Circulating levels of β2-microglobulin and cystatin C are associated with left atrial size: additional link between the kidney and the heart.

OBJECTIVE: More attention is being paid to the relationship between kidney dysfunction and cardiovascular events Characteristic features include renal dysfunction, left ventricular (LV) and left atrial (LA) enlargement. The aim of this study is to evaluate the relationships between circulating levels of β2-microglobulin (β2-m) and cystatin C and left atrial size in patients with coronary artery disease.

MATERIALS AND METHODS: We recruited 300 patients who presented with chest tightness or chest pain and subsequently underwent coronary angiography. Of these, 202 patients were diagnosed with coronary artery disease (CAD) and 98 patients without CAD (non-CAD). Laboratory measurements included liver, kidney function (urea nitrogen, creatinine, β2-m and cystatin C), fasting glucose, and lipid analysis. CrCl were calculated according to Cockroft-Gault formula. Echocardiology was used to evaluate the cardiac structure and function.

RESULTS: Significant differences of β2-m and cystatin C exist and no difference of creatinine and CrCl existed between the two groups. LA diameters were positively related to circulating levels of β2-m in the CAD group (r = 0.452, p < 0.001) and non-CAD group (r = 0.360, p < 0.001), and the similar relationships between LAD and circulating levels of cystatin C in the CAD group (r = 0.302, p < 0.001) and non-CAD group (r = 0.243, p = 0.016). LA diameters were negatively related to CrCl in both groups. After multivariate logistic regression analysis, the data indicated that the independent cardiovascular risk factors of LA enlargement for the patients with CAD were age, BMI, systolic blood pressure, LV mass, LVEDD, E/A, Em/Am, CrCl, and circulating levels of β2-m (OR = 1.630, 95% CI: 1.115 - 2.384, p = 0.012), cystatin C (OR = 4.504, 95% CI: 1.478 - 13.726, p = 0.008).

CONCLUSIONS: A linear correlation exists between circulating levels of β2-m or cystatin C and LA diameters. Higher circulating levels of β2-m or cystatin C are independent cardiovascular risk factors of LA enlargement in patients with CAD, and could be a link between the kidney and the heart.