RESUMEN
CONTEXT: ST-segment elevations in two or more contiguous leads or new left bundle branch block (LBBB) on electrocardiography (ECG) in a patient with acute onset chest pain are diagnostic criteria for acute myocardial infarction (AMI) and generally warrant urgent coronary angiography and cardiac catheterization. However, the significance of new right bundle branch block (RBBB) without other acute ECG changes is unclear and is currently not considered a criterion. CASE REPORT: We present a patient with chest pain, positive biomarkers of myocardial necrosis and isolated new right bundle block on ECG. He was diagnosed with AMI but did not undergo urgent reperfusion therapy in the absence of ST-segment elevations or new LBBB. However, angiography ultimately demonstrated complete coronary occlusion. CONCLUSION: The established criteria for emergent catheterization may prove to be more sensitive with the inclusion of the presence of new RBBB on ECG.