What is endomyocardial fibrosis?

Endomyocardial fibrosis (EMF) is a type of restrictive cardiomyopathy commonly found in tropical regions, including Africa, South America and Asia. It is one of the leading causes of heart attacks in these regions. Restrictive cardiomyopathy is a type of heart muscle disease in which the walls of the ventricles become stiff and less flexible but do not thicken. Due to this stiffness, the heart has trouble relaxing and filling with blood during diastole. 

While some medicines can help relieve symptoms, they do not reverse fibrosis, and hence, surgical intervention remains the definitive option to restore ventricular cavity size and relieve valve dysfunction.¹

This article aims to review the main indications for surgery in EMF, including the procedures performed and the outcomes that patients and clinicians can expect. 

Pathophysiology of EMF

Several factors play a role in causing EMF. These can include long-term inflammation from high levels of eosinophils, certain parasitic infections, problems with the immune system and poor nutrition. Over time, this ongoing inflammation causes thick scarring of the inner heart lining. In some patients, calcium can build up in the scarring, making the heart chambers smaller, preventing the heart from filling up properly, and forming blood clots. EMF can affect both the right and left sides of the heart, although it more commonly affects the right side in some parts of the world. 

Indications for surgery

Surgical intervention is considered for patients with advanced EMF who remain symptomatic despite optimal medical management. The main indications and signs include:

• The heart is too stiff to fill properly, and symptoms like shortness of breath, belly swelling (ascites), or leg swelling (oedema) do not improve with medicines
• Heart valves are leaking badly because scarring has pulled them out of place
• Blood clots form inside the scarred heart chambers, creating a high risk of stroke or other complications
• Medicines stop working well, meaning drugs like diuretics and blood thinners are no longer enough to control symptoms²

Patient selection is critical, as surgical outcomes vary depending on the extent of disease and the presence of comorbidities.

Surgical techniques

Surgical treatment for EMF is complex. The main aim is to relieve the restriction caused by fibrotic tissue, restore heart filling, reduce valve leakage, and, in some cases, remove blood clots. Below are the main steps, considerations, variations and outcomes, drawn from real cases.

Access and exposure

Many surgeries are done through median sternotomy, which involves opening the chest through the sternum and using bypass. Ischaemic arrest is often used, where the heart is stopped temporarily and protected. 

Depending on which chamber is affected, different entry points are used, like right atriotomy (surgical opening of the atrium) for right disease, left atriotomy or transaortic (via the aorta) approaches for the left ventricle.³

Endocardiectomy

The fibrotic scar tissue that lines the ventricle is peeled from the myocardium. Surgeons try to preserve as much normal heart lining as possible. In some cases, surgeons leave a thin rim of fibrotic tissue near the valves to avoid damaging conduction tissue, reducing the risk of atrioventricular block.³

Valve replacement

As the fibrosis usually distorts or tears the atrioventricular valves, such as the mitral and tricuspid valves, they need to be replaced. If the damaged valve is salvageable, annuloplasty is attempted, where a band or ring is placed around the valve's annulus (the base or ring that supports it) to reinforce it and help the valve close properly. If not, then complete valve replacement is done with either a mechanical or a bioprosthetic valve. This surgical intervention depends on the extent of damage, patient age, annular size and presence of fibrosis.⁴

Thrombus removal

Many patients also experience clot formation in the fibrotic chambers, so during surgery, these clots are removed to reduce the risk of embolism (blockage of an artery). 

Case example

In a 155-patient study conducted at the Uganda Heart Institute, Uganda, who were diagnosed with EMF between 2007 and 2020, no significant differences were found in gender, age at diagnosis, or EMF subtype during the period under review. Complications present included significant atrioventricular valve regurgitation, pericardial effusion, intracardiac thrombus (clot inside the heart) and pulmonary hypertension (predominantly seen in cases with biventricular EMF compared to those with right EMF. Right ventricular involvement remained predominant in most of the cases.⁵

Risk and difficulties

The risks of surgery for endomyocardial fibrosis are quite high, especially in patients who are already very weak, malnourished, or have advanced disease affecting both sides of the heart. Possible complications during or after surgery include heavy bleeding, irregular heart rhythms, weak pumping of the heart, damage to the heart’s electrical system (which can cause heart block), problems related to artificial heart valves, and, in some cases, blood clots that may travel to other parts of the body.⁵

FAQs

Why does EMF mainly occur in tropical countries?

The exact reason is unclear, but factors such as parasitic infections, repeated inflammation from eosinophilia, poor nutrition, and environmental triggers are thought to contribute.⁶

Can medications cure EMF?

No, medications such as diuretics, anticoagulants, and drugs for heart failure can relieve symptoms but cannot reverse or stop the scarring process.

When is surgery recommended?

Surgery is usually advised when patients develop severe symptoms such as heart failure, valve leakage, or blood clots, and when medical treatment is no longer effective.

What does the surgery involve?

The main procedure is endocardiotomy, where surgeons remove the scarred heart lining. Often, they also repair or replace damaged valves to restore proper blood flow.⁷

What are the risks of surgery?

Risks include bleeding, arrhythmias, conduction system damage, low heart function after surgery, and valve-related complications. Risk is higher in patients who are very sick, malnourished, or have advanced disease.

What are the chances of survival after surgery?

Survival rates depend on the patient’s condition and the hospital’s expertise. In experienced centres, many patients experience significant relief of symptoms and improved quality of life.

Is early surgery better?

Yes, patients tend to do better when surgery is performed before the fibrosis and heart damage become too advanced.

Can EMF come back after surgery?

In some cases, fibrosis can recur, especially if the underlying cause, such as parasitic infection or eosinophilia, is not controlled. Long-term follow-up is essential.

Summary

Endomyocardial fibrosis (EMF) is a rare but serious heart disease that mostly affects people in tropical regions. It causes scarring inside the heart, which makes it stiff and unable to fill properly. Over time, this leads to heart failure, valve leakage, and dangerous blood clots. While medicines such as diuretics and anticoagulants can ease symptoms, they do not stop the disease from progressing.

Surgery, mainly removing the scar tissue, remains the only treatment that can change the course of the illness. Often, this procedure is combined with repairing or replacing the heart valves, which are usually damaged by the fibrosis. Surgery is challenging and carries risks, especially in patients who are very weak or have advanced disease. However, when performed in specialised centres by experienced teams, outcomes are significantly better and can be life-saving.

The best results are usually achieved when surgery is done early, before the heart is too damaged and the body becomes severely weakened. With growing surgical expertise and improved patient care, many people with EMF now have a chance at longer and better-quality lives.