A 64-year-old woman presented to the emergency department with productive cough, fever, and fatigue. Her medical history included hypertension, multinodular goiter, and asthma.

On admission, she was prostrated, afebrile, with hypotension (98/68 mmHg), tachycardia (122 bpm), and hypoxemia (SpO2 90%). Cardiac and pulmonary auscultation were unremarkable. Laboratory investigations revealed leukocytosis (13.7×109/L), marked eosinophilia (3.7×109/L), elevated inflammatory and myocardial injury markers (CRP 14.7 mg/dL, D-dimer 3426 ng/mL, TnT 1786 ng/mL, NT-proBNP 11,808 pg/mL). Influenza A virus was detected; parasitic tests were negative.

Electrocardiogram revealed sinus rhythm with a in lead III. Transthoracic echocardiogram (TTE) showed increased wall thickness in the mid-basal lateral and posterior segments of the left ventricle, preserved left ventricular ejection fraction, and small pericardial effusion (Figure 1A). Coronary computed tomography angiography (CT) ruled out obstructive coronary disease.

Figure 1.

Initial etiological workup of increased left ventricular wall thickness. (A) Transthoracic echocardiogram at admission showed increased wall thickness in the mid and basal segments of the lateral and posterior walls of the left ventricle. (B) Contrast-enhanced chest computed tomography revealed an image suggestive of thrombus adherent to the anterior, lateral, and inferior walls of the left ventricle. (C) Contrast-enhanced transthoracic echocardiogram documented a left ventricular mass with reduced perfusion, suggestive of thrombus.

The patient was admitted for further evaluation of suspected acute myocarditis with non-obstructive coronary arteries. Within hours, her respiratory status worsened, and chest CT angiography revealed a segmental pulmonary embolism. Therapeutic anticoagulation was initiated. There were no clinical signs of deep vein thrombosis, and echocardiography showed no evidence of an intracardiac shunt. Forty-eight hours later, she developed right upper limb weakness. Cranial CT identified multiple small infarcts, consistent with cardioembolic stroke despite anticoagulation.

To investigate the increased left ventricular wall thickness, contrast-enhanced TTE was performed, revealing hypoperfusion in thickened segments, raising suspicion of thrombus, infiltration, or an inflammatory process with a thrombotic component (Figure 1C). Chest CT identified a hypodense mass within the left ventricle attached to the anterior, lateral, and inferior walls, suggestive of thrombus (Figure 1B).

Cardiac magnetic resonance (CMR) imaging confirmed mild left ventricular hypertrophy (12 mm) and severe segmental thickening (25 mm) in the basal lateral and posterior walls (Figure 2A). A large non-perfused intraventricular mass (31×17 mm), consistent with thrombus, was identified (Figure 2B). T2-weighted imaging showed myocardial oedema in the meso-basal posterior and lateral segments (Figure 2C), while late gadolinium enhancement (LGE) revealed a subendocardial pattern involving anterior, posterior, lateral, and inferior walls (Figure 2D), consistent with eosinophilic myocarditis associated with a large intraventricular thrombus.

Figure 2.

Etiological investigation of MINOCA using cardiac magnetic resonance (CMR). (A) CMR in 4-chamber and 3-chamber views showed increased left ventricular wall thickness, more pronounced in the basal segment of the lateral and posterior walls. (B) Adherent mass suggestive of thrombus (29×16 mm) on early late gadolinium enhancement sequence. (C) T2-weighted sequence showing increased signal in the mid segments of the anterior, lateral and posterior walls. (D) Subendocardial late gadolinium enhancement in the mid-basal region of the posterior, lateral, anterior, and inferior walls and irregular not-enhanced mass adherent to the basal lateral wall suggestive of thrombus.

The case was reviewed by a multidisciplinary team (Cardiology, Internal Medicine, Rheumatology). In the context of the increasing peripheral eosinophilia, given the previous history of asthma, acute myocarditis, and multiple embolic events, a diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA) was suspected.

To support the diagnosis, paranasal sinus CT revealed rhinosinusitis with a small polyp; nasal biopsy demonstrated eosinophilic necrotizing vasculitis. The clinical presentation, imaging findings, histopathological evidence, and severe peripheral eosinophilia were consistent with EGPA, fulfilling the 2022 American College of Rheumatology/ European Alliance of Associations for Rheumatology classification criteria1 (obstructive airway disease, eosinophilia >10%, and histopathological evidence of eosinophilic vasculitis).

High-dose intravenous methylprednisolone was initiated, followed by oral prednisolone. Her eosinophil count dropped within two days (0.02×109/L), and the patient improved clinically.

Follow-up TTE at 13 days showed a significant reduction in the thickness of the mid-basal segments of the left ventricular lateral and posterior walls (now measuring 16 mm), along with an image suggestive of a left ventricular thrombus (Figure 3A). The patient was discharged on corticosteroids, azathioprine, and anticoagulation. At six-month follow-up, she remained asymptomatic. CMR showed asymmetric wall thickening in the basal segments of the anterior septal, anterior, lateral, and posterior walls, although less pronounced (13 mm) (Figure 3B). There was no evidence of active inflammation, and LGE was observed in the subepicardial region of the basal posterior wall, consistent with sequelae of acute myocarditis (Figure 3C and D). No intraventricular thrombus was identified. The patient remains on low-dose prednisolone without evidence of clinical relapse.

Figure 3.

Imaging assessment following initiation of immunosuppressive therapy. (A) Echocardiogram performed 13 days later showing localized wall thickness reduction. (B) Cardiac magnetic resonance (CMR) imaging in four-chamber view, performed 6 months later, showing mild hypertrophy in the basal segment of the lateral wall of the left ventricle. (C) T2-weighted CMR sequence showing no evidence of myocardial oedema. (D) CMR showing subepicardial/mid-wall late gadolinium enhancement with linear distribution in the basal segment of the posterior wall.

This case highlights the importance of recognizing cardiac involvement as a possible first presentation of EGPA and including EGPA in the differential diagnosis of myocarditis, particularly in patients with severe eosinophilia.1,2 Influenza A infection likely triggered disease onset.3 Multimodality cardiac imaging was essential for diagnosis, guiding immunosuppressive therapy, and monitoring response.4 While myocarditis typically shows subepicardial or mid-wall LGE, eosinophilic myocarditis may present with subendocardial, patchy subepicardial, and intramural patterns.5 In this patient, the shift from subendocardial to subepicardial/mid-wall LGE at follow-up likely reflects healing and residual fibrosis after resolution of acute inflammation and thrombus, illustrating the dynamic nature of myocardial involvement in EGPA.5

Although the left ventricular thrombus accounted for systemic embolic events, the absence of deep vein thrombosis and the exclusion of an intracardiac shunt on echocardiography make paradoxical embolism unlikely. Eosinophil-mediated microvascular injury and activation of coagulation pathways contribute to both arterial and venous thrombosis, further increasing thrombotic risk in EGPA.1

Given the severe presentation, the patient received intravenous corticosteroid pulses followed by oral corticosteroids, achieving rapid clinical remission. Following this favorable response, azathioprine was initiated as steroid-sparing maintenance therapy,1 while cyclophosphamide and biologics (rituximab) were not required due to the prompt improvement and absence of refractory/relapsing disease.