Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies: a report from the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation

High-frequency optical coherence tomography for endovascular management of cerebral aneurysms

Endovascular management of intracranial aneurysms has become the mainstay of treatment in recent years; however, retreatment rates remain as high as 1 in 5. High-frequency optical coherence tomography (HF-OCT) is an emerging imaging modality for the assessment, treatment and follow-up of cerebral aneurysms. EMBASE and SCOPUS databases were searched for studies relating to the management of intracranial aneurysm with OCT. A combination of keywords were used including 'cerebral aneurysm', 'intracranial aneurysm', 'high-frequency optical coherence tomography', 'optical coherence tomography', and 'optical frequency domain imaging'. There were 23 papers included in this review. For the assessment of intracranial aneurysm, OCT was able to accurately assess aneurysm morphology as well as detailed analysis of arterial wall layers. During IA treatment, OCT was used to assess and troubleshoot stent placement to optimise successful isolation from the circulation. In the follow-up period, endothelial growth patterns were visualised by OCT imaging. OCT shows promise for the treatment of IAs at all stages of management. Due to the novel development of HF-OCT, there is limited longitudinal data in human studies. Further research in this area is required with a focus specifically on long-term treatment outcomes in humans.

The impact of statins treatments for plaque characteristics in stable angina pectoris patients with very low and high low-density lipoprotein cholesterol levels: an intracoronary optical coherence tomography study

Low-density lipoprotein cholesterol (LDL-C) levels are recommended according to the patient's risk factors based on guidelines. In patients achieving low LDL-C levels, the need for statins is uncertain, and the plaque characteristics of patients not treated with statins are unclear. In addition, the difference in plaque characteristics with and without statins is unclear in similarly high LDL levels. We evaluate the impact of statins on plaque characteristics on optical coherence tomography (OCT) in patients with very low LDL-C levels and high LDL-C levels. A total of 173 stable angina pectoris patients with 173 lesions undergoing OCT before percutaneous coronary intervention were evaluated. We divided the LDL-C levels into three groups: < 70 mg/dL (n = 48), 70 mg/dL ≤ LDL-C < 100 mg/dL (n = 71), and ≥ 100 mg/dL (n = 54). Among patients with LDL-C < 70 mg/dL, patients not treated with statins showed a significantly higher C-reactive protein level (0.27 ± 0.22 mg/dL vs. 0.15 ± 0.19 mg/dL, p = 0.049), and higher incidence of thin-cap fibroatheromas (TCFAs; 44% [7/16] vs. 13% [4/32], p = 0.021) than those treated with statins. Among patients with LDL-C level ≥ 100 mg/dL, patients treated with statins showed a significantly higher prevalence of familial hypercholesterolemia (FH) (38% [6/16] vs. 5% [2/38], p = 0.004), lower incidence of TCFAs (6% [1/16] vs. 39% [15/38], p = 0.013), healed plaques (13% [2/16] vs. 47% [18/38], p = 0.015), and higher incidence of fibrous plaques (75% [12/16] vs. 42% [16/38], p = 0.027) than patients not treated with statins. While patients achieved a low LDL-C, patients not treated with statins had high plaque vulnerability and high systemic inflammation. While patients had a high LDL-C level with a high prevalence of FH, patients treated with statins had stable plaque characteristics.

Pathological Alterations of Coronary Arteries Late After Kawasaki Disease: An Optical Coherence Tomography Study

Background

The long-term impact of Kawasaki disease on coronary arteries in vivo is unclear.

Objectives

The purpose of this study was to investigate coronary arteries in the late convalescent phase, we followed patients with Kawasaki disease who developed coronary artery aneurysms (CAAs).

Methods

We followed 24 patients and used optical coherence tomography at a median of 16.6 years after the onset of Kawasaki disease.

Results

Of 72 coronary arteries, optical coherence tomography was performed on 61 arteries: 17 with a persistent CAA, 29 with a regressed CAA, and 15 without a CAA. Between-group comparison was performed by chi-square or Fisher's exact test, and intimal thickening (17 vs 29 vs 15, all 100%, P = NA) and medial disruption (17 [100%] vs 29 [100%] vs 14 [93%], P = 0.25) were commonly observed in the investigated arteries. Advanced features of atherosclerosis were more frequently seen in arteries with persistent CAAs than in those with regressed CAAs and in those without CAAs: calcification (12 [71%] vs 5 [17%] vs 1 [7%], P < 0.001), microvessels (12 [71%] vs 10 [35%] vs 4 [27%], P = 0.020), cholesterol crystals (6 [35%] vs 2 [7%] vs 0 [0%], P = 0.009), macrophage accumulation (11 [65%] vs 4 [14%] vs 4 [27%], P = 0.002), and layered plaque (8 [47%] vs 11 [38%] vs 0 [0%], P = 0.004).

Conclusions

Long after onset of Kawasaki disease, all arteries showed pathological changes. Arteries with persistent CAAs had more advanced features of atherosclerosis than those with regressed CAAs and those without CAAs.

Optical coherence tomography-guided versus angiography-guided percutaneous coronary intervention: A meta-analysis of randomized controlled trials

Background

Optical Coherence Tomography (OCT), a high-resolution imaging modality, guides stent implantation during percutaneous coronary intervention (PCI). However, OCT-guided PCI safety and efficacy data is limited.

Methods

MEDLINE, Embase, and Cochrane Central were searched for randomized controlled trials (RCTs) comparing OCT-guided PCI to Angiography-guided PCI from inception to August 2023. A random-effects model was used to pool risk ratios (RRs), mean differences (MDs), and 95% confidence intervals (CIs) for clinical endpoints.

Results

Our analysis included 5,139 patients from 11 studies. OCT-guided PCI resulted in a higher minimum stent area (MD = 0.35 [95 % CI, 0.21-0.49]; p < 0.00001), significantly reduced risk of cardiovascular mortality (RR = 0.56 [95 % CI, = 0.32-0.99]; p = 0.04), stent thrombosis (RR = 0.56 [95 % CI, 0.32-0.96]; p = 0.04), stent malapposition RR = 0.79 [95 % CI, 0.71-0.88]; p = < 0.0001) and major edge dissection (RR = 0.47 [95 % CI, 0.34-0.65]; p = <0.00001). However, no statistically significant difference was observed for all-cause mortality (RR = 0.71; p = 0.06), major adverse cardiovascular events (MACE) [RR = 0.80; p = 0.10], myocardial infarction (MI) [RR = 0.84; p = 0.16], target lesion revascularization (TLR) [RR = 0.94; p = 0.68], and target vessel revascularization (TVR) [RR = 0.91; p = 0.52].

Conclusion

OCT-guided PCI led to an increased MSA and decreased cardiovascular mortality, stent thrombosis, stent malapposition, and major edge dissection. The incidence of all-cause mortality, MACE, MI, TLR, and TVR remained comparable across the two groups.

Detection of atherosclerotic plaques with HDL-like porphyrin nanoparticles using an intravascular dual-modality optical coherence tomography and fluorescence system

Atherosclerosis is the build-up of fatty plaques within blood vessel walls, which can occlude the vessels and cause strokes or heart attacks. It gives rise to both structural and biomolecular changes in the vessel walls. Current single-modality imaging techniques each measure one of these two aspects but fail to provide insight into the combined changes. To address this, our team has developed a dual-modality imaging system which combines optical coherence tomography (OCT) and fluorescence imaging that is optimized for a porphyrin lipid nanoparticle that emits fluorescence and targets atherosclerotic plaques. Atherosclerosis-prone apolipoprotein (Apo)e-/- mice were fed a high cholesterol diet to promote plaque development in descending thoracic aortas. Following infusion of porphyrin lipid nanoparticles in atherosclerotic mice, the fiber-optic probe was inserted into the aorta for imaging, and we were able to robustly detect a porphyrin lipid-specific fluorescence signal that was not present in saline-infused control mice. We observed that the nanoparticle fluorescence colocalized in areas of CD68+ macrophages. These results demonstrate that our system can detect the fluorescence from nanoparticles, providing complementary biological information to the structural information obtained from simultaneously acquired OCT.

Impact of coronary calcium morphology on intravascular lithotripsy

BACKGROUND

Coronary calcification negatively impacts optimal stenting. Intravascular lithotripsy (IVL) is a new calcium modification technique.

AIMS

We aimed to assess the impact of different calcium morphologies on IVL efficacy.

METHODS

This was a prospective, multicentre study (13 tertiary referral centres). Optical coherence tomography (OCT) was performed before and after IVL, and after stenting. OCT-defined calcium morphologies were concentric (mean calcium arc >180°) and eccentric (mean calcium arc ≤180°). The primary outcomes were angiographic success (residual stenosis <20%) and the presence of fracture by OCT in concentric versus eccentric lesions.

RESULTS

Ninety patients were included with a total of 95 lesions: 47 concentric and 48 eccentric. The median number of pulses was 60 (p=1.00). Following IVL, the presence of fracture was not statistically different between groups (79.0% vs 66.0% for concentric vs eccentric; p=0.165). The number of fractures/lesion (4.2±4.4 vs 2.3±2.8; p=0.018) and ≥3 fractures/lesion (57.1% vs 34.0%; p=0.029) were more common in concentric lesions. Angiographic success was numerically but not statistically higher in the concentric group (87.0% vs 76.6%; p=0.196). By OCT, no differences were noted in final minimum lumen area (5.9±2.2 mm2 vs 6.2±2.1 mm2; p=0.570), minimum stent area (5.9±2.2 mm² vs 6.25±2.4 mm2; p=0.483), minimum stent expansion (80.9±16.7% vs 78.2±19.8%), or stent expansion at the maximum calcium site (100.6±24.2% vs 95.8±27.3%) (p>0.05 for all comparisons of concentric vs eccentric, respectively). Calcified nodules were found in 29.5% of lesions; these were predominantly non-eruptive (57%). At the nodule site, dissection was more common than fracture with stent expansion of 103.6±27.2%.

