Use of sodium zirconium cyclosilicate for up-titration of renin–angiotensin–aldosterone system inhibitor therapy in patients with heart failure: a case series

Background Patients often receive suboptimal dosing of renin–angiotensin–aldosterone system inhibitor (RAASi) therapy over concerns of hyperkalaemia. However, studies have shown associations between suboptimal dosing or interruptions to therapy and adverse clinical events. Therefore, effective treatments for hyperkalaemia that can enable optimal RAASi therapy are needed. This case series examines eight patients whose commencement on the novel potassium binder sodium zirconium cyclosilicate (SZC) allowed for the initiation and/or up-titration of RAASi therapy. Case summary Eight patients aged 64–87 years with heart failure (HF) with reduced ejection fraction all developed hyperkalaemia (serum potassium (sK+) >5.0 mmol/L) while receiving RAASi therapy. Following initiation of SZC, all patients experienced eventual stabilization of sK+ levels. All patients were able to initiate, restart, or up-titrate RAASi therapy with five patients achieving optimal medical therapy. Left ventricular ejection fraction improved in four patients, two patients are now re-classified as New York Heart Association Class I, and an additional patient had improved exercise tolerance. Follow-up for Patient 8 is still ongoing. Discussion These real-world cases demonstrate that use of SZC to manage hyperkalaemia in patients with HF is feasible and allows optimization of RAASi therapy.

The LIFT trial: study protocol for a double-blind, randomised, placebo-controlled trial of K+-binder Lokelma for maximisation of RAAS inhibition in CKD patients with heart failure

Background CKD is common in heart failure (HF) and associated with morbidity and mortality, yet life-prolonging medications such as renin-angiotensin-aldosterone inhibitors (RAASi) are underused due to risk of hyperkalaemia. Sodium zirconium cyclosilicate (SZC) is a potassium-binding medication that has been shown to reduce incidence of hyperkalaemia in CKD, non-CKD, and HF populations, which we propose will support maximisation of RAASi therapy. Methods We propose a 1:1 randomised, double-blind, placebo-controlled trial in which participants will receive either SZC or placebo. We will up-titrate participants’ RAASi therapy while monitoring their serum potassium levels and adjusting their SZC dose if necessary. Participants with CKD and HF will be recruited from CKD and HF clinics at St George’s Hospital. The total study period will be 18 months; 130 participants will be enrolled for approximately two months each following screening. Our primary outcome will be the proportion of participants who achieve maximum RAASi dose while maintaining normokalaemia. Secondary outcomes include participants reaching maximum RAASi dose without severe hyperkalaemia; time from randomisation to hyperkalaemia; time from randomisation to severe hyperkalaemia; number of RAASi dose escalations per participant; final doses of RAASi therapy; changes in quality of life score, eGFR, ACR, serum sodium, troponin T; number and duration of hospital admissions; and within-participant change in serum potassium compared to baseline. Discussion This trial will be the first to examine the use of SZC for the maximisation of RAASi dosing in patients with advanced CKD and HF. We will assess the impact of achieving target RAASi dosing on hospital admission rates and duration of stay, with the hope that optimum RAASi treatment will translate into reduced morbidity and improved QoL. If clinical benefit is demonstrated, we hope that the joint multidisciplinary CKD-HF approach will be expanded. Trial registration EudraCT number 2020–002946-18. Registered on 08 June 2020. Online record pending.