Optical Frequency Domain Imaging Analysis Research Articles

Intracoronary polarimetry for characterizing coronary plaque vulnerability in patients with coronary artery disease

Abstract Background Intracoronary polarimetry with polarization-sensitive (PS-) optical frequency domain imaging (OFDI) measures polarization properties, including birefringence and depolarization, in parallel with structural features of conventional OFDI (Figure 1A). Collagen, which imparts mechanical integrity to fibrous caps, and collagen-synthesizing smooth muscle cells exhibit elevated birefringence. Depolarization is increased by the presence of macrophages and lipid/necrotic cores. Purpose This study aimed to compare conventional OFDI and polarimetric signatures of coronary lesions between patients with acute coronary syndrome (ACS) and chronic coronary syndrome (CCS). Furthermore, we aimed to determine a birefringence cut-off value for identifying which fibrous caps belong to ACS culprit lesions. Methods This study consisted of 37 patients with ACS (n=23) or CCS (n=14). ACS culprit lesions (ACS-lesions) and CCS stenotic lesions (CCS-lesions) were included in the analysis (820 mm). Qualitative and quantitative conventional OFDI analysis included the presence of plaque rupture, macrophage infiltration, micro-vessels, thrombus, stenosis severity, fibrous cap thickness (FCT), lipid arc, lipid-burden and calcium-burden index. Birefringence and depolarization of the coronary lesions and fibrous caps were measured in the cross-sectional images showing the minimum FCT or minimum luminal area. Predictors of ACS-lesions were investigated by multivariate regression analysis. Receiver operating characteristic (ROC) analysis was used to determine the birefringence cut-off value identifying ACS fibrous caps (ACS-caps). Results There were no significant differences in clinical characteristics between the two groups, except for previous history of coronary artery disease. Compared to CCS-lesions, ACS-lesions featured higher lipid-burden index and maximum lipid arc (both p<0.05). ACS-lesions featured lower birefringence and higher depolarization than CCS-lesions (p<0.05). Multivariable regression demonstrated an independent association of birefringence with ACS-lesions (p<0.05), even after adjusting for the conventional OFDI findings. Limiting the analysis to the fibrous caps, ACS-caps exhibited significantly lower birefringence (p<0.05) and higher depolarization (p<0.05) that CCS-caps. ROC analysis for differentiating ACS-caps from CCS-caps found that a birefringence value of 0.0004 results in a sensitivity and specificity of 88% and 82%, respectively (Figure 1B, AUC = 0.82). Conclusions Intracoronary polarimetry provides quantitative assessment of coronary lesions related to their composition. Birefringence was an independent robust predictor of ACS-lesions. Decreased birefringence and pronounced depolarization within the ACS-caps may indicate increased collagenolytic activity and macrophage infiltration, respectively. These results suggest that polarization properties may serve as quantitative imaging markers for assessing plaque vulnerability. Figure 1 Funding Acknowledgement Type of funding source: Other. Main funding source(s): This work was supported by the National Institutes of Health and by Terumo Corporation.

Pay Attention on the Road: TAVR and Vascular Complications

To analyze the difference in morphological patterns between in-stent restenosis (ISR) lesions of overlapping segments and ISR lesions of non-overlapping segments with second- and third-generation drug-eluting stents (DESs) using optical frequency domain imaging (OFDI).We analyzed 23 consecutive ISR lesions after second- or third-generation DES implantation using OFDI.A total of 18 men and 5 women (median age, 68.0 years; interquartile range, 51.0–74.0 years) were included in the analysis. Fourteen and nine patients underwent second- and third-generation DES implantation, respectively. The median ISR detection timepoint was 10.0 months after implantation (interquartile range, 9.0–34.0 months). In 9 out of 23 lesions, ISR was found in the stent overlap area (overlapping segment group); the remaining 14 cases were categorized as the non-overlapping segment group. In OFDI analysis, homogeneous, layered, and heterogeneous patterns were found in 22%, 55%, and 22%, respectively, of lesions in the overlapping segment group and 14%, 50%, and 35%, respectively, of lesions in the non-overlapping segment group. There was no difference in the distribution of restenotic tissue structure patterns between the groups (p = .756).Morphological assessments of ISR tissue using OFDI showed no difference between the overlapping and non-overlapping segment groups with second and third-generation DESs in this hypothesis generating study.

