Characteristics of Atherosclerotic Plaques Left after Percutaneous Coronary Intervention in Patients with Acute Coronary Syndrome. Assessment According to Computed Tomographic Angiography of the Coronary Arteries.

Aim: To evaluate characteristics of atherosclerotic plaques (ASP) remaining after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS) by coronary computed tomography angiography (CCTA).

Material and methods: Among 249 patients (193 men) with ACS aged 58±10 years, 183 (73.5%) had myocardial infarction, 66 (26.5%) had unstable angina. CCTA was performed after PCI at 3-7 days after the onset of ACS according to the standard protocol: in 41 patients, on a 64-slice tomograph (Aquilion 64, Toshiba, Japan) and in 208 patients, on a 640-slice tomograph with 320 rows of detectors (Aquilion ONE Vision Edition, Toshiba, Japan). CCTA of all patients was performed on a Vitrea workstation. Patients with at least one non-calcified ASP were included.

Results: Among all ASPs, non-calcified ASPs predominated, 609 of 785 (77.6%), including 400 soft and 209 combined ones. Signs of obstruction (stenosis ≥50%) were noted in 72.2% of non-calcified ASPs. ASPs were characterized by a pronounced burden, 69 [61.4; 74.2]%, and a low minimum density, 31 [23; 37] HU, which was consistent with mature plaques with a lipid core. Various signs of ASP instability were observed in 6-35.3% of cases. There were 2 [2;3] (1 to 6) affected coronary arteries (CAs) and 3 [2;4] (1 to 7) ASPs, including calcified ones, per patient. 77.7% of ASPs were located in the CA proximal and middle segments. Obstructive stenosis was detected in 92% of patients. The number of ASPs with obstructive stenosis ranged from 0 to 7 per patient, with a median of 2 [1;3]. In 44% of patients, stenosis was 70% or more. The maximum burden of non-calcified ASPs was high, 74.3±12.1%; their maximum and total length were 13.8±10.4 mm and 26.5±19.7 mm, respectively; and the ASP minimum density was low, 25 [17;32] HU. ASPs with a low-density area of ≤46 HU and ≤30 HU were detected in 24.9% and 14.8% of patients, respectively. Other CCTA signs of instability were quite common: punctate calcifications in 52.2% of patients, coronary positive remodeling in 37%, the presence of "ring-like enhancement" in 16.1%, an uneven plaque contour in 26.7%, and at least one sign of ASP instability in 73% of patients.

Conclusion: After PCI, patients with ACS still have rather many ASPs, including those with CCTA signs of instability, with stenosis >50%; more than a third of the plaques had stenosis >70%; the plaques were extended and localized mainly in the proximal and middle sections of the main CAs.