CONCLUSIONS

In this prospective, multicentre study, the effectiveness of IVL followed by stenting was not significantly affected by coronary calcium morphology.

Artificial neural network for enhancing signal-to-noise ratio and contrast in photothermal optical coherence tomography

Optical coherence tomography (OCT) is a medical imaging method that generates micron-resolution 3D volumetric images of tissues in-vivo. Photothermal (PT)-OCT is a functional extension of OCT with the potential to provide depth-resolved molecular information complementary to the OCT structural images. PT-OCT typically requires long acquisition times to measure small fluctuations in the OCT phase signal. Here, we use machine learning with a neural network to infer the amplitude of the photothermal phase modulation from a short signal trace, trained in a supervised fashion with the ground truth signal obtained by conventional reconstruction of the PT-OCT signal from a longer acquisition trace. Results from phantom and tissue studies show that the developed network improves signal to noise ratio (SNR) and contrast, enabling PT-OCT imaging with short acquisition times and without any hardware modification to the PT-OCT system. The developed network removes one of the key barriers in translation of PT-OCT (i.e., long acquisition time) to the clinic.

Coronary artery calcification: concepts and clinical applications

Vascular calcification is an important hallmark of atherosclerosis. Coronary artery calcification (CAC) implies the presence of coronary artery disease (CAD), irrespective of risk factors or symptoms, is concomitant with the development of advanced atherosclerosis. Coronary thrombosis is the most common clinical end event leading to acute coronary syndrome (ACS). The least common type of pathology associated with thrombosis is the calcified nodule (CN). It usually occurs in elderly patients with severely calcified and tortuous arteries. The prevalence of calcified nodules in patients with ACS may be underestimated due to the lack of easily recognisable diagnostic methods. In this review, the authors will focus on the classification, clinical significance, pathogenesis, and diagnostic evaluation and treatment of CAC to further explore the clinical significance of CN.

Serial longitudinal changes of coronary calcified plaques with clear outer borders under intensive lipid management: insights from optical coherence tomography

Percutaneous coronary intervention (PCI) for calcified lesions is one of the most challenging procedures related to worse clinical outcomes. To stabilize vulnerable plaques, intensive lipid management is recommended; however, the serial changes of calcified plaques under intensive lipid management are unknown. A total of 31 patients (mean age, 63 ± 10 years; men, 29 patients) who underwent PCI with intensive lipid management were retrospectively studied. We evaluated the serial longitudinal changes of calcified plaques with clear outer borders using optical coherence tomography (OCT) at two time points: at the time of PCI (baseline) and the chronic phase. The median interval from PCI to chronic phase was 287 (233-429) days. Twenty-eight patients (90.3%) had increased calcium volume at the chronic phase compared with those at baseline (2.6 [1.3-5.1] vs. 1.8 [0.7-4.3] mm2, p < 0.05), and the median increase rate of calcium volume was 27.4% at the chronic phase. According to the median increase rate of calcium volume (27.4%), patients were divided into the following two groups: rapid progression (≥ 27.4%, RP group) and non-rapid progression (< 27.4%, non-RP group). The RP group had more patients with diabetes, and diabetes was independently associated with rapid progression by multivariate analysis. Furthermore, patients with diabetes had significantly higher changes in calcium index and volume from the baseline to the chronic phase than those without diabetes. Coronary calcification progression during relatively short intervals was observed using OCT even under intensive lipid management. Diabetes was an independent predictor for rapid coronary calcification progression.

Assessment of Residual Vasospasm in Patients with Plaque Rupture or Plaque Erosion using Optical Coherence Tomography

AIMS

Coronary vasospasm is associated with acute coronary syndrome (ACS) and may persist during primary percutaneous coronary intervention (PCI). We aimed to elucidate the incidence, morphological characteristics, and prognostic impact of residual vasospasm in plaque rupture (PR) and plaque erosion (PE) lesions using optical coherence tomography (OCT).

METHODS

We enrolled 142 patients with ACS who underwent OCT-guided primary PCI. All patients received intracoronary vasodilators before OCT examination. Residual vasospasm was identified as intimal gathering and categorised as polygonal- or wavy- patterned depending on the luminal shape. A wavy pattern was defined as a curved intimal surface line. A polygonal pattern was defined as a lumen with multiple angles. The incidence of major cardiovascular events, defined as death, non-fatal myocardial infarction, stroke, and any revascularization, within 1-year of PCI was identified.

RESULTS

The prevalence of residual vasospasm in PR and PE was 15.1% (13 of 86) and 21.4% (12 of 56), respectively. Wavy pattern was the major shape of the residual vasospasm. Polygonal-patterned lumen was more frequently observed in PR than in PE (38.5 vs. 8.3 %). The polygonal-patterned lumens had significantly larger lipid arcs (257.9 vs. 78.0 °; P＜0.01), and significantly smaller areas (1.27 vs. 1.88 mm2; P=0.05) than wavy-patterned lumens. Residual vasospasm had a prognostic impact on PR but not PE at 1-year of successful primary PCI.

CONCLUSION

Considerable proportion of ACS including both PR and PE had residual vasospasm with variable morphological feature and different prognostic impact.

Prevalence and anatomical factors associated with stent under-expansion in non-severely calcified lesions

BACKGROUND

Stent underexpansion, typically related to lesion calcification, is the strongest predictor of adverse events after percutaneous coronary intervention (PCI). Although uncommon, underexpansion may also occur in non-severely calcified lesions.

AIM

We sought to identify the prevalence and anatomical characteristics of underexpansion in non-severely calcified lesions.

METHODS

We included 993 patients who underwent optical coherence tomography-guided PCI of 1051 de novo lesions with maximum calcium arc <180°. Negative remodeling (NR) was the smallest lesion site external elastic lamina diameter that was also smaller than the distal reference. Stent expansion was evaluated using a linear regression model accounting for vessel tapering; underexpansion required both stent expansion <70% and stent area <4.5mm2.

RESULTS

Underexpansion was observed in 3.6% of non-heavily calcified lesions (38/1051). Pre-stent maximum calcium arc and thickness were greater in lesions with versus without underexpansion (median 119° vs. 85°, p = 0.002; median 0.95 mm vs. 0.78 mm, p = 0.008). NR was also more common in lesions with underexpansion (44.7% vs. 24.5%, p = 0.007). In the multivariable logistic regression model, larger and thicker eccentric calcium, mid left anterior descending artery (LAD) location, and NR were associated with underexpansion in non-severely calcified lesions. The rate of underexpansion was especially high (30.7%) in lesions exhibiting all three morphologies. Two-year TLF tended to be higher in underexpanded versus non-underexpanded stents (9.7% vs. 3.7%, unadjusted hazard ratio [95% confidence interval] = 3.02 [0.92, 9.58], p = 0.06).

CONCLUSION

Although underexpansion in the absence of severe calcium (<180°) is uncommon, mid-LAD lesions with NR and large and thick eccentric calcium were associated with underexpansion.

A transformer-based pyramid network for coronary calcified plaque segmentation in intravascular optical coherence tomography images

Characterizing coronary calcified plaque (CCP) provides essential insight into diagnosis and treatment of atherosclerosis. Intravascular optical coherence tomography (OCT) offers significant advantages for detecting CCP and even automated segmentation with recent advances in deep learning techniques. Most of current methods have achieved promising results by adopting existing convolution neural networks (CNNs) in computer vision domain. However, their performance can be detrimentally affected by unseen plaque patterns and artifacts due to inherent limitation of CNNs in contextual reasoning. To overcome this obstacle, we proposed a Transformer-based pyramid network called AFS-TPNet for robust, end-to-end segmentation of CCP from OCT images. Its encoder is built upon CSWin Transformer architecture, allowing for better perceptual understanding of calcified arteries at a higher semantic level. Specifically, an augmented feature split (AFS) module and residual convolutional position encoding (RCPE) mechanism are designed to effectively enhance the capability of Transformer in capturing both fine-grained features and global contexts. Extensive experiments showed that AFS-TPNet trained using Lovasz Loss achieved superior performance in segmentation CCP under various contexts, surpassing prior state-of-the-art CNN and Transformer architectures by more than 6.58% intersection over union (IoU) score. The application of this promising method to extract CCP features is expected to enhance clinical intervention and translational research using OCT.

Pancoronary plaque characteristics in STEMI patients with rapid plaque progression: An optical coherence tomography study

BACKGROUND

Non-culprit plaque progression is associated with recurrent cardiac ischemic events and worse clinical outcomes. Given that atherosclerosis is a systemic disease, the pancoronary characteristics of patients with rapid plaque progression are unknown. This study aims to identify pancoronary plaque features in patients with ST-segment elevation myocardial infarction (STEMI) with and without rapid plaque progression, focused on the patient level.

