The mineralocorticoid receptor is a steroid hormone receptor that is well known for its involvement in fluid and electrolyte homeostasis in epithelial cells present in the distal nephron. The inappropriate activation of this receptor is now known to be implicated in various pathophysiological mechanisms in heart failure. Mineralocorticoid receptor antagonists offer substantial clinical benefit in patients with heart failure with reduced ejection fraction; however, for patients with heart failure with preserved ejection fraction, the treatment benefit is less clear. Biomarkers that can predict response to mineralocorticoid receptor antagonist treatment do not currently exist. Potential biomarkers may be modulated either directly by the mineralocorticoid receptor or indirectly via downstream effects and be able to reflect treatment outcomes, particularly changes in key parameters of cardiac health and function. A biomarker or set of biomarkers that can reliably predict responsiveness to mineralocorticoid receptor antagonist treatment at an early stage may allow for the selection of patients who are most likely to benefit from treatment thereby avoiding any unnecessary side effects associated with the use of these medications.