Interstudy reproducibility of the second generation, Fourier domain optical coherence tomography in patients with coronary artery disease and comparison with intravascular ultrasound: a study applying automated contour detection

Recently, Fourier domain OCT (FD-OCT) has been introduced for clinical use. This approach allows in vivo, high resolution (15 micron) imaging with very fast data acquisition, however, it requires brief flushing of the lumen during imaging. The reproducibility of such fast data acquisition under intracoronary flush application is poorly understood. To assess the inter-study variability of FD-OCT and to compare lumen morphometry to the established invasive imaging method, IVUS. 18 consecutive patients with coronary artery disease scheduled for PCI were included. In each target vessel a FD-OCT pullback (MGH system, light source 1,310 nm, 105 fps, pullback speed 20 mm/s) was acquired during brief (3 s) injection of X-ray contrast (flow 3 ml/s) through the guiding catheter. A second pullback was repeated under the same conditions after re-introduction of the FD OCT catheter into the coronary artery. IVUS and OCT imaging was performed in random order. FD-OCT and IVUS pullback data were analyzed using a recently developed software employing semi automated lumen contour and stent strut detection algorithms. Corresponding ROI were matched based on anatomical landmarks such as side branches and/or stent edges. Inter-study variability is presented as the absolute difference between the two pullbacks. FD-OCT showed remarkably good reproducibility. Inter-study variability in native vessels (cohort A) was very low for mean and minimal luminal area (0.10 ± 0.38, 0.19 ± 0.57 mm², respectively). Likewise inter-study variability was very low in stented coronary segments (cohort B) for mean lumen, mean stent, minimal luminal and minimal stent area (0.06 ± 0.08, 0.07 ± 0.10, 0.04 ± 0.09, 0.04 ± 0.10 mm², respectively). Comparison to IVUS morphometry revealed no significant differences. The differences between both imaging methods, OCT and IVUS, were very low for mean lumen, mean stent, minimal luminal and minimal stent area (0.10 ± 0.45, 0.10 ± 0.36, 0.26 ± 0.54, 0.05 ± 0.47 mm², respectively). FD-OCT shows excellent reproducibility and very low inter-study variability in both, native and stented coronary segments. No significant differences in quantitative lumen morphometry were observed between FD-OCT and IVUS. Evaluating these results suggest that FD-OCT is a reliable imaging tool to apply in longitudinal coronary artery disease studies.     

Optical coherence tomography criteria for defining functional severity of intermediate lesions: a comparative study with FFR

Fractional flow reserve (FFR) is the gold standard in the assessment of severity of the coronary stenosis. The aim of the study was to compare optical coherence tomography (OCT) obtained intermediate coronary lesions lumen areas measurements with FFR assessments, with the goal to develop an OCT threshold to identify significant coronary stenosis. 48 patients (mean age 65 ± 10 years) was enrolled for the study. Within this population, 71 intermediate coronary lesions were investigated using both FFR and OCT. High dose bolus of Adenosine (120 μg) was used to obtain coronary hyperemia. OCT imaging was performed using non-occlusive technique to assess minimal lumen area (MLA) and diameter. The OCT cut-off value that showed the best correlation with the FFR cut-off of 0.80 was the MLA less than 2.05 mm² (accuracy 87 %, sensitivity 75 %, specificity 90 %, p < 0.001). The study did not disclose any relationship between FFR value and the lesion length. Vessel size influenced the OCT cut-off values, with greater values being found in presence of arteries with a reference diameter greater than 3.0 mm. OCT derived minimal lumen area might be complementary to FFR measurement in identifying ischemia related lesions. Further studies are warranted to assess threshold values in relation to vessel size and location.     

A head to head comparison of XINSORB bioresorbable sirolimus-eluting scaffold versus metallic sirolimus-eluting stent: 180 days follow-up in a porcine model

