Development and Validation of Artificial Intelligence-Based Algorithms for Predicting the Segments Debulked by Rotational Atherectomy Using Intravascular Ultrasound Images.

We develop and evaluate an artificial intelligence (AI)-based algorithm that uses pre-rotation atherectomy (RA) intravascular ultrasound (IVUS) images to automatically predict regions debulked by RA. A total of 2106 IVUS cross-sections from 60 patients with de novo severely calcified coronary lesions who underwent IVUS-guided RA were consecutively collected. The 2 identical IVUS images of pre- and post-RA were merged, and the orientations of the debulked segments identified in the merged images were marked on the outer circle of each IVUS image. The AI model was developed based on ResNet (deep residual learning for image recognition). The architecture connected 36 fully connected layers, each corresponding to 1 of the 36 orientations segmented every 10°, to a single feature extractor. In each cross-sectional analysis, our AI model achieved an average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 81%, 72%, 46%, 90%, and 75%, respectively. In conclusion, the AI-based algorithm can use information from pre-RA IVUS images to accurately predict regions debulked by RA and will assist interventional cardiologists in determining the treatment strategies for severely calcified coronary lesions.

Tip Detection-Antegrade Dissection and Re-Entry With New Puncture Wire in CTO Intervention: Revolution Through 3D-Wiring.

Background: The authors devised the tip detection (TD) method and developed AnteOwl WR intravascular ultrasound to standardize intravascular ultrasound-based 3-dimensional wiring for intraplaque tracking in chronic total occlusion (CTO)-percutaneous coronary intervention (PCI). The TD method also allowed antegrade dissection and re-entry (ADR). Combining TD-ADR with Conquest Pro 12 Sharpened Tip (CP12ST) wire, a new ADR wire with the strongest penetration force developed to date, enabled re-entry anywhere except calcification sites. Objectives: This study investigated the efficacy and feasibility of TD-ADR by comparison of procedural outcomes with Stingray-ADR in CTO-PCI. Methods: Twenty-seven consecutive CTO cases treated by TD-ADR with CP12ST wire between August 2021 and April 2023 and 27 consecutive CTO cases treated by Stingray-ADR with Conquest 8-20 (CP20) wire between March 2018 and July 2021 were retrospectively enrolled as the TD-ADR by CP12ST wire group and Stingray-ADR by CP20 wire group, respectively, from 4 facilities that could share technical information on these procedures. Results: The success rate of the ADR procedure was significantly improved (27 of 27 cases [100%] vs 18 of 27 cases [67%], respectively; P = 0.002) and total procedural time was significantly reduced (median procedural time: 145.0 [Q1-Q3: 118.0-240.0] minutes vs 185.0 [Q1-Q3: 159.5-248.0] minutes, respectively; P = 0.028) in the TD-ADR by CP12ST wire group compared to the Stingray-ADR by CP20 wire group. There were few in-hospital major adverse cardiac and cerebrovascular events or no complications in either group. Conclusions: TD-ADR by CP12ST wire can standardize highly accurate ADR in CTO-PCI.

Influence of ultrasound transmit frequency on measurement of global longitudinal strain on 2D speckle tracking echocardiography.

The reproducibility of longitudinal strain measured by 2D speckle tracking echocardiography (2DSTE) may be affected by ultrasound settings. This study investigated the effect of transmit ultrasound frequency on global longitudinal strain (GLS) by 2DSTE. Apical, 2- and 4-chamber, and long-axis views were obtained in consecutive 162 patients using Philips ultrasound devices. Three different frequency presets were used sequentially: high resolution (HRES, 1.9 to 2.1 MHz), general (HGEN, 1.6 to 1.8 MHz), and penetration mode (HPEN, 1.3 to 1.6 MHz). GLS values were determined for each preset using the Philips Q-station software, resulting in GLS-HRES, GLS-HGEN, and GLS-HPEN. Among the 151 patients with successfully measured GLS, a significant difference in GLS was observed among the three presets (p < 0.0001). GLS-HRES (- 17.9 ± 4.4%) showed a slightly smaller magnitude compared to GLS-HGEN (- 18.8 ± 4.5%, p < 0.0001) and GLS-HPEN (- 18.8 ± 4.5%, p < 0.0001), with absolute differences of 1.1 ± 1.0% and 1.1 ± 1.2%, respectively. This variation in GLS with frequency was evident in patients with both optimal (n = 104) and suboptimal (n = 47) image quality and remained consistent regardless of ultrasound devices, ischemic etiology, or ejection fraction. In conclusion, ultrasound frequency had only a modest effect on GLS measurements. GLS may be reliably assessed in most cases regardless of the ultrasound frequency used.