METHODS AND RESULTS

From January 2017 to July 2019, 291 patients underwent 3-vessel optical coherence tomography imaging at the time of the primary procedure and a follow-up angiography interval of 12 months. The final analysis included 237 patients. Overall, 308 non-culprit lesions were found in 78 STEMI patients with rapid plaque progression, and 465 non-culprit plaques were found in 159 STEMI patients without rapid plaque progression. These patients had a higher pancoronary vulnerability (CLIMA-defined high-risk plaque: 47.4% vs. 33.3%; non-culprit plaque rupture: 25.6% vs. 14.5%) and a significantly higher prevalence of other vulnerable plaque characteristics (i.e., lipid-rich plaque, cholesterol crystal, microchannels, calcification, spotty calcification, and thrombus) at baseline versus those without rapid plaque progression. Lesions with rapid progression were highly distributed at the LAD, tending to be near the bifurcation. In multivariate analysis, age ≥ 65 years was an independent predictor of subsequent rapid lesion progression at the patient level, whereas microchannel, spotty calcification, and cholesterol crystal were independent predictors for STEMI patients ≥65 years old.

CONCLUSIONS

STEMI patients with subsequent rapid plaque progression had higher pancoronary vulnerability and commonly presented vulnerable plaque morphology. Aging was the only predictor of subsequent rapid plaque progression.

Histological Features of In-Stent Restenosis after Iliac Vein Thrombus Removal and Stent Placement in a Goat Model

PURPOSE

To establish an animal model for in-stent restenosis (ISR) after postthrombotic iliac vein stent placement and characterize histopathological changes in tissue within the stented vein.

MATERIALS AND METHODS

Iliac vein thrombosis was induced using balloon occlusion and thrombin injection in 8 male Boer goats. Mechanical thrombectomy and iliac vein stent placement were performed 3 days after thrombosis induction. Restenosis was evaluated by venography and optical coherence tomography (OCT) at 1 and 8 weeks after stent placement, and stent specimens were taken for pathological examination after the animals were euthanized.

RESULTS

Thrombosis induction was successful in all 8 goats, with >80% iliac vein occlusion. After thrombus removal, OCT revealed considerable venous intimal thickening and a small number of mural thrombi. Neointimal hyperplasia with thrombus formation was observed in all goats 1 week after stent implantation; the degree of ISR was 15%-33%. At 8 weeks, the degree of ISR was 21%-32% in 3 goats, and stent occlusion was observed in 1 goat. At 1 week, the neointima predominantly consisted of fresh thrombi. At 8 weeks, proliferplastic fibrotic tissue and smooth muscle cells (SMCs) were predominant, and the stent surfaces were endothelialized in 2 of 3 goats and partially endothelialized in 1 goat.

CONCLUSIONS

In the goat model, postthrombotic neointimal hyperplasia in the venous stent may result from time-dependent thrombus formation and organization, accompanied by migration and proliferation of SMCs, causing ISR. These results provide a basis to further explore the mechanism of venous ISR and promote the development of venous stents that reduce neointimal hyperplasia.

Self-Apposing Stents in Coronary Chronic Total Occlusions: A Pilot Study

OBJECTIVES

This pilot study assessed the 12-month angiographic and clinical outcomes of self-apposing (SA) stents in patients undergoing chronic total occlusion (CTO) percutaneous coronary intervention (PCI).

BACKGROUND

Self-apposing (SA) stents may decrease incomplete strut apposition and stent strut coverage that are common after CTO PCI.

METHODS

We compared 20 patients who underwent CTO PCI using SA drug-eluting stents (DESs) with 20 matched control patients who underwent CTO PCI using balloon-expandable (BE)-DESs. All patients were followed up clinically for 12 months and had coronary angiography with optical coherence tomography at the end of the follow-up period. The primary end points were stent strut malapposition and strut coverage. The secondary end point was composite major adverse cardiovascular events (MACEs) at 12 months.

RESULTS

Both groups had high prevalence of diabetes mellitus, and most of the treated lesions were complex, with 62% having a J-CTO score of ≥3. All CTO PCI techniques were allowed for recanalisation, and 75% of the procedures were guided by intravascular ultrasound. At 12 months, the SA-DES group had fewer malapposed struts (0% [interquartile range (IQR) 0%-0%] vs 4.5% [IQR 0%-20%]; p<0.001) and uncovered struts (0.08% [IQR 0%-1.6%] vs 8.2% [IQR 0%-16%]; p<0.001). However, they showed significantly higher rates of MACEs due to clinically-driven target lesion revascularisation (45% vs 15%; p=0.038).

CONCLUSIONS

In this pilot study, compared with conventional BE-DESs, SA-DESs used in CTO PCI were associated with fewer malapposed and uncovered stent struts but also with significantly higher rates of in-stent restenosis and MACEs, mainly caused by clinically driven target lesion revascularisation.

Optical Coherence Tomography Measures Predicting Fractional Flow Reserve: The OMEF Study

Background

Optical coherence tomography (OCT) allows to carefully characterize coronary plaque morphology and lumen dimensions. We sought to evaluate the value of OCT in predicting fractional flow reserve (FFR).

Methods

We performed a multicenter, international, pooled analysis of individual patient-level data from published studies assessing FFR and OCT on the same vessel. Data from stable or unstable patients who underwent both FFR and OCT of the same coronary artery were collected through a dedicated database. Predefined OCT parameters were minimum lumen area (MLA), percentage area stenosis (%AS), and presence of thrombus or plaque rupture. Primary end point was FFR ≤0.80. Secondary outcome was the incidence of major adverse cardiac events in patients not undergoing revascularization based on negative FFR (>0.80).

Results

A total of 502 coronary lesions in 489 patients were included. A significant correlation was observed between OCT-MLA and FFR values (R = 0.525; P < .001), and between OCT-%AS and FFR values (R = -0.482; P < .001). In Receiver operating characteristic analysis, MLA <2.0 mm2 showed a good discriminative power to predict an FFR ≤0.80 (AUC, 0.80), whereas %AS >73% showed a moderate discriminative power (AUC, 0.73). When considering proximal coronary segments, the best OCT cutoff values predicting an FFR ≤0.80 were MLA <3.1 mm2 (AUC, 0.82), and %AS >61% (AUC, 0.84). In patients with a negative FFR not revascularized, the combination of lower MLA and higher %AS had a trend toward worse outcome (which was statistically significant in the analysis restricted to proximal vessels).

Conclusions

OCT lumen measures (MLA, %AS) may predict FFR, and different cutoffs are needed for proximal vessels.

Predicting Lipid-Rich Plaque Progression in Coronary Arteries Using Multimodal Imaging and Wall Shear Stress Signatures

BACKGROUND

Plaque composition and wall shear stress (WSS) magnitude act as well-established players in coronary plaque progression. However, WSS magnitude per se does not completely capture the mechanical stimulus to which the endothelium is subjected, since endothelial cells experience changes in the WSS spatiotemporal configuration on the luminal surface. This study explores WSS profile and lipid content signatures of plaque progression to identify novel biomarkers of coronary atherosclerosis.

METHODS

Thirty-seven patients with acute coronary syndrome underwent coronary computed tomography angiography, near-infrared spectroscopy intravascular ultrasound, and optical coherence tomography of at least 1 nonculprit vessel at baseline and 1-year follow-up. Baseline coronary artery geometries were reconstructed from intravascular ultrasound and coronary computed tomography angiography and combined with flow information to perform computational fluid dynamics simulations to assess the time-averaged WSS magnitude (TAWSS) and the variability in the contraction/expansion action exerted by WSS on the endothelium, quantifiable in terms of topological shear variation index (TSVI). Plaque progression was measured as intravascular ultrasound-derived percentage plaque atheroma volume change at 1-year follow-up. Plaque composition information was extracted from near-infrared spectroscopy and optical coherence tomography.

RESULTS

Exposure to high TSVI and low TAWSS was associated with higher plaque progression (4.00±0.69% and 3.60±0.62%, respectively). Plaque composition acted synergistically with TSVI or TAWSS, resulting in the highest plaque progression (≥5.90%) at locations where lipid-rich plaque is exposed to high TSVI or low TAWSS.

CONCLUSIONS

Luminal exposure to high TSVI, solely or combined with a lipid-rich plaque phenotype, is associated with enhanced plaque progression at 1-year follow-up. Where plaque progression occurred, low TAWSS was also observed. These findings suggest TSVI, in addition to low TAWSS, as a potential biomechanical predictor for plaque progression, showing promise for clinical translation to improve patient prognosis.

Procedural and clinical impact of intravascular lithotripsy for the treatment of peri-stent calcification

BACKGROUND

Use of intravascular lithotripsy (IVL) for treating peri-stent calcification is increasing. However, this indication remains 'off-label'. We aimed to investigate the efficacy and clinical outcomes of in-stent IVL.

METHODS

Patients from five European centers who underwent in-stent IVL were included between 2019 and 2023. Demographic, clinical, procedural and follow-up data were collected from electronic hospital records. Angiographic and intracoronary imaging (ICI) data were analyzed in a centralized core-laboratory.

