Renal-based Optimization of QUADruple Therapy in Patients With Heart Failure With Reduced Ejection Fraction.

Inclusion Criteria: * Left ventricular ejection fraction ≤ 40%, assessed LVEF with imaging within last three months before randomization (TTE/KT/MIBI/MRI) * NYHA ≥ II Exclusion Criteria: * Hemodynamic instability * Recent acute coronary syndrome (\< 1 month before randomisation) * Already on quadruple heart failure therapy or on triple GDMT in case of eGFR \< 30ml/min/1.73m2 or a potassium above 6mmol/L * eGFR \< 20ml/min/1.73², planned for dialysis or already actively treated with chronic dialysis. * Implantation of a cardiac resynchronization therapy (CRT) within 3 months * Adult congenital heart disease * Previous heart transplantation or currently/planned for ventricular assist device * Women who are pregnant or breastfeeding * Unable to participate in 3 months follow-up