Heart Failure

Overview

Heart failure, also known as congestive heart failure (CHF), is a chronic, progressive condition in which the heart muscle is unable to pump blood efficiently enough to meet the body’s demands for blood and oxygen. Despite its name, heart failure does not mean the heart has stopped working entirely—rather, it indicates that the heart’s pumping power is weaker than normal or the heart has become too stiff to fill properly.

Heart failure affects approximately 64 million people worldwide and is one of the leading causes of hospitalization in adults over 65 years of age. In the United States alone, about 6.7 million adults are living with heart failure, with nearly 1 million new cases diagnosed each year. The condition significantly impacts quality of life and carries a substantial mortality risk, with approximately 50% of people diagnosed with heart failure dying within five years.

Heart failure is typically a progressive condition that develops over time as the heart gradually loses its pumping capacity. However, with proper treatment, lifestyle modifications, and medical management, many people with heart failure can lead active, fulfilling lives.

How the Heart Works

To understand heart failure, it’s helpful to understand how a healthy heart functions. The heart is a muscular organ roughly the size of a fist, located slightly left of center in the chest. It consists of four chambers: two upper chambers (atria) and two lower chambers (ventricles).

The right side of the heart receives oxygen-poor blood from the body through the veins and pumps it to the lungs, where it picks up oxygen and releases carbon dioxide. The left side receives oxygen-rich blood from the lungs and pumps it through the arteries to supply tissues throughout the body. In a healthy adult at rest, the heart pumps approximately 5 liters of blood per minute.

When heart failure develops, this efficient pumping mechanism becomes compromised. The heart may become too weak to pump effectively (systolic dysfunction), too stiff to fill properly (diastolic dysfunction), or both. As a result, blood may back up in the lungs, liver, gastrointestinal tract, and extremities, causing the congestion that gives congestive heart failure its name.

Types of Heart Failure

Left-Sided Heart Failure

Left-sided heart failure is the most common type and occurs when the left ventricle—the heart’s main pumping chamber—cannot pump blood efficiently to the rest of the body. This causes blood to back up into the lungs, leading to shortness of breath and fluid accumulation (pulmonary congestion). Left-sided heart failure is further classified into two subtypes based on the ejection fraction (EF), which measures the percentage of blood pumped out of the left ventricle with each contraction:

Heart Failure with Reduced Ejection Fraction (HFrEF)

Also called systolic heart failure, HFrEF occurs when the left ventricle loses its ability to contract normally and cannot pump with enough force. The ejection fraction is 40% or less (normal EF is 55-70%). The heart muscle has become weakened, and each beat pumps less blood than it should. This is the classic form of heart failure that most people envision when they hear the term.

Heart Failure with Preserved Ejection Fraction (HFpEF)

Also called diastolic heart failure, HFpEF occurs when the left ventricle loses its ability to relax normally due to stiffening of the muscle. The heart can contract and pump blood adequately (ejection fraction is 50% or higher), but it cannot properly fill with blood during the resting phase between beats. HFpEF is more common in older adults, women, and people with conditions such as high blood pressure, obesity, and diabetes.

Heart Failure with Mid-Range Ejection Fraction (HFmrEF)

This category, sometimes called heart failure with mildly reduced ejection fraction, includes patients with an ejection fraction between 41-49%. This classification recognizes that some patients fall between the traditional categories and may have characteristics of both HFrEF and HFpEF.

Right-Sided Heart Failure

Right-sided heart failure occurs when the right ventricle loses its pumping power. The right ventricle is responsible for pumping blood to the lungs to pick up oxygen. When it fails, blood backs up in the veins, causing swelling (edema) in the legs, ankles, feet, abdomen, and sometimes the liver.

Right-sided heart failure most commonly occurs as a result of left-sided heart failure. When the left side fails, increased fluid pressure is transferred back through the lungs, ultimately damaging the right side of the heart. Right-sided heart failure can also be caused by lung diseases such as chronic obstructive pulmonary disease (COPD) or pulmonary hypertension.

Biventricular Heart Failure

Biventricular heart failure occurs when both the left and right sides of the heart are affected. This typically happens when heart failure has progressed, and both ventricles are unable to pump effectively. Patients with biventricular failure experience symptoms related to both pulmonary congestion (shortness of breath) and systemic venous congestion (peripheral edema).

