Background: Restenosis rates are high after percutaneous coronary intervention on bifurcation lesions, especially at the ostium of the side branch (SB). However, the mechanism of restenosis in the SB ostium has not been fully understood.
Methods: We evaluated 84 bifurcation lesions with SB ≥2.25 mm, which were treated successfully by provisional T stenting and small protrusion technique using drug-eluting stents under intravascular ultrasound (IVUS) guidance. Postintervention IVUS studies in both branches and 9-month angiographic follow-ups were performed. IVUS analysis of the SB included 2 distinct locations: SB ostium (<5 mm distal to the neo-carina), and SB distal lesion (≥5 mm distal to the neo-carina).
Results: SB stenting was performed in 56 lesions (67%). Regarding the SB, angiographic restenosis (diameter stenosis ≥50%) developed in 8 patients (9%). Of these, 6 cases occurred at the ostium of the SB and focal (SB ostium restenosis group). There was no significant difference in post-procedural minimum lumen area (MLA) at the SB ostium between the SB ostium restenosis group and the SB ostium non-restenosis group (4.6±1.8 mm² versus 4.4±1.7 mm², p = 0.88). However, the SB ostium restenosis group showed a significant larger late lumen loss compared with the SB ostium non-restenosis group (1.6±1.0 mm versus 0.3±0.7 mm, p < 0.001). Post-procedural MLA did not correlated to late loss in the SB ostium (r = 0.2, p = 0.07). In 2-stent group, there was no significant difference in post-procedural minimum stent area at the SB ostium between the SB ostium restenosis group and the SB ostium non-restenosis group (5.4±1.6 mm² versus 4.8±1.7 mm², p = 0.49). Again, the SB ostium restenosis group showed a significant larger late lumen loss compared with the SB ostium non-restenosis group (1.9±1.0 mm versus 0.5±0.7 mm, p < 0.001).
Conclusion: The SB ostium may show a high restenosis rate due to increased neointimal hyperplasia rather than small post-procedural MLA.
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