A 42-year-old female with a history of asthma presented to the emergency department with chest tightness and shortness of breath. Her electrocardiogram showed diffuse ST-segment depression with reciprocal elevation in lead aVR. Physical examination revealed petechiae and purpura on the back, and troponin was markedly elevated (51687 ng/L; reference <16 ng/L), prompting admission for suspected non-ST elevation myocardial infarction. Laboratory results showed leukocytosis (14.2 x 109/L) with significant eosinophilia (41.1%) and elevated C-reactive protein (82.8 mg/L). Coronary angiography revealed normal coronary arteries. Transthoracic echocardiography demonstrated a large, non-perfused mass occupying the apical and mid-cavity segments of the left ventricle, with regional wall motion abnormalities. Further history uncovered chronic sinusitis and polyneuropathy. Chest and paranasal computed tomography revealed diffuse ground-glass opacities and chronic ethmoid sinusitis. Despite a normal neurological exam, brain magnetic resonance imaging identified multiple small cortical and subcortical infarcts. Stool parasite examination and autoimmune serologies including cytoplasmic antineutrophil cytoplasmic antibody, and perinuclear antineutrophil cytoplasmic antibody were negative. Multidisciplinary evaluation integrating clinical, radiological, and laboratory findings supported a diagnosis of eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome) complicated by Loeffler's endocarditis. The patient was treated with intravenous methylprednisolone (1000 mg/day for 3 days), followed by oral prednisone (1 mg/kg/day), and anticoagulated with heparin, later switched to warfarin. She showed marked improvement, with normalization of eosinophil count, inflammatory markers, and cardiac function. Multimodality imaging played a pivotal role in unveiling Loeffler's endocarditis as the initial cardiac manifestation of eosinophilic granulomatosis with polyangiitis.