Subintimal Shift at the Bifurcation: A Cause of Side Branch Occlusion in Chronic Total Occlusion Intervention

Bifurcation lesions are frequently found in chronic total occlusion (CTO) percutaneous coronary intervention and are associated with lower procedural success and higher rates of complications, including side branch loss. In this report, we describe a poorly understood mechanism for side branch loss in CTO PCI: subintimal shift. This involves the extension of a dissection plane caused by subintimal (extraplaque) crossing in the main branch at the level of the side branch ostium, causing exclusion of the latter upon vessel preparation or stent placement. Subintimal shift (as compared to carina shift in non-CTO bifurcation intervention) appears to be under-recognized, and CTO operators should be aware that, from a technical standpoint, ballooning of the side branch is unlikely to restore and maintain flow, and a two-stent strategy is indicated to preserve the bifurcation.