Effect of patiromer on serum potassium in hyperkalemic patients with heart failure: Pooled analysis of 3 randomized trials

Background: Hyperkalemia (HK) is a serious medical condition that can cause potentially fatal cardiac arrhythmias. Patients with heart failure (HF) are at risk of HK due to underlying chronic kidney disease and use of guideline-recommended renin-angiotensin-aldosterone system inhibitors. Patiromer, a sodium-free, non-absorbed potassium (K⁺) binder, is indicated for the treatment of HK.

Objective: To evaluate the consistency of patiromer's effect on lowering serum K⁺ in patients with HF and HK using pooled data from three clinical trials.

Methods: This post-hoc analysis evaluated the efficacy and safety of patiromer for management of HK over a 4-week treatment period using combined data from three clinical trials (AMETHYST-DN, OPAL-HK and TOURMALINE). Eligible patients had HK (serum K⁺ > 5.0 mEq/L) at study entry. Starting doses of patiromer ranged from 8.4 to 33.6 g/day. In this analysis, efficacy was assessed as the mean (± standard error [SE]) change in serum K⁺ from baseline to Week 4. Safety outcomes evaluated included the incidence and severity of adverse events (AEs) during the 4-week treatment period.

Results: In total, 653 patients who received ≥1 dose of patiromer were evaluable for efficacy (214 diagnosed with HF and 439 without HF). Mean baseline serum K⁺ was 5.4 mEq/L. Patient characteristics were generally similar between the HF and non-HF subgroups. Serum K⁺ decreased to <5.0mEq/L within one week of patients starting patiromer, reaching a nadir after 3 weeks in both the HF and non-HF subgroups (4.59 mEq/L and 4.64 mEq/L, respectively). The mean ± SE change from baseline to Week 4 in serum K⁺ was -0.79 ± 0.06 mEq/L (95% CI: -0.91, -0.68) in patients with HF and - 0.75 ± 0.02 mEq/L (95% CI: -0.79, -0.70) in patients without HF. AEs occurred in 31% of patients with HF and 37% of patients without HF and were mostly mild or moderate in severity. The most common AEs were constipation (HF patients: 7%, non-HF patients: 5%) and diarrhea (HF patients: 2%, non-HF patients: 4%). AEs leading to discontinuation of patiromer occurred in 6% of patients with HF and in 3% of patients without HF.

Conclusions: In this pooled analysis of patients with HK, patiromer was generally well tolerated and reduced serum K⁺ similarly in patients with and without HF over 4 weeks.

Keywords: Heart failure; Hyperkalemia; Patiromer; Potassium binder; RAAS inhibitor.