Acute vs. Chronic Heart Failure

Acute heart failure refers to the rapid onset or worsening of heart failure symptoms, often requiring emergency medical attention and hospitalization. It can occur in someone with no prior history of heart problems (de novo acute heart failure) or as a sudden worsening of existing chronic heart failure (acute decompensation).

Chronic heart failure is a long-term condition that develops gradually over months or years. Symptoms may remain stable for extended periods but can worsen over time. Most people with heart failure have the chronic form and require ongoing management.

Causes and Risk Factors

Common Causes of Heart Failure

Coronary Artery Disease (CAD)

Coronary artery disease is the most common cause of heart failure. CAD occurs when the arteries that supply blood to the heart become narrowed or blocked by atherosclerosis (buildup of fatty plaques). This reduces blood flow to the heart muscle, which can weaken it over time. A heart attack (myocardial infarction) occurs when a coronary artery becomes completely blocked, causing part of the heart muscle to die. The damaged tissue can no longer contribute to the heart’s pumping function, increasing the risk of heart failure.

High Blood Pressure (Hypertension)

When blood pressure is elevated, the heart must work harder to pump blood throughout the body. Over time, this increased workload causes the heart muscle to thicken and stiffen (left ventricular hypertrophy), eventually leading to heart failure. Uncontrolled hypertension is a major risk factor for both HFrEF and HFpEF.

Cardiomyopathy

Cardiomyopathy refers to diseases of the heart muscle that make it harder for the heart to pump blood. Types include:

• Dilated cardiomyopathy: The heart chambers enlarge and weaken, reducing pumping efficiency
• Hypertrophic cardiomyopathy: The heart muscle thickens abnormally, often due to genetic factors
• Restrictive cardiomyopathy: The heart muscle becomes rigid and less elastic, impairing filling
• Arrhythmogenic cardiomyopathy: Heart muscle is replaced by fatty or fibrous tissue, causing arrhythmias

Valvular Heart Disease

The heart has four valves that keep blood flowing in the correct direction. When these valves are damaged or diseased—due to infection, congenital defects, or degenerative changes—the heart must work harder to pump blood. Valve stenosis (narrowing) or regurgitation (leaking) can eventually lead to heart failure.

Arrhythmias

Abnormal heart rhythms, particularly chronic rapid heart rates (tachycardia) or atrial fibrillation, can weaken the heart over time. When the heart beats too fast, it may not fill adequately between beats. When it beats too slowly or irregularly, it may not pump enough blood to meet the body’s needs.

Other Causes

• Congenital heart defects: Heart abnormalities present at birth
• Myocarditis: Inflammation of the heart muscle, often caused by viral infections
• Diabetes mellitus: Increases the risk of heart disease and can directly damage the heart muscle
• Thyroid disorders: Both overactive and underactive thyroid can affect heart function
• Chemotherapy and radiation: Certain cancer treatments can damage the heart
• Alcohol and substance abuse: Excessive alcohol consumption can lead to alcoholic cardiomyopathy
• Sleep apnea: Untreated sleep apnea contributes to hypertension and heart stress
• Viral infections: Including COVID-19, which has been associated with cardiac complications

Risk Factors

Several factors increase the likelihood of developing heart failure:

• Age: Risk increases significantly after age 65
• Sex: Men have a higher incidence, but women are more likely to develop HFpEF
• Race: African Americans have a higher risk and often develop heart failure at younger ages
• Family history: Genetic predisposition plays a role, especially in cardiomyopathies
• Obesity: Excess weight strains the heart and contributes to other risk factors
• Smoking: Damages blood vessels and contributes to coronary artery disease
• Sedentary lifestyle: Physical inactivity contributes to obesity, hypertension, and diabetes
• Unhealthy diet: High sodium, saturated fat, and processed food consumption
• Chronic kidney disease: Often coexists with heart failure and worsens outcomes

Signs and Symptoms

Heart failure symptoms can develop gradually or appear suddenly, depending on the underlying cause and whether the condition is acute or chronic. Symptoms may be constant or may come and go. The severity of symptoms often correlates with the degree of heart function impairment.