RESULTS

Of 101 patients (71.2 ± 9.2 years), 56(55 %) received in-stent IVL for late stent failure (median 109 days post-PCI) due to calcific neoatherosclerosis or extra-stent calcification(late-IVL), while 45(45 %) underwent bail-out IVL due to stent infraexpasion (immediate-IVL). Both late-IVL and immediate-IVL significantly improved angiographic %diameter stenosis (73.7[59.6-89.8]% to 16.4 [10.4-26.9]%;p < 0.0001 and 28.6[22.5-43.3]% to 14.1[10.3-29.4]%;p < 0.0001, and minimum lumen area (MLA) (3.4 ± 1.2 to 8.6 ± 2.5 mm2;p < 0.002 and 5.4 ± 1.9 to 7.3 ± 1.9;p < 0.0001).Device(98 %) and procedural success(80 %) were high. MACE rates in-hospital (2 %), 30-days (3 %),6-months(5 %) and 1-year(7 %) were low and comparable in both groups. Acute diameter gain was lower in immediate-IVL (2.1 ± 0.7 mm vs. 0.5 ± 0.4 mm;p < 0.0001). This, however, was explained by significant differences in pre-IVL angiographic and ICI parameters (%diameter stenosis 73.7[59.6-89.8] vs. 28.6[22.5-43.3]%; p < 0.0001 and MLA (3.4 ± 1.2 vs 5.4 ± 1.9 mm2; p < 0.0001), whereas post-IVL percentage diameter stenosis (16.4(10.4-26.9) vs. 14.1(10.3-29.4);p = 0.914) and MLA (8.6 ± 2.5vs. 7.4 ± 1.9 mm2;p = 0.064) in late- and immediate-IVL were comparable.

CONCLUSIONS

IVL in-stent due to peri-stent calcification is an effective strategy, both late and immediately after stent implantation. Overall, MACE rates at short- and mid-term were low and comparable in both groups, although clinical findings should be taken with caution.

Optimal lesion preparation before implantation of a Magmaris bioresorbable scaffold in patients with coronary artery stenosis: Rationale, design and methodology of the OPTIMIS study

Introduction

Percutaneous coronary intervention with implantation of a bioresorbable scaffold (BRS) provide the vessel support for a limited period allowing the vessel to restore normal vasomotion after degradation of the BRS, opposed to treatment with drug-eluting stents where the metal persist in the vessel wall. Late lumen loss and reduction in lumen area after implantation have been reported. The purpose of this study was to investigate whether intense pre-dilatation before BRS implantation resulted in less reduction of minimal lumen area at 6- and 12-month follow-up after implantation of a Magmaris BRS (MgBRS). Coronary imaging with optical coherence tomography (OCT) and intravascular ultrasound (IVUS) was assessed to track changes in lumen and vessel dimensions.

Methods

The prospective Optimal lesion PreparaTion before Implantation of the Magmaris bioresorbable scaffold In patients with coronary artery Stenosis (OPTIMIS) study randomly assigned eighty-two patients with chronic coronary syndrome to two pre-dilatation treatment strategies. Patients were randomized in a 1:1 ratio to pre-dilatation with either a non-compliant scoring balloon or a standard non-compliant balloon prior to implantation of a MgBRS. The treated segment was evaluated with OCT and IVUS at baseline, after 6 and 12 months to assess changes in lumen and vessel dimensions. The hypothesis was that more intense pre-dilatation with a non-compliant scoring balloon before MgBRS implantation can reduce the risk of late lumen reduction compared to standard pre-dilatation. The power calculation used expected MLA after 6 months (6.22 mm2 for the scoring balloon and 5.01 mm2 for the standard non-compliant balloon), power of 80 %, significance level of 0.05 and expected drop-out rate of 15 %, requiring 82 patients to be enrolled.

Results

Eighty-two patients were included in the study. Enrollment was from December 2020 to September 2023.

Conclusion

The hypothesis was that more intense pre-dilatation with a non-compliant scoring balloon before MgBRS implantation can reduce the risk of late lumen reduction compared to standard pre-dilatation.

Assessing the efficacy of saline flush in frequency-domain optical coherence tomography for intracoronary imaging

BACKGROUND

The increased amount of contrast media in frequency-domain optical coherence tomography (FD-OCT) imaging during percutaneous coronary intervention (PCI) has raised potential concerns regarding impairment of renal function.

OBJECTIVES

This study aimed to evaluate the effectiveness of heparinized saline flush in FD-OCT-guided PCI and identify clinical factors contributing to optimal image quality.

METHODS

We retrospectively collected 100 lesions from 90 consecutive patients, and a total of 200 pullbacks were analyzed for the initial and final evaluation in which saline was used as the flushing medium.

RESULTS

The study population had a mean age of 73, with 52% having chronic kidney disease (CKD). The median amount of contrast used was 28 ml, and no complications were observed associated with saline flush OCT. Imaging quality was then categorized as excellent, good, or unacceptable. Among the total runs, 87% demonstrated clinically acceptable image quality, with 66.5% classified as excellent images and 20.5% classified as good images. Independent predictors of excellent images included lumen area stenosis ≥ 70% (adjusted odds ratio [OR] 2.37, 95% confidence interval [CI] 1.02-5.47, P = 0.044), and the use of intensive flushing (adjusted OR 2.06, 95% CI 1.11-3.86, P = 0.023) defined as a deep engagement of guiding catheter (GC) or a selective insertion of guide extension catheter (GE). Intensive flushing was performed in 60% of the total pullbacks, and it was particularly effective in improving image quality in the left coronary artery (LCA).

CONCLUSION

The use of saline flush during FD-OCT imaging was safe and feasible, which had a benefit in renal protection with adequate imaging quality.

A Combined Measure of the Triglyceride Glucose Index and Trimethylamine N-Oxide in Risk Stratification of ST-Segment Elevation Myocardial Infarction Patients with High-Risk Plaque Features Defined by Optical Coherence Tomography: A Substudy of the OCTAMI Registry Study

Background and Aim

An elevated triglyceride-glucose (TyG) level is associated with increased risk of mortality in patients with CAD. Trimethylamine N-oxide (TMAO) has mechanistic links to atherosclerotic coronary artery disease (CAD) pathogenesis and is correlated with adverse outcomes. However, the incremental prognostic value of TMAO and TyG in the cohort of optical coherence tomography (OCT)-defined high-risk ST-segment elevation myocardial infarction (STEMI) patients is unknown.

Methods

We studied 274 consecutive aged ≥18 years patients with evidence of STEMI and detected on pre-intervention OCT imaging of culprit lesions between March 2017 and March 2019.

Outcomes

There were 22 (22.68%), 27 (27.84%), 26 (26.80%), and 22 (22.68%) patients in groups A-D, respectively. The baseline characteristics according to the level of TMAO and TyG showed that patients with higher level in both indicators were more likely to have higher triglycerides (p < 0.001), fasting glucose (p < 0.001) and higher incidence of diabetes (p = 0.008). The group with TMAO > median and TyG ≤ median was associated with higher rates of MACEs significantly (p = 0.009) in fully adjusted analyses. During a median follow-up of 2.027 years, 20 (20.6%) patients experienced MACEs. To evaluate the diagnostic value of the TyG index combined with TMAO, the area under the receiver operating characteristic curve for predicting MACEs after full adjustment was 0.815 (95% confidence interval, 0.723-0.887; sensitivity, 85.00%; specificity, 72.73%; cut-off level, 0.577). Among the group of patients with TMAO > median and TyG ≤ median, there was a significantly higher incidence of MACEs (p=0.033). A similar tendency was found in the cohort with hyperlipidemia (p=0.016) and diabetes mellitus (p=0.036).

Conclusion

This study demonstrated the usefulness of combined measures of the TyG index and TMAO in enhancing risk stratification in STEMI patients with OCT-defined high-risk plaque characteristics.

Trial Registration

This study was registered at ClinicalTrials.gov as NCT03593928.

Endovascular Drug Delivery

Drug-eluting stents (DES) and balloons revolutionize atherosclerosis treatment by targeting hyperplastic tissue responses through effective local drug delivery strategies. This review examines approved and emerging endovascular devices, discussing drug release mechanisms and their impacts on arterial drug distribution. It emphasizes the crucial role of drug delivery in modern cardiovascular care and highlights how device technologies influence vascular behavior based on lesion morphology. The future holds promise for lesion-specific treatments, particularly in the superficial femoral artery, with recent CE-marked devices showing encouraging results. Exciting strategies and new patents focus on local drug delivery to prevent restenosis, shaping the future of interventional outcomes. In summary, as we navigate the ever-evolving landscape of cardiovascular intervention, it becomes increasingly evident that the future lies in tailoring treatments to the specific characteristics of each lesion. By leveraging cutting-edge technologies and harnessing the potential of localized drug delivery, we stand poised to usher in a new era of precision medicine in vascular intervention.

Temporal changes in coronary plaque as assessed by an artificial intelligence-based optical coherence tomography: from the first-in-human trial on DREAMS 3G scaffold

AIMS

The aim of the study is to assess the impact of the baseline plaque composition on the DREAMS 3G luminal late loss and to compare the serial plaque changes between baseline and 6 and 12 months (M) follow-up.

METHODS AND RESULTS

A total of 116 patients were enrolled in the BIOMAG-I trial. Patients were imaged with optical coherence tomography (OCT) pre- and post-DREAMS 3G implantation and at 6 and 12 M. OCTPlus software uses artificial intelligence to assess composition (i.e. lipid, calcium, and fibrous tissue) of the plaque. The differences between the OCT-derived minimum lumen area (MLA) post-percutaneous coronary intervention and 12 M were grouped into three terciles. Patients with larger MLA differences at 12 M (P = 0.0003) had significantly larger content of fibrous tissue at baseline. There was a reduction of 24.8% and 20.9% in lipid area, both P < 0.001, between the pre-DREAMS 3G OCT and the 6 and 12 M follow-up. Conversely, the fibrous tissue increased by 48.4% and 36.0% at 6 and 12 M follow-up, both P < 0.001.