We aimed to investigate the safety and efficacy of XINSORB bioresorbable sirolimus-eluting scaffold in porcine model. XINSORB scaffolds and metallic Firebird2? stents were randomly implanted into minipigs’ coronary arteries. Angiography, optical coherent tomography (OCT) and histopathological analyses were performed at post-procedure and 14-, 28-, 90-, 180-day follow-up. Thirty-two minipigs were enrolled. Eight XINSORB scaffolds and 8 Firebird2 stents were examined at each time point. Quantitative coronary angiography showed that in-scaffold late luminal loss (LLL) of XINSORB scaffold was 0.26?±?0.13, 0.50?±?0.16, 0.88?±?0.29 and 0.43?±?0.24 mm at 14-, 28, 90-, and 180-day follow-up respectively, and the corresponding diameter stenosis (DS) was 7.3?±?4.7, 12.0?±?9.5, 22.1?±?8.0, and 16.0?±?9.5%. Neither in-scaffold LLL nor DS of XINSORB scaffold was significantly different in comparison with Firebird2 stent. No difference of luminal area, device area, neointimal hyperplasia, and area stenosis was detected between two devices under OCT. Scaffold area of XINSORB remained steady through the observation. Histopathology revealed the similar findings. The greatest late recoil of XINSORB scaffold was about 4.12% at 90-day follow-up, which was comparable to Firebird2 stent. Both devices showed low injury or inflammation of vessel wall. XINSORB scaffold showed early neointimal coverage on struts within 28 days under scanning electron microscopy. XINSORB scaffold suppressed neointimal hyperplasia as effectively as Firebird2 did without obvious late device recoil during the 180 days follow-up. It is feasible to carry out clinical trial to investigate the safety and efficacy of XINSORB scaffold for patients with coronary artery diseases.     

Automatic quantification and characterization of coronary atherosclerosis with computed tomography coronary angiography: cross-correlation with intravascular ultrasound virtual histology

Plaque constitution on computed tomography coronary angiography (CTA) is associated with prognosis. At present only visual assessment of plaque constitution is possible. An accurate automatic, quantitative approach for CTA plaque constitution assessment would improve reproducibility and allows higher accuracy. The present study assessed the feasibility of a fully automatic and quantitative analysis of atherosclerosis on CTA. Clinically derived CTA and intravascular ultrasound virtual histology (IVUS VH) datasets were used to investigate the correlation between quantitatively automatically derived CTA parameters and IVUS VH. A total of 57 patients underwent CTA prior to IVUS VH. First, quantitative CTA quantitative computed tomography (QCT) was performed. Per lesion stenosis parameters and plaque volumes were assessed. Using predefined HU thresholds, CTA plaque volume was differentiated in 4 different plaque types necrotic core (NC), dense calcium (DC), fibrotic (FI) and fibro-fatty tissue (FF). At the identical level of the coronary, the same parameters were derived from IVUS VH. Bland–Altman analyses were performed to assess the agreement between QCT and IVUS VH. Assessment of plaque volume using QCT in 108 lesions showed excellent correlation with IVUS VH (r = 0.928, p < 0.001) (Fig. 1). The correlation of both FF and FI volume on IVUS VH and QCT was good (r = 0.714, p < 0.001 and r = 0.695, p < 0.001 respectively) with corresponding bias and 95 % limits of agreement of 24 mm³ (?42; 90) and 7.7 mm³ (?54; 70). Furthermore, NC and DC were well-correlated in both modalities (r = 0.523, p < 0.001) and (r = 0.736, p < 0.001). Automatic, quantitative CTA tissue characterization is feasible using a dedicated software tool.

Validation of a new quantitative coronary angiography analysis system used to evaluate densitometric lumen remodelling

Arterial lumen volume, determined by sequential coronary angiography, could have advantages over more commonly used variables (such as percent stenosis or minimal lumen diameter) as a primary endpoint in clinical trials evaluating post-angioplasty restenosis or atherosclerotic plaque progression. We validated a quantitative coronary angiography analysis (QCA) system aimed at measuring lumen volume from coronary angiography films by a densitometric method. Using images of polyacrylate models filled with different concentrations of contrast medium, accuracy (mean of the differences between known and measured values of a measurement) and precision (standard deviation of the difference) were lower than or equal to 0.09 and 0.21 mm, respectively, for diameters ranging from 1.5 to 16 mm. In terms of volume measurement, accuracy was 30.2 mm³ and precision 5.7 mm³ for a known volume of 620.2 mm³. To assess the short-term variations of lumen volume measurements under conditions resembling those encountered in clinical trials, a special image comparison program of the QCA system was used to measure the same coronary artery segment on two images taken 10 minutes apart in 21 patients. The mean difference between the two measurements was 1.7 ± 12.4 mm³, with a coefficient of variation of 15%. An error of ± 2 frames in the selection of images to be analyzed had little influence on the results. We conclude that the QCA system provides easy-to-achieve standardization of the image acquisition process and sufficient reproducibility for repeated measurement of volume of a coronary artery segment, which can serve as the primary endpoint in clinical trials evaluating atherosclerotic plaque progression or restenosis after angioplasty.     

