Among the biomarkers investigated—such as natriuretic peptides (BNP and ANP), cardiac troponin T, soluble interleukin-1 receptor-like 1 (ST2), TIMP1, adhesion molecules (e.g., ICAM1 and VCAM), pro-inflammatory cytokines (e.g., CCL2), and protease-activated receptors (PAR1, PAR2, and PAR4)—most have been evaluated in the context of both AF and atrial fibrosis [90,95,96]. Here, IL1RL1 is linked to atrial fibrillation.