EM is a rare, rapidly progressing form of myocarditis characterised by marked eosinophilic infiltration and inflammation of the myocardium causing myocyte necrosis and endomyocardial fibrosis [1]. It may be associated with hypersensitivity reactions, intercurrent infection, malignancy or immune-mediated disorders, such as eosinophilic granulomatosis with polyangiitis (EGPA) or as part of a hypereosinophilic syndrome (HES) [2,3].
EM associated with Ulcerative Colitis (UC) has previously been described in the literature and is associated with more fulminant forms of myocarditis [4]. Myocarditis related to Infliximab use has also been described, due to a hypersensitivity reaction, but this as the cause of myocarditis in this patient is unlikely given the absence of peripheral eosinophilia [5].
Though the vast majority (over 75%) of cases of EM have marked peripheral eosinophilia, particularly when associated with inflammatory bowel disease or hypersensitivity reactions, normal eosinophil counts in EM have rarely been described [6,7].
The clinical presentation and severity of EM can vary. According to a systematic review, patients with EM who develop arrythmias in the acute phase, tend to be ventricular tachycardia or fibrillation [8]. High grade atrio-ventricular block, as seen in this patient, has yet to be described and may be suggestive of advanced infiltration of the conduction pathways, reflective of the severity of his disease.
EM can rapidly cause cardiogenic shock and temporary mechanical support may be indicated in a minority of patients [8]. Despite advanced acute heart failure therapies and immunosuppression, the risk of in-hospital mortality remains high, thus prompt diagnosis and treatment are crucial to prevent adverse outcomes [9].
Currently, there is a lack of consensus regarding immunosuppression in these patients, particularly as maintenance therapy. There is evidence for the efficacy of corticosteroid therapy, and currently remain the basis of treatment for the majority of patients with EM. However, the duration of treatment and regimen for long-term immunosuppression remains controversial [10].
In this case, the patient had previously developed pancreatitis related to Azathioprine use. Therefore, the choice of long-term immunosuppression that would prevent relapse of UC and recurrence of EM, while avoiding the deleterious effects of long-term corticosteroid therapy, required careful consideration. Crucially, peripheral eosinophil count was not a reliable marker of adequate immunosuppression, having been within the normal range throughout his illness. This case highlights the role of using other tests such as circulating Troponin levels and evidence of myocardial inflammation on serial PET-CT imaging, as markers to reflect the degree of disease activity and thus adequacy of immunosuppressive therapy.
To our knowledge, this is the first case reported in the literature of EM associated with UC in the absence of peripheral eosinophilia. This patient was maintained on long term immunosuppression with Ciclosporin and MMF, thereby avoiding long-term steroid use.
This case highlights the importance of prompt EMB in these patients to guide immunosuppression, the role of mechanical circulatory support to aid myocardial recovery, and the role of multi-modality imaging including TTE, CMR and PET-CT to assess for improvement in cardiac function and to monitor for response to treatment.
EM is a rare condition with potentially fatal consequences. The risk of EM recurrence, development of dilated cardiomyopathy or ventricular arrythmias is unknown. Given the lack of clinical trials for the treatment of EM, it is by encouraging the reporting and follow-up of cases of EM that a consensus can be made on the treatment and risk-stratification of these patients.