Approximately every minute, someone will die from a myocardial infarction (MI). A MI is the result of an obstruction of blood supply causing the heart to undergo complex structural and functional changes in the left ventricular wall, known as ventricular remodeling. Cardiomyocytes undergo necrosis rapidly after the onset of injury, leading to early accumulation of neutrophils, activation of metalloproteinases, and degradation of the stromal tissue, eventually leading to formation of a collagen scar. Circulating factors related to inflammatory and fibrotic responses are key predictors of extracellular matrix (ECM) changes that occur after MI. Changes in the collagen network of the ECM can alter myocardial stiffness, consequently leading to cardiac hypertrophy, fibrosis, and LV dysfunction. Proteins and peptides of the ECM are promising biomarkers for MI. This book chapter provides an overview of key ECM biomarkers involved in adverse remodeling post-MI and their practical applications.