Effect of AZD9977 and spironolactone on serum potassium in heart failure with preserved or mildly reduced ejection fraction, and renal impairment: A randomized trial

This phase Ib study compared the effects of AZD9977, a selective mineralocorticoid receptor modulator with predicted low hyperkalemia risk, with spironolactone on serum potassium (sK+) in patients with heart failure (HF) with preserved or mildly reduced ejection fraction (EF; ≥40%), and renal impairment. Patients with HF with EF greater than or equal to 40% and estimated glomerular filtration rate of 40–70 ml/min/1.73 m2 were randomized to once‐daily AZD9977 100 mg or spironolactone 25 mg for 14 days, up‐titrated to AZD9977 200 mg or spironolactone 50 mg for another 14 days. The primary end point was relative change (%) in sK+ for AZD9977 versus spironolactone (baseline to day 28). Serum/urinary electrolytes, fractional excretion (FE) of Na+/K+, plasma aldosterone, cortisol, and renin, and safety were also assessed. Sixty‐eight patients were randomized (AZD9977, n = 33; spironolactone, n = 35). Mean (SD) age was 73.0 (8.5) years, 51.5% men. Mean sK+ change from baseline to day 28 was 5.7% (AZD9977) and 4.2% (spironolactone), and 1.5% and 4.2% at day 14. Relative change (95% confidence interval) in sK+ with AZD9977 versus spironolactone was −0.3% (−5.3% to 4.4%; day 28), and 3.4% (−0.8% to 7.5%; day 14). Median increase from baseline in plasma aldosterone at day 28 was 89.8 pmol/L for AZD9977 and 67.4 pmol/L for spironolactone. Median FE of K+ was 12.9% (AZD9977) and 10.1% (spironolactone). AZD9977 was well‐tolerated. No discontinuations due to hyperkalemia occurred with either treatment. Evidence of target engagement for AZD9977 with a favorable safety profile, supports further evaluation of AZD9977 in patients with HF and renal impairment.