MMP2 and atrial fibrillation: After reviewing previous studies of AF biomarkers, 15 biomarkers were selected (IL-6, IL-8, IL-10, IL-18, TNF-α, Hsp27, Hsp60, Hsp70, PDGF-BB, MMP-2, MMP-9, MPO, TGF-β1, Gal-3, and sST2).