Introduction

Endomyocardial fibrosis (EMF) is a long-term, often fatal type of heart disease characterised by a localised or widespread thickening of the innermost layer of the heart within one or both ventricles, resulting from extensive fibrous tissue accumulation beneath that layer. It primarily impacts the tip of the heart (the apex) but may also affect the top region (the base), the walls of the left ventricle, as well as the muscles and cords of the valves. It is marked as a thick scar on the inner heart walls.

It remains common in warm and damp locations like Africa, South Asia, and some parts of South America, where the environment and food play a role in its cause. The signs of EMF often mix with those of many other heart issues, which makes it hard to spot. 

When EMF is found alongside other heart issues like rheumatic heart disease (RHD), hypertrophic cardiomyopathy (HCM), constrictive pericarditis (CP), dilated cardiomyopathy (DCM), or ischemic heart disease (IHD), the signs, test results, and heart function signs look a lot alike. This makes it hard to differentiate the problems apart.^1,2,3 In this article, we will review the other heart disorders that coexist with EMF and their diagnostic dilemmas, which cause a delayed diagnosis and wrong treatment.

Coexistence with other cardiac disorders

Rheumatic heart disease (RHD)

RHD and EMF often show up together in places where they are common, making it hard to tell them apart. They both can lead to:⁴

• Bigger heart chambers
• Valve issues
• Signs of heart failure

Rheumatic injury typically presents as joined valve flaps and thickened edges, whereas EMF results in scar tissue within the heart and adhered valves. Cardiac scans are key, but shared traits often make it hard to read them right.

Hypertrophic cardiomyopathy (HCM)

Both HCM and EMF lead to problems in the heart muscle relaxation and filling, but the reasons behind them are not the same. HCM leads to uneven thickening with a block in flow, while EMF causes stiffening at the lower end and blocks inflow. Cardiac MRI can tell them apart, with special dye showing a clear difference in scar lines.^5,6

Constrictive pericarditis (CP)

CP is among the most challenging conditions to distinguish from EMF, as both result in right-sided heart failure. CP causes robust and thick outer heart layers, whereas EMF promotes fibre growth internally within the heart without affecting the outer layer. 

Normal examinations reveal their similarities, such as comparable stable heart rates. MRI and CT imaging, on the other hand, can show external and internal problems, differentiating the disorders. Incorrect diagnoses can disrupt care plans because different types of surgery are done to treat CP compared to EMF.^7,8

Dilated cardiomyopathy (DCM)

In severe cases, EMF can look like DCM because of big heart chambers and poor pumping power. Both lead to gradual heart failure, irregular heartbeats, and blood clot complications. Nonetheless, EMF advances slowly in the initial phases and deteriorates with the thickening of the heart tips, whereas DCM begins with weak pumping and enlargement.⁹

Ischemic heart disease (IHD)

Myocardial scarring due to low blood flow can look like fibrotic shifts in EMF. Both show up with:

• Heart failure
• Arrhythmias
• Lower exercise ability

A heart MRI with dye can differentiate ischemic scars (found in specific heart areas) from wide fibrotic damage seen in EMF.¹⁰

Diagnostic modalities

Accurate diagnosis of endomyocardial fibrosis (EMF) coexisting with other cardiac disorders requires a multimodal strategy, as no single test is sufficient. The following modalities are frequently employed:^1,3,11,12,13

Electrocardiography (ECG)

ECG signs in EMF are frequently difficult to identify. They present low QRS counts, heart flutter, or common ST-T wave tweaks. These traits mix with signs of heart block and giant heart disease, making it hard to tell them apart when EMF and other problems are both present.

Cardiac Hemodynamics

Cardiac catheterisation and hemodynamic monitoring reveal restricted heart activity with elevated and consistent calm heart rates, displaying a distinct dip-and-flat (square root) appearance. Nevertheless, these symptoms are not exclusive to EMF and can also occur in constrictive pericarditis, complicating the diagnosis when both conditions exist.

Cardiac magnetic resonance (CMR)

CMR allows doctors to view the heart in detail, identifying areas that are scarred or experiencing blockages. Identifying whether the heart issue is due to EMF or another reason is crucial. However, there are instances when the pictures lack clarity to be certain.

