Eosinophilic myocarditis mimicking acute coronary syndrome secondary to idiopathic hypereosinophilic syndrome: a case report

Abstract

Introduction: Eosinophilic myocarditis is a rare form of myocarditis. It is characterized pathologically by diffuse or focal myocardial inflammation with eosinophilic infiltration, often in association with peripheral blood eosinophilia. We report a case of eosinophilic myocarditis secondary to hypereosinophilic syndrome.

Case presentation: A 74-year-old Caucasian woman with a history of asthma, paroxysmal atrial fibrillation, stroke and coronary artery disease presented to the emergency department of our hospital with chest pain. Evaluations revealed that she had peripheral blood eosinophilia and elevated cardiac enzymes. Electrocardiographic findings were nonspecific. Her electrocardiographic finding and elevated cardiac enzymes pointed to a non-ST-elevated myocardial infarction. Echocardiogram showed a severe decrease in the left ventricular systolic function. Coronary angiogram showed nonobstructive coronary artery disease. She then underwent cardiac magnetic resonance imaging, which showed neither infiltrative myocardial diseases nor any evidence of infarction. This was followed by an endomyocardial biopsy which was consistent with eosinophilic myocarditis. Hematologic workup regarding her eosinophilia was consistent with hypereosinophilic syndrome. After being started on steroid therapy, her peripheral eosinophilia resolved and her symptoms improved. Her left ventricular ejection fraction, however, did not improve.

Conclusion: Eosinophilic myocarditis can present like an acute myocardial infarction and should be considered in the differential diagnosis of acute coronary syndrome in patients with a history of allergy, asthma or acute reduction of the left ventricular function with or without peripheral eosinophilia.

Figure 1

Electrocardiogram showing low voltage, left axis deviation and questionable old anterior myocardial infarction.

Figure 2

Chest X-ray showing bilateral pleural effusion and pulmonary venous congestion.

Figure 3

Echocardiogram in systole (left ventricle systolic dysfunction).

Figure 4

Echocardiogram in diastole (left ventricle systolic dysfunction).

Figure 5

Endomyocardial biopsy showing the following: (A) Organizing thrombus in small vessels of endocardium (Hematoxylin and Eosin staining, ×20 magnification). (B) Older areas show organized endocardial scar with rare eosinophils and hemosiderin-laden macrophages (Hematoxylin and Eosin staining, ×40 magnification). (C) Close-up of intact and degranulating eosinophils in the interstitial space, without myocyte necrosis (Hematoxylin and Eosin staining, ×40 magnification). (D) A larger cluster of non-degranulated eosinophils (Hematoxylin and Eosin staining, ×40 magnification).