Factors associated with underuse of mineralocorticoid receptor antagonists in heart failure with reduced ejection fraction: an analysis of 11 215 patients from the Swedish Heart Failure Registry

Aim Mineralocorticoid receptor antagonists (MRAs) improve outcomes in heart failure with reduced ejection fraction (HFrEF), but are underutilized. Hyperkalaemia may be one reason, but the underlying reasons for underuse are unknown. The aim of this study was to investigate the independent predictors of MRA underuse in a large and unselected HFrEF cohort. Methods and results We included patients with HFrEF (ejection fraction <40%), New York Heart Association (NYHA) class II-IV and heart failure (HF) duration >= 6months from the Swedish HF Registry. Logistic regression analysis identified independent associations between 39 demographic, clinical, co-treatment, and socioeconomic predictors and MRA non-use. Of 11 215 patients, 27% were women; mean age was 75 +/- 11 years; only 4443 (40%) patients received MRA. Selected characteristics independently associated with MRA non-use were in descending order of magnitude: lower creatinine clearance (<60 mL/min), no need for diuretics, no cardiac resynchronization therapy/implantable cardioverter-defibrillator, higher blood pressure, no digoxin use, higher ejection fraction, outpatient setting, older age, lower income, ischaemic heart disease, male sex, follow-up in primary vs. specialty care, lower NYHA class, and absence of hypertension diagnosis. Plasma potassium and N-terminal pro B-type natriuretic peptide levels were not associated with MRA non-use. Conclusion Mineralocorticoid receptor antagonists remain underused in HFrEF. Their use does not decrease with elevated potassium but does with impaired renal function, even in the creatinine clearance 30-59.9mL/min range where MRAs are not contraindicated. MRA underuse may be further related to non-specialist care, milder HF and no use of other HF therapy.