Optimizing aldosterone receptor antagonist therapy by sodium zirconium cyclosilicate in heart failure - OPRA-HF trial
Authors: Basic C , Karstrom P , Spaak J , Paren P , Ljungman C , Heijl C , Thunstrom E , Fu M 
Published: October 2024

Abstract

Background
Heart failure remains a significant health burden, characterized by disabling symptoms and mortality rates comparable to cancer. Mineralocorticoid antagonists (MRAs), pivotal in treating heart failure with reduced ejection fraction (HFrEF), are underutilized due to concerns of hyperkalemia. Sodium Zirconium Cyclosilicate (SZC) enables optimized MRA therapy by reducing hyperkalemia. However, prospective studies on the efficacy and safety of SZC in patients with HFrEF and high hyperkalemia risk are lacking, particularly in the context of contemporary heart failure quadruple-therapy including angiotensin receptor neprilysin inhibitor (ARNI) and Sodium-Glucose Transport Protein 2 (SGLT2) Inhibitors.

Purpose
The OPRA-HF trial aims to assess the efficacy and safety of SZC in optimizing MRA treatment in symptomatic patients with HFrEF with risk for hyperkalemia on top of optimal guideline-directed medical therapy including ARNI and SGLT2 Inhibitors.

Methods
This investigator-initiated multicentred, randomized, placebo-controlled, and double-blinded trial include patients with HFrEF on suboptimal MRA treatment due to (1) history of hyperkalemia due to MRA, or (2) risk of hyperkalemia due to reduced renal function (eGFR 30-45 ml/min/m2) and current potassium 4.5-5-0 mmol/L. Patients undergo a Run-In phase with SZC, initiating or up-titrating MRA to target doses for 4-7 weeks and SZC was initiated in those patients that became hyperkalemic (K+&gt;5 mEq/L. Those normokalemic and tolerating MRA ≥ 25 mg daily or at least 25 mg dose increase vs before run-in were randomized to SZC (5g or 10g) or placebo for 6 months. Study is powered to randomize 110 patients. Primary outcomes include maintaining daily MRA dose ≥ 25 mg or dose increase by 25 mg with normal potassium levels without rescue therapy. Secondary outcomes include evaluating the safety and tolerability of SZC as well as impact of SZC on quality of life.

Results
In this ongoing trial, so far 40 patients have been randomized. Of these, mean age was 74.3 years, 88.9% men. Most patients had ischemic etiology (54.2%), 36.1% had diabetes mellitus, 52.8% had hypertension.n. At screening 94.4% had beta-blockers, 35% ACEI/ARB, 60% ARNI and 72.2% had SGLT2 inhibitors, 33.3% had no MRAs and 35,6% of patients had less than 25 mg MRA daily,62,2% had 25 mg MRA daily, mean p-potassium was 4.7+0.4 mmol/L, and eGFR was 57.3 ml/min/1.73m². After run-in, 85.2% were on 50 mg MRA daily. A substantial number (51.2%) of eligible patients with previous hyperkalemia had Run-In failure as they now successfully tolerated target dose of MRA at 50 mg daily without recurrent hyperkalemia. SZC dosing was 5g once daily in 78.9% of patients.

Conclusion
This ongoing trial will provide evidence for the use of SZC to optimize MRA treatment in contemporary HFrEF patients. Preliminary findings suggest SZC effectively maintains normokalemia, enabling MRA optimization, potentially improving patients’ otcome.