Morphological features of non-culprit plaques on optical coherence tomography and integrated backscatter intravascular ultrasound in patients with acute coronary syndromes

AIMS: We sought to compare the morphological features of non-culprit plaques with >50% diameter stenosis in patients with acute coronary syndromes (ACS) with those of culprit plaques in patients with ACS and stable angina pectoris (SAP) using optical coherence tomography (OCT) and integrated backscatter intravascular ultrasound (IB-IVUS). METHODS AND RESULTS: A total of 150 culprit and non-culprit coronary plaques (non-culprit vessels) in 150 patients with coronary artery disease were interrogated by OCT before percutaneous coronary intervention (PCI). Patients were categorized as follows: 73 culprit plaques in patients with ACS (ACS-C), 32 non-culprit plaques in patients with ACS (ACS-NC), and 45 culprit plaques in patients with SAP. The fibrous cap thickness was thinner in the ACS-C and ACS-NC groups than in the SAP group and was thinnest in the ACS-C group (ACS-C vs. ACS-NC vs. SAP, 60 vs. 82 vs. 114 μm, P < 0.001). IB-IVUS sub-analysis of 95 patients demonstrated that % lipid volume was greater and % fibrous volume was lower in the ACS-NC group than those in the SAP group (ACS-C vs. ACS-NC vs. SAP, 56.3 ± 11.0 vs. 59.9 ± 11.2 vs. 50.1 ± 13.9%, P < 0.05 and 39.5 ± 9.0 vs. 35.0 ± 9.0 vs. 43.9 ± 11.3%, P < 0.01, respectively). CONCLUSION: Plaques of non-culprit vessels in patients with ACS had a thinner fibrous cap and a higher percentage of lipid content than culprit plaques in patients with SAP. However, the fibrous cap thickness was thinner in the culprit lesions in patients with ACS than in the non-culprit lesions in patients with ACS, while plaque compositions were not significantly different between the groups.