CONCLUSION

The larger the fibrous tissue in the lesion at baseline, the larger the luminal loss seen at 6 and 12 M. Following the implantation of DREAMS 3G, favourable healing of the vessel coronary wall occurs as shown by a decrease in the lipid area and an increase in fibrous tissue.

Cholesterol crystals at the culprit lesion in patients with acute coronary syndrome are associated with worse cardiovascular outcomes at two years follow up - results from the translational OPTICO-ACS study program

BACKGROUND

Cholesterol crystals (CCs) represent a feature of advanced atherosclerotic plaque and may be assessed by optical coherence tomography (OCT). Their impact on cardiovascular outcomes in patients presenting with acute coronary syndromes (ACS) is yet unknown.

METHODS

The culprit lesion (CL) of 346 ACS-patients undergoing preintervention OCT imaging were screened for the presence of CCs and divided into two groups accordingly. The primary end-point was the rate of major adverse cardiac events plus (MACE+) consisting of cardiac death, myocardial infarction, target vessel revascularization and re-hospitalization due to unstable or progressive angina at two years.

RESULTS

Among 346 patients, 57.2% presented with CCs at the CL. Patients with CCs exhibited a higher prevalence of ruptured fibrous caps (RFC-ACS) (79.8% vs. 56.8%; p < 0.001) and other high-risk features such as thin cap fibroatheroma (80.8% vs. 64.9%; p = 0.001), presence of macrophages (99.0% vs. 85.1%; p < 0.001) as well as a greater maximum lipid arc (294.0° vs. 259.3°; p < 0.001) at the CL as compared to patients without CCs. MACE+ at two years follow-up occurred more often in CC-patients (29.2% vs. 16.1%; p = 0.006) as compared to patients without CCs at the culprit site. Multivariable cox regression analysis identified CCs as independent predictor of MACE+ (HR 1.705; 1.025-2.838 CI, p = 0.040).

CONCLUSIONS

CCs were associated with conventional high-risk plaque features and associated with increased MACE+-rates at two years follow up. The identification of CCs might be useful as prognostic marker in patients with ACS and assist "precision prevention" in the future.

Clinical Background and Coronary Artery Lesions Characteristics in Japanese Patients With Acute Coronary Syndrome Suffering Major Bleeding

Background: Although the clinical factors that predict major bleeding in Western patients with acute coronary syndrome (ACS) are becoming elucidated, they have not been fully investigated, especially coronary lesion characteristics, in a Japanese population. Methods and Results: ACS patients (n=1,840) were divided into a "bleeding group" and a "no-bleeding group," according to whether they had major bleeding during the 2-year follow-up period, to investigate the prognostic effect of bleeding and the predictive factors of bleeding. Among them, patients who underwent primary percutaneous coronary intervention with optical coherence tomography (OCT) guidance (n=958) were examined to identify the effect of coronary lesion characteristics on bleeding. Of the 1,840 enrolled patients, 124 (6.7%) experienced major bleeding during the 2-year follow-up period. Incidence of cardiovascular death during the 2-year follow-up period was significantly higher among patients with major bleeding (26.4% vs. 8.5%, P=0.001). OCT examination showed that disrupted fibrous cap (DFC: 68% vs. 48%, P=0.014) and calcified plaque (63% vs. 42%, P=0.011) were more prevalent in the bleeding group. DFC was a predictor of major bleeding in the multivariate Cox proportional hazards analyses (hazard ratio 2.135 [95% confidence interval 1.070-4.263], P<0.001). Conclusions: ACS patients with major bleeding had poorer cardiac outcomes. Advanced atherosclerosis at the culprit lesion influences the higher incidence of major bleeding in ACS patients.

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.

Clinical Impact of In-Stent Calcification in Coronary Arteries: Optical Coherence Tomography Study

In-stent restenosis with neoatherosclerosis has been known as the predictor of target lesion revascularization (TLR) after percutaneous coronary intervention. However, the impact of in-stent calcification (ISC) alone on clinical outcomes remains unknown since neoatherosclerosis by optical coherence tomography includes in-stent lipid and calcification. We aimed to assess the effect of ISC on clinical outcomes and clinical differences among different types of ISC. We included 126 lesions that underwent optical coherence tomography-guided percutaneous coronary intervention and divided those into the ISC group (n = 38) and the non-ISC group (n = 88) according to the presence of ISC. The cumulative incidence of clinically driven TLR (CD-TLR) was compared between the ISC and non-ISC groups. The impact of in-stent calcified nodule and nodular calcification on CD-TLR was evaluated using the Cox hazard model. The incidence of CD-TLR was significantly higher in the ISC group than in the non-ISC group (p = 0.004). In the multivariate Cox hazard model, ISC was significantly associated with CD-TLR (hazard ratio [HR] 3.58, 95% confidence interval [CI] 1.33 to 9.65, p = 0.01). In-stent calcified nodule/nodular calcification and in-stent nodular calcification alone were also the factors significantly associated with CD-TLR (HR 3.34, 95%CI 1.15 to 9.65, p = 0.03 and HR 5.21, 95%CI 1.82 to 14.91, p = 0.002, respectively). ISC without in-stent calcified nodule/nodular calcification, which was defined as in-stent smooth calcification, was not associated with CD-TLR. In conclusion, ISC was associated with a higher rate of CD-TLR. The types of calcifications that led to a high rate of CD-TLR were in-stent calcified nodule/nodular calcification and in-stent nodular calcification alone but not in-stent smooth calcification. In-stent calcified nodule and nodular calcification should be paid more attention.

Association between apolipoprotein B/A1 ratio and quantities of tissue prolapse on optical coherence tomography examination in patients with atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) continues to be a major health concern globally. Apolipoprotein (Apo) B/A1 ratio is a reliable predictor of ASCVD and an important factor in assessing the risk of myocardial infarction. Tissue prolapse (TP) is defined as the tissue extrusion into the lumen through the stent struts after implantation, which is a significant factor for poor short-term outcomes such as acute and subacute thrombosis, severe myocardial necrosis, and vulnerable plaque. Therefore, the aim of this study was to investigate the relationship between Apo B/A1, plaque vulnerability, and tissue prolapse on optical coherence tomography (OCT). This study enrolled 199 patients with atherosclerotic cardiovascular disease (ASCVD) who underwent percutaneous coronary intervention (PCI). Both pre- and post-procedural optical coherence tomography (OCT) examinations were conducted to assess TP volume and plaque morphology. Logistic regression analyses were performed to identify potential risk factors for tissue prolapse volume. Receiver operator characteristic (ROC) curve analysis was carried out to evaluate the value of the Apo B/A1 ratio for tissue prolapse volume. The high Apo B/A1 ratio group showed a larger TP volume (P = 0.001) and a higher percentage of plaque rupture and erosion in comparison to the low Apo B/A1 ratio group (P = 0.022 and P = 0.008). The high Apo B/A1 ratio group and the high TP volume group also had a higher proportion of thin-cap fibroatheroma (TCFA) (P = 0.046, P = 0.021). Multivariate logistic regression analysis revealed that both Apo B/A1 ratio (odds ratio [OR]: 1.041, 95% confidence interval [CI] 1.007-1.076; P = 0.019) and TCFA (OR: 3.199, 95%CI 1.133-9.031; 0.028) were significantly related to high TP volume. Furthermore, the area under the curve (AUC) for predictive value of TP volume was 0.635 for Apo B/A1 (95% CI 0.554-0.717, P = 0.002) compared to 0.615 for low density lipoprotein cholesterol (LDL-C) (95% CI 0.533-0.697, P = 0.008). The Apo B/A1 ratio is an independent predictor of TP volume on OCT and is related to plaque vulnerability.

Structurally constrained and pathology-aware convolutional transformer generative adversarial network for virtual histology staining of human coronary optical coherence tomography images

Significance

There is a significant need for the generation of virtual histological information from coronary optical coherence tomography (OCT) images to better guide the treatment of coronary artery disease (CAD). However, existing methods either require a large pixel-wise paired training dataset or have limited capability to map pathological regions.

Aim

The aim of this work is to generate virtual histological information from coronary OCT images, without a pixel-wise paired training dataset while capable of providing pathological patterns.

Approach

We design a structurally constrained, pathology-aware, transformer generative adversarial network, namely structurally constrained pathology-aware convolutional transformer generative adversarial network (SCPAT-GAN), to generate virtual stained H&E histology from OCT images. We quantitatively evaluate the quality of virtual stained histology images by measuring the Fréchet inception distance (FID) and perceptual hash value (PHV). Moreover, we invite experienced pathologists to evaluate the virtual stained images. Furthermore, we visually inspect the virtual stained image generated by SCPAT-GAN. Also, we perform an ablation study to validate the design of the proposed SCPAT-GAN. Finally, we demonstrate 3D virtual stained histology images.

Results

Compared to previous research, the proposed SCPAT-GAN achieves better FID and PHV scores. The visual inspection suggests that the virtual histology images generated by SCPAT-GAN resemble both normal and pathological features without artifacts. As confirmed by the pathologists, the virtual stained images have good quality compared to real histology images. The ablation study confirms the effectiveness of the combination of proposed pathological awareness and structural constraining modules.

Conclusions

The proposed SCPAT-GAN is the first to demonstrate the feasibility of generating both normal and pathological patterns without pixel-wisely supervised training. We expect the SCPAT-GAN to assist in the clinical evaluation of treating the CAD by providing 2D and 3D histopathological visualizations.

