Predictors of Side Branch Obstruction Following Stenting of the Main Vessel in Coronary Bifurcation Lesions

INTRODUCTION: Percutaneous coronary intervention (PCI) of bifurcation lesions is complicated by the presence of side branch blockage, which contributes to a low procedural success rate and an elevated rate of adverse cardiac events. A shift in the position of the carina and plaque buildup have been proposed as possible causes of SB occlusion. 1,2 It is estimated that between 15-20% of PCI procedures are done to address lesions at coronary bifurcations.3-5 Multiple randomized clinical trials have concluded that an interim stenting procedure should be used for routine bifurcation stenting. 6-11 AIM AND OBJECTIVE: To assess the predictors of side branch obstruction following stenting of the main vessel in coronary bifurcation lesions. MATERIAL AND METHODS: Total 300 patients were enrolled with coronary bifurcation lesions who were undergoing PCI and had at least one major SB. Major SB definition was the same as what had been found in other studies: diameter ?2.0mm. Patients with SB stenting before MV stenting, LMS disease, or in-stent restenosis were excluded. Using quantitative coronary analysis (QCA) software, all of the baseline and procedure characteristics were analyzed. The Student's t-test was used to compare continuous data. A p-value < 0.05 was considered significant. RESULTS: Out of 300 patients, side branch blockage was found in 23 (7.6%) of the patients. The patients were distributed into two groups based on whether they had SB occlusion (SBO) or not. Mean age (years) in the study was 50.36+12.54 in SBO group and 50+30.34 in no-side-branch occlusion (NSBO) group. There were 19(82%) male and 4(18%) female patients in SBO group and 215(77%)male and 62(23%) female in NSBO group. Diameter stenosis of side branch before MV stenting (55%+20 vs30+25%), side branch diameter (2.1+0.3 vs2.2+0.2), bifurcation angle (70+20degree vs 45+22 degree, p=<0.01) and lower TIMI flow in side branch were found significant predictors of major side branch occlusion. CONCLUSION: The bifurcation angle, diameter stenosis of the SB, side branch diameter before to main vessel stenting, and TIMI flow grade of the SB prior to MV stenting were all predictive of severe SB occlusion following MV stenting. As a result, these criteria should be considered when designing PCI for bifurcation lesions in order to increase procedure success. KEYWORDS: Side branch obstruction, stenting, coronary bifurcation lesions.