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Objective: This study evaluated whether intravascular ultrasound (IVUS) images before rotational atherectomy (RA) can predict medial injury caused by RA burr passage in advance., Methods: Thirty-three patients with de-novo lesions located in the left anterior descending coronary artery (LAD) who underwent IVUS before and immediately after RA were enrolled. The spatial axes of the two matched pre- and post-RA IVUS cross-sectional images were merged. The segment was considered to have medial damage when the continuity of the intimal layer was disrupted and the medial layer was in direct contact with the lumen on post-RA IVUS., Results: Medial injuries on post-RA IVUS were identified in seven segments of five patients. All segments with medial injury were located near the bifurcation of the LAD and the diagonal branch, and the spatial orientations of the medial injury region were mostly distributed in the lateral side with a diagonal branch take-off. The lumen area was significantly smaller in segments with medial injury than in those without medial injury (P < 0.01). The IVUS catheter was in contact with the healthy side of the arterial wall on pre-RA IVUS images for more than 1 mm in length in all segments with medial injury., Conclusion: When the guidewire and IVUS catheter are close to the healthy side of the arterial wall on pre-RA IVUS images, there is a higher risk of medial injury due to the RA procedure, especially near the bifurcation of the LAD and diagonal branch., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Tangential signal dropout (TSD), which occurs when the optical frequency domain imaging (OFDI) beam strikes the vessel wall under a glancing angle and travels almost parallel to the vessel wall, is the most important imaging artefact leading to the erroneous diagnosis of lipid-rich plaques., Aims: This study aimed to evaluate the OFDI artefact of TSD, which mimics the appearance of lipid-rich plaque and macrophage (Mø) infiltration., Methods: A total of 1,019 histological cross-sections from 23 autopsy hearts were matched with the corresponding OFDI images. Of these, 232 OFDI cross-sections that contained signal-poor regions with diffuse borders were classified as lipid-rich plaques. The angle θ was calculated between the OFDI beam that strikes the edge of the luminal surface of the low-intensity region and that which strikes the surface line of the low-intensity region., Results: On histological evaluation, 182 (78%) cross-sections were classified as histologically lipidic/Mø infiltration, while the remaining 50 (22%) cross-sections were classified as histologically non-lipidic/Mø infiltration. The angle θ was significantly smaller in the non-lipidic/Mø infiltration group than in the lipidic/Mø infiltration group (12±6° versus 37±14°, p<0.001). Receiver operating curve analysis revealed that the optimal cut-off value of the incident angle for predicting TSD was 23° with an area under the curve of 0.98., Conclusions: When the OFDI imaging beam strikes the tissue at an angle θ<23°, TSD artefact could occur. To eliminate image misinterpretation, our findings suggest that the OFDI catheter geometry should be considered for the accurate diagnosis of lipid-rich plaques and Mø infiltration.

Background and Aims: We developed a deep learning (DL) model for automated atherosclerotic plaque categorization using optical frequency domain imaging (OFDI) and performed quantitative and visual evaluations., Methods: A total of 1103 histological cross-sections from 45 autopsy hearts were examined to compare the ex vivo OFDI scans. The images were segmented and annotated considering four histological categories: pathological intimal thickening (PIT), fibrous cap atheroma (FA), fibrocalcific plaque (FC), and healed erosion/rupture (HER). The DL model was developed based on pyramid scene parsing network (PSPNet). Given an input image, a convolutional neural network (ResNet50) was used as an encoder to generate feature maps of the last convolutional layer., Results: For the quantitative evaluation, the mean F-score and IoU values, which are used to evaluate how close the predicted results are to the ground truth, were used. The validation and test dataset had F-score and IoU values of 0.63, 0.49, and 0.66, 0.52, respectively. For the section-level diagnostic accuracy, the areas under the receiver-operating characteristic curve produced by the DL model for FC, PIT, FA, and HER were 0.91, 0.85, 0.86, and 0.86, respectively, and were comparable to those of an expert observer., Conclusions: DL semantic segmentation of coronary plaques in OFDI images was used as a tool to automatically categorize atherosclerotic plaques using histological findings as the gold standard. The proposed method can support interventional cardiologists in understanding histological properties of plaques., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: To date, there have been no data available regarding the diagnostic performance of optical frequency domain imaging (OFDI) for in vivo histological classification of atherosclerotic lesions. This study investigated whether OFDI can be used to diagnose and classify histological atherosclerotic lesions in the coronary artery by ex vivo histological examinations., Methods: Three-hundred-fifteen histological cross-sections from 21 autopsy hearts were matched with the OFDI images. Histological cross-sections were classified into six categories: adaptive intimal thickening (AIT), pathological intimal thickening (PIT), fibrous cap atheroma (FA), fibrocalcific plaque (FC), calcified nodule, and healed erosion/rupture. The five observers with different years of experience in the interpretation of OFDI provided a single diagnosis for the OFDI scans of each cross-section according to the aforementioned six histological categories. The diagnostic accuracy and interobserver variability of lesion types for each OFDI observer were determined using histology as the gold standard., Results: The overall agreement rates between OFDI and histopathologic diagnosis for OFDI observers 1-5 were 81%, 70%, 68%, 61%, and 50% (κ values of 0.75, 0.61, 0.58, 0.49, and 0.36), respectively. Although the diagnostic accuracy of OFDI for detecting AIT and FC was excellent for all five observers, the sensitivity, and positive predictive values of OFDI for detecting PIT and FA were low in proportion to years of experience., Conclusion: The diagnostic accuracy of atherosclerotic tissue properties from OFDI scans correlated with the observers' years of experience, especially when lesions contained lipid components., Competing Interests: Declaration of Competing Interest The authors declare that there is no conflict of interest., (Copyright © 2020. Published by Elsevier Ltd.)