Long-term follow-up of renal arteries after radio-frequency catheter-based denervation using optical coherence tomography and angiography

Optical coherence tomography (OCT) imaging at the time of renal denervation (RDN) showed that procedure might cause spasm, intimal injury or thrombus formation. In the present study, we assessed the healing of renal arteries after RDN using OCT and renal angiography in long-term follow-up. OCT and renal angiography were performed in 12 patients (22 arteries) 18.41 ± 5.83 months after RNS. There were no adverse events or complications during the long-term follow-up. In ten patients (83 %), significant reductions of blood pressure was achieved without a change of the antihypertensive medications. We demonstrated the presence of 26 areas of focal intimal thickening identified by OCT in 10 (83 %) patients and in 14 (63 %) arteries. The mean area of focal intimal thickening was 0.054 ± 0.033 mm². No vessel dissection, thrombus, intimal tear or acute vasospasm were observed during the OCT analysis. Also, the quantitative angiography analysis revealed a significant reduction of the minimal and proximal lumen diameters at follow-up as compared to measurements obtained before RDN. Renal arteries have a favorable “long-term” vessel healing response after RDN. Focal intimal thickening and a modest reduction of the minimal lumen diameter may be observed after RF denervation. Further studies are needed to determine whether intravascular imaging may be helpful in evaluating the vessel healing of RF RDN.     

Quantitative multi-modality imaging analysis of a fully bioresorbable stent: a head-to-head comparison between QCA,IVUS and OCT

The bioresorbable vascular stent (BVS) is totally translucent and radiolucent, leading to challenges when using conventional invasive imaging modalities. Agreement between quantitative coronary angiography (QCA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) in the BVS is unknown. Forty five patients enrolled in the ABSORB cohort B1 study underwent coronary angiography, IVUS and OCT immediately post BVS implantation, and at 6 months. OCT estimated stent length accurately compared to nominal length (95% CI of the difference: −0.19; 0.37 and −0.15; 0.47 mm² for baseline and 6 months, respectively), whereas QCA incurred consistent underestimation of the same magnitude at both time points (Pearson correlation = 0.806). IVUS yielded low accuracy (95% CI of the difference: 0.77; 3.74 and −1.15; 3.27 mm² for baseline and 6 months, respectively), with several outliers and random variability test–retest. Minimal lumen area (MLA) decreased substantially between baseline and 6 months on QCA and OCT and only minimally on IVUS (95% CI: 0.11; 0.42). Agreement between the different imaging modalities is poor: worst agreement Videodensitometry-IVUS post-implantation (ICCa 0.289); best agreement IVUS-OCT at baseline (ICCa 0.767). All pairs deviated significantly from linearity (P < 0.01). Passing-Bablok non-parametric orthogonal regression showed constant and proportional bias between IVUS and OCT. OCT is the most accurate technique for measuring stent length, whilst QCA incurs systematic underestimation (foreshortening) and solid state IVUS incurs random error. Volumetric calculations using solid state IVUS are therefore not reliable. There is poor agreement for MLA estimation between all the imaging modalities studied, including IVUS-OCT, hence their values are not interchangeable.     

The impact of Fourier-Domain optical coherence tomography catheter induced motion artefacts on quantitative measurements of a PLLA-based bioresorbable scaffold

Intracoronary Fourier-Domain optical coherence tomography (FD-OCT) enables imaging of the coronary artery within 2–4 seconds, a so far unparalleled speed. Despite such fast data acquisition, cardiac and respiratory motion can cause artefacts due to longitudinal displacement of the catheter within the artery. We studied the influence of longitudinal FD-OCT catheter displacement on serial global lumen and scaffold area measurements in coronary arteries of swine that received PLLA-based bioresorbable scaffolds. In 10 swine, 20 scaffolds (18 × 3.0 mm) were randomly implanted in two epicardial coronary arteries. Serial FD-OCT imaging was performed immediately after implantation (T1) and at 3 (T2) and 6 months (T3) follow-up. Two methods for the selection of OCT cross-sections were compared. Method A did not take into account longitudinal displacement of the FD-OCT catheter. Method B accounted for longitudinal displacement of the FD-OCT catheter. Fifty-one OCT pullbacks of 17 scaffolds were serially analyzed. The measured scaffold length differed between time points, up to one fourth of the total scaffold length, indicating the presence of longitudinal catheter displacement. Between method A and B, low error was demonstrated for mean area measurements. Correlations between measurements were high: R² ranged from 0.91 to 0.99 for all mean area measurements at all time points. Considerable longitudinal displacement of the FD-OCT catheter was observed, diminishing the number of truly anatomically matching cross-sections in serial investigations. Global OCT dimensions such as mean lumen and scaffold area were not significantly affected by this displacement. Accurate co-registration of cross-sections, however, is mandatory when specific regions, e.g. jailed side branch ostia, are analyzed.     

