Effects of hyperkalaemia and non‐adherence to renin–angiotensin–aldosterone system inhibitor therapy in patients with heart failure in Italy: 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 < 0.001) and 70% (P < 0.001), respectively, more at risk of cardiovascular events and of dying for all‐cause mortality compared to non‐HK patients. Among the HK group, patients non‐adherent to RAASi therapy had a 39% (P = 0.105) higher risk of cardiovascular events and a twofold increased risk (P < 0.001) of all‐cause death. CONCLUSION: Findings from this real‐world study showed that in a cohort of HF patients under RAASi therapy, subjects with HK had an enhanced risk of cardiovascular events or death compared to patients without HK. Moreover, in HK patients, sub‐optimal adherence to RAASi therapy was associated with an increased risk of all‐cause mortality.