Hyperkalaemia in acute heart failure: clinical profile and outcomes

Introduction

Hyperkalaemia is a frequent and clinically relevant complication in patients with heart failure and has been associated with increased morbidity and mortality. It is commonly related to renal dysfunction and the use of renin–angiotensin–aldosterone system (RAAS) inhibitors, potentially limiting the optimisation of guideline-directed medical therapy. This study aimed to characterise the clinical profile of patients with and without hyperkalaemia at discharge after hospitalisation for acute heart failure decompensation and to assess its prognostic impact.

Methods

This observational, analytical study included all patients admitted to our heart failure programme between 2019 and 2025. Clinical and echocardiographic variables were analysed. Follow-up included major adverse cardiovascular events (MACE). Hyperkalaemia was defined as a serum potassium concentration >5.0 mEq/L at hospital discharge.

Results

A total of 446 patients were analysed, of whom 37.7% (n = 168) were women. Patients with hyperkalaemia at discharge were slightly older than those without hyperkalaemia (75 ± 10 vs. 73 ± 11 years; p = 0.228), and female sex was less frequent (23% vs. 41%; p = 0.003). No significant differences were observed in the prevalence of hypertension, diabetes mellitus, or chronic kidney disease, although diabetes showed a non-significant trend towards higher prevalence in patients with hyperkalaemia (60% vs. 48%; p = 0.082). Alcohol use was more frequent in the hyperkalaemia group (15% vs. 6%; p = 0.019).

Mean left ventricular ejection fraction did not differ between groups (44 ± 16% vs. 42 ± 15%; p = 0.360). Predominantly left-sided heart failure was less frequent in patients with hyperkalaemia (70% vs. 80%; p = 0.050), while low cardiac output was significantly less common (2.5% vs. 11%; p = 0.029).

At discharge, patients with hyperkalaemia more frequently received angiotensin receptor blockers (33% vs. 21%; p = 0.039) and mineralocorticoid receptor antagonists (66% vs. 37%; p < 0.001). Length of hospital stay, in-hospital mortality, and MACE incidence during follow-up were similar between groups. Kaplan–Meier analysis showed no significant differences in event-free survival according to potassium levels at discharge (log-rank p = 0.249).

Conclusions

Hyperkalaemia at discharge following hospitalisation for acute heart failure decompensation was not associated with most comorbidities or markers of disease severity and was not linked to worse short- or mid-term outcomes. It was more frequent in male patients and those with alcohol use and was associated with a distinct clinical profile, including a lower prevalence of low cardiac output. The higher prevalence of hyperkalaemia at discharge is likely related to the more frequent use of RAAS-modifying therapies, suggesting that elevated potassium levels may reflect successful implementation of guideline-directed medical treatment rather than increased clinical risk.For image description, please refer to the figure legend and surrounding text.For image description, please refer to the figure legend and surrounding text.