Definitive diagnosis requires an endomyocardial biopsy [8]
Definitive diagnosis requires an endomyocardial biopsy [8]. In EM, the eosinophils may be associated with myocardial inflammation in three distinct forms [1]. eosinophilic myocarditis. Non-invasive cardiac imaging in the setting of peripheral eosinophilia can be strongly suggestive of eosinophilic myocarditis with potential for earlier diagnosis. Failure to diagnose eosinophilic myocarditis and the delay of therapy may lead to irreversible myocardial injury. Therapies for this disease have yet to be validated in large prospective studies. Keywords:Eosinophilia, Myocarditis, Endomyocardial, Biopsy == Background == Myocarditis refers to heart muscle inflammation secondary to direct external antigen exposure such as viruses, bacteria, parasites, and drugs or to autoimmune activation against self-antigens. Traditionally the diagnosis of myocarditis was based on the histological Dallas criteria on endomyocardial biopsy which mandates the visualization of inflammatory cells and myocardial necrosis on the same microscopic section; if concomitant necrosis is not detected the diagnosis of myocarditis is considered borderline. Given the limitations of endomyocardial biopsies, in particular its low sensitivity from the often patchy nature of the disease and potential procedural risks, more recent and broader definitions of myocarditis were introduced. These encompass a hybrid of clinical, laboratory, and imaging criteria that may help secure the diagnosis and forgo the need for a biopsy in all cases [1]. The prevalence of myocarditis in general is not well established given the lack of consensus on its diagnostic criteria in the scientific community. As such, among unselected autopsy series, its prevalence is as high as 1 to 5% [1]. The most common causes of myocarditis include infectious and autoimmune etiologies [1]. Eosinophilic myocarditis (EM) is a rare subtype of myocarditis characterized by focal or diffuse myocardial inflammation with infiltrating eosinophils and is often associated with peripheral blood eosinophilia [2,3]. To date there are less than 30 published case reports of EM and include patients ranging STAT3-IN-3 from 2 to 83 years of age [2]. Given the rarity of this form of myocarditis, it is often under-recognized and first discovered on postmortem examination [4]. EM was observed in 0.5% of unselected autopsy series and in more than 20% of explanted hearts from heart transplant recipients secondary to drug-induced hypersensitivity [4]. In this review article STAT3-IN-3 we present two cases of eosinophilic myocarditis and outline the current scientific literature on this topic including its pathophysiology, diagnosis, and recommended therapy. == Case presentation == == Case 1 == A 76-year-old Caucasian gentleman with a history of hypertension and asthma presents with history of sharp and pleuritic chest pain radiating to the shoulders with associated dyspnea with gradual deterioration of functional status to New York heart Association (NYHA) functional class III. Laboratory investigations revealed a normal creatine kinase (CK), elevated troponin T at 2.74 ug/L, C reactive protein (CRP) at 140 mg/L (normal: 08), and eosinophilia at 3.92105/L. The initial presumptive diagnosis was acute coronary syndrome however coronary angiography revealed no significant coronary artery disease. The patient was found to have global reduction in left ventricular systolic function, ejection fraction (EF) 30-35%, along with mildly impaired right ventricular dysfunction on echocardiography. In addition, an uninfused computed tomography (CT) scan of the chest revealed a small right pleural effusion and multiple small centrilobar nodules in the lungs bilaterally with upper lung zone predominance and ground glass attenuation consistent with pulmonary eosinophilia. Magnetic resonance imaging (MRI) identified mild subendocardial delayed enhancement with a near circumferential distribution raising the possibility of eosinophilic myocarditis (Figures1,2). There were no suggestions of underlying infection and stool for ova and parasites as well as serology for trypanosome and strongyloides were negative. A vasculitis screen including anti-neutrophil cytoplasmic antibodies (ANCAs) was negative. There were no recently started medications to STAT3-IN-3 suggest a drug induced hypersensitivity reactions and physical exam and history were negative for malignancy. == Figure 1. == Magnetic resonance imaging with arrow depicting circumferential subendocardial delayed enhancement on the short axis view. == Figure 2. == Magnetic resonance imaging with arrow depicting subendocardial FHF1 delayed enhancement in the 4 chamber axial view. Given this presentation, a diagnosis of clinically suspected eosinophilc myocarditis, STAT3-IN-3 idiopathic hypereosinophilic syndrome subtype (HES) STAT3-IN-3 in particular, with possible pulmonary involvement was made. The patient declined to undergo a confirmatory endomyocardial biopsy. In addition to the standard medical management of heart failure he was started on oral prednisone at 60 mg per day with 10 mg tapering doses per week to a baseline maintenance dose of 10 mg per day. Unfortunately he showed little to no recovery.