Eosinophilic myocarditis

Clinic

• Eosinophilic myocarditis is inflammation in the heart muscle that is caused by the infiltration and destructive activity of eosinophil.
• Typically associated with hypereosinophilia
• It is distinguished from non-eosinophilic myocarditis, which is heart inflammation caused by other types of white blood cells, i.e. lymphocytes and monocytes, as well as the respective descendants of these cells, NK cells and macrophages.
• This distinction is important because the eosinophil-based disorder is due to a particular set of underlying diseases.
• It is often viewed as a disorder that has three progressive stages.
  1. First stage involves acute inflammation and cardiac cell necrosis. Symptoms are the acute coronary syndrome (Angina/ Heart attack / Congestive heart failure)
  2. Second stage is a thrombotic stage wherein the endocardium forms blood clots which break off or block blood through systemic or pulmonary arteries.
  3. Third stage is a fibrotic stage wherein scarring replaces damaged heart muscle tissue to cause a clinical presentation dominated by a poorly contracting heart and cardiac valve disease.

Signs /Symptoms

• 66% of cases have symptoms of a common cold
• 33% have symptoms of asthma, rhinitis, urticarial, or other allergic disorder. Cardiac manifestations of eosinophilic myocarditis range from none to life-threatening conditions such as cardiogenic shock or sudden death due to abnormal heart rhythms.
• The presenting cardiac symptoms are the same as those seen in other forms of heart disease: Chest pain, Shortness of breath, Fatigue, Palpitations, Light headedness, and Syncope.
• In its most extreme form, however, eosinophilic myocarditis can present as acute necrotizing eosinophilic myocarditis, i.e. with symptoms of chaotic and potentially lethal heart failure and heart arrhythmias. This rarest form of the disorder reflects a rapidly progressive and extensive eosinophilic infiltration of the heart that is accompanied by massive myocardial cell necrosis.

• Hypereosinophilia or, less commonly, eosinophilia are found in the vast majority of cases of eosinophilic myocarditis and are valuable clues that point to this rather than other types of myocarditis or myocardial injuries.

Cause

Primary conditions that may lead to eosinophilic myocarditis are:

• Clonal hypereosinophilia.
• Chronic eosinophilic leukemia.
• The idiopathic hypereosinophilic syndrome.

Secondary conditions:

• Infections agents
  • Parasitic worms: various Ascaris, Strongyloides, Schistosoma, filaria, Trematoda, and Nematode species. Parasitic infestations often cause significant heart valve disease along with myocarditis and the disorder in this setting is sometimes termed Tropical endomyocardial fibrosis.
  • Infections by protozoa: various Toxoplasma gondii, Trypanosoma cruzi, trichinella spiralis, Entamoeba, and Echinococcus species.
  • Viruses: While some viral infections (e.g. HIV)

• Allergic / Autoimmune diseases such as Severe asthma, Rhinitis, or urticarial, Chronic sinusitis, Aspirin-exacerbated respiratory disease, Allergic bronchopulmonary aspergillosis, Chronic eosinophilic pneumonia, Kimura's disease, Polyarteritis nodosa, Eosinophilic granulomatosis with polyangiitis (i.e. Churg–Strauss syndrome), and rejection of transplanted hearts.

• Malignancies and/or premalignant hematologic conditions not due to a primary disorder in eosinophils such as Gleich's syndrome, Lymphocyte-variant hypereosinophilia Hodgkin disease, certain T-cell lymphomas, AML, the myelodysplastic syndromes, systemic mastocytosis, chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, myelofibrosis, chronic myelomonocytic leukemia, and T-lymphoblastic leukemia/lymphoma-associated or myelodysplastic–myeloproliferative syndrome-associated eosinophilias; IgG4-related disease and Angiolymphoid hyperplasia with eosinophilia as well as non-hematologic cancers such as solid tumors of the lung, gastrointestinal tract, and genitourinary tract.

DRESS syndrome

Drug Reaction with Eosinophilia and Systemic Symptoms is a severe immunological drug reaction. It differs from other drug reactions in that it:

• It is caused by a particular set of drugs
• It typically occurs after a delay of 2 to 8 weeks following intake of an offending drug
• It presents with a specific set of signs and symptoms (i.e. modest or extreme elevations in blood eosinophil and atypical lymphocyte counts; acute onset of a skin rash; lymphadenopathy; fever; neuralgia; and involvement of at least one internal organ such as the liver, lung, or heart;
• It develops in individuals with particular genetic predispositions;
• It involves reactivation of latent viruses, most commonly HHV-6 or more rarely CMV, HHV-7, and EBV.
• These viruses usually become dormant after infecting humans but under special circumstances, such as drug intake, are reactivated and may contribute to serious diseases such as the DRESS syndrome.

Eosinophilic coronary periarteritis

Eosinophilic coronary periarteritis is an extremely rare heart disorder caused by extensive eosinophilic infiltration of the adventitia and periadventitia, i.e. the soft tissues, surrounding the coronary arteries. The intima, tunica media, and tunica intima layers of these arteries remain intact and are generally unaffected. Thus, this disorder is characterized by episodes of angina, particularly Prinzmetal's angina, and chaotic heart arrhythmias which may lead to sudden death. The disorder is considered distinct from eosinophilic myocarditis as well as other forms of inflammatory arterial disorders in that it is limited to the coronary artery system.

Related disease

• Eosinophilic granulomatosis with polyangiitis
  • Is a rare systemic necrotizing vasculitis of medium and small arteries, characteristically affects the upper and lower respiratory tract and may present with neuropathy and other organ manifestations
  • Cardiac manifestations are estimated to be as high as 27–47%
  • This report describes a case of EGPA complicated by an EBV inflammatory cardiomyopathy.

Entities / Miasms

Myocarditis + Eosinophilia:

• EBV, CMV, HHV-6