Common Symptoms

• Dyspnea (Shortness of breath): May occur during activity, at rest, or when lying flat (orthopnea). Paroxysmal nocturnal dyspnea refers to sudden breathlessness that wakes a person from sleep
• Fatigue and weakness: Feeling tired and lacking energy, even with minimal exertion
• Edema (Swelling): Fluid buildup in the legs, ankles, feet, or abdomen (ascites)
• Rapid or irregular heartbeat: Palpitations or a sensation of the heart racing or pounding
• Persistent cough or wheezing: Often producing white or pink blood-tinged mucus
• Reduced ability to exercise: Decreased exercise tolerance and stamina
• Rapid weight gain: From fluid retention (2-3 pounds in 24 hours or 5 pounds in a week may indicate worsening heart failure)
• Nausea and lack of appetite: Reduced blood flow to the digestive system can cause these symptoms
• Difficulty concentrating: Reduced blood flow to the brain may cause confusion or impaired thinking
• Increased need to urinate at night (nocturia): Fluid that accumulated during the day is processed when lying down

Symptoms Requiring Immediate Medical Attention

• Sudden, severe shortness of breath
• Chest pain or pressure
• Fainting or severe weakness
• Rapid or irregular heartbeat with shortness of breath, chest pain, or fainting
• Coughing up pink, foamy mucus
• Sudden swelling in legs or abdomen

Classification and Staging

Heart failure is classified using several systems that help healthcare providers assess severity and guide treatment decisions.

New York Heart Association (NYHA) Functional Classification

The NYHA classification categorizes heart failure based on symptom severity and functional limitations:

• Class I: No limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, or dyspnea
• Class II: Slight limitation of physical activity. Comfortable at rest, but ordinary physical activity results in fatigue, palpitation, or dyspnea
• Class III: Marked limitation of physical activity. Comfortable at rest, but less than ordinary activity causes fatigue, palpitation, or dyspnea
• Class IV: Unable to carry on any physical activity without discomfort. Symptoms of heart failure present at rest. If any physical activity is undertaken, discomfort increases

ACC/AHA Stages of Heart Failure

The American College of Cardiology (ACC) and American Heart Association (AHA) staging system emphasizes the progressive nature of heart failure:

• Stage A (At Risk): High risk for heart failure but no structural heart disease or symptoms. Includes patients with hypertension, diabetes, obesity, coronary artery disease, or family history of cardiomyopathy
• Stage B (Pre-Heart Failure): Structural heart disease (such as reduced ejection fraction, left ventricular hypertrophy, or valvular disease) but no signs or symptoms of heart failure
• Stage C (Symptomatic Heart Failure): Structural heart disease with prior or current symptoms of heart failure
• Stage D (Advanced Heart Failure): Refractory heart failure requiring specialized interventions such as mechanical circulatory support, continuous inotropic therapy, cardiac transplantation, or palliative care

Diagnosis

Diagnosing heart failure involves a combination of medical history review, physical examination, and various diagnostic tests.

Physical Examination

During a physical exam, the healthcare provider will:

• Listen to the heart for abnormal sounds (murmurs, gallops) using a stethoscope
• Listen to the lungs for signs of fluid accumulation (crackles or rales)
• Check for swelling in the legs, ankles, abdomen, and neck veins (jugular venous distention)
• Assess vital signs including blood pressure and heart rate
• Evaluate for signs of poor circulation such as cool extremities

Blood Tests

• B-type Natriuretic Peptide (BNP) or NT-proBNP: These biomarkers are released when the heart is stressed or stretched. Elevated levels strongly suggest heart failure and help assess severity
• Complete blood count (CBC): To check for anemia, which can worsen heart failure symptoms
• Metabolic panel: To assess kidney and liver function, electrolytes, and blood glucose
• Thyroid function tests: To rule out thyroid disorders as a contributing cause
• Lipid profile: To evaluate cardiovascular risk factors
• Cardiac troponins: To detect heart muscle damage

Imaging Studies

Echocardiogram

The echocardiogram is the most important imaging test for heart failure diagnosis. This ultrasound of the heart provides information about heart size, structure, and function, including the ejection fraction. It can identify valve problems, wall motion abnormalities, and pericardial disease.