Medically Treated Nonischemic Thin-Cap Fibroatheroma Lesions Versus Fractional Flow Reserve-Guided Complete Revascularization in Diabetic Patients

Background

Fractional flow reserve (FFR) is an established method to guide decisions on revascularization; however, in patients with diabetes mellitus (DM), FFR-negative lesions carrying an optical coherence tomography-detected thin-cap fibroatheroma (TCFA) remain at high risk for adverse cardiac events.

Methods

In this prespecified subanalysis of the COMBINE OCT-FFR trial, DM patients with ≥1 FFR-negative, TCFA-positive medically treated target lesions referred to as vulnerable plaque (VP group), were compared to patients with exclusively FFR-positive target lesions who underwent complete revascularization (CR group). The primary endpoint was first and recurrent event analysis for target lesion failure and the secondary endpoint was a composite of cardiac death, target vessel myocardial infarction, target lesion revascularization, or hospitalization due to unstable angina.

Results

Among 550 patients enrolled, 98 belonged to the VP group while 93 to the CR group and were followed up to 5 years. The VP group had a higher occurrence of the primary endpoint (20.4% vs 8.6%; HR, 2.22; 95% CI, 0.98-5.04; P = .06). Recurrent event analysis showed that the VP group had significantly higher rates of the primary and secondary endpoints (9.17 vs 3.76 events per 100 PY; RR, 2.44; 95% CI, 1.16-5.60; P = .01 and 13.45 vs 5.63 events per 100 PY; RR, 2.39; 95% CI, 1.30-4.62; P < .01).

Conclusions

In a population with DM, medically treated nonischemic, TCFA-carrying target lesions were associated with higher risk of reoccurring adverse cardiac events compared to target lesions that underwent complete revascularization, opening the discussion about whether a focal preventive revascularization strategy could be contemplated for highly vulnerable lesions.

Short-term air pollution exposure and mechanisms of plaque instability in acute coronary syndromes: An optical coherence tomography study

BACKGROUND AND AIMS

Air pollution is emerging as an important risk factor for acute coronary syndrome (ACS). In this study, we investigated the association between short-term air pollution exposure and mechanisms of coronary plaque instability evaluated by optical coherence tomography (OCT) imaging in ACS patients.

METHODS

Patients with ACS undergoing OCT imaging were retrospectively selected. Mechanism of culprit lesion instability was classified as plaque rupture (PR) or intact fibrous cap (IFC) by OCT. Based on each case's home address, the mean daily exposures to several pollutants, including particulate matter 2.5 (PM2.5), on the same day of ACS and in the immediate days (up to 6 days) prior to the index ACS, were collected.

RESULTS

139 ACS patients were included [69 (49.6%) had PR and 70 (50.4%) IFC]. Patients with PR, compared to those with IFC, had higher PM2.5 exposure levels on the same day of ACS, without differences in the immediate 6 days before index ACS. At multivariate analysis, PM2.5 exposure on the same day of ACS was the only independent predictor of PR [OR = 1.912 per SD (8.6 μg/m3), CI95 % (1.087-3.364), p = 0.025]. Patients with PR presented a steady increase in PM2.5 daily exposure levels in the days preceding the occurrence of ACS, with a peak the day of ACS (p for trend = 0.042) CONCLUSIONS: This study demonstrates for the first time that a higher short-term PM2.5 exposure, on the same day of ACS, is associated with an increased risk of PR as a pathobiological mechanism of coronary plaque instability.

Morphological characteristics of in-stent restenosis with different degrees of area stenosis: an optical coherence tomography study

The morphological characteristics of in-stent restenosis (ISR) in relation to varying degrees of area stenosis have not been comprehensively examined. This study aimed to explore the tissue characteristics of patients experiencing ISR with different degrees of area stenosis through the utilization of optical coherence tomography (OCT). In total, 230 patients with ISR who underwent OCT were divided into the following three groups: area stenosis (AS) < 70% (n = 26); 70-80% (n = 119) and AS ≥ 80% (n = 85). Among the 230 patients, the clinical presentation as stable angina was 61.5% in AS < 70%, followed by 47.2% in 70% < AS ≤ 80%, and 31.8% in AS ≥ 80% (P = 0.010). The OCT findings showed that heterogeneous neointima, ISNA, LRP, neointima rupture, TCFA-like pattern, macrophage infiltration, red and white thrombus was more common with AS increased. Ordinal logistic regression analysis showed that higher AS was associated with previous dyslipidemia (odds ratio [OR], 4.754; 95% confidence interval [CI], 1.419-15.927, P = 0.011), neointimal rupture (OR: 3.640; 95% CI, 1.169-11.325, P = 0.026), red thrombus (OR: 4.482; 95% CI, 1.269-15.816, P = 0.020) and white thrombus (OR: 5.259; 95% CI, 1.660-16.659, P = 0.005). Patients with higher degrees of area stenosis in the context of ISR exhibited a greater number of discernible morphological characteristics as identified through OCT analysis. Furthermore, previous dyslipidemia, neointimal rupture, white thrombus and red thrombus were highly associated with and the progression of ISR lesions.

Deep learning segmentation of fibrous cap in intravascular optical coherence tomography images

Thin-cap fibroatheroma (TCFA) is a prominent risk factor for plaque rupture. Intravascular optical coherence tomography (IVOCT) enables identification of fibrous cap (FC), measurement of FC thicknesses, and assessment of plaque vulnerability. We developed a fully-automated deep learning method for FC segmentation. This study included 32,531 images across 227 pullbacks from two registries (TRANSFORM-OCT and UHCMC). Images were semi-automatically labeled using our OCTOPUS with expert editing using established guidelines. We employed preprocessing including guidewire shadow detection, lumen segmentation, pixel-shifting, and Gaussian filtering on raw IVOCT (r,θ) images. Data were augmented in a natural way by changing θ in spiral acquisitions and by changing intensity and noise values. We used a modified SegResNet and comparison networks to segment FCs. We employed transfer learning from our existing much larger, fully-labeled calcification IVOCT dataset to reduce deep-learning training. Postprocessing with a morphological operation enhanced segmentation performance. Overall, our method consistently delivered better FC segmentation results (Dice: 0.837 ± 0.012) than other deep-learning methods. Transfer learning reduced training time by 84% and reduced the need for more training samples. Our method showed a high level of generalizability, evidenced by highly-consistent segmentations across five-fold cross-validation (sensitivity: 85.0 ± 0.3%, Dice: 0.846 ± 0.011) and the held-out test (sensitivity: 84.9%, Dice: 0.816) sets. In addition, we found excellent agreement of FC thickness with ground truth (2.95 ± 20.73 µm), giving clinically insignificant bias. There was excellent reproducibility in pre- and post-stenting pullbacks (average FC angle: 200.9 ± 128.0°/202.0 ± 121.1°). Our fully automated, deep-learning FC segmentation method demonstrated excellent performance, generalizability, and reproducibility on multi-center datasets. It will be useful for multiple research purposes and potentially for planning stent deployments that avoid placing a stent edge over an FC.

Simultaneous 18-FDG PET and MR imaging in lower extremity arterial disease

Background

Simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) is a novel hybrid imaging method integrating the advances of morphological tissue characterization of MRI with the pathophysiological insights of PET applications.

Aim

This study evaluated the use of simultaneous 18-FDG PET/MR imaging for characterizing atherosclerotic lesions in lower extremity arterial disease (LEAD).

Methods

Eight patients with symptomatic stenoses of the superficial femoral artery (SFA) under simultaneous acquisition of 18-FDG PET and contrast-enhanced MRI using an integrated whole-body PET/MRI scanner. Invasive plaque characterization of the SFA was performed by intravascular imaging using optical coherence tomography. Histological analysis of plaque specimens was performed after directional atherectomy.

Results

MRI showed contrast enhancement at the site of arterial stenosis, as assessed on T2-w and T1-w images, compared to a control area of the contralateral SFA (0.38 ± 0.15 cm vs. 0.23 ± 0.11 cm; 1.77 ± 0.19 vs. 1.57 ± 0.15; p-value <0.05). On PET imaging, uptake of 18F-FDG (target-to-background ratio TBR > 1) at the level of symptomatic stenosis was observed in all but one patient. Contrast medium-induced MR signal enhancement was detected in all plaques, whereas FDG uptake in PET imaging was increased in lesions with active fibroatheroma and reduced in fibrocalcified lesions.

Conclusion

In this multimodal imaging study, we report the feasibility and challenges of simultaneous PET/MR imaging of LEAD, which might offer new perspectives for risk estimation.

The role of optical coherence tomography in guiding percutaneous coronary interventions: is left main the final challenge?

Left main (LM) coronary artery disease is a high-risk lesion subset, with important prognostic implications for the patients. Recent advances in the field of interventional cardiology have narrowed the gap between surgical and percutaneous approach of this complex lesion setting. However, the rate of repeat revascularization remains higher in the case of percutaneous coronary intervention (PCI) on long-term follow-up. As such, the need for better stent optimization strategies has led to the development of intravascular imaging techniques, represented mainly by intravascular ultrasound (IVUS) and optical coherence tomography (OCT). These techniques are both able to provide excellent pre- and post-PCI guidance. While IVUS is an established modality in optimizing LM PCI, and is recommended by international revascularization guidelines, data and experience on the use of OCT are still limited. This review paper deeply analyzes the current role of OCT imaging in the setting of LM disease, particularly focusing on its utility in assessing plaque morphology and distribution, vessel dimensions and proper stent sizing, analyzing mechanisms of stent failure such as malapposition and underexpansion, guiding bifurcation stenting, as well as offering a direct comparison with IVUS in this critical clinical scenario, based on the most recent available data.

