Vessel remodeling and plaque distribution in side branch of complex coronary bifurcation lesions: a grayscale intravascular ultrasound study.

To investigate vessel remodeling and plaque distribution in side branch (SB) of true coronary bifurcation lesions with SB disease extending from its ostium. A total of 62 patients with single de novo true bifurcation lesions with SB with severe and extensive disease were enrolled. Of that, 45 patients/lesions underwent pre-intervention intravascular ultrasound (IVUS) at the SB. Left anterior descending was the most prevalent target vessel (>85%). All lesions had significant involvement of both branches of the bifurcation, and the majority were classified as type 1,1,1 according to the Medina classification. Considering the subset with IVUS imaging, mean lesion length, reference diameter and % diameter stenosis in the SB were 8.88 ± 4.61 mm, 2.68 ± 0.59, and 70.2 ± 16.0%, respectively. Also, mean proximal (take-off) and distal (carina) angles were 142.3 ± 21.9° and 60.7 ± 22.4°, respectively. At minimum lumena area (MLA) site, mean external elastic membrane and MLA cross-sectional areas were 6.70 ± 2.08 and 1.87 ± 0.93 mm2, respectively; given that the mean distance measured between the SB origin and MLA site was <1 mm. In addition, mean plaque burden was 67.9% and mean remodeling index was 0.78 ± 0.21. Importantly, only 9 cases out of 45 presented remodeling index > 1.0. Also, plaque distribution analysis within the SB ostium demonstrated preferable plaque positioning in the opposite side to the flow divider. In conclusions, significant negative remodeling is a frequent encounter in SB of complex coronary bifurcation lesions presenting with extensive and severe disease; in addition, plaque distribution in the SB ostium appears to be asymmetric in relation to the parent vessel, as plaque burden is mostly found in regions of low wall shear stress including the opposite side to the flow divider within the bifurcation anatomy.