A rare case of eosinophilic myocarditis with massive left ventricular thrombus and involvement of the mitral valve requiring surgery

A 65-year-old female patient presented to our emergency department with shortness of breath, atypical chest pain and signs of congestion. Transthoracic echocardiography revealed a large left ventricular (LV) mass with involvement of the LV wall extending from the apex to the mitral valve (MV) with significant mitral regurgitation (MR) (F1) and pericardial effusion. Systolic LV function was hyperdynamic. Transesophageal echocardiography confirmed an extensive homogeneous LV mass, highly indicative of thrombus, which almost occupied the whole LV cavity with involvement of the MV apparatus and restriction of the posterior mitral leaflet resulting in severe MR. Cardiac magnetic resonance imaging (MRI) confirmed the presence of a vast LV thrombus with MV involvement.(F2) Diffuse signs of edema were present in T2 weighted images, T1 mapping showed myocardial fibrosis and myocardial relaxation time was increased. According to MRI criteria, the images were consistent with a typical presentation of eosinophilic myocarditis (EM) with myocardial and pericardial inflammation. Histologic results of right-ventricular (RV) endomyocardial biopsy (EMB) showed endomyocardial fibrosis. Peripheral eosinophilia was not found. Comprehensive medical history assessment revealed an incident of a significant allergic reaction to rituximab, that occurred few months prior to the current presentation. Hence, after ruling out other possible conditions including infections, malignancies and immunologic disorders associated with EM, hypersensitivity was considered the most likely underlying cause. The size of the thrombus and the interference with the MV prompted interdisciplinary case discussion. Conservative treatment alone was considered highly unlikely to be successful. The patient ultimately underwent surgical thromb- and endocardectomy followed by reconstruction of the MV via annuloplasty. She was discharged on warfarin and immunosuppressive therapy and presented well recovered and stable at 4-month-follow-up. 
CONCLUSION
EM is a rare inflammatory myocardial disease associated with poor outcome and high mortality. We report a rare case of hypersensitivity EM with huge LV thrombus involving the MV apparatus resulting in severe MR. To our best knowledge it is one of the first cases to describe a massive thrombus requiring surgical treatment. Hence, it offers several crucial educational messages. First, it illustrates the pivotal role of thorough medical history taking in the initial patient work-up especially when suspecting hypersensitivity as the underlying cause. Clinical and laboratory findings, f.e. the presence or absence of peripheral eosinophilia, can be inconclusive. Due to the diffuse pattern of endomyocardial eosinophilic infiltrates, EMBs often return negative for eosinophilic cells only showing unspecific signs of inflammation and fibrosis. Therefore, second, it underlines the importance of combining various diagnostic tools, including different imaging modalities as well as invasive approaches. Third, our case illustrates the value and potential need of an interdisciplinary approach in complex cases of EM. Thrombi are a known EM complication, however, previous reports mostly described smaller LV apical or RV thrombi. So far there are only few reports on cases requiring surgery, let alone valve reconstruction. In the presence of large thrombi and/or restrictions in cardiac or valvular function patients benefit from an early surgical consultation.


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