Standardized evaluation framework for evaluating coronary artery stenosis detection,stenosis quantification and lumen segmentation algorithms in computed tomography angiography

Though conventional coronary angiography (CCA) has been the standard of reference for diagnosing coronary artery disease in the past decades, computed tomography angiography (CTA) has rapidly emerged, and is nowadays widely used in clinical practice. Here, we introduce a standardized evaluation framework to reliably evaluate and compare the performance of the algorithms devised to detect and quantify the coronary artery stenoses, and to segment the coronary artery lumen in CTA data. The objective of this evaluation framework is to demonstrate the feasibility of dedicated algorithms to: (1) (semi-)automatically detect and quantify stenosis on CTA, in comparison with quantitative coronary angiography (QCA) and CTA consensus reading, and (2) (semi-)automatically segment the coronary lumen on CTA, in comparison with expert’s manual annotation. A database consisting of 48 multicenter multivendor cardiac CTA datasets with corresponding reference standards are described and made available. The algorithms from 11 research groups were quantitatively evaluated and compared. The results show that (1) some of the current stenosis detection/quantification algorithms may be used for triage or as a second-reader in clinical practice, and that (2) automatic lumen segmentation is possible with a precision similar to that obtained by experts. The framework is open for new submissions through the website, at http://coronary.bigr.nl/stenoses/.     

Angiographically uncertain left main coronary artery narrowings: correlation with multidetector computed tomography and intravascular ultrasound

Background Angiographic assessment of left main coronary artery (LMCA) stenosis is often difficult and unreliable. To date, intravascular ultrasound (IVUS) is used to determine the significance of lesions in patients with LMCA stenosis of uncertain significance. We aimed to prospectively show the ability of multidetector computed tomography (MDCT) to assess LMCA luminal and plaque dimensions, and to characterize atherosclerotic plaque, as compared to IVUS and quantitative coronary angiography (QCA), in patients with angiographically uncertain LMCA stenosis. Methods Twenty patients, with angiographically uncertain LMCA stenosis, underwent coronary evaluation with IVUS, QCA and 16-slice MDCT. Minimal lumen diameter (MLD), minimal lumen area (MLA), lumen area stenosis (LAS) and plaque burden (PB) were assessed. Results The MLD (median [interquartile range]) was 3.2 mm (2.5–3.7) by IVUS, 2.8 mm (2.3–3.3) by QCA (r = 0.52, P < 0.05), and 2.8 mm (2.5–3.8) by MDCT (r = 0.77, P < 0.01). MDCT estimated MLA as 10.7 mm² (7.1–12.6) Vs. 9.9 mm² (6.5–13.5) by IVUS (r = 0.93, P < 0.01). Very high correlations were observed between MDCT and IVUS in assessing LAS (mean ± SD) (25.8 ± 19.1% and 29.0 ± 24.9% respectively, r = 0.83, P < 0.01), and PB (49.2 ± 15.8% and 49.2 ± 19.7% respectively, r = 0.94, P < 0.01). MDCT assigned plaque as being non-calcified with a sensitivity of 100%, while calcified plaques with a sensitivity of 75%. Conclusion A high degree of correlation was found between MDCT and IVUS regarding the assessment of minimal lumen diameter and area, lumen area stenosis and plaque burden as well as plaque characterization in patients with angiographically borderline LMCA stenosis. Therefore, in patients selected for non-invasive coronary tree evaluation, MDCT may provide a valuable tool for the assessment, decision-making and follow-up of patients with uncertain LMCA disease.     

