Background: The majority of bifurcation lesions are treated with 1-stent technique nowadays. However, the predictors and mechanism of lesion progression at the side branch (SB) ostium after 1-stent technique have not been fully elucidated.
Methods: We studied 72 bifurcation lesions with post-procedural and 9-month follow-up intravascular ultrasound (IVUS) images for both main vessel (MV) and SB. All lesions were treated with drug-eluting stents by MV stenting with or without kissing ballooning. In the left main distal bifurcation lesions, the left circumflex artery was regarded as the SB. IVUS analysis included 4 distinct locations: MV proximal stent, MV middle area, MV distal stent, and SB ostium (<5 mm distal to the carina). Lesion progression at the SB ostium was defined as decrease of the minimum lumen area (MLA) at follow-up compared with immediately after procedure. Plaque area was calculated as external elastic membrane (EEM) area - lumen area. Percent plaque area was calculated 100 x plaque area/EEM area.
Results: True bifurcation was noted in 23 lesions (32%) and left main lesions were observed in 29 lesions (40%). Final kissing ballooning was performed in 57 lesions (79%). At the SB ostium, follow-up MLA significantly correlated with post-procedural MLA (4.0กพ1.9 mm2 and 4.3กพ2.3 mm2, r=0.82, p<0.001), but lesion progression at the SB ostium developed in 37 lesions (51%). Left main lesions were significantly associated with lesion progression at the SB (69% in the left main versus 40% in the non-left main lesions, p=0.01). However, true bifurcation, angle between the MV and SB, and final kissing ballooning were not associated with lesion progression at the SB. Among IVUS parameters, change of the EEM area (-1.1กพ2.2 mm2 versus 0.5กพ0.9 mm2, p<0.001), but not change of the plaque area (0.1กพ1.6 mm2 versus -0.2กพ0.9 mm2, p=0.40), was associated with lesion progression at the SB ostium. Although the post-procedural and follow-up plaque area was significantly larger in the SB with lesion progression than those without lesion progression, percent plaque area was not significantly different between 2 groups.
Conclusion: Left main lesions are associated with the SB lesion progression. Serial IVUS analysis suggests that the negative remodeling be associated with the SB lesion progression.
