Originally designed to check if a patient was rejecting a heart transplant, an endomyocardial biopsy, or an EBM, has also become a method of diagnosing heart diseases and disorders when other methods are not able to. With the technological progress in this procedure over the years, its diagnostic accuracy has greatly improved.¹ If a patient has an enlarged heart, it is vital to identify the cause in order to treat it. If other diagnostic procedures are not successful, a healthcare professional may prescribe an endomyocardial biopsy. However, unlike these other diagnostic methods, such as a heart MRI or PET scan, an EMB can present complications, and it is for this reason that its use in diagnosing heart problems can be seen as controversial.²

What is an endomyocardial biopsy?

An endomyocardial biopsy (EBM), also sometimes referred to as a cardiac biopsy or a heart biopsy, was originally designed in the 60’s to determine if a patient’s body was rejecting their heart transplant, and to monitor it if so. However, over recent decades, it has emerged as a useful way to diagnose heart problems that cannot be diagnosed using other methods or procedures.¹ 

In an EMB procedure, a sample of myocardial tissue (tissue from the heart’s muscular layer) is removed to be tested. Usually, this procedure is carried out in a catheter laboratory in a hospital, and lasts around half an hour. Whilst you are lying down with an X-ray machine above you, a sheath (plastic tube) is inserted into a vein using a needle – a local anaesthetic will be applied before. The needle will normally be inserted into the internal jugular vein in the neck if a sample is being taken from the right ventricle (chamber) of the heart, or into the femoral artery in the groin if a sample is being taken from the left ventricle.³ Small samples of the myocardium (heart muscle) will then be removed using biopsy forceps and x-ray guidance. A chest x-ray will usually be carried out after the procedure.

What is heart enlargement?

Some causes of heart enlargement include:

• Coronary artery disease
• Arrythmia
• Cardiomyopathy 
• Congenital heart disease
• Myocarditis
• Heart valve disease

Endomyocardial biopsy in the context of heart enlargement

The cause of heart enlargement must be identified as swiftly as possible in order to decide on the best treatment approach. When non-invasive diagnostic procedures cannot form an accurate, clinical diagnosis, an endomyocardial biopsy may be recommended to identify why a patient’s heart is enlarged. 

Whilst an endomyocardial biopsy is considered a fairly safe procedure, this can depend on certain factors, and there are risks attached. 

Risks of an endomyocardial biopsy 

Endomyocardial biopsies can present a long list of potential complications. The likelihood and severity of these depend on the patient’s health condition, the level of experience of the professional conducting the procedure, the site where the needle is inserted, and whether the sample is taken from the right or left ventricle (chamber).⁴

The potential complications of an EBM procedure can include: 

• A collapsed lung 
• An abnormal heart rhythm (arrhythmia)
• Perforation of the heart ventricle’s (chamber) wall
• Fluid in the sac surrounding the heart 
• Pericardial/cardiac tamponade: fluid build-up in the sac surrounding the heart compressing the heart
• A defect in the connection between the heart chamber and coronary arteries (fistula) /in the connection of vessels in the brain/spinal cord surrounding tissue
• Accidental puncture of an artery rather than a vein 
• A blood clot in one of the blood vessels in the lungs
• Nerve injury
• Haematoma
• A blood clot in a vein (DVT)
• Tricuspid valve problems

Whilst this long list of potential complications may seem frightening, in reality, the overall complication rate only ranges from <1% to 6%, depending on the aforementioned parameters. Many experts believe that as long as the person performing the EMB is experienced, the risk of complications is low.⁴ 

In fact, in one analysis published in 2010 of 6361 endomyocardial biopsies, the major complication rate was only found to be 0.64% in left-ventricle EMBs, and 0.82% in right-ventricle EMBs.⁵ 

Benefits of an endomyocardial biopsy

In contrast to the low level of risk associated with an EBM, there is a high level of benefit to be gained in the context of heart enlargement. Some causes of heart enlargement, such as arrhythmias or cardiomyopathy, can be extremely dangerous and life-threatening. 

If these cannot be diagnosed through non-invasive testing, an EBM can allow for an ‘invaluable understanding’ of the clinical situation.⁶ This is because the sample taken from the heart can be pathologically examined, i.e. assessed under a microscope, and this level of examination is not possible with a non-invasive diagnostic method. 

In these cases, an EBM can have a very real impact on the way in which professionals treat an enlarged heart by revealing to them the true, underlying cause. It is for this reason that, despite the potential risks, many argue that not only is an EBM an incredibly useful tool for diagnosing heart disease, it is also underused in this context.⁷

Risks vs benefits: the bottom line 

All in all, whilst the use of endomyocardial biopsies in diagnosing heart problems may still be controversial, it can be very useful in reaching a diagnosis in certain circumstances where other tests cannot.² 

In the context of heart enlargement, diagnosing the cause of the enlargement is vital and can save lives. Therefore, if an EBM is the only way to accurately diagnose the cause, the benefits most likely outweigh the potential risks – given that the probability of these risks is relatively low. 

Summary 

• Endomyocardial Biopsy (EBM): also referred to as a cardiac/heart biopsy
• Designed to diagnose heart transplant rejection in the 60’s
• Now also a tool in diagnosing heart diseases when other tests are inconclusive
• It is essential to diagnose the cause of an enlarged heart as quickly as possible
• If other non-invasive methods cannot find the cause, an EBM is an invaluable method
• A sample of the heart muscle’s tissue is taken under local anaesthetic and examined
• There are many potential risks, but the chance of them occurring is relatively low
• In certain circumstances, an EBM can be the only way to achieve a diagnosis
• In these cases, the benefits outweigh the risks