Association between myocardial bridge and upstream plaque morphology in patients with acute coronary syndrome.

Myocardial bridging (MB), characterized by systolic coronary artery compression, alters coronary flow and may influence upstream atherosclerotic plaque morphology. We aimed to investigate the relationship between MB and morphological features of upstream culprit plaques in patients with acute coronary syndrome (ACS). We retrospectively analyzed 370 ACS patients who underwent optical coherence tomography (OCT)-guided PCI for a de novo culprit lesion in the proximal left anterior descending artery (LAD). OCT images identified plaque rupture (PR), classifying lesions into PR and intact fibrous cap (IFC) groups. The IFC group was further divided based on the presence of lipid-rich plaque (LRP), defined as a plaque with a maximum lipid angle > 90°. This study included 370 ACS patients (mean age 65.2 ± 12.3 years, 82.4% male). Angiographic evidence of MB was present in 8.6% (32/370) of patients prior to PCI and increased to 17.0% (63/370) post-PCI; all MBs identified pre-PCI were also observed post-PCI. OCT identified 213 lesions with plaque rupture and 157 lesions with IFC (of which 83 exhibited underlying LRP and 74 did not). The prevalence of post-PCI angiographically detected MB differed significantly among the OCT-defined morphological groups: 11.3% (24/213) in the PR group, 18.1% (15/83) in the IFC-LRP group, and 32.4% (24/74) in the IFC-non-LRP group (P < 0.01). No periprocedural myocardial injury occurred in the IFC-non-LRP group. In patients with ACS, the presence of MB was significantly associated with a lower likelihood of plaque rupture and LRP in the upstream culprit lesion as assessed by OCT.