Therapeutic effect of anti-IL-5 on eosinophilic myocarditis with large pericardial effusion

Abstract

Eosinophilic myocarditis (EM) is a rare myocardial disease that results from various eosinophilic diseases, such as idiopathic hypereosinophilic syndrome, helminth infection, medications and vasculitis. Patients with EM may present with different severities, ranging from mild symptoms to a life-threatening condition. Diagnosis of EM is a challenge and requires an extensive workup, including endomyocardial biopsy. Treatment options are limited because EM is rare and there is a lack of randomised controlled trials. We report a case of EM that presented as cardiac tamponade, which was initially treated with high-dose prednisone and immunosuppressant medications without significant improvement. Mepolizumab (anti-interleukin (IL)-5 antibody) was then applied, leading to an increased ejection fraction and stabilised cardiac function. This case report shows, for the first time, that mepolizumab has novel effects in treating EM. Our findings suggest that mepolizumab can be used as a steroid-sparing agent for treating EM.

Keywords: Cardiovascular medicine; Immunology.

Figure 1

An echocardiogram on initial presentation shows pericardial effusion (PE) with an EF of 30%. (A) Parasternal long axis view. (B) Apical four-chamber view. Ao, aorta; LA, left atrium; EF, ejection fraction; LV, left ventricle; PE, pericardial effusion; RA, right atrium; RV, right ventricle.

Figure 2

A biopsy shows two fragments of endomyocardium each with moderate interstitial infiltrate dominated by eosinophils and lymphocytes. There was single-cell necrosis, interstitial oedema and early endocardial thrombus formation. There was no evidence of vasculitis, granuloma, viral inclusions or organisms. (A) H&E-stained section at 150× with interstitial eosinophils and lymphocytes. Fibrin deposition and early endocardial thrombus are present. (B) Same section as (A), but at a power of 300×.

Figure 3

Echocardiogram at relapse with a decrease in EF to less than 20%. Ao, aorta; LA, left atrium; EF, ejection fraction; LV, left ventricle; RV, right ventricle.

Figure 4

Echocardiogram after 6 months of mepolizumab treatment shows an EF of 35%–45%. (A) Parasternal view. (B) Apical four-chamber view. Ao, aorta; EF, ejection fraction; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.