Fulminant eosinophilic myocarditis: A rare cardiac cause of splinter hemorrhages

Background:
Eosinophilic myocarditis (EM) is a rare, potentially lethal inflammatory disease of the heart muscle, diagnosed mainly in male patients between 20 and 51 years of age, often associated with other comorbidities. Due to a variety of clinical symptoms, making a diagnosis is often challenging and demands a multidisciplinary approach. Cardiac magnetic resonance (CMR) can decisively contribute to the diagnostic process because of a pathognomonic phenotype.

Case summary:
This is the case of a 25-year-old female who presented with a headache, confusion and short memory impairment. Physical examination revealed splinter hemorrhages (Figure 1).

Initially, a cranial computed tomography (CT) showed no pathologies. Cranial magnetic resonance (MR) revealed multiple supratentorial lesions consistent with embolisms or vasculitis (Figure 2).

Transesophageal echocardiography (TOE) was performed but remained inconclusive. Significantly elevated inflammatory markers in the absence of positive blood cultures and high troponin levels led to the suspicion of myocarditis. Therefore, CMR was performed. Widespread intramural biventricular myocardial edema was evident, accompanied by a diffuse subendocardial fibrosis and thrombosis, the latter being CMR hallmarks of EM (Figure 3).

Due to biventricular thrombosis, an endomyocardial biopsy (EMB) was contraindicated. Based on the clinical picture and CMR report, immunosuppression and anticoagulation therapy were initiated following interdisciplinary case discussion. However, due to an increase in cerebral lesions in a follow-up cranial MR, an escalation to combination immunosuppressive therapy was necessary. This led to an improvement of all symptoms and the disappearance of splinter hemorrhages. The patient was discharged home with scheduled clinical and CMR follow-ups.

Discussion:
This case of EM illustrates the broad spectrum of possible manifestations of this rare disease and a crucial role of cardiac imaging in the diagnostic process. Physicians should be alerted by neurological symptoms in patients with hypereosinophilia and elevated troponin levels. Notably, patients with EM may develop abacterial Loeffler’s endocarditis and present with splinter hemorrhages, that are more frequently be seen in infectious endocarditis. CMR can make a decisive contribution to the diagnosis due to a pathognomonic phenotype. Although EMB is the gold standard to diagnose EM, CMR is a non-invasive alternative for patients, in which a biopsy is contraindicated or not possible to perform and timely treatment decisions are to be made.

Conclusion:
This case of EM illustrates a clinical presentation with dominant neurological symptoms being extra-cardiac complications of this rare but potentially life-threatening cardiac disease. Moreover, it exemplifies a rare cardiac cause of splinter hemorrhages in eosinophilic myocarditis. CMR can make a decisive non-invasive contribution to the diagnosis due to a pathognomonic phenotype and allows instant initiation and possibly guidance of immunosuppressive therapy that is of prognostic importance, especially in cases where EMB is contraindicated or not possible to perform.