Effects of hyperkalaemia and non‐adherence to renin–angiotensin–aldosterone system inhibitor therapy in patients with heart failure in <scp>Italy</scp> : a propensity‐matched study

Aims The aims of this study were to evaluate if the risk of cardiovascular events and all‐cause mortality was higher in the presence of hyperkalaemia (HK) in patients with heart failure (HF) treated with renin–angiotensin–aldosterone system inhibitors (RAASi), and to investigate in this cohort the increased risk of cardiovascular events and all‐cause mortality among HK patients with non‐optimal adherence to RAASi therapy. Methods and results In this retrospective cohort study based on administrative databases of five Italian Local Health Units, all adult patients with a HF diagnosis between January 2010 and December 2017 were included only if they were prescribed RAASi therapy during the first 3 months after the index date, that corresponded to the date of first HF diagnosis during the inclusion period. Patients were considered to have HK if serum potassium level was ≥5.5 mmol/L. A propensity score matching was applied before evaluation of hazard ratios. Patients with HK were 37% (P