What Is Heart Failure? A Clear Guide to Symptoms, Causes and Living Well
What Is Heart Failure? Symptoms, Causes and Treatment
The words heart failure can sound final. They are not.
Heart failure does not mean that the heart has stopped, or that it is about to stop. It means the heart is not filling with blood or pumping it around the body as effectively as it should.
Some hearts become too weak to squeeze properly. Others become stiff and cannot relax and fill as well as they need to. In both situations, the body may receive less oxygen-rich blood, while pressure and fluid can build up behind the heart.
This can lead to breathlessness, tiredness, swelling and a noticeable loss of stamina. Heart failure is serious and usually needs long-term medical care, but treatment can help manage symptoms, reduce hospital stays and support a better quality of life.
What Is Heart Failure?
Your heart has two closely linked jobs:
- It must fill with enough blood between beats.
- It must pump that blood forward with enough force to supply the body.
Heart failure can develop when either job is disrupted.
A useful way to picture it is as a pump serving an entire house. If the pump cannot push strongly enough, less water reaches the rooms that need it. If it cannot refill properly, the amount sent forward may still be too low. At the same time, pressure can build behind the pump and cause water to back up.
In the body, reduced forward flow can leave the muscles and organs short of the oxygen and nutrients they need. Backward pressure can allow fluid to collect in the lungs, legs, ankles or abdomen.
This is why heart failure can cause two apparently different groups of symptoms: low energy because less blood is reaching the body, and breathlessness or swelling because fluid is building up.
Is Heart Failure the Same as Congestive Heart Failure?
The term congestive heart failure is often used when fluid congestion is a prominent part of the condition.
“Congestion” refers to fluid backing up in the lungs or other tissues. It may cause swollen ankles, a bloated abdomen, rapid weight gain or difficulty breathing when lying flat.
However, not everyone with heart failure has obvious swelling at all times. For this reason, healthcare professionals often use the broader term heart failure.
Does Heart Failure Mean the Heart Is Stopping?
No. Heart failure is different from both a heart attack and cardiac arrest.
- Heart failure is a condition in which the heart does not fill or pump as effectively as the body needs.
- A heart attack occurs when blood flow to part of the heart muscle is severely reduced or blocked, causing injury.
- Cardiac arrest occurs when the heart suddenly stops pumping blood effectively, usually because of an electrical problem.
A heart attack can damage the heart muscle and later contribute to heart failure, but the terms are not interchangeable.
AtheroCare’s guide to heart attack versus cardiac arrest explains the distinction in more detail.
What Are the Main Types of Heart Failure?
Heart failure can affect the left side, the right side or both sides of the heart. It may develop suddenly, known as acute heart failure, or continue as a long-term condition, known as chronic heart failure.
Doctors also describe heart failure using a measurement called ejection fraction.
What Is Ejection Fraction?
Ejection fraction, or EF, is the percentage of blood that the left ventricle pumps out with each contraction.
It is usually measured during an echocardiogram. The result helps doctors understand how the heart is working and which treatments may be appropriate.
A person can have heart failure even when the ejection fraction is within the usual range. EF is useful, but it is only one part of the diagnosis. Symptoms, examination findings, blood tests, imaging and the underlying cause all matter.
Heart Failure With Reduced Ejection Fraction
Heart failure with reduced ejection fraction is often shortened to HFrEF.
In this form, the heart muscle has become weaker and does not contract effectively. Less blood is pushed out with each beat, and fluid may begin to back up in the lungs or other parts of the body.
It has also traditionally been called systolic heart failure.
Heart Failure With Preserved Ejection Fraction
Heart failure with preserved ejection fraction is shortened to HFpEF.
In this form, the heart may squeeze reasonably well, but the muscle is stiff and does not relax or fill normally. The percentage pumped out can look normal even though the total amount of blood entering and leaving the ventricle is not enough for the body’s needs.
It has also traditionally been called diastolic heart failure.
Why the Labels May Change Over Time
You may also hear terms such as mildly reduced or improved ejection fraction.
An international heart failure definition published in 2026 moved away from relying on one rigid EF cut-off. It emphasises clinically useful categories, the underlying cause and the fact that heart failure can improve, remit or progress over time.
That means the label in a medical record may change as the heart responds to treatment. The number is important, but it should never be interpreted in isolation.
What Are the Symptoms of Heart Failure?
Symptoms can develop gradually or appear more suddenly. They may be mild at first and can be mistaken for being unfit, sleeping badly or simply getting older.
