Classes & Stages of Heart Failure

Introduction

Heart failure is a widespread condition affecting over 64 million people across the globe^1,2. Despite its name, heart failure doesn’t mean the heart has stopped working; it means the heart isn’t pumping blood as it should^2,3. This condition may cause serious health challenges, leading to reduced functional capacity, a lower quality of life, and increased medical costs^1,2.

Heart failure often stems from other underlying health issues, and its severity can vary widely. So, doctors use classification systems to describe its progression and impact. The two most commonly used systems include the New York Heart Association (NYHA) system and the American College of Cardiology (ACC)/American Heart Association (AHA) staging. These classifications can be essential for monitoring disease progression and guiding treatment decisions⁴.

In this article, we’ll guide you through the different heart failure stages and classes so you can better understand the condition and ensure treatment adherence to improve outcomes.

What is Heart Failure?

Heart failure occurs when the heart muscles do not stretch efficiently and lose their ability to pump blood properly. This means your body may not get enough oxygen-rich blood to meet its needs, affecting various organs and causing a range of symptoms⁵.

Heart failure can affect individuals differently and symptoms can range from mild to severe, which can worsen over time^4,5. In the early stages, you might only notice them during physical activity. As the condition progresses, symptoms can become more persistent, even at rest. In some cases, heart failure symptoms may appear suddenly, especially after a heart attack or another serious heart-related event⁵.

Common symptoms of heart failure include^5,6:

• Shortness of breath (even during daily chores)
• Breathing troubles while lying down
• Waking up breathless during the night
• Swollen feet, ankles, legs (or even abdomen)
• Weight gain
• Coughing
• Fatigue or tiredness
• Weakness
• Loss of appetite or feeling full quickly
• Fainting feeling or feeling lightheaded
• Rapid or irregular heartbeat (palpitations)

How Does Heart Failure Happen?

Heart failure typically develops as a result of other underlying health conditions that damage or strain the heart over time. More often it occurs gradually due to conditions that weaken the heart muscle over time, reducing its ability to pump blood effectively⁴.

Here are some of the most common causes of heart failure^4,5,7:

1. High Blood Pressure (Hypertension)

When blood pressure remains elevated over time, it puts extra stress on the heart. This pressure makes the heart work harder, eventually leading to thickening or weakening of the heart muscle and, in some cases, heart failure.

2. Coronary Artery Disease (CAD)

This condition arises when the arteries delivering blood to the heart become narrowed/obstructed. As a result, the heart has to work harder to circulate blood, which over time can weaken the heart muscle and reduce its pumping ability.

3. Heart Attack (Myocardial Infarction)

A heart attack may sometimes leave behind some tissue (usually scar tissue) that could disrupt the heart’s normal pumping function.

Other health conditions that may contribute to heart failure include:

• Anaemia: A shortage of red blood cells means less oxygen reaches your tissues, causing the heart to work harder to supply the body⁷.
• Diabetes: This long-term condition may raise the risk of other health issues, such as high blood pressure⁴.
• Thyroid Gland Disease: Both an underactive (hypothyroidism) or overactive (hyperthyroidism) thyroid can disrupt the heart’s rhythm and function by disrupting hormone regulation⁷.
• Infections: Viral or Bacterial infections such as endocarditis might damage the heart by causing inflammation of the heart muscles^4,7.
• Arrhythmias (Irregular Heartbeat): Abnormal rhythms of the heart might interfere with its ability to pump blood effectively^4,7.
• Lung Diseases: Chronic conditions like chronic obstructive pulmonary disease (COPD) may lower oxygen levels in the blood, placing additional stress on the heart⁴.
• Cardiomyopathy: This is a condition where the heart muscle becomes thickened. This may be caused by diseases such as amyloidosis (protein buildup in heart muscles), making the heart less efficient at pumping blood^4,7.
• Congenital Heart Defects: Heart problems present at birth may affect how well the heart works⁴.
• Alcohol Abuse: Regularly consuming more than the recommended limit of 14 units per week can potentially weaken the heart muscles⁷.