Comparison of Morphological Patterns Between In-Stent Restenosis Lesions of Overlapping and Non-Overlapping Second- and Third-Generation Stents Using Optical Frequency Domain Imaging

PurposeTo analyze the difference in morphological patterns between in-stent restenosis (ISR) lesions of overlapping segments and ISR lesions of non-overlapping segments with second- and third-generation drug-eluting stents (DESs) using optical frequency domain imaging (OFDI). MethodsWe analyzed 23 consecutive ISR lesions after second- or third-generation DES implantation using OFDI. ResultsA total of 18 men and 5 women (median age, 68.0 years; interquartile range, 51.0–74.0 years) were included in the analysis. Fourteen and nine patients underwent second- and third-generation DES implantation, respectively. The median ISR detection timepoint was 10.0 months after implantation (interquartile range, 9.0–34.0 months). In 9 out of 23 lesions, ISR was found in the stent overlap area (overlapping segment group); the remaining 14 cases were categorized as the non-overlapping segment group. In OFDI analysis, homogeneous, layered, and heterogeneous patterns were found in 22%, 55%, and 22%, respectively, of lesions in the overlapping segment group and 14%, 50%, and 35%, respectively, of lesions in the non-overlapping segment group. There was no difference in the distribution of restenotic tissue structure patterns between the groups (p = .756). ConclusionsMorphological assessments of ISR tissue using OFDI showed no difference between the overlapping and non-overlapping segment groups with second and third-generation DESs in this hypothesis generating study.

P5366Eicosapentaenoic acid therapy is associated with decreased coronary plaque instability assessed using optical frequency domain imaging

Abstract Background The relationship between eicosapentaenoic acid (EPA) therapy and coronary plaque stability assessed by optical frequency domain imaging (OFDI) has not been thoroughly described. Hypothesis EPA therapy is associated with decreased plaque instability in patients undergoing percutaneous coronary intervention (PCI) using OFDI. Methods Data on coronary artery plaques from 121 patients presenting with acute coronary syndrome or stable angina who consecutively underwent PCI between October 2015 and July 2018 were retrospectively analyzed. Of these patients, 109 were untreated (no-EPA group), whereas 12 were treated with EPA (EPA group). Each plaque's morphological characteristics were analyzed using OFDI. Results We used 1:4 propensity score matching for patients who received or did not receive EPA therapy before PCI. Baseline characteristics were balanced between both groups (age, sex, body mass index, diabetes mellitus, hypertension, dyslipidemia, chronic kidney disease, smoking, previous PCI or coronary artery bypass grafting, previous myocardial infarction, prior statin use, acute coronary syndrome, hemoglobin A1c level, low-density lipoprotein cholesterol concentration, triglyceride concentration, and high-density lipoprotein cholesterol concentration). The EPA group had significantly lower mean lipid index (818±806 vs. 1,574±891) and macrophage grade (13.5±5.9 vs. 19.3±7.4) but higher mean minimum fibrous cap thickness (109.2±55.7 vs. 81.6±36.4 μm) than the no-EPA group (P=0.010, 0.019, and 0.040, respectively). Multiple logistic regression analyses showed that prior EPA use was independently associated with lower lipid index and macrophage grade (P=0.043 and 0.024, respectively). Conclusion This OFDI analysis suggests that EPA therapy is associated with decreased plaque instability in patients undergoing PCI. Acknowledgement/Funding None

Abstract 754: The Relationship Between Obstructive Sleep Apnea and Coronary Plaque Instability: An Optical Frequency Domain Imaging Study

Background and purpose: Obstructive sleep apnea (OSA) is associated with coronary artery disease (CAD) and with an increased risk of myocardial infarction, stroke or death due to cardiovascular disease. Optical frequency-domain imaging (OFDI) is a useful modality for evaluating the characteristics of atherosclerotic plaque. The purpose of the study was to use OFDI to investigate the association of OSA with coronary plaque characteristics in patients undergoing percutaneous coronary intervention (PCI). Methods: We retrospectively analyzed OFDI data for coronary artery plaques from 15 patients with OSA and 35 non-OSA patients treated between October 2015 and October 2018. Plaque morphology was evaluated for 70 lesions, including 21 from patients with OSA and 49 from non-OSA patients. Results: Compared with the non-OSA group, patients with OSA had significantly higher prevalences of thinned cap fibroatheroma (TCFA) (67% vs. 35%, P=0.014) and microchannels (86% vs. 55%, P=0.014); a significantly higher mean lipid index (1,392±982 vs. 817±699, P=0.021), macrophage grade (8.4±6.4 vs. 4.8±4.5, P=0.030), and maximum number of microchannels (1.5±1.0 vs. 0.7±0.7, P=0.001); and a significantly lower mean minimum fibrous cap thickness (69.4±28.7 vs. 96.1±51.8 μm, P=0.008). Conclusions: This OFDI analysis suggests that OSA is associated with unstable plaque characteristics in patients with CAD. More intensive medical management for stabilization of coronary atherosclerotic plaque is required in patients with OSA.