Common symptoms include:
- Shortness of breath during everyday activity
- Becoming more breathless than expected during exercise
- Difficulty breathing when lying flat
- Waking at night feeling short of breath
- Needing more pillows to sleep comfortably
- Tiredness, weakness or reduced stamina
- Swelling in the feet, ankles or legs
- Abdominal swelling or a bloated feeling
- Sudden or unexplained weight gain caused by fluid retention
- A persistent cough, particularly at night
- A racing, pounding or irregular heartbeat
- Dizziness or light-headedness
- Reduced appetite or nausea
- Difficulty concentrating or unusual confusion, particularly when symptoms are severe
No single symptom proves that someone has heart failure. Lung disease, anaemia, kidney disease, medication effects and several other conditions can cause similar problems.
The pattern matters. For example, a person may notice that a familiar walk now requires several stops, that climbing one flight of stairs causes unexpected breathlessness.
New, recurring or worsening symptoms should be assessed by a qualified healthcare professional rather than self-diagnosed.
Why Does Heart Failure Become More Relevant After 50?
There is no sudden dividing line at age 50. Risk tends to rise gradually because the conditions that can strain or damage the heart often build over many years.
Long-term high blood pressure, coronary heart disease, diabetes, kidney disease, heart rhythm problems and valve disease become more common with age. Heart failure has an especially large impact among adults aged 65 and over.
For people in midlife and later life, a drop in stamina deserves attention. Becoming breathless while doing something that was previously comfortable, developing new ankle swelling or needing to sleep more upright should not automatically be dismissed as normal ageing.
Care may also become more complicated later in life because people are more likely to have several health conditions, take multiple medicines or experience changes in strength, balance or memory. Good heart failure care should account for the whole person, not just one scan result.
What Causes Heart Failure?
Heart failure is usually the result of another condition that has damaged, weakened, stiffened or overloaded the heart.
Common causes and contributors include:
Coronary Heart Disease and Heart Attack
Narrowed coronary arteries can reduce the heart muscle’s blood supply. A heart attack can permanently injure part of the muscle, leaving the heart less able to pump effectively.
High Blood Pressure
When blood pressure remains high, the heart must work harder to push blood through the arteries. Over time, the heart muscle may thicken, stiffen or weaken.
Learn more about what blood pressure means and why it matters.
Cardiomyopathy and Myocarditis
Cardiomyopathy is disease of the heart muscle. It may be inherited or linked to infection, inflammation, alcohol, certain drugs, some medical treatments or an unknown cause.
Myocarditis is inflammation of the heart muscle and can sometimes lead to heart failure.
Heart Valve Disease
Valves keep blood moving through the heart in the correct direction. A narrowed or leaking valve can increase the heart’s workload and eventually affect its pumping ability.
Heart Rhythm Problems
A heartbeat that remains too fast, too slow or irregular can reduce pumping efficiency. Atrial fibrillation is one rhythm condition that may occur alongside heart failure.
Other Health Conditions
Diabetes, chronic kidney disease, thyroid disorders, severe anaemia, iron-overload conditions, congenital heart conditions and some lung diseases can contribute to heart failure.
Heart failure can also occur during or after pregnancy, and in some people the cause remains uncertain even after testing.
Genes may influence several underlying causes. A family history of heart disease does not make heart failure inevitable, but it is useful information to share with a healthcare professional.
Can Heart Failure Be Prevented?
Not every case can be prevented. Some causes are genetic, congenital, pregnancy-related or unpredictable.
However, reducing strain on the heart and treating contributing conditions may lower the risk or delay progression. Helpful steps can include:
- Not smoking or vaping
- Managing blood pressure, cholesterol and blood sugar with professional guidance
- Following treatment for coronary heart disease, valve disease or heart rhythm problems
- Being physically active at a level appropriate for your health
- Eating a varied, balanced diet
- Limiting alcohol or avoiding it when advised
- Maintaining a weight that supports overall health
- Seeking assessment for possible sleep apnoea
- Taking prescribed medicines as directed
- Attending recommended health reviews
Restorative sleep is also part of cardiovascular wellbeing. Read more about the connection between sleep and heart health.
People with symptoms or a known heart condition should ask a healthcare professional before making a major change to their exercise routine.
How Is Heart Failure Diagnosed?
There is no single test that diagnoses every case.
A healthcare professional will usually begin by asking about symptoms, when they occur and whether they are changing. They may also ask about previous heart problems, other medical conditions, medicines, alcohol use and family history.
The physical examination may include checking:
- Heart rate and rhythm
- Blood pressure
- Heart and lung sounds
- Swelling in the legs or abdomen
- Oxygen levels
- Body weight and signs of fluid retention
Tests may include:
Blood Tests
Blood tests can look for anaemia, thyroid problems and changes in kidney or liver function. They may also measure natriuretic peptides, such as BNP or NT-proBNP, which can rise when the heart is under strain.
Electrocardiogram
An electrocardiogram, or ECG, records the heart’s electrical activity. It may identify a rhythm problem, evidence of a previous heart attack or other changes that need investigation.
