MPO and hydrops fetalis: A plethora of biomarkers have been defined in myocardial pathologies, in particular HF and HCM, and are associated with pathophysiological pathways in disease progression, such as markers of neurohormonal activation (ET-1) (Widyantoro et al., 2010), oxidative stress (Myeloperoxidase (MPO)), and myocyte injury and stress (cardiac troponins, Brain Natriuretic Peptide (BNP) and NT-ProBNP) (Ho et al., 2017; Captur et al., 2020).