The treatment of heart failure has seen considerable advances in the past decades. In particular, a therapeutic focus on the renin-angiotensin-aldosterone system has provided significant improvements in outcomes. Multiple inhibition points in the renin-angiotensin-aldosterone system, including direct renin inhibitors, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and mineralocorticoid receptor antagonists, have the common feature of either blocking aldosterone production (direct renin inhibitor, angiotensin-converting enzyme inhibitor, angiotensin receptor blocker) or the mineralocorticoid receptor. As a consequence of this inhibition, sodium and water reabsorption is blocked, and potassium (K(+)) excretion is reduced. Hyperkalemia may result from the use of multiple renin-angiotensin-aldosterone inhibitors or blockers, particularly in patients with heart failure and concomitant chronic kidney disease. Interventions to reliably control serum K(+) during renin-angiotensin-aldosterone inhibition have not been available to date, and would be of particular value with the use of mineralocorticoid receptor antagonists that have been shown to reduce mortality in patients with heart failure and a reduced left ventricular ejection fraction. In this review, we examine the PEARL-HF study, which has tested the combined use of RLY5016, a novel nonabsorbed K(+) binding polymer, with spironolactone in heart failure patients receiving standard care but with previous documented hyperkalemia or chronic kidney disease. RLY5016 significantly lowered serum K(+) levels from baseline relative to placebo, lowered the incidence of hyperkalemia and allowed a higher proportion of heart failure patients to receive spironolactone at a dose of 50 mg/day.