Reduced circulating apelin in essential hypertension and its association with cardiac dysfunction.

OBJECTIVE: Apelin--a novel multifunction peptide implicated in regulation of the cardiovascular system, including blood pressure and cardiac function control - has been postulated to be involved in the pathophysiology of hypertension and hypertensive heart disease. We investigated the circulating apelin level and its relationship to left ventricular function in patients with essential hypertension.
METHODS: We enrolled 232 hypertensive patients without concomitant diseases affecting cardiovascular functions and 76 healthy controls. Each patient underwent plasma apelin measurement and echocardiographic assessment of left ventricular systolic and diastolic function using myocardial velocities and deformation parameters, and myocardial reflectivity using calibrated integrated backscatter.
RESULTS: Hypertensive patients demonstrated lower plasma apelin than the controls (265 ± 127 vs. 330 ± 159 pg/ml; P<0.001). Patients with the lowest plasma apelin, that is, from the first tertile, exhibited more severe left ventricular systolic and diastolic function abnormalities than their peers from the other two tertiles. In multivariable regression analysis, apelin was, in addition to patient age, BMI, blood pressure, left ventricular mass index and calibrated integrated backscatter in the basal septum, an independent correlate of left ventricular systolic function parameters (β=0.18; P<0.001 for strain and β=0.12; P<0.03 for systolic strain rate) and diastolic function parameters (β=0.13; P<0.01 for early diastolic strain rate, β=0.11; P<0.04 for early diastolic myocardial velocity, and β=-0.11; P<0.04 for the ratio of mitral inflow to mitral annular early diastolic velocity).
CONCLUSION: In patients with essential hypertension, circulating apelin levels are reduced, and lower plasma apelin is independently associated with more profound left ventricular systolic and diastolic function impairment.