Impact of myocardial bridge on late lumen enlargement in distal reference segments after recanalization of coronary chronic total occlusion.

Successful recanalization of coronary chronic total occlusion (CTO) can induce subsequent positive vascular remodeling. Although myocardial bridge (MB) is known to alter endothelial function and wall shear stress, the impact of MB on late lumen enlargement in the distal segment is unclear. A total of 59 patients who underwent successful percutaneous coronary intervention (PCI) for CTO in the left anterior descending artery (LAD) under intravascular ultrasound (IVUS) guidance and follow-up angiography at 8-12 months were included. Gray-scale IVUS images were analyzed and MB was detected. Lumen diameter (LD) at distal reference at post-PCI was quantitatively compared with corresponding LD at follow-up coronary angiography to assess late lumen enlargement. MB on IVUS was detected in 17 patients (29%). The length from LAD ostium to the entry of CTO was shorter (11.7 ± 13.9 vs. 22.8 ± 13.4 mm, p = 0.006) and LD at distal reference at post-PCI was smaller (1.65 ± 0.54 vs. 1.97 ± 0.56 mm, p = 0.049) in patients with MB than those without. At the mean follow-up of 10.4 ± 2.4 months, LD at distal reference was significantly increased by 25% from baseline to follow-up in the overall population (1.88 ± 0.57 vs. 2.21 ± 0.41 mm, p < 0.001), with a greater increase in patients with MB compared to those without (46 ± 31% vs. 17 ± 29%, p < 0.001). Multivariable analysis indicated MB as an independent predictor of late lumen enlargement. In patients with MB on IVUS, CTO was located in more proximal segment of LAD than those without. Late lumen enlargement at follow-up was greater in patients with MB compared to the counterpart.