Stent implant follow-up in intravascular optical coherence tomography images

The objectives of this article are (i) to utilize computer methods in detection of stent struts imaged in vivo by optical coherence tomography (OCT) during percutaneous coronary interventions (PCI); (ii) to provide measurements for the assessment and monitoring of in-stent restenosis by OCT post PCI. Thirty-nine OCT cross-sections from seven pullbacks from seven patients presenting varying degrees of neointimal hyperplasia (NIH) are selected, and stent struts are detected. Stent and lumen boundaries are reconstructed and one experienced observer analyzed the strut detection, the lumen and stent area measurements, as well as the NIH thickness in comparison to manual tracing using the reviewing software provided by the OCT manufacturer (LightLab Imaging, MA, USA). Very good agreements were found between the computer methods and the expert evaluations for lumen cross-section area (mean difference = 0.11 ± 0.70 mm²; r ² = 0.98, P < 0.0001) and the stent cross-section area (mean difference = 0.10 ± 1.28 mm²; r ² = 0.85, P value <  0.0001). The average number of detected struts was 10.4 ± 2.9 per cross-section when the expert identified 10.5 ± 2.8 (r ² = 0.78, P value < 0.0001). For the given patient dataset: lumen cross-sectional area was on the average (6.05 ± 1.87 mm²), stent cross-sectional area was (6.26 ± 1.63 mm²), maximum angle between struts was on the average (85.96 ± 54.23°), maximum, average, and minimum distance between the stent and the lumen were (0.18 ± 0.13 mm), (0.08 ± 0.06 mm), and (0.01 ± 0.02 mm), respectively, and stent eccentricity was (0.80 ± 0.08). Low variability between the expert and automatic method was observed in the computations of the most important parameters assessing the degree of neointimal tissue growth in stents imaged by OCT pullbacks. After further extensive validation, the presented methods might offer a robust automated tool that will improve the evaluation and follow-up monitoring of in-stent restenosis in patients.     

Serial changes of minimal stent malapposition not detected by intravascular ultrasound: follow-up optical coherence tomography study

Morphologic changes of small-sized post-stent malapposition have not been sufficiently evaluated. We investigated serial changes of minimal post-stent malapposition with a follow-up optical coherence tomography (OCT) study. Post-stent OCT and intravascular ultrasound (IVUS) and follow-up OCT were performed in 26 patients with minimal post-stent malapposition. Serial changes of number and percent of malapposition struts, and mean extra-stent malapposition area were measured in OCT analysis. Zotarolimus-eluting stent (ZES), sirolimus-eluting stent (SES), and paclitaxel-eluting stent (PES) were deployed in 17, 7 and 2 patients, respectively. Mean durations of the follow-up OCT study were 5.7 ± 3.0 months. The minimal post-stent malapposition cannot be detected by the IVUS, but be visualized with an OCT examination. According to different drug-eluting stents, malapposed stent struts were defined as the struts with detachment from the vessel wall ≥160 μm for SES, ≥130 μm for PES, and ≥110 μm for ZES. The percent of malapposition struts significantly decreased from 12.2 ± 11.0% post-stent to 1.0 ± 2.2% follow-up (P < 0.001). There was a significant decrease in the mean extra-stent malapposition area from 0.35 ± 0.16 mm² post-stent to 0.04 ± 0.11 mm² follow-up (P < 0.001). Complete disappearance of stent malapposition was also observed in 22 (85%) patients. In conclusion, minimal stent malapposition which is not detectable by IVUS may disappear or decrease in follow-up OCT evaluation.     

Long-term internal thoracic artery bypass graft patency and geometry assessed by multidetector computed tomography

The left internal thoracic artery (LITA) undergoes vascular remodelling when used for coronary artery bypass grafting. In this study we tested the hypothesis that the extent of the LITA remodelling late after coronary artery bypass grafting assessed by multidetector computed tomography is related to the severity of stenosis in the native coronary vessel. One hundred and forty-two patients who had undergone coronary artery bypass grafting including implantation of LITA as conduit to the left anterior descending artery were studied 5 years after surgery. Arterial graft patency and geometry was assessed with 64-slice multidetector computed tomography. Quantitative volumetric assessment of the LITA was performed to measure the average vessel lumen area (mm²/m²). The native coronary vessel subtended by the LITA was evaluated by multidetector computed tomography and defined as a high-grade stenosis patient group, when the diameter stenosis was >70% and an intermediate grade stenosis patient group when <70%. Among patients with intermediate-grade stenosis of the native vessel 11 out of 65 patients (17%) had a totally occluded LITA, as opposed to none among the 77 patients with a high-grade stenosis. In patients with intermediate-grade stenosis of the proximal native vessel, the LITA lumen area was 4.9 compared to 5.3 mm²/m² in patients with a high-grade stenosis of the proximal native vessel (P = 0.0043). Lumen area of the LITA when used as a conduit in patients with coronary artery disease seems to be inversely correlated with the severity of disease in the native coronary vessel proximal to the anastomosis. Volumetric vessel multidetector computed tomography appears to be useful for evaluation of coronary bypass remodelling.     