Chest X-ray

A chest X-ray can show the size and shape of the heart and detect fluid in or around the lungs (pulmonary edema or pleural effusions). It can also reveal other conditions that may be causing symptoms.

Electrocardiogram (ECG/EKG)

An ECG records the electrical activity of the heart and can detect arrhythmias, prior heart attacks, and other abnormalities that may contribute to or result from heart failure.

Cardiac MRI

Cardiac magnetic resonance imaging provides detailed images of the heart’s structure and function. It is particularly useful for identifying the underlying cause of heart failure, such as cardiomyopathy, myocarditis, or infiltrative diseases.

Coronary Angiography

This invasive procedure uses contrast dye and X-rays to visualize the coronary arteries and identify blockages. It may be performed if coronary artery disease is suspected as the cause of heart failure.

Nuclear Imaging Studies

Tests such as MUGA (multigated acquisition) scan or myocardial perfusion imaging can assess heart function and blood flow to the heart muscle.

Other Diagnostic Tests

• Stress testing: Evaluates how the heart responds to physical exertion and can help assess functional capacity
• Holter monitor or event recorder: Continuous ECG monitoring to detect arrhythmias
• Cardiac catheterization: Measures pressures inside the heart chambers and may include coronary angiography
• Endomyocardial biopsy: Rarely needed, but may be performed to diagnose specific causes of cardiomyopathy

Complications

Heart failure can lead to numerous complications affecting multiple organ systems:

Kidney Damage or Failure

Heart failure reduces blood flow to the kidneys, which can cause kidney damage over time. Kidney dysfunction can worsen heart failure by causing fluid retention and electrolyte imbalances. This bidirectional relationship is often called cardiorenal syndrome.

Liver Damage

Fluid backup from right-sided heart failure can cause the liver to become congested (congestive hepatopathy). Over time, this can lead to liver scarring (cardiac cirrhosis) and impaired liver function.

Arrhythmias

Heart failure increases the risk of dangerous heart rhythm disturbances, including atrial fibrillation and ventricular arrhythmias. These arrhythmias can worsen heart failure symptoms and increase the risk of stroke and sudden cardiac death.

Sudden Cardiac Death

People with heart failure, particularly those with reduced ejection fraction, are at increased risk of sudden cardiac death due to ventricular arrhythmias. Implantable cardioverter-defibrillators (ICDs) can reduce this risk in appropriate candidates.

Pulmonary Hypertension

Chronic elevation of pressures in the left side of the heart can lead to increased pressure in the pulmonary arteries, causing pulmonary hypertension. This places additional strain on the right ventricle and can worsen overall heart function.

Cachexia (Cardiac Wasting)

Advanced heart failure can cause severe weight loss and muscle wasting due to metabolic changes, reduced appetite, and impaired nutrient absorption. Cardiac cachexia is associated with poor prognosis.

Depression and Anxiety

Living with a chronic condition like heart failure significantly increases the risk of depression and anxiety. These mental health conditions can affect medication adherence, lifestyle behaviors, and overall quality of life.

Treatment and Management

Heart failure treatment aims to improve symptoms, slow disease progression, reduce hospitalizations, and prolong survival. Treatment is individualized based on the type and stage of heart failure, underlying causes, and patient characteristics.

Medications

First-Line Medications for HFrEF

Current guidelines recommend four pillars of medical therapy for patients with heart failure with reduced ejection fraction:

• ACE Inhibitors/ARBs/ARNIs: Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) reduce the effects of hormones that worsen heart failure. Angiotensin receptor-neprilysin inhibitors (ARNIs), such as sacubitril/valsartan, have been shown to be superior to ACE inhibitors in reducing death and hospitalization
• Beta-blockers: Medications such as carvedilol, metoprolol succinate, and bisoprolol slow the heart rate, reduce blood pressure, and improve heart function over time. They have been proven to reduce mortality in heart failure patients
• Mineralocorticoid Receptor Antagonists (MRAs): Spironolactone and eplerenone block the effects of aldosterone, reducing fluid retention and providing survival benefits
• SGLT2 Inhibitors: Originally developed for diabetes, medications like dapagliflozin and empagliflozin have shown significant benefits in heart failure patients, reducing hospitalizations and cardiovascular death regardless of diabetes status

