Heart Failure

Key points

What it is

Heart failure is a condition in which the heart cannot pump blood around the body, or fill with blood, as effectively as it should. The name is misleading: it does not mean the heart has failed or stopped, but that it is struggling to keep up, so the body and organs may not get enough blood and fluid can back up into the lungs and tissues.¹

Heart failure is described by the ejection fraction, which is the share of the blood in the main pumping chamber that the heart pushes out with each beat. It is measured on a scan of the heart. There are three groups:²

• Reduced ejection fraction (HFrEF). An ejection fraction of 40% or less. The heart muscle is weakened and pumps poorly.
• Mildly reduced ejection fraction (HFmrEF). An ejection fraction of 41 to 49%, sitting between the other two.
• Preserved ejection fraction (HFpEF). An ejection fraction of 50% or more. The heart pumps reasonably but is stiff and fills poorly.

The 2026 European (ESC) guideline simplifies this to two groups, below 50% and 50% or more, because the middle group behaves and responds to treatment like the reduced group.³ NICE, which UK clinics follow, still uses three.

HFpEF is strongly associated with obesity, diabetes and high blood pressure,^3,4 and is the most common type in older people; more than 80% of people with HFpEF are overweight or obese.⁵ The type matters because it changes which treatments help.

What causes it, and who is at risk

Heart failure usually results from conditions that damage or overload the heart over time: coronary heart disease (narrowed arteries supplying the heart muscle) and heart attacks, long-standing high blood pressure, heart-valve problems, abnormal rhythms such as atrial fibrillation (an irregular, often fast heartbeat), and others.¹ HFpEF in particular is linked to the cluster of obesity, type 2 diabetes, insulin resistance and high blood pressure.^3,6 Risk factors therefore overlap heavily with poor metabolic health, alongside age and previous heart disease.

Symptoms and signs

• Breathlessness, on exertion, and in more advanced cases when lying flat or at night.
• Tiredness and reduced exercise capacity.
• Swelling of the ankles, legs or abdomen from fluid retention.
• Rapid weight gain from fluid.¹

Sudden, severe breathlessness needs emergency assessment.¹

How it is diagnosed

Assessment starts with your history and an examination. The first test is usually a blood test for NT-proBNP, a substance the heart releases when it is under strain, measured in ng/L. The higher the level, the more likely heart failure is,³ and current NICE guidance ties the result to how quickly you should be seen: above 2,000 ng/L means urgent referral for specialist assessment and a heart scan within 2 weeks, and 400–2,000 ng/L means within 6 weeks. A level below 400 ng/L, in someone not already on heart medicines, makes heart failure less likely.² Importantly, obesity lowers the NT-proBNP level.^2,3 The blood test can therefore under-read in the group most at risk of HFpEF.

An ECG (a tracing of the heart's electrical activity) is also done. The key test is an echocardiogram, an ultrasound scan of the heart. This shows how well the heart is pumping and filling, measures the ejection fraction, and so identifies which type it is.²

The metabolic health perspective

Metabolic health has a direct bearing on heart failure, especially the HFpEF type. Obesity, insulin resistance and type 2 diabetes promote a stiff, inflamed heart and an overloaded circulation. In a long-term study of older men, insulin resistance predicted heart failure independently of diabetes and appeared to explain much of the link between obesity and heart failure.⁶ Once HFpEF is established, the amount of body fat appears to matter more than insulin resistance itself.⁷ Excess fat, including the fat around the heart, is thought to drive inflammation and scarring of the heart muscle,^3,8 high blood pressure makes it work harder and thicken, and high blood sugar damages small vessels. This is why some specialists describe HFpEF as, in part, a metabolic disease of the heart.

These drivers are modifiable. In trials of people with HFpEF and obesity, losing weight through diet and exercise training each improved exercise capacity, and together the effect was larger,^4,5 and European guidance says weight loss in HFpEF with obesity relieves symptoms and may improve outcomes.³ Improving metabolic health, losing visceral fat (fat around the organs), controlling blood pressure and blood sugar, and reducing inflammation can ease the burden on the heart and improve symptoms. This works alongside specific heart treatments, not instead of them.

Treatment and management

The aims are to relieve symptoms, slow progression, reduce hospital admissions and prolong life. Treatment combines specific heart medicines and procedures with metabolic-health and lifestyle measures, shared between your GP and the specialist heart failure team.²

Lifestyle and the Health Foundations

Nutrition

Salt and fluid are handled individually in heart failure, and current NICE guidance is against restricting them as a matter of routine. Intake is asked about, and cut down only where there is a reason: fluid for people with a low blood sodium level, and salt or fluid for people whose intake is genuinely high.² Follow what your own heart team has advised.

Diets high in sugar, refined grains and processed food are linked with a higher risk of heart failure, especially HFpEF.³ Reducing sugar and ultra-processed food will benefit most people. A focus on building meals with plenty of protein and non-starchy vegetables can be helpful, with starchy carbohydrate reduced or personalised. This approach supports weight loss and improves metabolic health, and weight loss has been shown to improve exercise capacity in HFpEF,⁵ and European guidance says it relieves symptoms.³ The 28 Day Plan framework may be a useful approach.

