Biolimus-a9 eluting stent implantion for unprotected left main coronary artery stenosis: 9-month strut coverage as assessed by optical coherence tomography

OBJECTIVE: To evaluate strut coverage after biolimus-A9 eluting stent (BES) implantation for unprotected left main artery (ULMA) stenosis during follow-up and identify features associated with the length of uncovered stent segment, as assessed by frequency domain-optical coherence tomography (FD-OCT). BACKGROUND: Incomplete stent strut coverage is a risk factor for late stent thrombosis. Long-term interaction between vessel wall and BES in the context of ULMA stenting has not been investigated in depth. METHODS: We prospectively enrolled 32 patients with ULMA stenosis treated with BES. FD-OCT was performed at 9-month follow-up. Both malapposed and uncovered segment length were indexed for the segment between the distal and proximal cross-sections in which stent struts were circumferentially visible. Patients were divided into two groups according to the median value of maximal indexed uncovered segment length. Study endpoints were the rate of strut coverage and predictors of high uncovered segment length. RESULTS: We analyzed 3622 struts. The rate of covered struts was 87%. A high correlation was found between malapposed and uncovered segment length (r ≤ 0.82; P<.001). The median value of indexed-uncovered segment length was 0.308. On multivariable analysis, patients undergoing final kissing balloon were at lower risk of high uncovered segment length (odds ratio, 0.81; 95% confidence interval, 0.008-0.837; P≤.04). CONCLUSION: In patients undergoing BES implantation for treatment of ULMA stenosis, the rate of 9-month strut coverage is high. The use of final kissing balloon reduces the risk of high uncovered stent segment length.