Demonstration of the Glagov phenomenon in vivo by CT coronary angiography in subjects with elevated Framingham risk

Computed tomography coronary angiography (CTA) is a novel, non-invasive method for coronary plaque detection and quantification. We hypothesized that CTA can detect early vessel wall thickening with preserved luminal size in patients without known coronary artery disease and intermediate/high Framingham Risk Score (FRS) compared to those with low FRS. Vessel-wall and plaque geometrical and compositional parameters were measured on CTA in 375 coronary segments with a highly standardized method. These parameters were then compared in patients with low versus intermediate/high FRS. The relationship between coronary artery calcium by non-contrast CT scanning (Agatston score) and percent atheroma volume (PAV) was determined by linear regression. P value <0.05 was considered significant. PAV and remodeling index were significantly higher in patients with intermediate/high FRS compared to those with low FRS (45.9 ± 6.8 vs. 42.3 ± 6.7; P = 0.004) and (0.97 ± 0.15 vs. 0.92 ± 0.13; P = 0.04), while minimal luminal diameter and minimal luminal area were similar. There was significant correlation between Agatston score and PAV (r ² = 0.42, P = 0.0036). However, Agatston score and plaque compositional parameters were similar between the groups. In conclusion, we demonstrated that CTA can detect early vessel-wall thickening with preserved luminal size in patients with intermediate/high versus low FRS.     

Quantitative coronary plaque analysis predicts high-risk plaque morphology on coronary computed tomography angiography: results from the ROMICAT II trial

Semi-automated software can provide quantitative assessment of atherosclerotic plaques on coronary CT angiography (CTA). The relationship between established qualitative high-risk plaque features and quantitative plaque measurements has not been studied. We analyzed the association between quantitative plaque measurements and qualitative high-risk plaque features on coronary CTA. We included 260 patients with plaque who underwent coronary CTA in the Rule Out Myocardial Infarction/Ischemia Using Computer Assisted Tomography (ROMICAT) II trial. Quantitative plaque assessment and qualitative plaque characterization were performed on a per coronary segment basis. Quantitative coronary plaque measurements included plaque volume, plaque burden, remodeling index, and diameter stenosis. In qualitative analysis, high-risk plaque was present if positive remodeling, low CT attenuation plaque, napkin-ring sign or spotty calcium were detected. Univariable and multivariable logistic regression analyses were performed to assess the association between quantitative and qualitative high-risk plaque assessment. Among 888 segments with coronary plaque, high-risk plaque was present in 391 (44.0%) segments by qualitative analysis. In quantitative analysis, segments with high-risk plaque had higher total plaque volume, low CT attenuation plaque volume, plaque burden and remodeling index. Quantitatively assessed low CT attenuation plaque volume (odds ratio 1.12 per 1 mm³, 95% CI 1.04–1.21), positive remodeling (odds ratio 1.25 per 0.1, 95% CI 1.10–1.41) and plaque burden (odds ratio 1.53 per 0.1, 95% CI 1.08–2.16) were associated with high-risk plaque. Quantitative coronary plaque characteristics (low CT attenuation plaque volume, positive remodeling and plaque burden) measured by semi-automated software correlated with qualitative assessment of high-risk plaque features.     

