Background Leptin, a product of theobgene, is known to increase energy expenditure. Given that chronic heart failure is a hypercatabolic state, we sought to determine whether congestive heart failure involves elevations in plasma leptin levels. Since leptin secretion is up-regulated by insulin, we also explored whether in congestive heart failure, a hyperinsulinaemic state, plasma leptin levels relate to plasma insulin levels.
Methods Male patients with weight-stable congestive heart failure (n=25, aged 55·5±2·0, mean±SEM, body mass index=27·4±0·8, radionuclide left ventricular ejection fraction=29·3±3·0%) and 18 controls, matched for age, sex and body fat (dual energy X-ray absorp-tiometry), underwent measurement of fasting plasma leptin (radioimmunoassay) and insulin levels.
Results Compared to controls, patients with congestive heart failure had higher plasma leptin [8·12 (−1·12,+1·31) vs 4·48 (−0·61,+0·70) ng.ml−1, mean±asymmetrical SEM,P=0·003], 41·5% higher plasma leptin per percent body fat mass (P<0·001), and higher fasting insulin levels [67·8 (−11·1,+13·3) vs 32·9 (−5·7,+6·9) pmol.l−1,P=0·010]. In the congestive heart failure group, plasma leptin correlated with total body fat (r=0·66) and fasting insulin (r=0·68) (bothP<0·001). In multivariate regression analyses of the congestive heart failure group, fasting insulin (standardized coefficient=0·41,P=0·011) emerged as a predictor of plasma leptin levels, independent of total body fat (standardized coefficient=0·73,P=0·002, R2=0·66,P<0·001).
Conclusions Plasma leptin levels are raised in patients with congestive heart failure. The observation of a positive relationship between plasma leptin and insulin concentrations suggests that the insulin–leptin axis may be related to the increased energy expenditure observed in patients with congestive heart failure.
Correspondence: Dr Francisco Leyva, MD, Department of Cardiac Medicine, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, U.K.