REN and heart failure: Although the evidence for renin–angiotensin system inhibitors (RASi) and mineralocorticoid receptor antagonists (MRAs) may be less strong for heart failure with mildly reduced (HFmrEF) or preserved ejection fraction (HFpEF) than for heart failure with reduced ejection fraction (HFrEF), these agents are often required for the treatment of comorbidities such as hypertension.