Guide extension proximal locking method: standardization of maximum backup force in percutaneous coronary intervention.

We developed the smallest diameter guide-extension catheter (GUIDE PLUS® 5Fr) to enable a new technique, the guide-extension proximal locking method (GP-Lock), and assessed its efficacy in the present experimental and clinical study. Sufficient guide catheter backup is sometimes crucial for PCI. We developed the KIWAMI-Lock direct anchoring method to obtain the strongest backup force by locking a Kiwami® 4Fr child catheter (Terumo Corp. Tokyo, Japan) directly to the coronary artery by ballooning from outside the child catheter. However, this method is complicated due to the requirement for a child catheter. We compared the backup power of the GP-Lock method and other conventional methods in an experimental study and compared the procedural outcomes of 17 cases treated using the initial GP-Lock method with 17 cases using the recent KIWAMI-Lock method before GP-Lock. The GP-Lock method had the highest backup force among the methods examined (GP-Lock: 293.7 ± 10.2 g force (gf), KIWAMI-Lock: 270.4 ± 12.9 gf, side branch balloon anchoring technique: 182.7 ± 8.1 gf, respectively, P < 0.0001). The preparation time was significantly shorter for the GP-Lock group than the KIWAMI-Lock group (5.0 [4.0, 5.0] min vs. 11.0 [8.0, 13.0] min, respectively, P < 0.001). The GP-Lock method makes it possible to easily obtain the strongest backup force, which can overcome situations where devices cannot pass through, especially in complex PCI procedures.

A randomized controlled trial to evaluate the safety and efficacy of transluminal injection of foam sclerotherapy compared with ultrasound-guided foam sclerotherapy during endovenous catheter ablation in patients with varicose veins.

OBJECTIVE: We compared the safety, need for additional foam sclerotherapy, and 1-year venous clinical severity score (VCSS) improvement in the limbs of patients with chronic venous disease and great saphenous vein (GSV) reflux. These patients had undergone endovenous laser ablation (EVLA) using a 1470-nm diode laser and concurrent foam sclerotherapy (1% polidocanol) through the access sheath (transluminal injection of foam sclerotherapy [TLFS]) or EVLA and concurrent direct-puncture ultrasound-guided foam sclerotherapy (UGFS). METHODS: In the present study, we screened 467 patients (577 legs) with symptomatic primary GSV reflux for randomization to either TLFS with EVLA (n = 103 legs; TLFS group) or UGFS with EVLA (n = 94 legs; UGFS group). The exclusion criteria were (1) recurrent varicose veins after previous intervention; (2) hypersensitivity reaction to sclerotherapy; (3) acute deep vein thrombosis; (4) serious lower limb ischemic disease; (5) a coagulation disorder; and (6) simultaneous EVLA of both GSVs and small saphenous veins. The correlations of the VCSS changes with the clinical features, such as age, sex, CEAP (clinical, etiologic, anatomic, pathophysiologic) classification, total amount of sclerosant used at the original procedure, multiple punctures (more than two) for sclerotherapy at the original procedure, the use of TLFS, and linear endovenous energy density, were estimated using logistic regression. RESULTS: No significant differences in the distribution of the CEAP classification were observed between the two groups. After 12 months of follow-up, all truncal veins were occluded. The VCSS had significantly improved in the TLFS group compared with the UGFS group (UGFS, -7.4 ± 1.8; TLFS, -8.7 ± 1.5; P < .0001). Multivariate analysis revealed that TLFS was the only significant factor for an improved VCSS (hazard ratio, 0.63; 95% confidence interval, 0.32-0.96; P < .0001). The need for additional second-stage sclerotherapy was significantly avoided in the TLFS group (n = 10; 10%) compared with the UGFS group (n = 51; 54%; P < .0001). CONCLUSIONS: TLFS combined with EVLA is a safe and feasible procedure that improves the VCSS and reduces the need for additional second-stage interventions compared with UGFS combined with EVLA.