Eicosapentaenoic acid therapy is associated with decreased coronary plaque instability assessed using optical frequency domain imaging.

BackgroundThe relationship between eicosapentaenoic acid (EPA) therapy and coronary plaque stability assessed by optical frequency domain imaging (OFDI) has not been thoroughly described.HypothesisEPA therapy is associated with decreased plaque instability in patients undergoing percutaneous coronary intervention (PCI) using OFDI.MethodsData on coronary artery plaques from 121 patients who consecutively underwent PCI between October 2015 and July 2018 were retrospectively analyzed. Of these patients, 109 were untreated (no‐EPA group), whereas 12 were treated with EPA (EPA group). Each plaque's morphological characteristics were analyzed using OFDI.ResultsWe used 1:4 propensity score matching for patients who received or did not receive EPA therapy before PCI. Baseline characteristics were balanced between both groups (age, sex, body mass index, diabetes mellitus, hypertension, dyslipidemia, chronic kidney disease, smoking, previous PCI or coronary artery bypass grafting, previous myocardial infarction, prior statin use, acute coronary syndrome, hemoglobin A1c level, low‐density lipoprotein cholesterol concentration, triglyceride concentration, and high‐density lipoprotein cholesterol concentration). OFDI data from 60 patients were analyzed in this study. The EPA group had significantly lower mean lipid index (818 ± 806 vs 1574 ± 891) and macrophage grade (13.5 ± 5.9 vs 19.3 ± 7.4) but higher mean minimum fibrous cap thickness (109.2 ± 55.7 vs 81.6 ± 36.4 μm) than the no‐EPA group (P = 0.010, 0.019, and 0.040, respectively). Multiple logistic regression analyses showed that prior EPA use was independently associated with lower lipid index and macrophage grade (P = 0.043 and 0.024, respectively).ConclusionThis OFDI analysis suggests that EPA therapy is associated with decreased plaque instability in patients undergoing PCI.

Obstructive sleep apnea is associated with increased coronary plaque instability: an optical frequency domain imaging study

Obstructive sleep apnea (OSA) is associated with coronary artery disease (CAD) and with an increased risk for myocardial infarction, stroke or death due to cardiovascular disease. Optical frequency-domain imaging (OFDI) is a useful modality for evaluating the characteristics of atherosclerotic plaque. The purpose of the study was to use OFDI to investigate the association of OSA with coronary plaque characteristics in patients undergoing percutaneous coronary intervention (PCI). We retrospectively analyzed OFDI data for coronary artery plaques from 15 patients with OSA and 35 non–OSA patients treated between October 2015 and October 2018. Plaque morphology was evaluated for 70 lesions, including 21 from patients with OSA and 49 from non–OSA patients. Compared with the non–OSA group, patients with OSA had significantly higher prevalences of thinned cap fibroatheroma (TCFA) (67% vs. 35%, P = 0.014) and microchannels (86% vs. 55%, P = 0.014); a significantly higher mean lipid index (1392 ± 982 vs. 817 ± 699, P = 0.021), macrophage grade (8.4 ± 6.4 vs. 4.8 ± 4.5, P = 0.030), and maximum number of microchannels (1.5 ± 1.0 vs. 0.7 ± 0.7, P = 0.001); and a significantly lower mean minimum fibrous cap thickness (69.4 ± 28.7 vs. 96.1 ± 51.8 μm, P = 0.008). This OFDI analysis suggests that OSA is associated with unstable plaque characteristics in patients with CAD. More intensive medical management for stabilization of coronary atherosclerotic plaque is required in patients with OSA.

