INTRODUCTION
Variations in coronary anatomy are extremely common, including alterations in left/right dominance, dual anatomy and recessive vessels. For the left main stem (LMS), the commonest anomaly is either a short vessel or absent vessel (i.e. the LAD and circumflex emerge as a bifurcation at the left coronary ostia).
However, atresia of LMS is an extremely a rare condition: here, the left system is supplied completely by the right coronary artery (RCA) via retrograde collateral circulation. According to the literature these cases present at a very early age with signs of heart failure, and rarely in adults.