RESUMEN
Isolated left main coronary ostial stenosis is a very rare condition. In the majority of cases there are coexisting diseases in multiple coronary vessels. Here, a case of isolated left main coronary ostial stenosis due to an acute angle take-off, with clockwise rotation of the coronary sinus, confirmed by cardiac MRI is presented. A 44-year old female patient presented with an exertional and stabbing anterior chest pain. The patient had no premedical history. A coronary angiogram showed an isolated left main coronary ostial stenosis due to an acute take-off of the left main coronary artery. A cardiac MRI showed an acute angle take-off of the left main coronary artery, with clockwise rotation of the coronary sinus. The patient underwent surgical angioplasty of the coronary ostia, with a patch of autologous pericardium. This acute angle take-off may be due to rotation of the coronary sinus.