia demonstrate a particularly abnormal neurohormonal profile and have a high risk of death is not known. Impaired reflex control within the cardiac and respiratory systems, and ab normal heart rate variability have both been linked to a poor outcome. Musc le reflexes may contribute to persistent neurohormonal overactivity in wast ed patients. Thus, we hypothesized that patients with cardiac cachexia migh t exhibit particularly profound abnormalities in cardiorespiratory reflexes and heart rate variability. Methods and Results We investigated 39 chronic heart failure patients: 13 w ith cardiac cachexia (non-intentional, non-oedematous, documented weight lo ss of >75% of previous normal weight over more than 6 months), and 26 non-c achectic chronic heart failure patients matched according to the severity o f chronic heart failure tall men, mean age: 59 vs 60 years, NYHA functional class: 2.6 vs 2.5, peak O-2 consumption: 16.2 vs 16.8 ml.kg(-1).min(-1), l eft ventricular ejection fraction: 23 vs 24%, all p>0.2 for cachectic vs no n-cachectic). In the assessment of the cardiorespiratory reflex control we investigated: cardiac sympathovagal balance (using spectral analysis of hea rt rate variability to derive low (LF, 0.04-0.15Hz) and high frequency (HF, 0.15-0.4Hz) components), baroreflex sensitivity (using the phenylephrine m ethod), and peripheral chemosensitivity (using the transient hypoxic freque ncy sensitivity method). There was a severely abnormal pattern of cardiores piratory reflex control in patients with cachexia compared with non-cachect ic patients. The former group exhibited severely impaired autonomic reflex control, characterized by an abnormal profile of heart rate variability (re duced LF component), and depressed baroreflex sensitivity (P=0.0001 and P=0 .02, respectively, vs non-cachectics). Patients with cachexia also demonstr ated an increased peripheral chemosensitivity (0.91 vs 0.461.min(-1).%SaO(2 )(-1), P<0.001, cachectic vs non-cachectic, respectively). In the correlati on analyses the degree of impairment in the reflex control was more closely related to wasting, and to the level of neurohormonal activation las measu red by the levels of epinephrine and norepinephrine) than to conventional m arkers of the severity of heart failure. Conclusions Chronic heart failure patients who developed cardiac cachexia d emonstrate an abnormal rifler control within the cardiovascular and respira tory systems. The nature of the link between this phenomenon and hormonal c hanges and the poor prognosis of cachectic chronic heart failure patients w arrants further investigation. (C) 1999 The European Society of Cardiology.