Circular RNAs (circRNAs) are involved in cardiovascular disease development and progression. We identified has_circ_0000437 from three pairs of clinical samples using a circRNA microarray and predicted the has_circ_0000437 sponge let-7f-5p using bioinformatics. We expanded the sample to confirm the expression, correlation, and diagnostic value of has_circ_0000437, let-7f-5p and RAS-like proto-oncogene B (RALB) in rheumatic val...