OPtimizing Aldosterone Receptor Antagonist Therapy by Sodium Zirconium Cyclosilicate in Heart Failure

Mineralocorticoid receptor antagonists (MRA) is one of cornerstones in the treatment of heart failure with reduced ejection fraction (HFrEF). However, MRA has been extremely under-used globally. The main reason for this seems to be increased risk of hyperkalemia in individuals on MRA. Theoretically, by limiting the risk of hyperkalemia it could thus be possible to optimize MRA therapy. This is studied in this randomized controlled trial in which it is investigated whethere adding a potassium-binder in combination with MRA treatment prevent hyperkalemia to a greater extent than only using MRA. The specific aim of this study is to demonstrate the efficacy and safety of Sodium Zirconium Cyclosilicate (SZC) in optimizing MRA in symptomatic patients with HFrEF. A multicenter, randomized, placebo-controlled, double-blinded study in Sweden (n=110) The study consists of 2 phases: 1) open-label run-in within maximum 2 months, where all are treated with SZC to test tolarability, and 2) a 1:1 randomized, double-blinded and placebo-controlled treatment during 6 months. The open-label phase, in turn, consists of three periods: run-in (1 - 2 weeks), correc-tion (maximum 72 hours) and maintenance (4-7 weeks). In addition, post-randomization phase, all patients will be followed by 3 visits (Follow-Up 1, 2 and 3) at 1, 2 and 4 weeks after End of Study (EOS) / End of Treatment (EOT) (which comes first) for further control of kalium and creatinine levels and documentation of current MRA use incl dose. Sodium Zirconium Cyclosilicate (SZC) (Lokelma)®, 5 g, 10 g, orally, is an approved drug in Sweden. For correction of hyperkalemia, the recommended starting dose is 10 g, three times daily. Once normokalemia has been achieved, the maintenance reg-imen should be started with 5 g once daily. The dose can be titrated up to 10 g once daily or lowered to 5 g once every other day as needed, to maintain a normal level of potassium. Primary Objective: To demonstrate the efficacy of Sodium