Can an ECG Detect Heart Failure?

Heart failure, or congestive heart failure, occurs when the heart cannot pump blood to all body parts sufficiently.. This results in fatigue, breathlessness, and fluid retention.

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Though an ECG is not the definitive test for diagnosing heart failure, it provides clues for its diagnosis. An ECG is the first test done when suspecting heart failure because of its easy availability and non-invasive nature. Further investigations confirm its severity.

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Early detection allows for timely intervention to stop heart failure from progressing. In this blog, we delve into how ECG contributes to heart failure diagnosis, its limitations, and why it is an essential tool in heart health.

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Understanding Heart Failure and How it Occurs:-

Heart failure is when the heart muscles can’t pump blood to meet the body's need for oxygen and blood. The heart tries to make up for this by:-

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• The heart tries to contract strongly to keep up with the body’s demand to pump more blood, which results in an enlarged heart.

• The heart muscles increase in mass as the contracting cells get bigger to pump more strongly.

• The heart pumps blood faster to increase the output. 

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The body tries to compensate for this by

• Narrowing blood vessels to keep blood pressure up.

• Retaining more salt and water increases blood volume and subsequently maintains blood pressure. Over time, this causes the heart to pump the extra volume, eventually overburdening it. 

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The body tries to mask problems of heart failure, but the compensatory processes do not work for long, and heart failure continues to worsen.

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Causes of heart failure

Heart failure is caused by damaged heart muscle, which occurs due to infections, alcohol use, recreational drug use, chemotherapy, and genetics.

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They cause:-

• The chambers become bigger, which means they cannot pump blood sufficiently. 

• Ventricles stiffen and cannot fill with enough blood in between the beats.

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The conditions that damage or weaken the heart and cause heart failure include:-

• Coronary artery disease and heart attack are common causes of heart failure and result from a buildup of fat deposits in the arteries. They narrow the arteries and reduce blood flow, which can lead to a heart attack. Damage to the heart muscle means the heart can no longer pump blood as it should.

• High blood pressure makes the heart work harder than it should to pump blood to the body. The extra workload weakens the heart muscles.

• Valvular heart diseases: Improperly working valves make the heart work harder to pump blood, weakening the muscles over time.

• Inflammation of the heart muscle, like myocarditis, is caused by viruses like COVID-19.

• Congenital heart defects, such as improperly formed heart structures like the valves or chambers, make the heart work harder to pump blood.

• Arrhythmias: A heart beating too fast or too slow adds extra work on the heart.

• Other diseases that can cause heart failure are diabetes, HIV infections, an overactive or underactive thyroid, or a buildup of iron.

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Symptoms of heart failure:-

• Shortness of breath.

• Swelling in the legs, ankles, and feet.

• Rapid or irregular beat.

• Fatigue and weakness.

• Rapid or irregular heartbeat.

• Reduced ability to exercise.

• Wheezing.

• Chronic coughing.

• Swelling in the abdomen.

• Rapid weight gain.

• Difficulty in alertness, such as drowsiness, trouble concentrating.

• Nausea and lack of appetite.

• Chest pain.

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Types of heart failure

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1. Right-sided heart failure affects the right ventricle. Fluid fills the abdomen, legs, and feet, causing swelling.

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2. Left-sided heart failure affects the left ventricle. Fluid fills up the lungs, causing shortness of breath.

• Heart failure with reduced ejection fraction (HFrEF) is systolic heart failure. The left ventricles cannot pump blood as strongly as they should.

•  Heart failure with preserved ejection fraction HFpEF also called diastolic heart failure. The left ventricle does not relax to fill itself.

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Heart failure and the severity of symptoms:- 

Heart failure is classified according to the severity of its symptoms. The functional classification of heart failure is:

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Class 1:

• No limitation on physical activity.

• Ordinary activities do not cause fatigue, palpitation, or dyspnea.

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Class 2:

• slight limitation of physical activity.

• comfortable at rest.

• Physical activities result in fatigue, palpitation, and dyspnea.

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Class 3

• considerable limitation of physical activity.

• comfortable at rest.

• Activities less than ordinary cause fatigue, palpitation, or dyspnea.

