Effect of Patiromer on Reducing Serum Potassium and Preventing Recurrent Hyperkalaemia in Patients with Heart Failure and Chronic Kidney Disease on Raas Inhibitors

AIMS: We evaluated the effects of patiromer, a potassium (K(+))-binding polymer, in a pre-specified analysis of hyperkalaemic patients with heart failure (HF) in the OPAL-HK trial. METHODS AND RESULTS: Chronic kidney disease (CKD) patients on renin-angiotensin-aldosterone system inhibitors (RAASi) with serum K(+) levels ≥5.1 mEq/L to <6.5 mEq/L (n = 243) received patiromer (4.2 g or 8.4 g BID initially) for 4 weeks (initial treatment phase); the primary efficacy endpoint was mean change in serum K(+) from baseline to week 4. Eligible patients (those with baseline K(+) ≥5.5 mEq/L to <6.5 mEq/L and levels ≥3.8 mEq/L to <5.1 mEq/L at the end of week 4) entered an 8-week randomized withdrawal phase and were randomly assigned to continue patiromer or switch to placebo; the primary efficacy endpoint was the between-group difference in median change in the serum K(+) over the first 4 weeks of that phase. One hundred and two patients (42%) had heart failure (HF). The mean ± standard error (SE) change in serum K(+) from baseline to week 4 was -1.06 ± 0.05 mEq/L 95% confidence interval (CI), -1.16,-0.95; P < 0.001; 76% (95% CI, 69,84) achieved serum K(+), 3.8 mEq/L to <5.1 mEq/L. In the randomized withdrawal phase, the median increase in serum K(+) from baseline of that phase was greater with placebo (n = 22) than patiromer (n = 27) (P < 0.001); recurrent hyperkalaemia (serum K(+), ≥5.5 mEq/L) occurred in 52% on placebo and 8% on patiromer (P < 0.001). Mild-to-moderate constipation was the most common adverse event (11%); hypokalaemia occurred in 3%. CONCLUSION: In patients with CKD and HF who were hyperkalaemic on RAASi, patiromer was well tolerated, decreased serum K(+), and, compared with placebo, reduced recurrent hyperkalaemia.