Echocardiogram
An echocardiogram uses ultrasound to show the heart’s chambers, valves and movement. It can measure ejection fraction and help identify whether the heart is weak, stiff, enlarged or affected by valve disease.
Chest X-Ray
A chest X-ray may show an enlarged heart or fluid congestion in the lungs. It can also help identify other possible causes of breathlessness.
Other Tests
Depending on the situation, a doctor may recommend cardiac MRI, coronary imaging, a stress test, heart-rhythm monitoring, lung-function testing or cardiac catheterisation.
The aim is not only to confirm heart failure, but also to identify its type, severity and underlying cause.
How Is Heart Failure Treated?
Treatment is tailored to the individual. It depends on the type of heart failure, its cause, symptoms, kidney function, blood pressure, heart rhythm and other health conditions.
The goals may include:
- Relieving breathlessness and swelling
- Helping the heart work more efficiently
- Treating the underlying cause
- Slowing or preventing further progression
- Reducing the likelihood of hospital admission
- Supporting independence and quality of life
Most people need a combination of approaches rather than one treatment alone.
Medicines
Heart failure medicines have different jobs. Depending on the type of heart failure, a treatment plan may include:
- Diuretics, which help the body remove excess fluid and can ease swelling and breathlessness
- ACE inhibitors, angiotensin receptor blockers or ARNIs, which affect blood vessels and hormonal pathways involved in heart strain
- Beta blockers, which slow the heart and reduce its workload
- Mineralocorticoid receptor antagonists, which block some effects of the hormone aldosterone
- SGLT2 inhibitors, which are now used in several forms of heart failure, including in some people without diabetes
- Other medicines for blood pressure, heart rhythm, coronary disease or an underlying condition
Many people take several medicines because each addresses a different part of the condition.
Do not stop, skip or change a heart medicine because you feel better or because of a side effect. Speak with the prescriber or pharmacist, as the dose or medicine may need to be adjusted safely.
Devices and Procedures
Some people may benefit from:
- A pacemaker to support an appropriate heart rate
- Cardiac resynchronisation therapy to help the ventricles contract in a more coordinated way
- An implantable cardioverter defibrillator to detect and correct dangerous rhythms
- Treatment to repair or replace a damaged heart valve
- A procedure or surgery to improve coronary blood flow
- A left ventricular assist device or heart transplant in selected cases of advanced heart failure
These options are not suitable or necessary for everyone. A cardiology team will consider likely benefits, risks, general health and personal preferences.
Cardiac Rehabilitation and Specialist Support
Cardiac rehabilitation combines individually appropriate activity, education and support. A heart failure or rehabilitation programme may also involve nurses, cardiologists, pharmacists, dietitians, physiotherapists and mental-health professionals.
A suitable programme can help people understand their medicines, build confidence with movement, recognise symptom changes and manage everyday life more effectively. Availability differs between countries and health systems, so ask what services are offered locally.
Can You Live Well With Heart Failure?
Many people live with heart failure for years. The experience varies widely, and symptoms may change over time.
Practical self-management does not replace medical treatment, but it can make treatment more effective.
Take Medicines as Prescribed
Use a routine, pill organiser or written schedule if that helps. Keep an updated list of prescriptions, over-the-counter medicines and supplements.
Tell every prescriber and pharmacist about everything you take. Some non-prescription medicines and complementary products can interact with heart medicines, affect blood pressure, alter potassium levels or encourage fluid retention.
Always check before starting a supplement or “natural” product.
Know Your Usual Pattern
Your healthcare team may ask you to monitor symptoms, pulse, blood pressure or body weight. The purpose is to notice a change from your normal pattern before it becomes a crisis.
There is no universal weight-change rule that is right for everyone. Ask your care team how often to weigh yourself and exactly what change they want you to report.
Ask About Salt and Fluid
Some people with heart failure are advised to reduce sodium or limit fluids. Others may not need the same restrictions.
The right approach depends on symptoms, kidney function, medicines and the amount of fluid retention. Avoid adopting a strict fluid or salt limit without personalised guidance.
Keep Moving Safely
Regular, appropriately paced activity can improve fitness, confidence and daily function. Cardiac rehabilitation can provide a structured and supervised way to begin when it is available.
The aim is not to push through severe symptoms. Stop and seek advice if activity causes chest discomfort, marked breathlessness, faintness or a sudden change from your usual ability.
Protect Your Emotional Wellbeing
Living with a long-term heart condition can bring worry, low mood or loss of confidence. Support from family, friends, a heart failure team, a counsellor or a peer group can be valuable.
Mental wellbeing is part of heart failure care, not an optional extra.
Which Changes Should Be Reported Promptly?
People who have been diagnosed with heart failure should have an action plan from their healthcare team.
