Internal Medicine Resident1, Cardiovascular Disease Fellow2, Department of Cardiology3
Virginia Tech Carilion School of Medicine, Roanoke, VA
Clinical History
64-year-old female presented with intermittent dyspnea and worsening acute upper abdominal pain radiating to her neck, shoulders, and jaw. Her past medical history included type 2 diabetes mellitus, chronic obstructive pulmonary disease / asthma overlap syndrome, chronic abdominal pain, and recent cholecystectomy (2 months prior). She was tachycardic to 109 bpm and hypertensive to 165/79 mmHg. Physical exam was remarkable for mild upper abdominal tenderness and mild wheezing in the bilateral lung fields. There were no murmurs, rubs, or gallops. Investigations were significant for an elevated high-sensitivity troponin of 6,890 ng/L which trended upward and peaked at 15,114 ng/L (normal <37 ng/L), elevated N-terminal pro-brain natriuretic peptide of 3,736 pg/mL (normal <125 pg/mL), leukocytosis of 18.4 K/uL (normal 4.0 - 10.5 K/uL), and absolute eosinophilia of 9.2 K/uL (normal 0.0 - 0.4 K/uL). Electrocardiography demonstrated sinus tachycardia without evidence of acute ischemia. Transthoracic echocardiography demonstrated basal inferior hypokinesis with overall preserved left ventricular ejection fraction (Movie 1). Computed tomography imaging showed circumferential thickening of the esophagus. Coronary angiography showed minimal non-obstructive coronary artery disease. Cardiac magnetic resonance imaging (CMR) was pursued to elucidate the cause of her troponin elevation and continued symptoms.
 |
| Movie 1. Apical two chamber view demonstrating basal inferior hypokinesis of the left ventricle. |
CMR Findings
CMR was performed on a 1.5 T Aera (Siemens Healthineers, Erlangen, Germany) and demonstrated normal global left ventricular systolic function with basal inferior wall focal hypokinesis (Movie 2). The left ventricle was normal in size (end-diastolic volume 122 ml, reference: 82-162 ml). The right ventricle was normal in size with normal systolic function. Extracellular volume (ECV) was elevated at 46% (pre-contrast T1 myocardium elevated at 1195 ms, normal reference 980 ms +/- 30 ms). T2 signal was diffusely elevated (global average 60 ms, normal reference 47 +/- 5 ms) suggestive of acute myocardial edema. Post-contrast images demonstrated diffuse patchy subendocardial late gadolinium enhancement (LGE) involving the primarily the basal- to mid-portions of multiple myocardial segments consistent with non-ischemic myocardial injury (Figure 1). There was a possible small LV thrombus (Figure 1, 2). These findings were consistent with myocarditis based on the modified Lake Louis Criteria, and the pattern of LGE was consistent with eosinophilic myocarditis.
 |
| Movie 2. Basal short axis cine steady state free precession showing normal global left ventricular systolic function with basal inferior wall hypokinesis. |
 | Figure 1. Basal to mid short axis (A, B) and two chamber (C) phase sensitive inversion recovery (PSIR) post contrast imaging with inversion time to null myocardium. There is diffuse, patchy subendocardial late gadolinium enhancement (LGE) (yellow arrows) in the basal to mid cavity in multiple wall segments in short and long axes. There is a thrombus (red arrow) in the left ventricle. |
 |
| Figure 2. Basal (A) to mid (B) short axis PSIR post contrast imaging with inversion time at 600 msec. There are hypointense areas of the left ventricle concerning for mural thrombus (red arrows). |
Conclusion
The diffuse, patchy subendocardial LGE found on CMR, in conjunction with negative coronary angiography, was supported a diagnosis of eosinophilic myocarditis. An extensive multidisciplinary evaluation was undertaken. Esophageal biopsy revealed eosinophilic infiltration into esophageal tissue with formation of microabscesses and some eosinophils in a perivascular distribution. Bronchoalveolar lavage demonstrated 36% eosinophils with negative bacterial cultures. Nasal endoscopy revealed copious nasal polyps. Bone marrow biopsy showed mildly hypercellular marrow for age with trilineage maturation, increased eosinophils and eosinophilic precursors, and increased megakaryocytes with subset atypical morphology. Ancillary bone marrow studies including immunohistochemistry, cytogenetics, and flow cytometry were unrevealing for an identifiable cause. Antineutrophil cytoplasmic antibody (ANCA) screening was negative.
