Relationship of OCT-defined plaque characteristics with CCTA-derived coronary inflammation and CMR-derived global coronary flow reserve in patients with acute coronary syndrome

Layered plaque is associated with high levels of vascular inflammation and vulnerability in patients with stable angina pectoris

Layered plaque, a signature of previous plaque destabilization and healing, is a known predictor for rapid plaque progression; however, the mechanism of which is unknown. The aim of the current study was to compare the level of vascular inflammation and plaque vulnerability in layered plaques to investigate possible mechanisms of rapid plaque progression. This is a retrospective, observational, single-center cohort study. Patients who underwent both coronary computed tomography angiography (CTA) and optical coherence tomography (OCT) for stable angina pectoris (SAP) were selected. Plaques were defined as any tissue (noncalcified, calcified, or mixed) within or adjacent to the lumen. Perivascular inflammation was measured by pericoronary adipose tissue (PCAT) attenuation at the plaque levels on CTA. Features of plaque vulnerability were assessed by OCT. Layered plaques were defined as plaques presenting one or more layers of different optical densities and a clear demarcation from underlying components on OCT. A total of 475 plaques from 195 patients who presented with SAP were included. Layered plaques (n = 241), compared with non-layered plaques (n = 234), had a higher level of vascular inflammation (-71.47 ± 10.74 HU vs. -73.69 ± 10.91 HU, P = 0.026) as well as a higher prevalence of the OCT features of plaque vulnerability, including lipid-rich plaque (83.8% vs. 66.7%, P < 0.001), thin-cap fibroatheroma (26.1% vs. 17.5%, P = 0.026), microvessels (61.8% vs. 34.6%, P < 0.001), and cholesterol crystals (38.6% vs. 25.6%, P = 0.003). Layered plaque was associated with a higher level of vascular inflammation and a higher prevalence of plaque vulnerability, which might play an important role in rapid plaque progression.Clinical trial registration: https://classic.clinicaltrials.gov/ct2/show/NCT04523194 .

Relationship between peri-coronary inflammation and coronary vascular function in patients with suspected coronary artery disease

Background

In this study, we aim to investigate the relationship between the attenuation of peri-coronary adipose tissue (PCAT) in patients with suspected coronary artery disease (CAD) and the assessment of coronary vascular functions using coronary flow reserve (CFR).

Methods

We included 364 patients who underwent 13N-NH3 positron emission tomography/computed tomography and coronary computed tomography angiography (CCTA). We determined the relationship between fat attenuation index (FAI), PCAT volume, and other qualitative CT-derived anatomic parameters with CFR.

Results

We detected a decrease in CFR (<2.5) in 206 (57%) patients. At the patient level, those with reduced CFR showed a significantly higher prevalence of diffused atherosclerosis (41% vs. 23%; P < 0.001) and higher FAI (-75.5 HU vs. -77.1 HU; P = 0.014). In patients without obstructive CAD, FAI was significantly higher in those with reduced CFR (-75.5 HU vs. -77.7 HU, P = 0.026). On the vessel level, 1,092 vessels were analyzed, and 642 (59%) exhibited reduced CFR. The vessels with reduced CFR presented a significantly higher prevalence of obstructive CAD (37% vs. 26%; P < 0.001), diffused atherosclerosis (22% vs. 11%; P < 0.001), low-attenuation plaque (6% vs. 3%; P = 0.030), and positive remodeling (7% vs. 2%; P = 0.001). FAI was higher in vessels with reduced CFR (-80.8 HU vs. -81.8 HU; P = 0.045) than in normal CFR. In the patient-level analysis, obstructive CAD, diffused atherosclerosis, and FAI were independently linked with CFR. FAI was still associated with global CFR after adjusting for traditional risk factors (age, hypertension, diabetes, hyperlipidemia, and smoking). FAI remained independently associated with reduced CFR in patients without obstructive CAD.

Conclusions

Coronary perivascular inflammation evaluated by CCTA was independently associated with coronary vascular function. In patients without obstructive CAD, FAI was higher in the presence of reduced CFR. Altogether, FAI can help reveal microcirculatory damage in patients who do not exhibit epicardial artery stenosis.