 Initial strategy for PCI will be provisional stenting. The choice of vascular access, guiding catheters and coronary wires are left to the operators discretion. Heparin in doses of 80-100 IUkg will be used as periprocedural anticoagulation. After placing the guidewires in the MB and SB lesion, the MB will be predilated. After predilation and nitroglycerin administration intracoronary, coronary angiogram will be performed. Based on this angiogram, a second generation drug eluting stent DES will be placed in the MB across the SB, so that its diameter will be chosen according to Murrays law. The stent will have to be long enough so that proximal margin of the stent is at least 10 mm proximal to the carina of the bifurcation. After stenting, proximal optimization POT of the stent in the MB will be performed using short noncompliant balloon catheter 0,5 mm larger than the diameter of the stent. The distal marker of the balloon catheter will be positioned at the level of carina. Inflation of the balloon catheter must be at least up to the nominal diameter. After POT and intracoronary nitroglycerin administration, coronary angiograms in two orthogonal projections will be done. If the SB does not have more than 75 diameter stenosis DS on quantitative coronary angiography analysis QCA andor coronary blood flow less than TIMI III, the procedure is finished. If the SB has more than 75 DS stenosis or TIMI flow 