Organized thrombus is a frequent underlying feature in culprit lesion morphology in non-ST-elevation myocardial infarction. A study using optical coherence tomography and magnetic resonance imaging

The concept that the culprit lesion in non-ST segment elevation myocardial infarction (NSTEMI) is caused by sudden plaque rupture with acute thrombus formation has recently been challenged. While angiography is an old gold-standard for culprit identification it merely visualizes the lumen contour. Optical coherence tomography (OCT) provides a detailed view of culprit features. Combined with myocardial edema on cardiac magnetic resonance (CMR), indicating acute ischemia and thus culprit location, we aimed to characterize culprit lesions using OCT. Patients with NSTEMI referred for angiography were prospectively enrolled. OCT was performed on angiographic stenoses ≥50% and on operator-suspected culprit lesions. Hierarchical OCT-culprit identifiers were defined in case of multiple unstable lesions, including OCT-defined thrombus age. An OCT-based definition of an organizing thrombus as corresponding to histological early healing stage was introduced. Lesions were classified as OCT-culprit or non-culprit, and characteristics compared. CMR was performed in a subset of patients. We included 65 patients with 97 lesions, of which 49 patients (75%) had 53 (54%) OCT-culprit lesions. The most common OCT-culprit identifiers were the presence of acute (66%) and organizing thrombus (19%). Plaque rupture was visible in 45% of OCT-culprit lesions. CMR performed in 38 patients revealed myocardial oedema in the corresponding territories of 67% of acute thrombi and 50% of organizing thrombi. A culprit lesion was identified by OCT in 75% patients with NSTEMI. Acute thrombus was the most frequent feature followed by organizing thrombus. Applying specific OCT-criteria to identify the culprit could prove valuable in ambiguous cases.

Invasive coronary imaging of inflammation to further characterize high-risk lesions: what options do we have?

Coronary atherosclerosis remains a leading cause of morbidity and mortality worldwide. The underlying pathophysiology includes a complex interplay of endothelial dysfunction, lipid accumulation and inflammatory pathways. Multiple structural and inflammatory features of the atherosclerotic lesions have become targets to identify high-risk lesions. Various intracoronary imaging devices have been developed to assess the morphological, biocompositional and molecular profile of the intracoronary atheromata. These techniques guide interventional and therapeutical management and allow the identification and stratification of atherosclerotic lesions. We sought to provide an overview of the inflammatory pathobiology of atherosclerosis, distinct high-risk plaque features and the ability to visualize this process with contemporary intracoronary imaging techniques.

Coronary microevaginations characterize culprit plaques and their inflammatory microenvironment in a subtype of acute coronary syndrome with intact fibrous cap: results from the prospective translational OPTICO-ACS study

AIMS

Coronary microevaginations (CMEs) represent an outward bulge of coronary plaques and have been introduced as a sign of adverse vascular remodelling following coronary device implantation. However, their role in atherosclerosis and plaque destabilization in the absence of coronary intervention is unknown. This study aimed to investigate CME as a novel feature of plaque vulnerability and to characterize its associated inflammatory cell-vessel-wall interactions.

METHODS AND RESULTS

A total of 557 patients from the translational OPTICO-ACS study programme underwent optical coherence tomography imaging of the culprit vessel and simultaneous immunophenotyping of the culprit lesion (CL). Two hundred and fifty-eight CLs had a ruptured fibrous cap (RFC) and one hundred had intact fibrous cap (IFC) acute coronary syndrome (ACS) as an underlying pathophysiology. CMEs were significantly more frequent in CL when compared with non-CL (25 vs. 4%, P < 0.001) and were more frequently observed in lesions with IFC-ACS when compared with RFC-ACS (55.0 vs. 12.7%, P < 0.001). CMEs were particularly prevalent in IFC-ACS-causing CLs independent of a coronary bifurcation (IFC-ICB) when compared with IFC-ACS with an association to a coronary bifurcation (IFC-ACB, 65.4 vs. 43.7%, P = 0.030). CME emerged as the strongest independent predictor of IFC-ICB (relative risk 3.36, 95% confidence interval 1.67-6.76, P = 0.001) by multivariable regression analysis. IFC-ICB demonstrated an enrichment of monocytes in both culprit blood analysis (culprit ratio: 1.1 ± 0.2 vs. 0.9 ± 0.2, P = 0.048) and aspirated culprit thrombi (326 ± 162 vs. 96 ± 87 cells/mm2, P = 0.017), while IFC-ACB confirmed the accumulation of CD4+ T cells, as recently described.

CONCLUSION

This study provides novel evidence for a pathophysiological involvement of CME in the development of IFC-ACS and provides first evidence for a distinct pathophysiological pathway for IFC-ICB, driven by CME-derived flow disturbances and inflammatory activation involving the innate immune system.

TRIAL REGISTRATION

Registration of the study at clinicalTrials.gov (NCT03129503).

Role of intravascular ultrasound and optical coherence tomography in intracoronary imaging for coronary artery disease: a systematic review

Coronary angiography has long been the standard for coronary imaging, but it has limitations in assessing vessel wall anatomy and guiding percutaneous coronary intervention (PCI). Intracoronary imaging techniques like intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can overcome these limitations. IVUS uses ultrasound and OCT uses near-infrared light to visualize coronary pathology in unique ways due to differences in temporal and spatial resolution. These techniques have evolved to offer clinical utility in plaque characterization and vessel assessment during PCI. Meta-analyses and adjusted observational studies suggest that both IVUS and OCT-guided PCI correlate with reduced cardiovascular risks compared to angiographic guidance alone. While IVUS demonstrates consistent clinical outcome benefits, OCT evidence is less robust. IVUS has progressed from early motion detection to high-resolution systems, with smaller compatible catheters. OCT utilizes near infrared light to achieve unparalleled resolutions, but requires temporary blood clearance for optimal imaging. Enhanced visualization and guidance make IVUS and OCT well-suited for higher risk PCI in patients with diabetes and chronic kidney disease by allowing detailed visualization of complex lesions and ensuring optimal stent deployment and positioning in PCI for patients with type 2 diabetes and chronic kidney disease, improving outcomes. IVUS and recent advancements in zero- and low-contrast OCT techniques can reduce nephrotoxic contrast exposure, thus helping to minimize PCI complications in these high-risk patient groups. IVUS and OCT provide valuable insights into coronary pathophysiology and guide interventions precisely compared to angiography alone. Both have comparable clinical outcomes, emphasizing the need for tailored imaging choices based on clinical scenarios. Continued refinement and integration of intravascular imaging will likely play a pivotal role in optimizing coronary interventions and outcomes. This systematic review aims to delve into the nuances of IVUS and OCT, highlighting their strengths and limitations as PCI adjuncts.

Drug-Coated Balloon for de-novo Coronary Artery Lesions Exceeding 2.5 mm in Diameter: Optical Coherence Tomography Analysis and Clinical Follow-Up

Objective

To investigate the precise changes in the lumen and lesions, and clinical outcomes after DCB treatment for de-novo coronary lesions exceeding 2.5 mm in diameter through a detailed analysis of OCT.

Methods

This is a prospective study including 53 consecutive patients with 55 de-novo coronary lesions, who underwent DCB angioplasty-only between January 2021 and April 2022. Quantitative coronary angiography (QCA) and OCT were performed before percutaneous coronary interventions (PCI), immediately after PCI, and at 6-9 months follow-up after PCI. Target lesion failure (TLF) was the primary endpoint of the present study. Multivariate logistic regression analysis was performed to identify the predictors or risks for late lumen enlargement (LLE).

Results

A total of 52 patients were successfully treated with DCB. The median follow-up was 7 months, and the incidence of TLF was 7.5%. After the DCB procedure, 43 patients had their scheduled angiographic and OCT examination. QCA demonstrated that the late lumen loss was -0.79 ± 0.28 mm. OCT demonstrated LLE in 79.1% and dissection healing in 65.1% of lesions. After multivariable logistic analysis, type B dissection (odds ratio [OR] 2.92, 95% confidence interval [CI] 1.34-7.41, p = 0.037) was found to be a predictor of LLE, but lipid plaque (OR 0.09, 95% CI 0.01-0.63, p = 0.015) was a risk of LLE.

Conclusion

This is the first and largest prospective study to assess the outcomes of DCB treatment for de-novo coronary lesions exceeding 2.5 mm in diameter and the detection of significant vessel enlargement and dissection healing guide by OCT. DCB could be a novel, safe and effective treatment for de-novo coronary lesions exceeding 2.5 mm in diameter through a detailed analysis of OCT.

Lipid Content Distribution and its Clinical Implication in Patients with Acute Myocardial Infarction-Plaque Erosion: Results from the Prospective OCTAMI Study

AIMS

Plaque erosion (PE) is one of the main plaque phenotypes of acute coronary syndrome (ACS). However, the underlying plaque component and distribution have not been systematically analysed. This study aims to investigate the distribution of lipid and calcium content in culprit lesions assessed by optical coherence tomography (OCT) in patients with PE and explore its relationship with prognosis in a cohort of ST segment elevation myocardial infarction (STEMI) patients.

METHODS

A prospective cohort of 576 patients with STEMI was enrolled in our study. After exclusion, 152 PE patients with clear underlying plaque components were ultimately analysed. The culprit lesion was divided into the border zone, external erosion zone and erosion site in the longitudinal view. Each pullback of the culprit lesions was assessed by 3 independent investigators frame-by-frame, and the quantity and distribution of lipid and calcium components were recorded.

