Rolling the rock uphill during left main stenting: The Sisyphus myth in percutaneous coronary intervention?

Left main (LM) coronary artery lesions remain a challenging target for percutaneous coronary intervention (PCI) despite significant advancements in procedural techniques and technologies. Intravascular ultrasound (IVUS) if useful in assessing vessel wall size in the typically tapering and branching segment. Optical coherence tomography (OCT) is another invasive imaging modality that provides high-resolution images of coronary lumen outline and its dimensions, albeit with lower tissue penetration than IVUS. It can be used to produce automated outlines of stent outline along the contour of the treated vessel segment. The necessity of clearing the lumen from blood (with timed contrast injection) so close to the aorta and the above noted tissue penetration limitation due to the typically wide LM diameter pose unique challenges to OCT imaging in this coronary location. Hence, OCT in the LM is not well described, whereas IVUS data for such interventions are well established. Cortese et al report on a three-center registry investigating the utility of OCT in the LM PCI. The aim of the study was to analyze the acute and mid-term angiographic outcome of percutaneous treatment of the LM coronary stem percutaneous intervention (LM PCI) guided by OCT capitalizing on their expertise with this imaging modality. The side branch was not assessed. The primary endpoint of the study was late lumen loss (LLL) at 6 months in two locations: the proximal/mid LM and the distal segment that included the ostial portions of the left anterior descending artery and left circumflex artery. Secondary endpoints were binary restenosis and clinical outcome measures at 6-month follow-up; these centers routinely recommend follow-up angiography/imaging after LM stenting. The manuscript reports the results of the retrospective ROCK-I registry of 112 patients treated with LM stent implantation under OCT guidance versus no OCT guidance (which also included IVUS in 10 patients). The authors found that OCT use was associated with less LLL at follow-up, particularly at the distal LM area. Could it be that the proximally wider LM dimension and its proximity to the aorta posed image quality challenges as we described above? As the authors acknowledge, the inherent bias of patient selection in a retrospective nonrandomized comparison is amplified by the absence of clear criteria to determine the OCT use in their practice. An analysis of a purely angiographic control group (ie, after the exclusion of IVUS cases) would have been helpful; alternatively, we would have liked to read the reasons for preferring IVUS over OCT and learn from this experience. Importantly, the authors have tabulated details of vessel dimensions, stent sizes, and balloons used to optimize the results based on the imaging techniques used. The data are very detailed and show no significant differences between the groups. Might the use of aggressive proximal optimization minimize the impact of PCT imaging in the proximal LM area? According to previous reports, restenosis is usually located in the LM side-branch ostium which was not assessed in the present study; however, the rate of repeat PCI was less than 4% and the overall adverse clinical events were less than 10% without much difference between the study groups. Hence, we may deduce that side-branch restenosis was not a major factor in this study of LM successful provisional stenting. In case two-stent bifurcation techniques were used, the side branch and its angle of take-off would be very important analyses. Received: 16 September 2020 Accepted: 16 September 2020