Layered Plaque Characteristics and Layer Burden in Acute Coronary Syndromes

Intravascular Imaging Findings After PCI in Patients With Focal and Diffuse Coronary Artery Disease

BACKGROUND

Following percutaneous coronary intervention (PCI), optical coherence tomography provides prognosis information. The pullback pressure gradient is a novel index that discriminates focal from diffuse coronary artery disease based on fractional flow reserve pullbacks. We sought to investigate the association between coronary artery disease patterns, defined by coronary physiology, and optical coherence tomography after stent implantation in stable patients undergoing PCI.

METHODS AND RESULTS

This multicenter, prospective, single-arm study was conducted in 5 countries (NCT03782688). Subjects underwent motorized fractional flow reserve pullbacks evaluation followed by optical coherence tomography-guided PCI. Post-PCI optical coherence tomography minimum stent area, stent expansion, and the presence of suboptimal findings such as incomplete stent apposition, stent edge dissection, and irregular tissue protrusion were compared between patients with focal versus diffuse disease. Overall, 102 patients (105 vessels) were included. Fractional flow reserve before PCI was 0.65±0.14, pullback pressure gradient was 0.66±0.14, and post-PCI fractional flow reserve was 0.88±0.06. The mean minimum stent area was 5.69±1.99 mm2 and was significantly larger in vessels with focal disease (6.18±2.12 mm2 versus 5.19±1.72 mm2, P=0.01). After PCI, incomplete stent apposition, stent edge dissection, and irregular tissue protrusion were observed in 27.6%, 10.5%, and 51.4% of the cases, respectively. Vessels with focal disease at baseline had a lower prevalence of incomplete stent apposition (11.3% versus 44.2%, P=0.002) and more irregular tissue protrusion (69.8% versus 32.7%, P<0.001).

CONCLUSIONS

Baseline coronary pathophysiological patterns are associated with suboptimal imaging findings after PCI. Patients with focal disease had larger minimum stent area and a higher incidence of tissue protrusion, whereas stent malapposition was more frequent in patients with diffuse disease.

Coronary Atherosclerosis Phenotypes in Focal and Diffuse Disease

BACKGROUND

The interplay between coronary hemodynamics and plaque characteristics remains poorly understood.

OBJECTIVES

The aim of this study was to compare atherosclerotic plaque phenotypes between focal and diffuse coronary artery disease (CAD) defined by coronary hemodynamics.

METHODS

This multicenter, prospective, single-arm study was conducted in 5 countries. Patients with functionally significant lesions based on an invasive fractional flow reserve ≤0.80 were included. Plaque analysis was performed by using coronary computed tomography angiography and optical coherence tomography. CAD patterns were assessed using motorized fractional flow reserve pullbacks and quantified by pullback pressure gradient (PPG). Focal and diffuse CAD was defined according to the median PPG value.

RESULTS

A total of 117 patients (120 vessels) were included. The median PPG was 0.66 (IQR: 0.54-0.75). According to coronary computed tomography angiography analysis, plaque burden was higher in patients with focal CAD (87% ± 8% focal vs 82% ± 10% diffuse; P = 0.003). Calcifications were significantly more prevalent in patients with diffuse CAD (Agatston score per vessel: 51 [IQR: 11-204] focal vs 158 [IQR: 52-341] diffuse; P = 0.024). According to optical coherence tomography analysis, patients with focal CAD had a significantly higher prevalence of circumferential lipid-rich plaque (37% focal vs 4% diffuse; P = 0.001) and thin-cap fibroatheroma (TCFA) (47% focal vs 10% diffuse; P = 0.002). Focal disease defined by PPG predicted the presence of TCFA with an area under the curve of 0.73 (95% CI: 0.58-0.87).

CONCLUSIONS

Atherosclerotic plaque phenotypes associate with intracoronary hemodynamics. Focal CAD had a higher plaque burden and was predominantly lipid-rich with a high prevalence of TCFA, whereas calcifications were more prevalent in diffuse CAD. (Precise Percutaneous Coronary Intervention Plan [P3]; NCT03782688).

Sex Differences in Coronary Atherosclerotic Phenotype and Healing Pattern on Optical Coherence Tomography Imaging

BACKGROUND

Layered plaque, a signature of previous plaque disruption, is a known predictor of rapid plaque progression. Layered plaque can be identified in vivo by optical coherence tomography. Studies have reported differences in plaque burden between women and men, but sex differences in the pattern of layered plaque are unknown.