Our patient was ultimately diagnosed with eosinophilic granulomatosis with polyangiitis (EGPA). She was treated with a prolonged systemic corticosteroid taper followed by mepolizumab and was initiated on apixaban for her left ventricular thrombus. The patient reported significant improvement in dyspnea with some residual abdominal discomfort at her 3-month outpatient follow-up visit. She underwent a 5 month follow-up CMR which demonstrated resolution of her intracardiac thrombus (Figure 3) and small patchy mid-wall late gadolinium enhancement consistent with fibrosis from prior inflammation (Figure 4).
 |
| Figure 3. Basal (A) to mid (B) short axis PSIR post contrast imaging with inversion time at 600 msec. There are no hypointense areas of the left ventricle. |
 |
| Figure 4. Basal short axis (A) and two chamber (B) phase sensitive inversion recovery (PSIR) post contrast imaging with inversion time to null myocardium. There is small patchy mid-wall late gadolinium enhancement (yellow arrow) consistent with fibrosis from prior inflammation. |
Perspective
Eosinophilic myocarditis is a rare but treatable cause of myocarditis. The presentation involves acute myocardial injury without evidence of obstructive coronary disease, though the clinical presentation varies widely from minimal symptoms to fulminant heart failure and cardiogenic shock. Peripheral eosinophilia is an important clue to the diagnosis, though importantly it is not universally present (only 75% of biopsy proven cases).[1] Historically, endomyocardial biopsy (EMB) demonstrating eosinophilic infiltration of the myocardium was required for diagnosis, and biopsy is recommended by current American College of Cardiology (ACC) consensus statement [2] in symptomatic myocarditis with peripheral eosinophilia. However, EMB involves risk and is not readily available at all centers. In our case, we decided to forgo biopsy given the relatively mild course and the ability to confirm evidence of eosinophilic inflammation in a non-cardiac site. Our case illustrates the critical role of CMR in the evaluation of patients with myocarditis with the potential for safe, non-invasive diagnosis.
Particularly, the pattern of late gadolinium enhancement in this case is highly suggestive of eosinophilic myocarditis.[3] In EM, there is typically diffuse subendocardial LGE compared mid-wall or epicardial LGE seen in typical viral/idiopathic myocarditis, and the LGE does not follow a coronary distribution compared to subendocardial LGE seen is ischemic heart disease. The subendocardial inflammation in EM is highly thrombotic and left ventricular thrombus is common, seen in up to 14% of cases, even in the absence of severe regional wall motion abnormalities.[1] It can be easily missed on transthoracic echocardiography, as demonstrated in this case.
The treatment of idiopathic myocarditis is typically supportive, but EM is one of few uncommon clinical conditions that warrant immunosuppressive therapy (namely giant cell myocarditis, sarcoidosis, and immune checkpoint inhibitor mediated), highlighting the management-changing information obtained by CMR in this case. Treatment includes high dose corticosteroids with slow taper with consideration of steroid sparing agents such as mepolizumab (IL-5 inhibition).
Importantly, the discovery of EM should prompt diligent evaluation for an underlying cause. The largest-to-date case series on histologically-proven EM showed that EM is most commonly attributed to an idiopathic or undefined cause (35.7%), followed by hypersensitivity (34.7%), and EGPA (12.8%).[1] Our patient met diagnostic criteria for EGPA due to her steroid-dependent asthma, nasal polyps, biopsy-proven gastrointestinal involvement, peripheral eosinophilia, and lack of primary hypereosinophilic pathology. Our patient falls into the eosinophilic phenotype of EGPA (vs. the vasculitic phenotype) given her negative ANCA screening and lack of necrotizing features, palpable purpura, alveolar hemorrhage, or coronary arteritis.[4] Additionally, patients with the eosinophilic phenotype of EGPA have a higher incidence of EM.[4] EGPA is perhaps under-recognized by cardiologists, and it has been purported to represent a larger proportion of EM than is currently attributed in clinical practice.[1] This case serves as a reminder to the diagnostic utility of CMR with regard to EM and the crucial role of cardiologists in the diagnosis of EGPA.
Click here to review the initial CMR on CloudCMR.
Click here to review the follow-up CMR on CloudCMR.
References
- Pöyhönen P, Rågback J, Mäyränpää MI, et al. Cardiac magnetic resonance in histologically proven eosinophilic myocarditis. J Cardiovasc Magn Reson. 2023;25(1):79. doi:10.1186/s12968-023-00979-0
- Kuchynka P, Palecek T, Masek M, et al. Current Diagnostic and Therapeutic Aspects of Eosinophilic Myocarditis. BioMed Res Int. 2016;2016(1):2829583. doi:10.1155/2016/2829583
- Brambatti M, Matassini MV, Adler ED, Klingel K, Camici PG, Ammirati E. Eosinophilic Myocarditis: Characteristics, Treatment, and Outcomes. J Am Coll Cardiol. 2017;70(19):2363-2375. doi:10.1016/j.jacc.2017.09.023
- Mikhail ES, Ghatol A. Hypereosinophilic Syndrome. [Updated 2024 Jan 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK599558/
Acknowledgements: David LeBel, MD, Dominon Pathology Associates and Assistant Professor, Virginia Tech Carilion School of Medicine, Department of Basic Science Education, Roanoke, VA
Case prepared by:
Jeffrey M. Dendy, MD
Editorial Board Member, Cases of SCMR
Vanderbilt University Medical Center
Division of Cardiovascular Medicine