Impact of post-dilatation on longitudinal stent elongation: An in vitro study

ObjectivesTo evaluate whether balloon inflation for post-dilatation causes longitudinal stent deformation (LSD). Methods and resultsTwo stents, sized 2.5mm×28mm and 3.5mm×28mm (Nobori®, biodegradable polymer biolimus-eluting stent; Ultimaster®, biodegradable polymer sirolimus-eluting stent; Terumo Co., Tokyo, Japan), were deployed at nominal pressure in straight and tapered silicon vessel models. Then, post-dilatation was performed in two ways: dilatation from the distal (D-P group) or proximal (P-D group) side of the stent. Microscopic findings showed that the stents were elongated during every step of the procedure regardless of the post-dilatation method and type of vessel model. The D-P group showed linear elongation during each step of post-dilatation (straight model: 28.7±0.3mm vs. 29.9±0.3mm, p=0.002; tapered model: 28.0±0.1mm vs. 29.9±0.1mm, p<0.001). In contrast, in the P-D group, the most significant change was observed in the first step of post-dilatation and only slight changes were observed thereafter (straight model: 28.6±0.1mm vs. 29.5±0.1mm, p<0.001; tapered model: 28.2±0.1mm vs. 29.5±0.1mm, p<0.001). Optical frequency domain imaging analysis showed that the frequency of stent strut malapposition was positively correlated with the percentage change in stent length (r=0.74, p<0.0001). ConclusionLSD was observed during every step of post-dilatation in both the straight and tapered vessel models. However, some differences were observed between the D-P and P-D groups. Minimizing stent strut malapposition may reduce the risk of LSD.

TCT-228 Early neointimal coverage of new biodegradable polymer drug-eluting stent compared with durable polymer everolimus-eluting stent: optical frequency domain imaging analysis

TCT-228 Early neointimal coverage of new biodegradable polymer drug-eluting stent compared with durable polymer everolimus-eluting stent: optical frequency domain imaging analysis

Cholesterol crystal depth in coronary atherosclerotic plaques: A novel index of plaque vulnerability using optical frequency domain imaging

BackgroundThe involvement of cholesterol crystals (CCs) in plaque progression and destabilization of atherosclerotic plaques has been recently recognized. This study aimed to evaluate the association between the intraplaque localization of CCs and plaque vulnerability.MethodsWe investigated 55 acute coronary syndrome (ACS) and 80 stable angina pectoris (stable AP) lesions using optical frequency domain imaging (OFDI) prior to percutaneous coronary intervention. The distance between CCs and the luminal surface of coronary plaques was defined as CC depth.ResultsAlthough the incidence of CCs had similar frequencies in the ACS and stable AP groups (95% vs. 89%, p = 0.25), CC depth was significantly less in patients with ACS than in those with stable AP (median [25th to 75th percentile]: 68 μm [58 to 92 μm] vs. 152 μm [115 to 218 μm]; p < 0.001). The incidences of plaque rupture, thrombus, lipid-rich plaques, and thin-cap fibroatheroma were significantly greater in patients with ACS than in those with stable AP (62% vs. 18%, p < 0.001; 67% vs. 16%, p < 0.001; 84% vs. 57%, p < 0.01; and 56% vs. 19%, p < 0.001, respectively).ConclusionOFDI analysis revealed that CCs were found in the more superficial layers within the coronary atherosclerotic plaques in patients with ACS than in those with stable AP, suggesting that CC depth is associated with plaque vulnerability. CC depth, a novel OFDI-derived parameter, could be potentially used as an alternative means of evaluating plaque vulnerability in coronary arteries.

Potential of New-Generation Double-Layer Micromesh Stent for Carotid Artery Stenting in Patients with Unstable Plaque: A Preliminary Result Using OFDI Analysis.

One disadvantage of carotid artery stenting (CAS) is a high incidence of distal embolism (DE) during or after the procedure. Patients with unstable plaque are considered at high risk for DE and plaque protrusion (PP) after stent placement, which can cause postprocedural ischemic complications. This study was conducted to compare the rate and size of PP between the CASPER stent, a new-generation double-layer micromesh stent, and conventional stents as assessed by optical frequency domain imaging (OFDI), and also to evaluate the efficacy of CAS with the CASPER stent in cases with unstable plaque. The study group comprised 46 consecutive patients with unstable plaque, identified on magnetic resonance imaging, undergoing CAS with OFDI image acquisition. Cross-sectional OFDI images within the stented segments were evaluated at 0.125-mm intervals, and the rate and size of PP were compared between the CASPER stent and conventional stents. The CASPER stent was used in 9 patients. No procedural complications occurred. On OFDI analysis, the presence of PP was apparently lower in CASPER stent group compared with the conventional stent group (44% vs. 88%; P= 0.022). In addition, mean PP area was significantly smaller in the CASPER stent group (mean PP area, 0.013 ± 0.034 mm2 vs. 0.057 ± 0.09 mm2; P= 0.006). On OFDI evaluation after CAS, the degree of PP was significantly smaller in the CASPER stent group compared with the conventional stent group. This result provides new insight into the use of CAS to treat carotid artery stenosis with unstable plaque.

