Cardiology > Loeffler Endocarditis )   

Background 

Loeffler endocarditis, also known as eosinophilic endomyocardial disease, is a rare form of restrictive cardiomyopathy characterized by eosinophil-mediated damage to the endocardium and myocardium. It is most often associated with hypereosinophilic syndromes (HES) and marked by fibrotic thickening of the endocardium, mural thrombus formation, and eventual progression to restrictive heart failure and valvular dysfunction. 

II) Classification/Types

By Disease Stage: 

• • Acute Necrotic Stage: Eosinophilic infiltration and myocardial necrosis 

• • Thrombotic Stage: Formation of mural thrombi along damaged endocardium 

• • Fibrotic Stage: Endomyocardial fibrosis leading to restrictive physiology 

By Association: 

• • Idiopathic Hypereosinophilic Syndrome (HES) 

• • Secondary Eosinophilia: Parasitic infections, malignancy, autoimmune diseases, drug reactions 

By Cardiac Involvement: 

• • Left-sided Loeffler Endocarditis (more common) 

• • Right-sided involvement (less common but associated with pulmonary embolism) 

Pathophysiology 

Eosinophil degranulation releases cytotoxic proteins (e.g., major basic protein, eosinophil cationic protein) that injure the endocardium and myocardium. This leads to inflammation, necrosis, and subsequent thrombus formation. Over time, healing occurs via fibrosis, resulting in restrictive cardiomyopathy and potential entrapment of chordae tendineae, causing mitral and/or tricuspid regurgitation. 

Epidemiology 

• • Rare, incidence unknown 

• • Predominantly affects males aged 20–50 

• • Common in tropical/subtropical areas (e.g., Africa, Asia, South America) 

• • Frequently linked to idiopathic hypereosinophilic syndrome or parasitic infections (e.g., Strongyloides, Schistosoma) 

Etiology 

I) Causes

• • Idiopathic HES 

• • Parasitic infections (e.g., filariasis, schistosomiasis) 

• • Malignancies (e.g., T-cell lymphoma, eosinophilic leukemia) 

• • Drug-induced hypersensitivity reactions 

• • Autoimmune disorders (e.g., Churg-Strauss/Eosinophilic granulomatosis with polyangiitis) 

II) Risk Factors

• • Chronic eosinophilia 

• • Residence in endemic parasitic regions 

• • Underlying hematologic malignancies 

• • Autoimmune conditions 

Clinical Presentation 

I) History (Symptoms)

• • Progressive dyspnea 

• • Orthopnea, paroxysmal nocturnal dyspnea 

• • Fatigue, palpitations 

• • Peripheral edema 

• • Embolic events (stroke, pulmonary embolism) 

• • Constitutional symptoms (fever, weight loss, night sweats) 

• • History of eosinophilia or allergic symptoms (e.g., asthma, rash) 

II) Physical Exam (Signs)

• • S3/S4 gallop (restrictive physiology) 

• • Elevated jugular venous pressure 

• • Peripheral edema, ascites 

• • Hepatomegaly 

• • Murmurs of mitral/tricuspid regurgitation 

• • Evidence of embolic complications (e.g., stroke signs, splenomegaly) 

Differential Diagnosis (DDx) 

• • Endomyocardial fibrosis (non-eosinophilic) 

• • Restrictive cardiomyopathy (amyloidosis, hemochromatosis, sarcoidosis) 

• • Constrictive pericarditis 

• • Infective endocarditis with mural thrombi 

• • Cardiac tumors (e.g., myxoma) 

• • Acute myocarditis 

• • Drug-induced myocarditis (e.g., clozapine, methyldopa) 

Diagnostic Tests 

Initial Work-Up 

• • CBC with differential: Marked eosinophilia 

• • ESR/CRP: May be elevated 

• • Echocardiography: 

• • Apical thrombus 

• • Restrictive filling pattern 

• • Endocardial thickening 

• • Cardiac MRI: Fibrosis, thrombus, delayed gadolinium enhancement 

• • Endomyocardial biopsy (gold standard): Eosinophilic infiltration, necrosis, fibrosis 

• • Serologies: Parasitic infections, ANCA (if autoimmune suspected) 

• • Bone marrow biopsy: Rule out eosinophilic leukemia 

Treatment 

I) Initial Approach

• • Treat underlying cause (e.g., HES, parasitic infection) 

• • Suppress eosinophilia and inflammation 

• • Anticoagulation if mural thrombi present 

• • Manage heart failure symptoms 

II) Medications

Patient Education, Screening, Vaccines 

Education 

• • Adherence to immunosuppressive or antiparasitic therapy 

• • Regular follow-up for cardiac function 

• • Recognize early signs of embolic events or heart failure 

Screening/Prevention 

• • Screen for eosinophilia in patients with unexplained restrictive cardiomyopathy 

• • Early evaluation of eosinophilic syndromes 

• • Deworming and public health measures in endemic regions 

Vaccinations 

• • Influenza and pneumococcal vaccination 

• • COVID-19 vaccine per guidelines 

Consults/Referrals 

• • Cardiology: For advanced cardiac imaging and management 

• • Hematology: For evaluation of clonal eosinophilia or HES 

• • Infectious Disease: If parasitic etiology suspected 

• • Cardiothoracic Surgery: For surgical resection or valve replacement in advanced fibrosis 

• • Neurology: If embolic complications (e.g., stroke) 

Follow-Up 

Short-Term 

• • Monitor eosinophil count and response to therapy 

• • Repeat echocardiography or MRI to assess thrombus resolution 

• • Evaluate for signs of heart failure progression 

Long-Term 

• • Periodic cardiac imaging for fibrosis progression 

• • Adjust immunosuppressive therapy as needed 

• • Long-term anticoagulation if embolic risk persists 

• • Consider surgery if fibrotic obstruction or severe regurgitation 

Prognosis 

• • Depends on disease stage at diagnosis and response to therapy 

• • Favorable outcomes with early diagnosis and eosinophil control 

• • Poor prognosis if diagnosis delayed until fibrotic stage 

• • Complications: 

• • Refractory heart failure 

• • Recurrent thromboembolism 

• • Valvular dysfunction 

• • Sudden cardiac death