Wire Cutting Method Using Rotational Atherectomy for Stretched Spring Wire During Coronary Intervention.

During removal of an entrapped guidewire, the core wire can fracture, allowing stretching of the spring wire while the distal guidewire is still entrapped. We resolved this issue with rotational atherectomy, allowing cutting of the spring wire at the intended site, regardless of the proximal spring wire fracture. (Level of Difficulty: Advanced.).

Aspiration After Sealing the Entrance by Stenting Is a Promising Method to Treat Subintimal Hematoma.

Creation of a distal re-entry site is widely performed to treat subintimal hematoma. However, this method has a risk of further vessel damage. The present aspiration technique after sealing the entry site by stenting is more promising because the hematoma can be reduced without additional vessel damage. (Level of Difficulty: Advanced.).

Mechanisms of gradual pressure drop in angiographically normal left anterior descending and right coronary artery: Insights from wave intensity analysis.

BACKGROUND: This study evaluated the mechanism of decline in coronary pressure from the proximal to the distal part of the coronary arteries in the left anterior descending (LAD) versus the right coronary artery (RCA) from the insight of coronary hemodynamics using wave intensity analysis (WIA). METHODS: Twelve patients with angiographically normal LAD and RCA were prospectively enrolled. Distal coronary pressure, mean aortic pressure, and average peak velocity were measured at 4 different positions: 9, 6, 3, and 0 cm distal from each coronary ostium. RESULTS: The distal-to-proximal coronary pressure ratio during maximum hyperemia gradually decreased in proportion to the distance from the ostium (0.92±0.03 and 0.98±0.03 at 9 cm distal to the LAD and RCA ostium). WIA showed the dominant forward-traveling compression wave gradually decreased and the backward-traveling suction wave gradually decreased in proportion to the decrease in coronary pressure through the length of the non-diseased LAD but not the RCA. CONCLUSIONS: The pushing wave and suction wave intensities on WIA were diminished in proportion to the distance from the ostium of the LAD despite the wave intensity not changing across the length of the RCA, which may lead to gradual intracoronary pressure drop in the angiographically normal LAD.

Impact of IVUS-Derived Vessel Size on Midterm Outcomes After Stent Implantation in Femoropopliteal Lesions.

Purpose: To identify intravascular ultrasound (IVUS) findings that predict midterm stent patency in femoropopliteal (FP) lesions. Materials and Methods: A retrospective analysis was undertaken of 335 de novo FP lesions in 274 consecutive patients (mean age 72.4±8.2 years; 210 men) who had IVUS assessment before and after successful stent implantation. The mean lesion length was 13.2±9.8 cm. The primary outcome was primary patency at 24 months, defined as freedom from major adverse limb event (MALE) and in-stent restenosis (ISR). MALE was defined as major amputation or any target lesion revascularization (TLR). ISR was defined by a peak systolic velocity ratio >2.4 by duplex ultrasonography. Logistic regression analyses were performed to identify independent predictors of stent patency at 24 months; the results are presented as the odds ratio (OR) and 95% confidence interval (CI). Receiver operator characteristic (ROC) curve analysis was performed to determine the optimal threshold for prediction of stent patency at 24 months. Results: Over the 24-month follow-up, 18 (7%) patients died and 43 (15%) of 286 lesions were responsible for MALE (42 TLRs and 1 major amputation). Primary patency was estimated at 82.5% (95% CI 78.1% to 86.9%) at 12 months and 73.2% (95% CI 67.9% to 78.5%) at 24 months. Multivariable analysis revealed that longer lesion length (OR 0.89, 95% CI 0.82 to 0.97, p<0.01) was an independent predictor of declining patency, while cilostazol use (OR 3.45, 95% CI 1.10 to 10.78, p=0.03) and increasing distal reference external elastic membrane (EEM) area (OR 1.18, 95% CI 1.02 to 1.37, p=0.03) were associated with midterm stent patency. ROC curve analysis identified a distal reference EEM area of 29.0 mm2 as the optimal cut-point for prediction of 24-month stent patency (area under the ROC curve 0.764). Kaplan-Meier estimates of 24-month primary patency were 83.7% (95% CI 78.3% to 89.2%) in lesions with a distal EEM area >29.0 mm2 vs 53.1% (95% CI 42.9% to 63.3%) in those with a distal EEM area ≤29.0 mm2 (p<0.001). Conclusion: In FP lesions with a larger distal vessel area estimated with IVUS, stent implantation can be considered as a reasonable treatment option, with the likelihood of acceptable midterm results.

