Visualizing the evolution of drug-induced endomyocardial fibrosis with CMR: A case study (QF_FR_085)

Eosinophilic endocarditis is a rare endomyocardial disorder shown to be associated with parasitic infections, malignancies, allergies and autoimmune conditions.^1,2,3,4  With limited published reviews on the condition and little known about the true prevalence, data is limited and clinicians resort to case reports and cases series to elucidate defining traits.^1,2 Whilst the pathophysiology has not been fully elucidated, it is thought that eosinophilic infiltration into the endocardium damages the myocardial cells through degranulation and the release of toxic granule proteins.^1,2,3 Inhibition of the coagulation regulatory protein complex and the activation of coagulation factors contribute to thrombus formation.^1,2,3 These pathophysiological mechanisms define the disease process, and are classified into three stages: acute necrotic stage, thrombotic formation stage, and fibrosis stage.¹

We present a 30 year old South African male with a rare case of drug-induced endomyocardial fibrosis, the progression of which has been documented by serial CMR assessment. Known with adult-onset asthma and depression for which he was on lamotrigine and butriopine, he presented to hospital with acute, dull chest pain. He was found to have ST segment depression in multiple leads on electrocardiogram (Figure 1), his troponin levels were markedly increased and he was noted to have eosinophilia of 15%.

Diagnostic Techniques and Their Most Important Findings:

Further imaging was conducted. Echocardiography showed a non-dilated left ventricle (LV) with mildly impaired LV systolic and diastolic function with no wall motion abnormalities. Angiography revealed normal epicardial vessels, mild anterior apical and infero-posterior hypokinesia.

Initial CMR showed normal bi-ventricular size and systolic function. Extensive sub-endocardial late gadolinium enhancement (LGE) was noted with increased prominence within the mid-to-apical LV walls, in keeping with eosinophilic myocarditis. He received corticosteroid therapy with subsequent resolution of his symptoms.

The following year, he represented with chest pain and elevated troponin levels. CMR revealed a similar pattern of sub-endocardial LGE with increased signal intensity (SI) in T2-weighted imaging indicative of inflammation. A new finding of LV apical thrombus was also noted and the patient was commenced on anticoagulant therapy. Following extensive work-up, lamotrigine was considered to be the likely trigger and the drug was suitably substituted. No further episodes of chest pain were subsequently reported and serial full blood counts showed no further episodes of eosinophilia.

Subsequent CMR studies showed a reduction in the SI in T2-weighted imaging and normalisation of T2 parametric mapping times, indicating a reduction in inflammation. There was some persistence in the sub-endocardial LGE initially seen, suggestive of fibrosis. These CMR findings correspond to the three stages of the condition described and are compared in figures 2 and 3.

Learning Points from this Case:

The ability of CMR to provide a virtual histological assessment of the myocardium through the use of parametric mapping and late gadolinium enhancement imaging assisted in narrowing a differential and establishing a rare diagnosis within an early stage of the disease. Furthermore, serial CMR assessments were key in informing clinical management of the manifestations of the condition and monitoring disease progression.