Moreover, certain medications can also contribute to or worsen heart failure, especially if they interfere with how the heart or other prescribed heart medications work. These include^4,8:

• Antihypertensive drugs like calcium channel blockers
• Antidepressants like serotonin reuptake inhibitors
• Some non-steroidal anti-inflammatory drugs (NSAIDs)
• Chemotherapy drugs like anthracyclines

Types of Heart Failure

The heart has two sides: the left side, which pumps oxygen-rich blood to the body, and the right side, which pumps oxygen-poor blood to the lungs to pick up oxygen. Heart failure can affect different parts of the heart, based on which, the main types of heart failure include:

1. Left-Sided Heart Failure

This happens when the left side of the heart becomes either weakened or stiff. There are two main subtypes based on how well the heart is pumping blood^4,9:

• Systolic Heart Failure (Heart Failure with Reduced Ejection Fraction (HfrEF)): In this, the heart muscles are unable to contract effectively. Therefore, the heart pumps less than the required amount of blood to the body.

• Diastolic Heart Failure (Heart Failure with Preserved Ejection Fraction (HfpEF)): Here, the heart muscles don’t relax properly. Thus, the heart has difficulty filling with blood sufficiently.

2. Right-Sided Heart Failure

Right-sided heart failure happens when the right side of the heart is unable to pump blood effectively to the lungs. It’s often a consequence of left-sided heart failure. When this happens, pressure backs up into the lungs, often putting extra strain on the right side of the heart. Eventually, the right side weakens too. As a result, blood backs up into the body’s veins, leading to swelling and other symptoms^4,9.

3. Congestive Heart Failure (CHF)

Congestive heart failure refers to the buildup of fluid in the body’s tissues, including the lungs. This may occur due to the heart’s inability to pump blood efficiently⁹.

Why Do Patients Need to Know Their Heart Failure Stage?

Before we move onto understanding why the knowledge on heart failure stages is important, let’s have a look at the two main classification systems used to determine how advanced your heart failure is:

1. NYHA Functional Classification System

The NYHA system focuses on how heart failure affects your ability to be active. It’s based on symptoms you experience during physical activity and can change over time as your condition improves or worsens⁴:

• Class I: Heart disease is present, but there are no evident symptoms during any physical activity.
• Class II: Mild symptoms may occur with regular activity, but daily routines are mostly unaffected.
• Class III: Noticeable limitations; even simple activities can cause fatigue or shortness of breath. Only rest brings relief.
• Class IV: Severe limitations of activities with presenting symptoms (even at rest).

This classification is helpful for adjusting treatments depending on how you’re feeling at any given time.

2. ACC/AHA Staging System

Developed by the ACC and the AHA, this system focuses on the development of heart failure over time. Once you’re diagnosed at a specific stage, you remain at that stage or may progress further⁴. Now, let us look at what the 4 stages of congestive heart failure are:

• Stage A or Stage 1 Heart Failure (Pre-Heart Failure): You do not have heart failure yet, but you have certain risk factors like high blood pressure, diabetes, or a family history.
• Stage B or Stage 2 Heart Failure (Silent Heart Failure): Changes in heart structure or function are present, but you haven’t had any symptoms.
• Stage C or Stage 3 Heart Failure (Symptomatic Heart Failure): You’ve been diagnosed and have experienced symptoms like breathlessness, fatigue, or swelling.
• Stage D or Stage 4 Heart Failure (Advanced Heart Failure): End stage heart failure symptoms persist even with treatment and may occur even while at rest or with minimal activity.

Knowing different heart failure stages is key to taking control of your health. Staging helps you and your doctor understand how much your heart is affected, so you can adjust your diet, activity, and medications to keep symptoms under control. Your stage also guides treatment choices from medications and lifestyle changes in early stages to devices or surgery in advanced cases. Understanding your stage helps you make informed decisions, set goals, and make plans for your heart health. In all, it is the first step toward better control, better care, and better living.

