Plasma leptin level is associated with myocardial wall thickness in hypertensive insulin-resistant men

Leptin, the product of the ob gene, has been shown to increase heart rate a nd blood pressure through a stimulation of cardiac sympathetic nervous syst em activity, a phenomenon also involved in the pathogenesis of left ventric ular hypertrophy in hypertensives. Thus, we hypothesize that plasma leptin concentration is associated with left ventricular hypertrophy. Forty hypert ensive males and 15 healthy male subjects underwent anthropometric and echo cardiographic evaluations, assessment of insulin sensitivity through euglyc emic glucose clamp combined with indirect calorimetry, and determination of fasting plasma leptin concentration. Fasting plasma leptin levels were hig her in hypertensives than in controls (6.48+/-2.9 versus 4.62+/-1.5 ng/mL, P<0.05); these results were unchanged after adjustment for body mass index (P<0.05). In the whole group of patients (n=55), fasting plasma leptin conc entration was correlated with body mass index (r=0.46, P<0.001) and waist/h ip ratio (r=0.50, P<0.001); independent of body mass index and waist/hip ra tio, fasting plasma leptin concentration was correlated (n=55) with whole-b ody glucose disposal (r=-0.27, P<0.04), interventricular septum thickness ( r=0.34, P<0.001), posterior wall thickness (r=0.38, P<0.003), and the sum o f wall thicknesses (r=0.68, P<0.001). In a multivariate analysis (n=55), ag e, body mass index, fasting plasma leptin concentration, plasma Na+ concent ration, whole-body glucose disposal, and diastolic blood pressure explained 68% of the variability of the sum of wall thicknesses with fasting plasma leptin concentration (P<0.03), whole body glucose disposal (P<0.002), and d iastolic blood pressure (P<0.001), which were significantly and independent ly associated with the sum of wall thicknesses; In conclusion, our study de monstrates that fasting plasma leptin levels are associated with increased myocardial wall thickness independent of body composition and blood pressur e levels in hypertensives.