[Incidental finding of negative T waves: a case of endomyocardial fibrosis].

We present the case of a 58-year-old man with negative T waves in the inferior and lateral leads observed on a routine ECG in the context of persistent peripheral eosinophilia, 6 months after an intestinal parasitic infection. The diagnostic workup excluded coronary artery disease and led to a diagnosis of endomyocardial fibrosis with apical thrombosis. Endomyocardial fibrosis, also known as Loeffler endocarditis, represents the cardiac involvement of the hypereosinophilic syndrome, resulting in a cardiomyopathy with a restrictive phenotype. After initiating specific therapy, further investigations identified chronic eosinophilic leukemia as the underlying cause of hypereosinophilia. The patient remained asymptomatic regarding heart failure manifestations. Additionally, diastolic function was pseudo normal on transthoracic echocardiography, with no restrictive pattern, and troponin and natriuretic peptide levels were only mildly elevated. The moderate peripheral eosinophilia was firstly attributed to the recent parasitic infection, supported by the decrease in eosinophil count following treatment with metronidazole. Cardiac involvement occurred relatively shortly after the onset of peripheral eosinophilia (approximately 6 months). Early diagnosis through advanced cardiac imaging allowed the detection of this condition before irreversible myocardial damage occurred and facilitated the initiation of targeted therapy for both ventricular thrombosis and cardiomyopathy.