Background: Patients with acute coronary syndrome (ACS) have a higher incidence of recurrent ischemic events. The aim of this study was to compare the plaque characteristics of nonculprit lesions between ACS and non-ACS patients using optical coherence tomography (OCT) imaging.
Methods and results: Patients who had 3-vessel OCT imaging were selected from the Massachusetts General Hospital (MGH) OCT Registry. MGH registry is a multicenter registry of patients undergoing OCT. The prevalence and characteristics of nonculprit plaques were compared between ACS and non-ACS patients. A total of 248 nonculprit plaques were found in 104 patients: 45 plaques in 17 ACS patients and 203 plaques in 87 non-ACS patients. Compared with plaques of non-ACS patients, plaques of ACS patients had a wider lipid arc (147.3 ± 29.5° versus 116.2 ± 33.7°, P<0.001), a longer lipid length (10.7 ± 5.9 mm versus 7.0 ± 3.7 mm, P=0.002), a larger lipid volume index [averaged lipid arc×lipid length] (1605.5 ± 1013.1 versus 853.4 ± 570.8, P<0.001), and a thinner fibrous cap (70.2 ± 20.2 µm versus 103.3 ± 46.8 µm, P<0.001). Moreover, thin-cap fibroatheroma (64.7% versus 14.9%, P<0.001), macrophage (82.4% versus 37.9%, P=0.001), and thrombus (29.4% versus 1.1%, P<0.001) were more frequent in ACS patients. Although the prevalence of microchannel did not differ between the groups, the closest distance from the lumen to microchannel was shorter in ACS subjects than in non-ACS (104.6 ± 67.0 µm versus 198.3 ± 133.0 µm, P=0.027).
Conclusions: Nonculprit lesions in patients with ACS have more vulnerable plaque characteristics compared with those with non-ACS. Neovascularization was more frequently located close to the lumen in patients with ACS.