Diagnosis of Heart Failure

Heart failure is typically diagnosed based on a person’s symptoms and physical examination. However, some tests can help understand the underlying cause, arrive upon a potential diagnosis and guide further treatment¹⁰. Here’s how your doctor may evaluate your condition:

1. Echocardiogram (Echo)

An echocardiogram uses sound waves to create live images of the heart, showing how well it pumps and how the heart valves are functioning¹⁰.

2. Electrocardiogram (ECG or EKG)

This quick, painless test uses small sensors (electrodes) placed on your skin to measure the electrical activity of your heart, measure heartbeats, and rhythm⁴.

3. Other Imaging Tests

Various imaging tests, such as the following, may be used to assess the structure and function of the heart more in detail¹⁰:

• Chest X-ray
• Magnetic resonance imaging (MRI)
• Computed tomography scans

4. Stress Tests

These tests check how well the heart works under pressure and include¹⁰:

• Exercise stress test
• Nuclear stress test
• Stress echocardiogram

5. Blood Tests

Blood tests may help provide useful insights about your heart health. Common blood tests include¹⁰:

• Blood urea nitrogen (BUN) and creatinine to check kidney function.
• Sodium and calcium tests to ensure medications don’t disrupt electrolyte balance.
• Complete blood count (CBC) to detect anaemia (which may worsen heart failure symptoms).
• NT-PROBNP test, specifically used to diagnose and prognosticate heart failure.

Treatment Options

Heart failure is typically a lifelong condition, but with the right medical guidance, many people are able to manage symptoms and lead a fulfilling life. Below are some effective ways¹¹:

1. Lifestyle Modifications

Adopting a heart-healthy lifestyle is essential. This includes eating a balanced, low-sodium diet, exercising regularly (as advised by your doctor), losing weight, quitting smoking, limiting alcohol, and managing stress. You may also ask your doctor about cardiac rehabilitation programs that could help support these changes.

2. Medications

The majority of people with heart failure will require a combination of medications to manage symptoms and enhance heart function. Common medication classes include:

• Angiotensin converting enzyme (ACE) inhibitors
• Angiotensin receptor blockers (ARBs) and inhibitors
• Beta blockers
• Diuretics
• Mineralocorticoid receptor antagonists
• Sodium-glucose co-transporter 2 inhibitors
• Soluble guanylate cyclase (sGC) stimulators

It is important to take these medications under medical supervision to avoid potential side effects.

3. Pacemaker Therapy

A pacemaker is a small device implanted under the skin that helps maintain a regular heart rhythm, especially in those whose heart beats too slowly.

4. Cardiac Resynchronisation Therapy (CRT)

In some patients, the left and right chambers of the heart don’t beat in sync. CRT uses a special pacemaker with multiple leads to coordinate the timing of heart muscle contractions, improving the heart’s efficiency and output.

5. Implantable Cardioverter Defibrillator (ICD)

For individuals at high risk of life-threatening heart rhythms, an ICD can monitor and manage abnormal rhythms by delivering an electric shock if needed. This may help avoid sudden cardiac death.

6. Combination Devices (CRT-D)

Some patients benefit from devices that combine both CRT and defibrillator capabilities (known as CRT-Ds). These offer the dual benefits of improved pumping efficiency and protection from dangerous arrhythmias.

7. Pulmonary Artery Pressure Sensors

These are small devices implanted in the pulmonary artery to monitor heart pressures remotely. They transmit data to your doctor or his team, helping them adjust treatment before symptoms worsen.

8. Left Ventricular Assist Devices (LVADs)

In the last stages of heart failure, mechanical support devices like LVADs can help the heart pump blood. These are used either as a temporary support before a heart transplant or as a long-term management option.

