Overview

Heart enlargement, also known as cardiomegaly, is defined when the width of the heart exceeds 50% of the chest width on a chest X-ray (a cardiothoracic ratio of over 50%). It is usually a product of an underlying health problem and is often linked to different types of heart muscle diseases, whether inherited or developed over time. Heart failure is a chronic condition where the heart muscle becomes less efficient at pumping blood around the body. 

Cardiomegaly is often a precursor to heart failure. It is a compensatory mechanism whereby the enlargement alters the heart structure, both thinning and stretching the heart muscle to meet the body’s demands. However, this impairs its ability to pump blood properly, eventually causing heart failure. 

Recognising the signs of progressive heart failure in individuals with an enlarged heart can be crucial for rapid intervention, effective treatment, and improved quality of life. This article will explore the key symptoms to watch for in those who face heart enlargement and the risk of heart failure.¹

Understanding heart enlargement

As previously mentioned, cardiomegaly is defined by a cardiothoracic ratio of over 50%. It can be due to the enlargement of the ventricles or the atria. Most cardiomyopathies are characterised by left ventricular dilation since it is the heart’s main pumping chamber, and therefore responsible for pumping oxygenated blood to the entire body. Furthermore, this ventricle has the highest workload of all the heart’s chambers and is more susceptible to remodelling to compensate for the heart’s reduced ability to pump blood effectively.²

Another cardiomyopathic characteristic is systolic dysfunction. In a healthy heart, systolic function refers to the ability of the heart to contract and pump blood out to the body. However, in cardiomegaly, the heart’s contractile ability is impaired, meaning less blood leaves the heart to meet the body’s demands.³

While these are the two major characteristics of cardiomyopathies, right ventricular impairment and diastolic dysfunction can also emerge.¹

What contributes to cardiomegaly?

It is important to remember that cardiomegaly isn’t a disease on its own. Rather, it’s a sign of an underlying heart condition or defect that induces a compensatory mechanism to work harder, such as:

• High blood pressure
• Hypertension
• Anaemia
• Myocarditis
• Heart valve disease
• Coronary artery disease
• Substance abuse
• Obesity
• Diabetes
• Pregnancy
• Heart attacks

The treatments for cardiomegaly depend upon the causes. This might include lifestyle changes, such as improving diet and regularly exercising. Other treatments may involve surgery. For example, for heart valve disease, surgery may be performed to repair the affected valve. This would restore efficient systolic function and reduce the need for the heart muscle to remodel. Coronary artery bypass graft (CABG) surgery may be performed for coronary artery disease.⁴

Overview of progressive heart failure

Progressive heart failure is a clinical syndrome caused by functional or structural abnormalities of the heart, which results in ineffective cardiac output or an increase in ventricular filling pressures. While the prevalence of heart failure increases with age, advancements in its treatment have led to increased survival rates.⁵

Several classification systems are used to categorise heart failure stages, allowing for prognostic insight and healthcare specialists to determine the best course of treatment. The most popular one is the American College of Cardiology and American Heart Association stages:

• Stage A – the patient is at risk of heart failure. The patient has no symptoms, evidence of increased cardiac biomarkers, or structural heart disease. However, this stage is determined by risk factors, such as hypertension (high blood pressure), diabetes, or being genetically predisposed to cardiomyopathy
• Stage B – this is known as pre-heart failure. Patients from this category also present with no symptoms of heart failure, but have structural heart disease or high levels of cardiac biomarkers
• Stage C – the patient has structural heart disease and a history of heart failure symptoms
• Stage D – the patient presents with heart failure symptoms that interfere with daily life or cause recurrent hospitalisation, despite receiving targeted therapies⁶

Therefore, early detection and treatment of cardiomegaly are important to prevent or slow the progression of heart failure. 

Common symptoms of progressive heart failure in individuals with heart enlargement

Since cardiomegaly can progress to heart failure, the following symptoms typically worsen over time. The ability of the heart to pump blood effectively is significantly reduced, contributing to many of these symptoms. Therefore, early detection and changes to lifestyle habits for people with cardiomegaly are vital for slowing the progression to heart failure. Early symptoms can include:

• Shortness of breath
• Fatigue and weakness
• Chest pain 
• Persistent cough
• Irregular heartbeat
• Swelling of the legs, ankles, and feet
• Dizziness⁷

Diagnosing progressive heart failure in individuals with heart enlargement

It is important to know that the term ‘heart failure’ does not truly refer to the heart ‘failing’ to function, which would cause death, but rather results in the heart having a limited capacity to increase its output to meet the body’s demand for oxygen. The heart can still meet basic needs, providing enough blood for organs to function. Nevertheless, progressive heart failure in individuals with heart enlargement can be diagnosed by:⁸

• Medical history can determine the stage of heart failure since stages C and D mean patients have pre-existing cardiomyopathies or have presented with symptoms of heart failure
• An echocardiogram with Doppler flow studies allows specialists to determine the severity of the disease and informs them which chambers of the heart are involved. This method also allows experts to identify the abnormalities of the heart, whether it is muscle texture, pericardium, or heart valves
• Blood test for the presence of elevated biomarkers, such as BNP, that are associated with heart failure

Treatment and management options

ACE inhibitors

ACE inhibitors have been well-described for the effective treatment of cardiomegaly. Left ventricular hypertrophy is associated with a variety of complications, such as arrhythmias, ischemic heart disease, and congestive heart failure. However, this class of drugs has been associated with restoring and maintaining normal coronary flow. This means they can reduce the workload on an enlarged heart, improving its function.

Beta-blockers

Beta-blockers have been FDA-approved for a variety of heart-related diseases, such as hypertension, congestive heart failure, coronary heart disease, and tachycardia. Beta-blockers are so-called because they bind to beta receptors, preventing them from increasing blood pressure. 

Binding to beta-2 receptors causes smooth muscles in the heart to relax, reducing cardiac output. Beta-blockers can also bind to alpha receptors, which would otherwise induce vasoconstriction, causing higher blood pressure and a higher heart rate.⁸

Lifestyle modifications

Medical professionals do not have many guidelines for advising lifestyle modifications when giving non-pharmacological treatments. Only brief recommendations are advised, such as avoiding excessive salt intake (reduces congestive symptoms), maintaining a healthy body weight, and undertaking regular exercise (this rehabilitates the heart’s functional capacity).⁹

Summary

Cardiomegaly, or an enlarged heart, is often caused by underlying conditions such as heart valve disease or cardiomyopathy. Initially, cardiomegaly works as a temporary compensatory mechanism to help the heart meet the body’s demands, remodelling the muscles to ensure blood can be pumped out effectively. However, over time, this weakens the heart’s capacity to pump blood properly and therefore poses as a precursor for heart failure. 

Progressive heart failure is a chronic condition that gradually worsens the heart’s structure and function. Therefore, it is important to be aware of its symptoms, such as shortness of breath, fatigue, and chest pain, to enable early diagnosis and intervention, which favours an improved survival rate. Treatment options for cardiomegaly and heart failure are abundant. ACE inhibitors and beta-blockers are the most well-described since they can effectively reduce blood pressure and heart rate, reducing the need for the heart’s compensatory mechanisms to exist.