The story of plaque shift and carina shift.

Side branch (SB) occlusion is one of the most serious complications of main vessel (MV) stenting. Although plaque shift has been considered the major mechanism of SB occlusion, recent studies have suggested carina shift to be the more important cause. Considering the recent pressure wire as well as intravascular ultrasonography studies, the relationship between carina shift and plaque shift in SB occlusion can be described as follows. The anatomical compromise of the SB after MV stenting is not as functionally significant as it appears, because it is mostly explained by carina shift, which is not the major cause of functional compromise. Superimposition of plaque shift over carina shift appears to be the mechanism of haemodynamically significant SB stenosis. Plaque is shifted mostly from the proximal MV, which explains why the plaque burden of the proximal MV is a significant risk factor of SB functional compromise or occlusion.