Endomyocardial biopsy (EMB)

Examining heart tissue closely is the most effective method to determine what is wrong. It may indicate areas of thickness and evidence of injury or inflammation. Nevertheless, obtaining a small sample of the heart for this examination is challenging, carries certain risks, and might overlook areas of damage, which is why physicians do not rely on it consistently. It is mainly reserved for cases where non-invasive imaging is inconclusive.

Diagnostic dilemmas

The coexistence of EMF with other cardiac disorders leads to several diagnostic challenges:^1,14,15

• Nonspecific clinical and ECG findings: symptoms such as heavy breathing, fatigue, and irregular heartbeats are typical in EMF. However, ECG tests are not very effective in distinguishing heart injury due to reduced blood circulation and heart conditions caused by fever vs EMF
• Overlap with CP: heart signs like high heart filling pressures and the dip-and-level pattern show up in both CP and EMF, making it hard to tell them apart. In areas with fewer resources, where TB-related heart diseases are common, this confusion can result in incorrect assumptions
• Histological limitations: analysing the heart muscle via a biopsy verifies EMF, but the dangers of the procedure and errors in sample collection complicate this. This issue can make it hard to distinguish EMF from conditions with excess eosinophils or cardiac enlargement when they occur simultaneously
• Imaging ambiguity with CMR: although CMR is highly sensitive for detecting fibrosis, late gadolinium enhancement patterns of EMF may resemble those of ischemic or inflammatory cardiomyopathy, leading to diagnostic confusion
• Clinical consequences of misdiagnosis: mistaking EMF for constrictive pericarditis may result in inappropriate pericardiectomy, while overlooking ischemic disease may delay revascularisation therapy. These dilemmas highlight the importance of combining clinical judgment with multimodal imaging

FAQs

What is the most reliable test to diagnose EMF?

Cardiac MRI with late gadolinium enhancement is currently the most reliable non-invasive diagnostic tool.

Why is EMF often confused with constrictive pericarditis?

Both conditions cause restrictive physiology and similar clinical signs, but CP involves the pericardium, while EMF affects the endocardium.

Can EMF occur with rheumatic heart disease?

Yes, coexistence is common in endemic regions, complicating diagnosis due to overlapping valvular and atrial changes.

Is a biopsy always necessary?

No. Biopsy is considered only when non-invasive imaging is inconclusive due to its invasive risks.

How does misdiagnosis affect treatment?

An incorrect diagnosis may result in inappropriate procedures, such as pericardiectomy, which would not benefit EMF patients.

Summary

Endomyocardial fibrosis (EMF) is a serious heart disease marked by thickening of the inner heart layer due to fibrous tissue build-up. It mainly affects the heart's apex but can also impact other parts of the heart. EMF is more common in warm areas like Africa and parts of South America, and its symptoms often overlap with other heart diseases, complicating diagnosis. EMF frequently coexists with several heart disorders, such as rheumatic heart disease (RHD), hypertrophic cardiomyopathy (HCM), constrictive pericarditis (CP), dilated cardiomyopathy (DCM), and ischemic heart disease (IHD). RHD and EMF can both cause enlarged heart chambers and valve issues, making distinction difficult; cardiac scans are useful, but their similarities pose challenges. HCM affects the heart muscle differently from EMF, and cardiac MRIs can help differentiate these conditions by revealing distinct scar patterns.

CP is particularly challenging to distinguish from EMF due to similar symptoms like right-sided heart failure, although imaging techniques can provide clarity. In cases of DCM, EMF can mimic its symptoms, but they progress differently. IHD presents symptoms similar to those of EMF, but MRIs can help identify the specific type of scarring. To diagnose EMF alongside other heart disorders, a comprehensive approach is necessary. Electrocardiography (ECG) often shows unclear signs in EMF, while cardiac catheterisation can reveal restricted heart activity. Cardiac magnetic resonance (CMR) imaging provides detailed views of the heart but may not always yield clear results. An endomyocardial biopsy (EMB) can confirm EMF but carries risks and challenges in obtaining samples. Several diagnostic dilemmas arise from the coexistence of EMF and other heart issues, including nonspecific symptoms, imaging ambiguities, and clinical consequences of misdiagnosis, such as inappropriate treatments. Accurate diagnosis requires careful clinical judgment and the use of multiple imaging methods.