Although patients with rheumatoid arthritis (RA) may have an increased incidence of cardiovascular events, the development of coronary artery disease and of myocardial infarction at young age is rather uncommon. Herein, we report a case of a 26-year-old man without classical cardiovascular risk factors, but with a 2-year history of RA, who experienced recurrent episodes of angina-like chest pain. His electrocardiogram showed ST-elevation and T-wave inversion in anterior chest leads, and the patient was sent for coronary angiography, which revealed multivessel coronary artery disease. Subsequently, the patient underwent coronary artery bypass grafting. Closer analysis of the patient's history and of the laboratory findings led to revision of the diagnosis of RA: the patient was found to meet the classification criteria for systemic lupus erythematosus. Pitfalls of the classification criteria and the impact of the revised diagnosis on the patient's care are discussed.