Evaluation with in vivo optical coherence tomography and histology of the vascular effects of the everolimus-eluting bioresorbable vascular scaffold at two years following implantation in a healthy porcine coronary artery model: implications of pilot results for future pre-clinical studies

To quantify with in vivo OCT and histology, the device/vessel interaction after implantation of the bioresorbable vascular scaffold (BVS). We evaluated the area and thickness of the strut voids previously occupied by the polymeric struts, and the neointimal hyperplasia (NIH) area covering the endoluminal surface of the strut voids (NIH_EV), as well as the NIH area occupying the space between the strut voids (NIH_BV), in healthy porcine coronary arteries at 2, 3 and 4?years after implantation of the device. Twenty-two polymeric BVS were implanted in the coronary arteries of 11 healthy Yucatan minipigs that underwent OCT at 2, 3 and 4?years after implantation, immediately followed by euthanasia. The areas and thicknesses of 60 corresponding strut voids previously occupied by the polymeric struts and the size of 60 corresponding NIH_EV and 49 NIH_BV were evaluated with both OCT and histology by 2 independent observers, using a single quantitative analysis software for both techniques. At 3 and 4?years after implantation, the strut voids were no longer detectable by OCT or histology due to complete polymer resorption. However, analysis performed at 2?years still provided clear delineation of these structures, by both techniques. The median [ranges] areas of these strut voids were 0.04 [0.03?C0.16] and 0.02 [0.01?C0.07] mm² by histology and OCT, respectively. The mean (±SD) thickness by histology and OCT was 220?±?40?and 120?±?20???m, respectively. The median [ranges] NIH_EV by histology and OCT was 0.07 [0.04?C0.20] and 0.03 [0.01?C0.08] mm², while the mean (±SD) NIH_BV by histology and OCT was 0.13?±?0.07?and 0.10?±?0.06?mm². Our study indicates that in vivo OCT of the BVS provides correlated measurements of the same order of magnitude as histomorphometry, and is reproducible for the evaluation of certain vascular and device-related characteristics. However, histology systematically gives larger values for all the measured structures compared to OCT, at 2?years post implantation.     

Optical coherence tomography guided in-stent thrombus removal in patients with acute coronary syndromes

The persistence of thrombus inside stent struts is a frequent event in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI), and this phenomenon might be associated with an increased risk of stent thrombosis. We sought to quantify by means of optical coherence tomography (OCT) the presence of in-stent thrombus after achievement of an optimal angiographic result in patients with ACS undergoing PCI. In addition, we evaluated the feasibility and safety of an OCT-guided strategy of in-stent thrombus removal. Eighty consecutive patients with ACS undergoing PCI were treated with two different strategies equally divided into two groups: angio-guided PCI, and OCT-guided PCI, in which additional OCT-driven in-stent balloon dilatation was adopted to reduce thrombus encroachment of the lumen. Overall in-stent thrombus area was 4.3 % with a maximal thrombus encroachment of 16.7 %. In the OCT-guided group, use of high pressure intra-stent dilatation led to a significant increase in stented area (9.6 ± 2.4 vs. 9.1 ± 2.49 mm², p = 0.002) and lumen area (9.2 ± 2.4 vs. 8.7 ± 2.3 mm², p < 0.001) and also significantly decreased in-stent thrombus area in absolute (0.35 ± 0.29 vs. 0.42 ± 0.30 mm², p = 0.001) and relative terms (3.58 ± 3.25 vs. 4.53 ± 3.01 %, p = 0.001). Values of TIMI flow, frame count and blush grade, as well as clinical outcomes were not detrimentally affected by such additional dilatations. The use of additional OCT-driven in-stent balloon dilatations is feasible, safe and might be effective in the treatment of in-stent thrombus for patients with ACS.     

Comparative assessment of three drug eluting stents with different platforms but with the same biodegradable polymer and the drug based on quantitative coronary angiography and optical coherence tomography at 12-month follow-up

The aim of this study was to compare neointima proliferation in three drug-eluting stents (DES) produced by the same company (Balton, Poland) which are covered with a biodegradable polymer and elute sirolimus (concentration: 1.0 and 1.2 µg/mm²), but have different stent platforms and strut thickness: stainless steel Prolim^® (115 µm) and BiOSS LIM^® (120 µm) and cobalt-chromium Alex^® (70 µm). We analyzed data of patients with quantitative coronary angiography (QCA) and optical coherence tomography (OCT) at 12 months from BiOSS LIM Registry, Prolim Registry and Alex OCT clinical trial. There were 56 patients enrolled, in whom 29 Prolim^® stents were deployed, in 11—BiOSS LIM^® and in 16—Alex stents. The late lumen loss was the smallest in Prolim^® subgroup (0.26?±?0.17 mm) and did not differ from Alex^® subgroup (0.28?±?0.47 mm). This parameter was significantly bigger in BiOSS^® subgroup (0.38?±?0.19 mm; p?<?0.05). In OCT analysis there was no statistically significant difference between Prolim^® and Alex^® subgroups in terms of mean neointima burden (24.6?±?8.6 vs. 19.27?±?8.11%) and neointima volume (28.16?±?15.10 vs. 24.51?±?17.64 mm³). In BiOSS^® group mean neointima burden (30.9?±?6.2%) and mean neointima volume (44.9?±?4.9 mm³) were significantly larger. The morphological analysis revealed that in most cases in all groups the neointima was homogenous with plaque presence only around stent struts. In the QCA and OCT analysis regular DES (Prolim^® and Alex^®) obtained similar results, whereas more pronounced response from the vessel wall was found in the BiOSS^® subgroup.     

