 Secondary aims are to determine whether MSCTA correctly identifies the degree of stenosis and atherosclerotic plaque composition in MB and SB of bifurcation lesions compared to invasive quantitative coronary angiography and IVUS. Also to determine correlation between endothelial wall shear stress, computed using mathematical model of fluid dynamic reconstruction of MSCTA findings, and the degree of stenosis and atherosclerotic plaque composition in MB and SB of bifurcation lesion. Another goal is to determine correlation between SB stenosis and coronary blood flow after provisional stenting and regional myocardial function assessed by myocardial deformation imaging echocardiography in the area of the left ventricle supplied by SB, immediately after intervention, and after three months. Study patients will be selected based on previous diagnostic coronary angiogram. They will undergo MSCTA on Toshiba Aquilion CXL 128 slice CT scanner using predefined protocol. The procedure will include calcium scoring Agatston then CT angiography using Ultravist 370 contrast agent iopromide concentration 370 mgml, Bayer Health Care, Germany. MSCTA angiograms will be analyzed using dedicated software Vital Vitrea Advanced 6.2, Vital Images, Minnetonka, Minnesota, US. The bifurcation lesion analyses will include: the measurement of the angle between MB and SB, measurement of the lesion length, reference diameter of the vessel, degree of stenosis, atherosclerotic plaque analysis 10 mm proximal and distal in the MB, and 5 mm from the ostium of the SB, and at the level of maximum stenosis minimal lumen diameter. 