Impact of stent diameter on vascular response after self-expanding paclitaxel-eluting stent implantation in the superficial femoral artery

BackgroundThe optimal sizing of self-expanding paclitaxel-eluting stents (PES) in the treatment for superficial femoral artery (SFA) lesions is unclear. This study sought to investigate the influence of PES diameter on stent patency in SFA lesions using optical frequency domain imaging (OFDI). MethodsA total of 20 de novo SFA lesions were randomized 1:1 to receive either self-expanding PES with a nominal diameter of 6mm or 8mm. Follow-up angiography and OFDI was scheduled six months after stent implantation, and volumetric OFDI analysis was performed to evaluate vascular response to the stents. Volume index (VI) was defined as the volume divided by the stent length. The primary end point was lumen VI at the 6-month follow-up. Secondary end point was minimum lumen diameter (MLD) by quantitative vascular angiography (QVA) at the follow-up. ResultsStent length was 78.0±23.9mm in the 6-mm group and 70.0±23.6mm in the 8-mm group (p=0.46). Baseline QVA data were also similar between the two groups. MLD immediately after stent implantation was similar between the two groups (4.2±0.5mm in the 6-mm group and 3.9±0.5mm in the 8-mm group, p=NS). At the 6-month follow-up, MLD was greater in the 8-mm group compared to the 6-mm group (4.0±1.0mm vs. 3.2±0.4mm, p<0.05). Stent VI was larger in the 8-mm group (28.4±6.7mm3/mm vs. 22.2±1.2mm3/mm, p=0.01). Neointimal VI was similar between the two groups (5.8±2.9mm3/mm vs. 5.2±2.6mm3/mm, p=0.68). Lumen VI was greater in the 8-mm group (23.2±7.6mm3/mm vs. 17.3±2.6mm3/mm, p=0.04). ConclusionsChronic stent enlargement resulted in greater lumen area after implantation of self-expanding PES with a large diameter at the mid-term follow-up. Stent diameter might be important for stent patency in procedure with PES for SFA lesions.

TCT-241 Optimal endpoint of rotational atherectomy for coronary severe calcified lesion: optical frequency-domain imaging analysis

TCT-241 Optimal endpoint of rotational atherectomy for coronary severe calcified lesion: optical frequency-domain imaging analysis

Coronary optical frequency domain imaging (OFDI) for in vivo evaluation of stent healing: comparison with light and electron microscopy

AimsCoronary late stent thrombosis, a rare but devastating complication, remains an important concern in particular with the increasing use of drug-eluting stents. Notably, pathological studies have indicated that the proportion of uncovered coronary stent struts represents the best morphometric predictor of late stent thrombosis. Intracoronary optical frequency domain imaging (OFDI), a novel second-generation optical coherence tomography (OCT)-derived imaging method, may allow rapid imaging for the detection of coronary stent strut coverage with a markedly higher precision when compared with intravascular ultrasound, due to a microscopic resolution (axial ∼10–20 µm), and at a substantially increased speed of image acquisition when compared with first-generation time-domain OCT. However, a histological validation of coronary OFDI for the evaluation of stent strut coverage in vivo is urgently needed. Hence, the present study was designed to evaluate the capacity of coronary OFDI by electron (SEM) and light microscopy (LM) analysis to detect and evaluate stent strut coverage in a porcine model.Methods and resultsTwenty stents were implanted into 10 pigs and coronary OFDI was performed after 1, 3, 10, 14, and 28 days. Neointimal thickness as detected by OFDI correlated closely with neointimal thickness as measured by LM (r = 0.90, P < 0.01). The comparison of stent strut coverage as detected by OFDI and SEM analysis revealed an excellent agreement (r = 0.96, P < 0.01). In particular, stents completely covered by OFDI analysis were also completely covered by SEM analysis. All incompletely covered stents by OFDI were also incompletely covered by SEM. Analyses of fibrin-covered stent struts suggested that these may rarely be detected as uncovered stent struts by OFDI. Importantly, optical density measurements revealed a significant difference between fibrin- and neointima-covered coronary stent struts [0.395 (0.35–0.43) vs. 0.53 (0.47–0.57); P < 0.001], suggesting that differences in optical density provide information on the type of stent strut coverage. The sensitivity and specificity for detection of fibrin vs. neointimal coverage was evaluated using receiver-operating characteristic analysis.ConclusionThe present study demonstrates that OFDI is a highly promising tool for accurate evaluation of coronary stent strut coverage, as supported by a high agreement between OFDI and light and electron microscopic analysis. Furthermore, our data indicate that optical density measurements can provide additional information with respect to the type of stent strut coverage, i.e. fibrin vs. neointimal coverage. Therefore, coronary OFDI analysis will provide important information on the biocompatibility of coronary stents.