In vivo comparison of lumen dimensions measured by time domain-, and frequency domain-optical coherence tomography, and intravascular ultrasound

Lumen dimensions measured by time-domain optical coherence tomography (TD-OCT) may be influenced by the hemodynamic effect of proximal balloon occlusion. Frequency-domain OCT (FD-OCT) does not require the interruption of blood flow. Therefore, we compared the coronary lumen dimensions measured by TD-OCT, FD-OCT, and intravascular ultrasound (IVUS) in both stented and non-stented segments. Twenty patients who underwent both IVUS and OCT imaging (10 for TD- and 10 for FD-OCT) after stent implantation were included. The maximum, minimum, and mean diameters and areas were measured at the proximal and distal stent edges, as well as 3 mm inside and 5 mm outside of both edges. The measurements inside stent showed no significant differences between IVUS and TD- or FD-OCT. The lumen mean diameters and areas measured by IVUS at 5 mm outside stent were similar to those measured by FD-OCT (Distal; 3.07 ± 0.7 vs 3.03 ± 0.7 mm, p = 0.08 and 7.80 ± 4.0 vs 7.72 ± 4.1 mm², p = 0.07, respectively. Proximal; 3.25 ± 0.7 vs 3.23 ± 0.7 mm, p = 0.09 and 8.78 ± 3.8 vs 8.65 ± 3.7 mm², p = 0.08, respectively), but were greater than those measured by TD-OCT (Distal; 2.75 ± 0.5 vs 2.29 ± 0.5 mm, p = 0.0001 and 6.15 ± 2.6 vs 4.38 ± 1.9 mm², p = 0.0002, respectively. Proximal; 3.27 ± 0.6 vs 2.69 ± 0.6 mm, p = 0.0001 and 8.64 ± 3.4 vs 6.12 ± 2.7 mm², p = 0.0001 respectively). The interaction between TD- and FD-OCT for lumen dimension measurements at 5 mm outside stent was statistically significant. Vessel dimension measurements were similar between IVUS and FD-OCT in native vessel unlike with TD-OCT. Therefore, we might adapt the IVUS criteria of lesion severity for percutaneous coronary intervention to FD-OCT.     

Predictors of acute scaffold recoil after implantation of the everolimus-eluting bioresorbable scaffold: an optical coherence tomography assessment in native coronary arteries

This study investigated the predictors of acute recoil after implantation of everolimus-eluting BRS based on optical coherence tomography (OCT). Thirty-nine patients (56 scaffolds) were enrolled. Acute absolute recoil by quantitative coronary angiography was defined as the difference between the mean diameter of the last inflated balloon (X) and the mean lumen diameter of BRS immediately after balloon deflation (Y). Acute percent recoil was defined as (X???Y)?×?100/X. Plaque eccentricity (PE) and plaque composition (PC) were assessed by OCT. PC was classified into two different types: calcific (score?=?1), fibrous and lipid (score?=?0). Based on the mean acute scaffold recoil value of the present study, scaffolds were divided into two groups: the low acute recoil group (LAR, n?=?34) and the high acute recoil group (HAR, n?=?22). Acute percent and absolute recoil were 6.4?±?3.0?% and 0.19?±?0.11 mm. PE, PC score and scaffold/artery ratio were significantly higher in HAR than in LAR. In multivariate logistic regression analysis, PE?>?1.49, PC score (score 1) and scaffold/artery ratio >1.07 were significant positive predictors for the occurrence of acute scaffold recoil (OR 10.7, 95?% CI 2.2–51.4, p?<?0.01; OR 5.6, 95?% CI 1.9–22.0, p?=?0.04; OR 12.4, 95?% CI 2.6–65.4, p?<?0.01, respectively). Acute recoil of BRS is influenced by BRS sizing as well as OCT-derived plaque characteristics.