Silent and Malignant Early Repolarization Syndrome Mimicking Hyper-Acute ST Elevation Myocardial Infarction.

A 55-year-old male with underlying type 2 diabetes mellitus and hypertension presented at our emergency department with ventricular fibrillation-related cardiac arrest. Hyper-acute ST elevation myocardial infarction was the preliminary diagnosis by 12-lead electrocardiography, which simultaneously showed J point ST elevation and tall T waves. However, the echocardiography showed concentric left ventricle hypertrophy and preserved left ventricular systolic function with no regional wall motion abnormalities, and coronary angiography did not show any critical coronary artery lesion. Malignant early repolarization syndrome was diagnosed, and an implantable cardioverter defibrillator was implanted. Early repolarization syndrome is associated with J point elevation, and more involved leads and an increased J point elevation amplitude can increase the risk of arrhythmogenicity. In summary, we report a case with asymptomatic type 3 early repolarization syndrome-induced idiopathic ventricular fibrillation mimicking hyper-acute ST elevation myocardial infarction.