Contact the team promptly if you notice a new or worsening pattern such as:
- More breathlessness during ordinary activity
- Difficulty breathing when lying flat
- Needing additional pillows to sleep
- Waking at night short of breath
- Increasing ankle, leg or abdominal swelling
- Sudden or unexplained weight gain
- A new night cough or worsening persistent cough
- New palpitations, dizziness or faint feelings
- Reduced appetite, nausea or increasing abdominal fullness
- A clear drop in the amount of activity you can manage
- Side effects that make it difficult to take prescribed medicine
Early advice may allow treatment to be adjusted before symptoms become severe.
When Should You Seek Emergency Medical Help?
Contact the emergency medical service for your location immediately if someone has:
- Severe difficulty breathing, is gasping or cannot speak in full sentences
- Pale, blue or grey lips or skin
- Collapsed, fainted or become unresponsive
- Sudden chest pressure, squeezing or pain, particularly with sweating, nausea or shortness of breath
- Sudden severe confusion or a rapid deterioration in their condition
Do not wait to see whether severe symptoms pass. Follow the emergency operator’s instructions and avoid driving yourself when emergency transport is available.
Can Heart Failure Improve?
Yes, heart function and symptoms can improve in some people, particularly when the cause can be treated and recommended therapy is followed.
An ejection fraction that was once reduced may rise. Symptoms may become milder, and daily activity may become easier.
However, improvement does not necessarily mean that the underlying tendency has disappeared. Stopping treatment without medical guidance can allow the condition to worsen again.
The 2026 international definition describes heart failure as dynamic: it may improve, enter remission or progress. Ongoing review remains important even when someone feels well.
Questions to Ask Your Doctor
You may wish to ask:
- What is the likely cause of my heart failure?
- Which type of heart failure do I have?
- What does my ejection fraction mean in my case?
- Which symptoms should I report on the same day?
- Which symptoms mean I should seek emergency help?
- Should I monitor my weight, pulse or blood pressure at home?
- Do I need a personalised salt or fluid limit?
- What type of exercise is appropriate for me?
- Would cardiac rehabilitation or a heart failure programme help?
- What is each medicine intended to do?
- Which side effects should I report?
- Are my over-the-counter medicines and supplements safe with my treatment?
- How often should I have follow-up appointments or repeat tests?
Take an up-to-date medicine list and a short record of symptoms to appointments. AtheroCare’s heart health checklist of questions to ask your doctor can help you prepare.
The Bottom Line
Heart failure does not mean the heart has stopped. It means the heart is not filling or pumping as effectively as the body requires.
A weak squeeze, a stiff filling chamber or problems elsewhere in the heart can reduce blood flow and cause fluid to build up. Breathlessness, swelling, tiredness and a decline in stamina are common warning signs, but symptoms vary and can have other causes.
Heart failure usually needs long-term care. Treatment may include medicines, cardiac rehabilitation, specialist programmes, devices or procedures, together with management of the condition that caused it.
For readers in their 50s and beyond, the most useful message is not to write off new breathlessness, swelling or loss of stamina as “just age”. Seek assessment, know your usual symptom pattern and report meaningful changes early.
Related AtheroCare Reading
What Is Blood Pressure and Why Does It Matter?
Learn how ongoing high blood pressure can place extra strain on the heart and arteries.
Family History of Heart Disease: What Does It Mean for You?
Understand how inherited factors and shared family habits can influence cardiovascular risk.
Heart Attack vs Cardiac Arrest
Learn why a heart attack, cardiac arrest and heart failure are related but different conditions.
The Critical Connection Between Sleep and Heart Health
Explore how sleep quality and sleep disorders can affect cardiovascular wellbeing.
What to Ask Your Doctor: A Heart Health Checklist
Prepare focused questions about symptoms, tests, medicines and follow-up care.
References
Heart Foundation: What Is Heart Failure?
National Heart, Lung, and Blood Institute: What Is Heart Failure?
National Heart, Lung, and Blood Institute: Diagnosing Heart Failure
National Heart, Lung, and Blood Institute: Heart Failure Treatment
National Heart, Lung, and Blood Institute: Living With Heart Failure
American Heart Association: Heart Failure Signs and Symptoms
American Heart Association: Ejection Fraction
American Heart Association: Second Universal Definition of Heart Failure
American Heart Association: Strategies for Optimising Heart Failure Care in Older Adults
American Heart Association: Complementary and Alternative Medicines in Heart Failure
Medical Disclaimer
This article is provided for general information and education only. It is not intended to provide medical advice, diagnosis or treatment.
Always speak with a qualified healthcare professional about symptoms, medicines, supplements, test results and personal cardiovascular risk. Do not begin, stop or change any treatment based only on information in this article.
