Specific biomarkers of the activation of these neurohormonal pathways, such as the natriuretic peptides, catecholamine levels and neprilysin and various newer ones, may be employed to better elucidate and gain insight into the mechanisms of HF drugs and also help to identify the subgroups of patients who might derive a benefit from specific therapies, irrespective of the degree of LV dysfunction. Here, MME is linked to hydrops fetalis.