PMC9300862_01
Clinical effects of corticosteroid treatment on TTE. TTE on admission reveals diffuse and symmetrical LV wall thickening (11 mm), decreased cavity size, reduced ventricular function, and GLS values of the LV (LVDd, 44 mm; LVEF, 43%; and GLS, -9.9%; respectively) (A-C). Follow-up TTE on day 21 after corticosteroid therapy reveals a significant decrease in LV wall thickness (8 mm) with concomitant improvement in cavity size, ventricular function, and GLS values of the LV (LVDd, 48 mm; LVEF, 50%; and GLS, -17.5%; respectively) (D-F). Ao, aorta; GLS, global longitudinal strain; LA, left atrium; LV, left ventricle; LVDd, left ventricular end-diastolic diameter; LVEF, left ventricular ejection fraction; TTE, transthoracic echocardiography.
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F1
The electrocardiogram (ECG) showed pathologic Q waves in V2 to V3, and negative QRS complexes including rS morphology in the inferior leads, diagnosed as a left anterior fascicular block (Supplementary Figure 1A). In addition, speckle-tracking echocardiography showed a reduced baseline global longitudinal strain of -9.9% (Figures 1A-C and Supplementary Video 1). The clinical response to steroid treatment was remarkable, with significant recovery of LV dysfunction, hypereosinophilia, and elevated cardiac enzyme levels within 21 days of steroid treatment (Figures 1D-F and Supplementary Video 3). Follow-up ECG showed resolution of all abnormal findings recognized during the initial ECG (Supplementary Figure 1B).
Changes in CMR findings in patients following corticosteroid treatment. CMR findings before (A-C) and after corticosteroid treatment (D-F). Myocardial first-pass perfusion imaging at rest (A,D), T2WI of the 2-chamber view (B,E), and LGE image (C,F). Ao, aorta; CMR, cardiac magnetic resonance; LGE, late gadolinium enhancement; LV, left ventricle; T2WI, T2-weighted image.
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F2
Therefore, acute EM was suspected, and cardiac magnetic resonance (CMR) was performed to assess the myocardial tissue (Figures 2A-C and Supplementary Video 2). On day 56, the patient remained asymptomatic, with fully recovered cardiac function observed on echocardiography (Supplementary Figure 2 and Supplementary Video 4). Moreover, the abnormal findings of the CMR resolved completely (Figures 2D-F and Supplementary Video 5).
Endomyocardial biopsy findings. Photomicrograph with hematoxylin and eosin staining (A-C) (bars: A, 100 mum; B and C, 20 mum). Photomicrograph showing immunostaining against the major basic protein (D) (bar: 50 mum).
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F3
A subsequent endomyocardial biopsy (EMB) was performed, which demonstrated marked extravascular eosinophilic infiltrates without granulomatous and fibrinoid necrotizing vasculitis (Figure 3A). Numerous eosinophilic infiltrations, with degranulated eosinophils admixed with lymphocytes and myocyte necrosis, were observed in the myocardial interstitium that extended to the endocardium (Figures 3B,C). Immunostaining was performed to identify the major basic proteins revealed extensive staining in the endocardium and myocardial interstitium (Figure 3D). The clinical response to steroid treatment was remarkable, with significant recovery of LV dysfunction, hypereosinophilia, and elevated cardiac enzyme levels within 21 days of steroid treatment (Figures 1D-F and Supplementary Video 3). As a supplement, we have presented a timeline for the case presentation (Supplementary Figure 3).