Additional Medications

• Diuretics: Loop diuretics (furosemide, bumetanide, torsemide) help remove excess fluid and relieve congestion. They are essential for symptom relief but do not improve survival
• Digoxin: May help control heart rate and reduce hospitalizations in some patients
• Hydralazine and Isosorbide Dinitrate: This combination is particularly beneficial in African American patients and those who cannot tolerate ACE inhibitors or ARBs
• Ivabradine: Slows heart rate in patients who remain symptomatic despite optimal beta-blocker therapy
• Vericiguat: A newer medication for patients with worsening chronic heart failure

Medications for HFpEF

Treatment options for heart failure with preserved ejection fraction have historically been limited, but recent trials have shown benefits with SGLT2 inhibitors. Diuretics are used for symptom relief, and treatment of underlying conditions (hypertension, atrial fibrillation, coronary artery disease) is essential.

Device Therapy

Implantable Cardioverter-Defibrillator (ICD)

An ICD is a small device implanted in the chest that monitors heart rhythm and delivers electrical shocks if dangerous arrhythmias are detected. ICDs are recommended for primary prevention of sudden cardiac death in patients with ejection fraction ≤35% despite optimal medical therapy.

Cardiac Resynchronization Therapy (CRT)

CRT, also known as biventricular pacing, uses a specialized pacemaker to coordinate the contractions of the left and right ventricles. It is indicated for patients with heart failure, reduced ejection fraction, and widened QRS complex on ECG. CRT can improve symptoms, quality of life, and survival in appropriate candidates.

Left Ventricular Assist Device (LVAD)

An LVAD is a mechanical pump implanted in the chest that helps the weakened left ventricle pump blood to the body. LVADs may be used as a bridge to heart transplantation or as destination therapy for patients who are not transplant candidates.

Surgical Options

Coronary Artery Bypass Grafting (CABG)

If coronary artery disease is the underlying cause of heart failure, bypass surgery may improve blood flow to the heart muscle and potentially improve heart function.

Valve Repair or Replacement

If heart failure is caused by or worsened by valvular heart disease, surgical or percutaneous valve repair or replacement may be beneficial.

Heart Transplantation

For patients with end-stage heart failure who have failed other treatments, heart transplantation offers the best chance for long-term survival. However, donor hearts are scarce, and not all patients are suitable candidates. Post-transplant survival rates have improved significantly, with many patients living 10-15 years or longer.

Lifestyle Modifications

Lifestyle changes are a critical component of heart failure management:

Sodium Restriction

Limiting sodium intake helps reduce fluid retention and ease the workload on the heart. Most guidelines recommend limiting sodium to 1,500-2,000 mg per day. Patients should avoid processed foods, canned goods, and restaurant meals, which tend to be high in sodium.

Fluid Management

Some patients may need to restrict fluid intake, typically to 1.5-2 liters per day, especially during periods of decompensation. Daily weight monitoring helps detect fluid retention early.

Physical Activity

Despite fatigue, regular physical activity is important for maintaining functional capacity and quality of life. Cardiac rehabilitation programs provide supervised exercise training tailored to the individual patient’s abilities and limitations.

Weight Management

Maintaining a healthy weight reduces the strain on the heart. Both obesity and unintentional weight loss (cachexia) are associated with worse outcomes in heart failure.

Smoking Cessation

Smoking damages blood vessels and worsens heart disease. Quitting smoking is one of the most important steps a patient can take to improve heart health.

Alcohol Limitation

Excessive alcohol can weaken the heart muscle and worsen heart failure. Patients should limit alcohol consumption or avoid it entirely, especially if alcoholic cardiomyopathy is the underlying cause.

Medication Adherence

Taking medications as prescribed is essential for optimal heart failure management. Missing doses can lead to worsening symptoms and increased risk of hospitalization.

Self-Monitoring

Patients with heart failure should monitor themselves for signs of worsening condition:

• Daily weight checks at the same time each day
• Monitoring for increased swelling in legs, ankles, or abdomen
• Tracking symptoms such as shortness of breath, fatigue, and exercise tolerance
• Regular blood pressure monitoring
• Recognizing warning signs that require medical attention

Prognosis

The prognosis for heart failure varies widely depending on several factors, including the underlying cause, ejection fraction, functional class, comorbidities, and response to treatment. While heart failure remains a serious condition, advances in medical therapy, device technology, and surgical options have significantly improved outcomes over the past decades.