Avoid salt substitutes that contain potassium, usually sold as low-sodium or reduced-sodium salt. Several of the standard heart failure medicines already raise potassium, and adding more can push it to a harmful level.²

Important. Any significant change in eating pattern should be discussed with your heart team, since fluid and salt intake need separate attention in heart failure. A sudden, significant dietary change can alter how the kidneys regulate salt and water.

Movement

Tailored physical activity improves exercise capacity and quality of life.^3,4 Everyone with heart failure should be offered a personalised, exercise-based cardiac rehabilitation programme, which also includes education and psychological support, and which can be run at home, in the community or in hospital.^1,2 It builds up gradually over weeks, and the pace and intensity should be guided by the heart team.

Sleep, stress and sleep apnoea

Aim for 7 to 9 hours of regular sleep, and reduce stress where you can. Sleep-disordered breathing, including sleep apnoea (stopping breathing during sleep), affects more than a third of people with heart failure and worsens its course,³ so tell your heart team if you snore loudly or wake unrefreshed: it can be assessed and treated.

Weight, alcohol and smoking

Reaching a healthier weight, limiting or avoiding alcohol, and not smoking all help.¹

Other non-pharmaceutical options

Iron deficiency is common in heart failure,³ and correcting it can improve symptoms and quality of life. In HFrEF, iron levels and haemoglobin are checked by blood test, and deficiency is corrected with iron given into a vein (a drip), which in trials improved symptoms, exercise tolerance and quality of life.^2,3 If iron deficiency anaemia is found it should not be assumed to be caused by the heart failure, and other causes are looked for.²

Evidence for most supplements is limited, and some can be harmful or interact with heart medicines, for example those affecting fluid or potassium balance. Only take a supplement on medical advice.

Medical and pharmaceutical treatments

Medicines are the core of treatment. The main classes are:

• ACE inhibitors. These relax blood vessels and reduce the work the heart has to do. If they cause side effects, an ARB (a similar medicine) or a newer combination tablet called an ARNI may be used instead.
• Beta-blockers. These slow the heart and shield it from stress hormones.
• Mineralocorticoid receptor antagonists (MRAs). These help the body clear excess salt and water, and protect the heart muscle from scarring.
• SGLT2 inhibitors. Originally diabetes medicines, these make the kidneys pass out extra sugar and salt in the urine, which eases the load on the heart. They help whether or not you have diabetes.
• Weight-loss injections. For people with an ejection fraction of 45% or more and obesity, the 2026 European guideline says semaglutide or tirzepatide should be considered, whether or not they have diabetes, to reduce weight and improve exercise capacity and quality of life.³
• Diuretics. Water tablets, which relieve fluid overload and breathlessness. They ease symptoms rather than change the course of the condition.

In HFrEF the first four medicines in the list are known as the four pillars, and together they improve survival, reduce hospital admissions and ease symptoms.^2,3 NICE updated its guidance in September 2025, and European guidance followed in 2026: the four are no longer added one at a time in a fixed order, and can be started together from diagnosis, with the order, the starting doses and the pace of increase tailored to the person, and the doses built up to the levels used in the trials or the highest you can tolerate.^2,3 If symptoms continue on the highest tolerated doses, the ACE inhibitor may be switched to an ARNI.²

In HFpEF, an MRA and an SGLT2 inhibitor are now both considered. In the mildly reduced group, all four pillars are considered.² SGLT2 inhibitors and MRAs are therefore used across the whole range of ejection fraction.^2,3

Kidney function and potassium are checked by blood test before an ACE inhibitor, ARB, ARNI or MRA is started, a week or two after starting and after each dose increase, and every 3 to 6 months once the dose is stable.²

Devices such as pacemakers and implantable defibrillators (which correct a dangerous heart rhythm), help selected people. For some people it is necessary to treat an underlying cause such as narrowed arteries or a heart valve problem.^1,2

All treatment decisions should be made with your GP or specialist team; the above is a summary for understanding, not prescribing guidance.

Routine review

If your condition is stable, typically you have a review at least every 6 months, covering symptoms, fluid, medicines, kidney function and iron levels. Review may be more frequent if your condition or medications have changed.²

Complications and outlook

Heart failure is a serious condition that can worsen over time and lead to hospital admissions and reduced life expectancy, though this varies widely with the cause and treatment. The outlook has improved with modern medicines,³ and addressing metabolic health, especially in HFpEF, offers a real opportunity to improve symptoms. Good self-care and regular review improve quality of life and reduce hospital admissions.³

When to see a doctor

• See a doctor to agree any significant change to your diet, or to your salt and water intake, before you make it.
• If you have heart failure, report rapid weight gain, increasing swelling or worsening breathlessness promptly.
• Sudden, severe breathlessness needs emergency assessment.
• Attend your regular heart failure reviews, and discuss any new medicine or supplement with your heart team or pharmacist first.

Summary