The aim of this thesis was to investigate consecutive cases treated at the University of Debrecen's institute of Cardiology that were treated with stent implantation due to left main coronary stenosis within a five year period between 2012 and 2016. The factors that have been investigated were: coronary artery disease risk factors, age, left ventricular ejection fraction, kidney function (GFR) and extension of the left main and coronary artery disease, protected or unprotected LM and circumstances of stenting – acute or elective, DES or BMS. The impact of variables on survival of patients treated with left main coronary stenting was also investigated. A comprehensive literature review was also done, and comparisms were made between the results gotten from our original work and the results from the established trials.