Renin-angiotensin-aldosterone system inhibitors (RAASi) have transformed prognosis of patients with heart failure with reduced ejection fraction, diabetic nephropathy and chronic kidney disease. However, in everyday clinical practice patients often receive suboptimal doses of RAASi. The development of hyperkalaemia is one of the reasons for dose reduction or complete withdrawal of RAASi and this in turn is likely to have an adverse impact on patient outcomes. Yet it remains unknown precisely how often hyperkalaemia leads to changes to RAASi doses, if it is the sole reason, or whether this occurs in combination with other clinical situations such as worsened renal function and hypotension. It is also unclear what influences the decision-making process of healthcare professionals in managing patients with hyperkalaemia who take RAASi and if this is influenced by specialty, experience or indications for RAASi.

In order to improve our understanding of the problem we are taking forward a research study (made up of 3 complimentary studies). These data are needed to help achieve our ultimate goal of improving the care of patients with prognostic indication for RAASi.

The study aims to answer the following research questions:

1. What is the incidence of hyperkalaemia following RAASi therapy initiation and uptitration in patients with a new diagnosis of HFrEF including those with a new diagnosis of post myocardial infarction (MI) left ventricular systolic dysfunction?
2. How does it impact on RAASi prescription?
3. How does hyperkalaemia impact on RAASi therapy according to the clinical indication for the drug(s) in an adult population of patients who are hospitalised or attending the emergency department (and not receiving dialysis) with hyperkalaemia and receiving RAASi?
4. At what level of hyperkalaemia do healthcare professionals consider making changes to RAASi and does it vary according to the clinical indication for the drug(s)?

For patients with heart failure

Inclusion criteria

1. Patients with newly diagnosed HFrEF (within 4 weeks of diagnosis, including those with post MI LVSD, identified as outpatients or during hospital admission, typically for decompensated heart failure or post myocardial infarction) who are initiated on RAASi or have a clinical indication for uptitration of current RAASi (in patients already receiving RAASi for other indications).
2. Able to provide informed consent.
3. Age 18 and above.

Exclusion criteria: 1. Patients receiving dialysis.

For patients with hyperkalaemia

Inclusion criteria

1. Patients in ED or inpatients who already receive RAASi and who have at least 1 blood test with a potassium level of ≥5.5 mmol/l.
2. Able to provide informed consent.
3. Age 18 and above.

Exclusion criteria: 1. Patients receiving dialysis.

For healthcare professionals:

Inclusion criteria

1. Doctors, pharmacists, non-medical prescribers working at primary and secondary care.
2. Able to provide informed consent.
3. Age 18 and above.

Exclusion criteria: 1. None

As this is an observational study, patients in other research studies or receiving any specific treatments for hyperkalaemia (other than chronic dialysis) will not be excluded. After consent, patients will also be permitted to participate in other research studies should they so wish. Patients with covid-19 can also be included.

Newly diagnosed heart failure with reduced ejection fraction (within 4 weeks of diagnosis, including those with post myocardial infarction left-ventricular systolic dysfunction)

Patients in ED or inpatients who already receive RAASi and who have at least 1 blood test with a potassium level of ≥5.5 mmol/l and not receiving dialysis prior to the episode of hyperkalaemia.

Healthcare professionals managing patients with hyperkalaemia and/or heart failure

No plan to share IDP