Key prognostic indicators include:

• Ejection fraction (lower EF generally indicates worse prognosis)
• NYHA functional class
• BNP or NT-proBNP levels
• Kidney function
• Exercise capacity
• Age and comorbid conditions
• Response to guideline-directed medical therapy

With optimal treatment, many patients with heart failure can live for years with good quality of life. However, heart failure remains a leading cause of death and hospitalization, emphasizing the importance of prevention, early detection, and adherence to treatment.

Prevention

Many cases of heart failure can be prevented or delayed by addressing modifiable risk factors:

• Control blood pressure: Maintaining blood pressure within normal limits reduces the risk of heart damage
• Manage cholesterol: Keeping cholesterol levels in check helps prevent coronary artery disease
• Control diabetes: Good glycemic control reduces the risk of cardiovascular complications
• Maintain a healthy weight: Achieving and maintaining a healthy BMI reduces cardiac workload
• Exercise regularly: Physical activity strengthens the heart and improves overall cardiovascular health
• Eat a heart-healthy diet: Emphasize fruits, vegetables, whole grains, lean proteins, and healthy fats while limiting sodium, saturated fats, and processed foods
• Avoid tobacco: Smoking cessation significantly reduces cardiovascular risk
• Limit alcohol: Moderate alcohol consumption and avoid binge drinking
• Manage stress: Chronic stress can contribute to high blood pressure and unhealthy behaviors
• Get adequate sleep: Treat sleep disorders such as sleep apnea
• Stay current with vaccinations: Influenza and pneumococcal vaccines are recommended for heart failure patients
• Regular health screenings: Early detection and treatment of conditions that can lead to heart failure

Living with Heart Failure

A diagnosis of heart failure can be life-changing, but with proper management, many people continue to lead active and meaningful lives. Key aspects of living well with heart failure include:

Building a Healthcare Team

Heart failure management often requires a multidisciplinary approach, including cardiologists, heart failure specialists, primary care physicians, nurses, pharmacists, dietitians, and cardiac rehabilitation specialists. Regular follow-up appointments are essential for monitoring disease progression and adjusting treatment.

Education and Self-Management

Understanding heart failure empowers patients to recognize warning signs, adhere to treatment plans, and make informed decisions about their care. Many hospitals and clinics offer heart failure education programs.

Emotional Support

Living with a chronic condition can take an emotional toll. Patients should not hesitate to seek support from mental health professionals, support groups, family, and friends. Depression and anxiety are common in heart failure patients and should be addressed as part of comprehensive care.

Advance Care Planning

Heart failure is a progressive condition, and patients should have conversations with their healthcare providers and loved ones about their goals of care and preferences for end-of-life care. Advance directives and healthcare proxies ensure that patients’ wishes are respected.

Palliative Care

Palliative care focuses on improving quality of life for patients with serious illnesses. It can be provided alongside curative treatments and is not limited to end-of-life care. Palliative care specialists can help manage symptoms, provide emotional support, and assist with complex decision-making.

Conclusion

Heart failure is a complex, chronic condition that affects millions of people worldwide. While it poses significant challenges, remarkable advances in understanding, prevention, and treatment have transformed heart failure from a uniformly fatal diagnosis to a manageable chronic condition for many patients. Early recognition of risk factors, prompt diagnosis, adherence to guideline-directed medical therapy, appropriate device and surgical interventions, and comprehensive lifestyle modifications form the foundation of successful heart failure management.

The key to living well with heart failure lies in a collaborative partnership between patients, families, and healthcare providers. Through education, self-monitoring, medication adherence, and lifestyle changes, patients can optimize their quality of life and outcomes. Ongoing research continues to advance our understanding of heart failure and develop new therapeutic options, offering hope for even better outcomes in the future.

This glossary entry is for educational purposes only and should not replace professional medical advice. If you have symptoms of heart failure or have been diagnosed with this condition, please work closely with your healthcare provider to develop an individualized treatment plan.