METHODS

Preintervention optical coherence tomography images of 533 patients with chronic coronary syndromes were analyzed. Detailed plaque characteristics of layered and nonlayered plaques of the target lesion were compared between men and women.

RESULTS

The prevalence of layered plaque was similar between men (N=418) and women (N=115; 55% versus 54%; P=0.832). In men, more features of plaque vulnerability were identified in layered plaque than in nonlayered plaque: lipid plaque (87% versus 69%; P<0.001), macrophages (69% versus 56%; P=0.007), microvessels (72% versus 39%; P<0.001), and cholesterol crystals (49% versus 30%; P<0.001). No difference in plaque vulnerability between layered and nonlayered plaques was observed in women. Layered plaque in men had more features consistent with previous plaque rupture than in women: interrupted pattern (74% versus 52%; P<0.001) and a greater layer index (1198 [781-1835] versus 943 [624-1477]; P<0.001).

CONCLUSIONS

In men, layered plaques exhibit more features of vascular inflammation and vulnerability as well as evidence of previous plaque rupture, compared with nonlayered plaques, whereas in women, no difference was observed between layered and nonlayered plaques. Vascular inflammation (plaque rupture) may be the predominant mechanism of layered plaque in men, whereas a less inflammatory mechanism may play a key role in women.

REGISTRATION

URL: http://www.

CLINICALTRIALS

gov; Unique Identifier: NCT01110538, NCT04523194.

Layered plaque and plaque volume in patients with acute coronary syndromes

BACKGROUND

Layered plaque is a signature of previous subclinical plaque destabilization and healing. Following plaque disruption, thrombus becomes organized, resulting in creation of a new layer, which might contribute to rapid step-wise progression of the plaque. However, the relationship between layered plaque and plaque volume has not been fully elucidated.

METHODS

Patients who presented with acute coronary syndromes (ACS) and underwent pre-intervention optical coherence tomography (OCT) and intravascular ultrasound (IVUS) imaging of the culprit lesion were included. Layered plaque was identified by OCT, and plaque volume around the culprit lesion was measured by IVUS.

RESULTS

Among 150 patients (52 with layered plaque; 98 non-layered plaque), total atheroma volume (183.3 mm³[114.2 mm³ to 275.0 mm³] vs. 119.3 mm³[68.9 mm³ to 185.5 mm³], p = 0.004), percent atheroma volume (PAV) (60.1%[54.7-60.1%] vs. 53.7%[46.8-60.6%], p = 0.001), and plaque burden (86.5%[81.7-85.7%] vs. 82.6%[77.9-85.4%], p = 0.001) were significantly greater in patients with layered plaques than in those with non-layered plaques. When layered plaques were divided into multi-layered or single-layered plaques, PAV was significantly greater in patients with multi-layered plaques than in those with single-layered plaques (62.1%[56.8-67.8%] vs. 57.5%[48.9-60.1%], p = 0.017). Layered plaques, compared to those with non-layered pattern, had larger lipid index (1958.0[420.9 to 2502.9] vs. 597.2[169.1 to 1624.7], p = 0.014).

CONCLUSION

Layered plaques, compared to non-layered plaques, had significantly greater plaque volume and lipid index. These results indicate that plaque disruption and the subsequent healing process significantly contribute to plaque progression at the culprit lesion in patients with ACS.

CLINICAL TRIAL REGISTRATION

http://www.

CLINICALTRIALS

gov , NCT01110538, NCT03479723, UMIN000041692.

Automated Coronary Optical Coherence Tomography Feature Extraction with Application to Three-Dimensional Reconstruction

Coronary optical coherence tomography (OCT) is an intravascular, near-infrared light-based imaging modality capable of reaching axial resolutions of 10-20 µm. This resolution allows for accurate determination of high-risk plaque features, such as thin cap fibroatheroma; however, visualization of morphological features alone still provides unreliable positive predictive capability for plaque progression or future major adverse cardiovascular events (MACE). Biomechanical simulation could assist in this prediction, but this requires extracting morphological features from intravascular imaging to construct accurate three-dimensional (3D) simulations of patients' arteries. Extracting these features is a laborious process, often carried out manually by trained experts. To address this challenge, numerous techniques have emerged to automate these processes while simultaneously overcoming difficulties associated with OCT imaging, such as its limited penetration depth. This systematic review summarizes advances in automated segmentation techniques from the past five years (2016-2021) with a focus on their application to the 3D reconstruction of vessels and their subsequent simulation. We discuss four categories based on the feature being processed, namely: coronary lumen; artery layers; plaque characteristics and subtypes; and stents. Areas for future innovation are also discussed as well as their potential for future translation.