HES is a rare group of disorders characterized by persistent and marked peripheral eosinophilia (> 1.5 × 109/L for > 6 months) of unknown origin with evidence of organs involvement[2]. Cardiac involvement, one of the most frequently involved organs, is a major cause of morbidity and mortality[2].
Loeffler’s endocarditis is one of main cardiac manifestations for which TTE is a valuable diagnostic tool. TTE could reveal typical increased endocardial thickness because of interstitial myocardial edema in early stage. The intermediate thrombotic stage is characterized by thromboembolic events in 4–29% of adult patients with HES [2]. Specific obliterative LV apical mural thrombus can be discovered by TTE and the thrombus may extend to the ventricular outflow tracts, the subvalvular regions or occasionally the atrium[2]. Finally, restrictive diastolic dysfunction can also be detected in late fibrotic stage[2]. Furthermore, LS could reflect true global and regional myocardial contractility while LVEF reflects only global LV volumetric changes. Thus, crucial information for diagnosing Loeffler’s endocarditis and true myocardial dysfunction can be well seen in TTE and STE.
Severe eosinophil inflammatory infiltration into coronary artery, known as ECPA, is seldom described and classically diagnosed in post-mortem examination in HES [1, 2]. The cytokines released by eosinophils into the coronary inflammatory lesion might contribute to the coronary artery spasm, which may lead to secondary angina pectoris, acute myocardial infarction (AMI) or even sudden death in ECPA[4].
Patients with ECPA often have similar clinical and ECG presentations as ACS. The change of diffuse ST-segment depression and biphasic T-wave in ECG mimicking acute NSTMI like our patient was inconsistent with non-obstructive stenosis of coronary artery. And the region of apical endocardial lesion showed by STE was not compliant with perfusion area of any coronary artery, which refuted the preliminary diagnosis of acute NSTMI. It is a pity that the patient refused endomyocardial biopsy which remains the gold standard for the diagnosis of cardiac involvement in HES. But considering the obvious increase of EO count, we could make a diagnosis of Loeffler’s endocarditis by cMRI on account of the significant correlation between late gadolinium enhancement and cardiac inflammatory infiltration presented by biopsy in HES[5]. And it could reasonably be inferred that the clinical presentation mimicking acute NSTMI in our patient occurred secondary to coronary spasm resulting from ECPA.
Thus, the significant increase of EO count and the detection of Loeffler’s endocarditis by quick TTE and regional myocardial dysfunction by STE could provide implicit information for coronary involvement in HES and thus avoided the unnecessary invasive coronary arteriography timely in patients with similar clinical and ECG presentations as ACS.
Corticosteroids remain the first-line therapy for a lymphocytic variant of HES to reduce eosinophil count and counteract inflammation, while a myeloproliferative variant with the FIP1L1-PDGFRA mutation should be given a tyrosine kinase inhibitor of possible effectiveness[1]. Although overall prognosis has improved for HES, cardiac involvement remains a major cause of morbidity and mortality[1]. Unfortunately, our patient gave up the treatment and died soon after discharge. We speculated the sudden death of our patient may derive from another severe coronary spasm due to ECPA, high atrioventricular block or ventricular arrhythmias.