The accurate identification of in-stent fibroatheroma by in vivo imaging is clinically important to preventing the late catch-up phenomenon after stent deployment. This study investigated the diagnostic accuracy of optical coherence tomography (OCT) for the detection of "in-stent fibroatheroma" following stent implantation. Fifty stented coronary arteries from the 31 autopsy hearts were examined to compare OCT and histological image findings. A histological in-stent fibroatheroma was defined as a neointima containing an acellular necrotic core generated by macrophage infiltration. OCT-derived in-stent fibroatheroma comprised a heterogeneous pattern with an invisible stent strut behind the low-signal-intensity region. A total of 122 matched OCT and histology cross-sections were evaluated. Using histological findings as the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value for OCT-derived in-stent fibroatheroma were 100%, 99%, 80%, and 100%, respectively. The only histological finding underlying the false-positive diagnosis of OCT-derived in-stent fibroatheroma was foam cell accumulation without a necrotic core on the neointimal surface. No false-negative diagnosis of OCT for in-stent fibroatheroma was apparent in this analysis. This study demonstrated the potential capability of OCT based on stent strut visualization behind low-signal-intensity regions to discriminate in-stent fibroatheroma from other neointimal tissues.

This study evaluated whether intravascular ultrasound (IVUS) examination before rotational atherectomy (RA) can predict the optimal route of passage of the RA burr along the vessel. 30 patients with calcified lesions who underwent IVUS before and immediately after RA were enrolled. IVUS analyses were performed at the minimum lumen area (MLA) site and at 0.5 mm intervals. Each IVUS cross-section was divided into 4 quadrants around the center of the lumen, and pre- and post-RA IVUS cross-section images were merged. Of 1140 cross-sections, 498 (44%) contained debulked regions. When the guidewire and IVUS were located within the same quadrant, the debulked region were distributed within the same quadrant in 96% of cross-sections. The debulked region and the guidewire were distributed within the same quadrant in 81% and the debulked region and the IVUS in 72% of cross-sections, in case the guidewire and IVUS were located in different quadrants. When the guidewire and the IVUS was apart > 1.0 mm, the debulked regions were distributed within the same quadrant as the guidewire in 100% and the IVUS in 0% of cross-sections. The position of the guidewire rather than that of the IVUS catheter on pre-RA IVUS images could predict the course of the RA burr's passage, especially when the guidewire and IVUS catheter were located apart from each other.

Objectives: This study evaluated whether the influence of lesion length on functional significance is similar between each target artery., Background: In the presence of a similar moderate degree of stenosis, the fractional flow reserve (FFR) in the left anterior descending coronary artery (LAD) is more often <0.80 than in the other arteries., Methods: A total of 221 lesions with intermediate stenosis on coronary angiography that underwent FFR measurement for the evaluation of myocardial ischemia were enrolled. Quantitative coronary angiographic analysis including percent diameter stenosis and lesion length was performed. The area under the receiver operating characteristics (ROC) curve was estimated for the best cutoff value as a predictor of FFR value of ≤0.80 for each coronary artery., Results: Although lesion length was similar among the lesions with an FFR >0.80 at different locations, the mean lesion length was significantly longer for lesions in the right coronary artery (RCA) with an FFR ≤0.80 than for those in the LAD and left circumflex artery (13.4 ± 3.4 vs. 8.6 ± 3.1 vs. 12.0 ± 3.7 mm, p < .001). ROC analysis demonstrated that the optimal cutoff value of lesion length for predicting an FFR ≤0.80 was 10.0 mm in the LAD (0.56 area under the curve [AUC], 48% sensitivity, and 76% specificity), whereas 13.1 mm in the RCA (0.84 AUC, 67% sensitivity, and 93% specificity)., Conclusions: The impact of lesion length on myocardial ischemia is different for each coronary artery. A longer lesion length is required in the RCA than in the LAD to achieve an FFR ≤0.80., (© 2019 Wiley Periodicals, Inc.)

The purpose of this study was to evaluate the vessel healing status 3 months after stent implantation of bioresorbable-polymer drug-eluting stents (BP-DESs) in comparison with durable-polymer DESs (DP-DESs) by angioscopy. Study design was a single-center all-comer prospective cohort study: the RESTORE registry (UMIN000033009). All patients who received successful angioscopic examination at planned 3-month follow-up after the DES implantation in the native coronary artery were enrolled. We evaluated main, maximum, minimum strut coverage grades and coverage heterogeneity score defined as a difference between maximum and minimum coverage grades. All lesions were divided into three segments: proximal, mid, and distal segments. A total of 108 patients (66.6 ± 10 years) with 124 lesions were analyzed (BP-DES 57 patients 61 lesions 226 segments vs. DP-DES 57 patients 63 lesions 203 segments; six patients had both BP-DES and DP-DES). Patient and lesion demographics, procedural characteristics were well balanced. Main coverage grade (mean ± standard error; 1.08 ± 0.02 vs. 1.05 ± 0.03, p = 0.354) and minimum coverage grade (1.00 ± 0.00 vs. 1.00 ± 0.00, p > 0.999) were not significantly different between BP-DES and DP-DES groups. Maximum coverage grade was significantly higher in the BP-DES than in the DP-DES (1.45 ± 0.04 vs. 1.35 ± 0.04, p = 0.049). Coverage heterogeneity score did not differ between BP-DES and DP-DES groups (1.05 ± 0.07 vs. 0.90 ± 0.07, p = 0.162). At 3-month follow-up, the current BP-DES had higher maximum stent coverage than the contemporary DP-DES, while main and minimum coverage grades and heterogeneity of the neointimal coverage were comparable. Further prospective randomized trials should be conducted to evaluate the clinical significance of the present imaging results.