We present the case of a woman in her third decade of life, known to have difficult-to-control mixed headaches and polycystic ovary syndrome under hormonal treatment. Without any other manifestation, the patient debuted with an acute coronary syndrome classified as unstable angina. Electrocardiogram showed anterior and lateral ST segment depression and ST elevation in aVR. Coronary computer tomography and coronary angiography showed evidence of significant obstruction of the left main coronary artery. The patient was diagnosed with systemic lupus erythematosus (SLE), and was classified as vasculitis secondary to SLE as an unusual initial manifestation.