9. Surgical Interventions

Surgery may be needed in certain cases or in the last stages of heart failure. Common types include:

• Valve Repair/Replacement
• Coronary Artery Bypass Grafting (CABG)
• Angioplasty with Stenting

In some cases (such as stage 4 heart failure), a heart transplant may be the only viable option^5,10.

When to Seek Medical Help?

Spotting the warning signs early can help avoid serious health complications. It’s important to stay alert to any changes in your health condition and know when to contact your doctor or seek emergency care.

Call your doctor if you notice⁵:

• Feeling unusually weak or tired
• More coughing or mucus than usual
• Sudden weight gain or swelling
• Any new or unexplained symptoms

Get emergency help right away if you⁵:

• Feel severe or crushing chest pain
• Have a fast/irregular heartbeat (with other related symptoms)
• Faint or lose consciousness

Conclusion

Managing heart failure requires a combination of lifestyle changes, regular monitoring, and the right treatment plan. It is crucial to recognise symptoms early, get a proper diagnosis, understand heart failure stages, and know when to seek medical attention, all of which are key to improving quality of life and overall outcomes. Always stay in touch with your doctor and take proactive steps toward better heart health.

Frequently Asked Questions (FAQs)

References

1. Shams P, Malik A, Chhabra L. Heart failure (congestive heart failure) [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 [updated 2025 Feb 26; cited 2025 Apr 10]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430873/

2. Savarese G, Becher PM, Lund LH, Seferovic P, Rosano GMC, Coats AJS. Global burden of heart failure: a comprehensive and updated review of epidemiology. Cardiovasc Res. 2023 Jan 18;118(17):3272-3287. doi: 10.1093/cvr/cvac013. Erratum in: Cardiovasc Res. 2023 Jun 13;119(6):1453. doi: 10.1093/cvr/cvad026. PMID: 35150240. Available from: https://pubmed.ncbi.nlm.nih.gov/35150240/

3. National Heart, Lung, and Blood Institute. Heart failure [Internet]. National Institutes of Health; [cited 2025 Apr 10]. Available from: https://www.nhlbi.nih.gov/health/heart-failure

4. Johns Hopkins Medicine. Heart failure [Internet]. Johns Hopkins University; [cited 2025 Apr 10]. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/heart-failure

5. MedlinePlus. Heart failure – congestive [Internet]. U.S. National Library of Medicine; [updated 2024 July 14; cited 2025 Apr 10]. Available from: https://medlineplus.gov/ency/article/000158.htm

6. Centers for Disease Control and Prevention (CDC). Heart failure [Internet]. CDC; [updated 2024 May 15; cited 2025 Apr 10]. Available from: https://www.cdc.gov/heart-disease/about/heart-failure.html

7. British Heart Foundation. Heart failure [Internet]. BHF; [cited 2025 Apr 10]. Available from: https://www.bhf.org.uk/informationsupport/conditions/heart-failure

8. Cleveland Clinic. Cardiotoxicity: Cancer treatment and the heart [Internet]. Cleveland Clinic; [cited 2025 Apr 11]. Available from: https://my.clevelandclinic.org/health/diseases/16858-chemotherapy–the-heart-cardiotoxicity

9. American Heart Association. Types of heart failure [Internet]. AHA; [updated 2023 Mar 23; cited 2025 Apr 10]. Available from: https://www.heart.org/en/health-topics/heart-failure/what-is-heart-failure/types-of-heart-failure

10. MedlinePlus. Heart failure – when to call the doctor [Internet]. U.S. National Library of Medicine; [updated 2022 Oct 04; cited 2025 Apr 10]. Available from: https://medlineplus.gov/ency/patientinstructions/000366.htm

11. NHS. Heart failure – Treatment [Internet]. National Health Service (UK); [updated 2022 May 19; cited 2025 Apr 10]. Available from: https://www.nhs.uk/conditions/heart-failure/treatment/

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