Data collection
Data were obtained on clinical history, and venous blood samples at the time of echocardiography. In the hospital, values for eGFR, a measure of glomerular filtration function, were calculated using the Chronic Kidney Disease Epidemiology Collaboration Formula, and serum brain natriuretic peptide (BNP) levels were measured by an enzyme immunoassay (E test TOSOH II (BNP), TOSOH Corporation, Tokyo, Japan) with a coefficient of variation <15%.