RESULTS

Of the 152 PE patients, lipid and calcium contents were more likely to exist in the external erosion zone than in the other regions. In particular, a high level of lipid content proximal to the erosion site was significantly associated with plaque vulnerability and a higher incidence of MACEs.

CONCLUSION

This study revealed that high level of lipid content in the proximal external erosion zone was related to high-risk plaque characteristics and poor prognosis, which provided a novel method for risk stratification and precise management in patients with plaque erosion.

Diagnosis and treatment of angiographically unclear coronary lesions

Although selective coronary angiography is the gold standard diagnostic technique for coronary lesions, this method does not provide all information regarding pathophysiologic mechanisms. We herein describe a patient in their early 60s with a 3-month history of pronounced angina. Coronary angiography revealed a central line of illumination in the proximomedial segment of the right coronary artery, suggesting a chronic coronary dissection/recanalized thrombus, along with positive remodeling and TIMI grade 2 flow. Optical coherence tomography showed a recanalized thrombus and multiple lumens separated by thin septa. Because of the significantly reduced flow and signs of ischemia in the right coronary artery irrigation territory, we decided to perform percutaneous coronary intervention. Post-treatment optical coherence tomography indicated optimal apposition and expansion of the stents with positive remodeling of the blood vessel. We believe that decisions regarding treatment modalities should be guided by the presence or absence of ischemia. Lesions that are causing myocardial ischemia should be revascularized; otherwise, medical treatment can be utilized.

Pathophysiology and diagnostic pathway of myocardial infarction with non-obstructive coronary arteries

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous and diverse disease entity, which accounts for about 6 % of all acute myocardial infarction (AMI) cases. In patients with chest pain and acute myocardial injury detected by a highly sensitive troponin assay, the absence of epicardial coronary stenosis of 50 % or greater on angiography leads to the working diagnosis of MINOCA. The updated JCS/CVIT/JCC 2023 Guideline described MINOCA as a new disease concept and recommended a multimodality approach to uncovering the underlying causes of MINOCA. Cardiac magnetic resonance (CMR) is useful in not only making a definite diagnosis of MINOCA, but also excluding non-ischemic causes that mimic AMI such as takotsubo cardiomyopathy and myocarditis. Meanwhile, intracoronary imaging, particularly optical coherence tomography (OCT), enables us to evaluate precisely intracoronary morphological alterations including plaque disruption and spontaneous coronary artery dissection which are not revealed by angiographic findings alone. Recent studies have shown that an initial workup with the combination of CMR and OCT could provide a definite diagnosis in a significant percentage of patients suspected of MINOCA. Consecutively, patients with inconclusive results of a series of CMR and OCT implementation are eligible for assessing the potential for coronary functional abnormalities or blood coagulopathy as another factor involved in the development of MINOCA. Although uncovering the pathogenesis of MINOCA might be essential for establishing an individualized treatment approach, significant knowledge gaps in terms of secondary prevention strategies for MINOCA focusing on the improvement of long-term prognosis remain to be overcome. In this review, we summarize our current understanding of MINOCA and highlight contemporary diagnostic approaches for patients with suspected MINOCA.

Associations Between Resolvin D1 and Culprit Plaque Morphologies: An Optical Coherence Tomography Study in Patients with ST-Segment Elevation Myocardial Infarction

Background

As a specialized pro-resolving lipid mediator, resolvin D1 (RvD1) inhibits atherosclerosis progression in vivo by reducing regional oxidative stress and chronic inflammation. However, it is unclear how RvD1 is involved in human coronary artery disease. This study aims to investigate the association between plasma levels of RvD1 and culprit-plaque characteristics in patients with ST-segment elevation myocardial infarction (STEMI).

Methods

A total of 240 STEMI patients undergoing optical coherence tomography (OCT) examination were analyzed. RvD1 levels were measured in patient plasma samples using an enzyme-linked immunosorbent assay. Logistic regression was performed to assess the association between RvD1 levels and various culprit plaque morphologies, and the receiver operating curve was used to search for an optimal cutoff threshold to predict certain pathological features.

Results

The median RvD1 level was 129.7 (56.6-297.8) pg/mL. According to multivariable logistic regression, high RvD1 was associated with plaque rupture (≥111.5 pg/mL, odds ratio [OR]: 2.09, 95% confidence interval [CI]: 1.20-3.66, P = 0.010), healed plaques (≥246.4 pg/mL, OR: 2.17, 95% CI: 1.11-4.24, P = 0.023), and calcification (≥293.38 pg/mL, OR: 2.10, 95% CI: 1.21-3.66, P = 0.008) at culprit lesions.

Conclusion

Increased levels of RvD1 were associated with higher instability of coronary atherosclerotic plaques in STEMI patients.

Machine Learning-Assisted Short-Wave InfraRed (SWIR) Techniques for Biomedical Applications: Towards Personalized Medicine

Personalized medicine transforms healthcare by adapting interventions to individuals' unique genetic, molecular, and clinical profiles. To maximize diagnostic and/or therapeutic efficacy, personalized medicine requires advanced imaging devices and sensors for accurate assessment and monitoring of individual patient conditions or responses to therapeutics. In the field of biomedical optics, short-wave infrared (SWIR) techniques offer an array of capabilities that hold promise to significantly enhance diagnostics, imaging, and therapeutic interventions. SWIR techniques provide in vivo information, which was previously inaccessible, by making use of its capacity to penetrate biological tissues with reduced attenuation and enable researchers and clinicians to delve deeper into anatomical structures, physiological processes, and molecular interactions. Combining SWIR techniques with machine learning (ML), which is a powerful tool for analyzing information, holds the potential to provide unprecedented accuracy for disease detection, precision in treatment guidance, and correlations of complex biological features, opening the way for the data-driven personalized medicine field. Despite numerous biomedical demonstrations that utilize cutting-edge SWIR techniques, the clinical potential of this approach has remained significantly underexplored. This paper demonstrates how the synergy between SWIR imaging and ML is reshaping biomedical research and clinical applications. As the paper showcases the growing significance of SWIR imaging techniques that are empowered by ML, it calls for continued collaboration between researchers, engineers, and clinicians to boost the translation of this technology into clinics, ultimately bridging the gap between cutting-edge technology and its potential for personalized medicine.

Coronary artery calcification and plaque stability： an optical coherence tomography study

Background

Coronary artery calcification (CAC), a surrogate of atherosclerosis, is related to stent underexpansion and adverse cardiac events. However, the effect of CAC on plaque stability is still controversial and the morphological significance of CAC has yet to be elucidated.

Methods

A retrospective series of 419 patients with acute coronary syndrome (ACS) who underwent optical coherence tomography (OCT) were enrolled. Patients were classified into three groups based on the calcification size in culprit plaques and the features of the culprit and non-culprit plaques among these groups were compared. Logistic regression was used to analyze independent risk factors for culprit plaque rupture and the nonlinear relationship between calcification parameters and culprit plaque rupture. Furthermore, we compared the detailed calcification parameters of different kinds of plaques.

Results

A total of 419 culprit plaques and 364 non-culprit plaques were identified. The incidence of calcification was 53.9 % in culprit plaques and 50.3 % in non-culprit plaques. Compared with culprit plaques without calcification, plaque rupture, macrophages and cholesterol crystals were more frequently observed in the spotty calcification group, and the lipid length was longer; the incidence of macrophages and cholesterol crystals was higher in the macrocalcification group. Calcification tended to be smaller in ruptured plaques than in non-ruptured plaques. Moreover, the arc and length of calcification were greater in culprit plaques than in non-culprit plaques.

Conclusions

Vulnerable features were more frequently observed in culprit plaques with spotty calcification, whereas the presence of macrocalcification calcifications did not significantly increase plaque vulnerability. Calcification tends to be larger in culprit plaques than in non-culprit plaques.

Heavy macrophage infiltration identified by optical coherence tomography relates to plaque rupture

OBJECTIVE

Risk stratification plays a critical role in patients with asymptomatic carotid atherosclerotic stenosis. Heavy macrophage infiltration (HMC) is an important factor of plaque destabilization. However, in vivo imaging technologies and screening criteria for HMC remain limited. We aimed to (i) introduce algorithms for in vivo detection of macrophage infiltrations using optical coherence tomography (OCT) and (ii) to investigate the threshold of HMC and its association with plaque vulnerability.

METHODS

Ex vivo OCT images were co-registered with histopathology in 282 cross-sectional pairs from 19 carotid endarterectomy specimens. Of these, 197 randomly selected pairs were employed to define the parameters, and the remaining 85 pairs were used to evaluate the accuracy of the OCT-based algorithm in detecting macrophage infiltrations. Clinical analysis included 93 patients receiving carotid OCT evaluation. The prevalence and burden of macrophage infiltration were analyzed. Multivariable and subgroup analysis were performed to investigate the association between HMC and plaque rupture.

RESULTS

The sensitivity and specificity of algorithm for detecting macrophage infiltration were 88.0% and 74.9%, respectively. Of 93 clinical patients, ruptured plaques exhibited higher prevalence of macrophage infiltration than nonruptured plaques (83.7% [36/43] vs 32.0% [16/50], p < 0.001). HMC was identified when the macrophage index was greater than 60.2 (sensitivity = 74.4%, specificity = 84.0%). Multivariable analysis showed that HMC and multiple calcification were independent risk factors for non-lipid-rich plaque rupture.

INTERPRETATION

This study provides a novel approach and screening criteria for HMC, which might be valuable for atherosclerotic risk stratification.