A CASE OF HYPEREOSINOPHILIC SYNDROME AFTER MEPOLIZUMAB CESSATION

Introduction Little is known about potential consequences of stopping mepolizumab therapy in asthmatic patients. This is a case of a 43 yr female diagnosed with eosinophilic myocarditis six months after cessation of mepolizumab. Case Description A 43 yr female with severe eosinophilic asthma was started on mepolizumab. She remained compliant for 2 yr with significant improvement of symptoms but due to a lapse of insurance coverage, therapy was interrupted. Six months later, she developed low-grade fever, cough, and dyspnea with infiltrates on CXR. She was diagnosed with atypical pneumonia and treated with antibiotics without improvement. Within a few days, she developed hypoxic respiratory failure requiring noninvasive ventilation support. WBC was 26.2 K/uL with eosinophilia of 9.69 K/uL. She had elevated troponin (7.58); EKG had lateral ST elevation myocardial infarction, and echocardiogram showed pericardial effusion with EF of 20-25%. Infectious workup was unremarkable. Heart catheterization revealed normal coronaries. Pericardiocentesis cytology demonstrated 89% eosinophils. Cardiac MRI showed circumferential subendocardial hyperenhancement of left ventricle and global ventricular hypokinesis. Bone marrow biopsy and cytogenetic testing were negative. She was diagnosed with eosinophilic myocarditis and started on IV methylprednisolone with marked improvement in symptoms. The patient was discharged on high dose prednisone and heart failure therapy. Three months later, she resumed mepolizumab and has been tolerating a slow prednisone taper. Discussion To our best knowledge, this is the first reported case of eosinophilic myocarditis and pneumonia after mepolizumab cessation. This patient may have had a rebound hypereosinophilia or an underlying hypereosinophilic syndrome which was masked by mepolizumab therapy.