case_images: PMC8260850_01
case_images: Electrocardiogram at admission (A) and on day 11 (B).
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case_images: F1
case_images: The electrocardiogram (ECG) revealed sinus rhythm, low voltage limb leads, inverted T-waves in V1, 2, and poor R-wave progression (Figure 1A). Echocardiography demonstrated symmetrically increased left ventricular wall thickness (ILVWT) of 13 mm with small left ventricular (LV) cavity size, preserved systolic function with an ejection fraction of 52%, and pericardial effusion (Figures 2A,B and Supplementary Videos 1, 2). Follow-up ECG revealed the resolution of all ECG abnormalities recognized during the initial ECG (Figure 1B). As a supplement, we present a summarized illustration of the case presentation (Supplementary Figure 1).
case_images: Serial TTE. Parasternal long-axis (A,C) and short-axis views (B,D). TTE on admission showing diffuse and symmetrical LV wall thickening (13mm), decreased cavity size (LVDd: 39 mm) with preserved LVEF (52%), and pericardial effusion (A,B). Follow-up echocardiography on day 4 after intravenous pulse steroid therapy reveals a rapid and dramatic decrease in LV wall thickness (7 mm) and concomitant increases in LVDd (45 mm) and LVEF (72%) (C,D). The improvement in pericardial effusion can be noted. TTE, transthoracic echocardiography; LA, left atrium; LV, left ventricle; RV, right ventricle; LVDd, left ventricular end-diastolic diameter; LVEF, left ventricular ejection fraction.
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case_images: F2
case_images: Echocardiography demonstrated symmetrically increased left ventricular wall thickness (ILVWT) of 13 mm with small left ventricular (LV) cavity size, preserved systolic function with an ejection fraction of 52%, and pericardial effusion (Figures 2A,B and Supplementary Videos 1, 2). ILVWT followed by treatment with corticosteroids (Figures 2C,D and Supplementary Videos 3, 4). In parallel, the patient's condition improved dramatically, with the disappearance of eosinophilia, resulting in weaning from inotrope and IABP support.
case_images: Chest/abdominal contrast-enhanced CT images. Axial (A,C,D) and sagittal (B) views. Contrast-enhanced CT reveals LV wall thickening with pericardial effusion, decreased myocardial enhancement of both mid-layer in the basal-to-mid septal wall and transmural myocardium in the mid anterolateral wall (A,B, arrowheads), and fluid accumulation in pericardial sinuses (C, arrows). Airless low-attenuating areas in the region of gallbladder wall thickening and around the hepatic round ligament and periportal space, indicating marked systemic edema (D, arrows). CT, computed tomography; Ao, aorta; LV, left ventricle; RV, right ventricle.
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case_images: F3
case_images: AEM. A subsequent contrast-enhanced chest/abdominal computed tomography (CT) scan showed diffuse LV wall thickening with heterogeneous non-ischemic hypoenhancement, suggesting acute inflammatory edema (Figures 3A-C). Moreover, we observed gallbladder wall edema and fluid accumulation around the hepatic round ligament and periportal space, suggestive of rapid systemic congestion caused by heart failure (Figure 3D). ILVWT followed by treatment with corticosteroids (Figures 2C,D and Supplementary Videos 3, 4). In parallel, the patient's condition improved dramatically, with the disappearance of eosinophilia, resulting in weaning from inotrope and IABP support.
case_images: Endomyocardial biopsy findings. Photomicrograph with hematoxylin and eosin stain (A). The prominent eosinophilic infiltrate with degranulated eosinophils and surrounding edema and the layers of thickening endocardium can be noted. Photomicrograph with immunostaining against the eosinophilic cationic protein (B). Bars: 50 mum. Transmission electron microscopy shows myocardial interstitial infiltration by degranulated eosinophils and mast cells in close proximity to cardiomyocytes (C). A high magnification view of the region outlined by the box in Figure 4C
  (D). Eosinophilic granules can be noted (arrowheads). Cm, cardiomyocyte; Eo, eosinophil; Mc, mast cell.
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case_images: F4
case_images: Subsequently, a CT-guided endomyocardial biopsy (EMB) was performed from the right ventricular septum, which revealed numerous eosinophilic infiltrations with degranulating eosinophils, admixed lymphocytes, and a thickened endocardium (Figures 4A,B). Transmission electron microscopy also confirmed similar findings, thereby reaching the definitive diagnosis of AEM (Figures 4C,D). ILVWT followed by treatment with corticosteroids (Figures 2C,D and Supplementary Videos 3, 4). In parallel, the patient's condition improved dramatically, with the disappearance of eosinophilia, resulting in weaning from inotrope and IABP support.