Abstract
AIMS: Natriuretic peptides have reportedly been associated with cardiac hypertrophy and insulin resistance; however, it has not been established if B-type natriuretic peptide (BNP) is associated with either insulin resistance or cardiac remodelling in a population with normal plasma BNP levels. We investigated the relationship among plasma BNP levels, insulin resistance, and left ventricular (LV) remodelling in a population with normal physiological plasma BNP levels. METHODS AND RESULTS: Among 1632 individuals who participated in annual health checks between 2005 and 2008 in Arita-cho, Saga, Japan, 675 individuals [median (interquartile range) for age 62 (51-69) years; 227 men (34%)] with LV ejection fraction 50% and BNP level <35 pg/mL were enrolled in this study. Insulin resistance was assessed using homeostatic model assessment of insulin resistance (HOMA-IR). LV geometry, including LV concentric remodelling, was classified based on relative wall thickness (RWT) and LV mass index values derived from echocardiographic findings. Factors associated with insulin resistance and LV geometry were investigated using multiple logistic regression analysis. Tertiles of BNP were inversely associated with HOMA-IR [1st tertile, 1.33 (0.76-1.74); 2nd tertile, 1.05 (0.72-1.59); 3rd tertile, 0.95 (0.66-1.58), P = 0.005]. Lower BNP was associated with the prevalence of insulin resistance, defined as HOMA-IR ≥1.37, even after full multivariate adjustment [1 SD increment in BNP = adjusted odds ratio (aOR) 0.740; 95% confidence interval (CI) 0.601-0.912; P = 0.005]. LV concentric remodelling (RWT >0.42; LV mass index ≤115 g/m(2) in men and ≤95 g/m(2) in women) was observed in 107 (16%) participants, while normal LV geometry (RWT ≤0.42; LV mass index ≤115 g/m(2) in men and ≤95 g/m(2) in women) was seen in 423 (63%), and LV hypertrophy (LV mass index >115 g/m(2) in men and >95 g/m(2) in women) in 145 (21%). Both low BNP level and higher insulin resistance were independently linked to LV concentric remodelling after multivariate adjustment (1 SD increment in BNP = aOR 0.714, 95% CI 0.544-0.938, P = 0.015; HOMA-IR ≥ 1.37 vs. <1.37: aOR 1.694, 95% CI 1.004-2.857, P = 0.048, respectively). CONCLUSIONS: Lower BNP levels are linked to either insulin resistance or LV concentric remodelling in a population with normal plasma BNP levels, suggesting that participants with lower natriuretic peptide level might be vulnerable to the development of metabolic disorders and LV morphological abnormalities.