Effect of patiromer on reducing serum potassium and preventing recurrent hyperkalaemia in patients with heart failure and chronic kidney disease on RAAS inhibitors

AimsWe 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 resultsChronic 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.