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Class 4

• Discomfort in carrying out any physical activity.

• Symptoms of heart failure at rest, if any physical activity is undertaken, discomfort increases.

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Stages of heart failure-

Heart failure is a chronic condition that worsens with time.

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Stage A: (At risk for heart failure): One has a high risk of developing heart failure.

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If they have 

• Diabetes.

• Hypertension.

• History of alcohol use.

• Coronary heart disease.

• Rheumatic fever.

• Family history of cardiomyopathy.

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Stage B: (Pre-heart failure), the structure of the ventricle becomes abnormal, it does not work well, and has no symptoms of heart failure.

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Stage C: (Symptomatic heart failure) A congestive heart failure is diagnosed with the presence of current or previous signs and symptoms.  

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Stage D: (Advanced heart failure) and reduced EF (ejection fraction), people who suffer from stage DHFrEF (heart failure with reduced ejection fraction) have advanced symptoms that do not improve with treatment. Management involves improving the quality of life.

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Diagnosis of chronic heart failure:-

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It is based on

• Medical history.

• Physical examination.

• Blood tests.

• 12-lead resting ECG.

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Medical history

A patient may give a history of shortness of breath, fatigue, swelling in the legs or abdomen, and rapid weight gain. He may also have a history of high blood pressure, coronary artery disease, diabetes, or lifestyle diseases.

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Physical examination may reveal swelling in the abdomen or feet. The heart and lung sounds may be abnormal.

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Laboratory tests

• Elevated Pro BNP or NTpro BNP test.

• CBC identifies anaemia or infection.

• Kidney and liver function tests, along with electrolyte and blood glucose levels.

• Thyroid function test, as some thyroid disorders mimic heart failure symptoms.

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Imaging test:-

• An electrocardiogram records the electrical activity within the heart to detect arrhythmias, old heart attack, or other abnormalities.

• An echocardiogram gives information about the heart's size, function, and ejection fraction.

• Chest X-ray helps to identify heart enlargement and fluid accumulation in the lungs.

• A stress test evaluates how the heart works under physical stress.

• Cardiac MRI or CT scan provides images of the heart structure and function.

• Coronary angiography is an invasive procedure to visualise coronary arteries and is done when blockages are suspected.

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Role of ECG in Detecting Heart Failure:-

ECGs have a high sensitivity and can detect the signs of heart failure.

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What can an ECG detect?

An ECG can detect heart rate, rhythm, and electrical impulses.

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It detects

• Arrhythmias are irregular heart rhythms, such as atrial fibrillation and ventricular tachycardia.

• Cardiomyopathy refers to an enlarged heart.

• Ischemia is reduced blood flow to the heart muscles, indicating coronary artery disease.

• Heart attack

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What an ECG does not detect:-

An ECG cannot diagnose heart failure specifically or tell about the heart.

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• Pumping efficiency.

• Overall structural health.

• Reasons for changes in heart rhythm or electrical activity.

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                                      ECG findings in heart failure   

• Tachycardia, a fast heartbeat
• Atrial fibrillation
• Left axis deviation due to ventricular hypertrophy
• P wave abnormalities
• Prolonged PR interval due to atrioventricular block
• Wide QRS complex > 120ms

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Complications:-

They depend on age, overall health, and severity of the disease. The complications include:-

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• Heart failure reduces the blood flow to the kidneys. When left untreated, it may cause kidney failure.

• Heart failure damages the heart's size and function, damaging heart valves and causing irregular heartbeats.

• Liver damage is also caused by heart failure.

• Sudden cardiac death.

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Prevention

Heart failure can be prevented by treating the underlying condition that causes it, and a healthy lifestyle also helps in its management.

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• Avoid smoking.

• Be regular in exercises.

• Eat healthy food.

• Keep your weight in check.

• manage stress.

• Be regular in taking your medicines .

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Conclusion

ECG is a valuable tool to diagnose heart conditions, but for heart failure, it provides clues for its diagnosis. Other tests need to be done along with an ECG to confirm a diagnosis.

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Medications and lifestyle changes play a role in improving the outcome. Gauze can help you with diagnosis and treatment. It provides a comprehensive diagnosis and treatment for heart failure.