Calcified Nodules in the Superficial Femoral Artery Confirmed by Intravascular Ultrasound, Angioscopy, and Histology.

An 84-year-old man was admitted to the authors' hospital for the treatment of intermittent claudication. Angiography revealed an exophytic calcified nodules in the distal superficial femoral artery. Angioscopy also revealed abundant exophytic atherosclerotic calcification. Histology confirmed the diagnosis. (Level of Difficulty: Beginner.).

New CTO-Specific IVUS: AnteOwl Success in Previously Failed CTO Case Treated With Navifocus IVUS.

The newer chronic total occlusion-specific intravascular ultrasound AnteOwl WR-based 3-dimensional wiring technique using the tip detection method allowed us easily to succeed in treating chronic total occlusion lesions that were previously unsuccessfully treated using Navifocus WR intravascular ultrasound. (Level of Difficulty: Advanced.).

Tip Detection Method Using the New IVUS Facilitates the 3-Dimensional Wiring Technique for CTO Intervention.

OBJECTIVES: This study assessed the efficacy of the tip detection method during intravascular ultrasound (IVUS)-based 3-dimensional (3D) wiring with a new chronic total occlusion (CTO)-specific IVUS system (AnteOwl IVUS [AO-IVUS]) for CTO percutaneous coronary intervention (PCI). BACKGROUND: The study developed angiography-based 3D wiring for CTO-PCI. Previously, the authors produced a short-tip CTO-specific IVUS system (Navifocus WR IVUS [Navi-IVUS]), which has been upgraded into the AO-IVUS system by adding a pullback transducer system for IVUS-based 3D wiring. METHODS: A CTO lesion 20 mm in length composed of 2.5% agar was experimentally inserted into the coronary artery of a beating heart model. The target (a microcatheter with a 0.6-mm lumen) was placed in the distal part of the CTO lesion. IVUS-guided wiring was performed to insert the guidewire into the target using the Navi-IVUS and then using the AO-IVUS 8 times each. In wiring with AO-IVUS, the IVUS-based 3D wiring using the tip detection method was performed. The crossing time and the number of punctures to the target were calculated. RESULTS: The crossing time was significantly shortened and the number of punctures was significantly reduced in AO-IVUS-based wiring compared with Navi-IVUS-based wiring (median crossing time 80.5 s [interquartile range: 44.0 to 112.3 s] vs. 333.0 s [interquartile range: 88.8 to 790.0 s]; p = 0.036; median 1.0 puncture [interquartile range: 1.0 to 2.0 punctures] vs. 24.0 punctures [interquartile range: 5.8 to 52.5 punctures]; p = 0.001). CONCLUSIONS: The tip detection method enables the authors to easily perform the IVUS-based 3D wiring, and the new CTO IVUS system will facilitate this method in clinical practice.

Efficacy and Feasibility of the 3-Dimensional Wiring Technique for Chronic Total Occlusion Percutaneous Coronary Intervention: First Report of Outcomes of the 3-Dimensional Wiring Technique.

OBJECTIVES: This study sought to compare the procedural outcomes of percutaneous coronary intervention for chronic total occlusion between the periods before and after introduction of 3-dimensional (3D) wiring. BACKGROUND: Previously, we reported a 3D wiring method by which the operator can construct real-time mental 3D images from 2 perpendicular angles of X-ray system monitor during percutaneous coronary intervention for chronic total occlusion. METHODS: A total of 137 chronic total occlusion lesions that could not be passed by tapered soft wires in our hospital between 2012 and 2017 were retrospectively enrolled in the study. RESULTS: Overall success rate was significantly higher in the 3D wiring group (n = 69) than the non-3D wiring group (n = 68) (98% vs. 90%, respectively; p = 0.027). In the primary antegrade cases, the first antegrade approach time was significantly shorter in the 3D wiring group than the non-3D wiring group (42 ± 29 vs. 30 ± 16 min, respectively; p = 0.01). In cases where the antegrade approach was continued throughout the procedure, the success rate was significantly higher in the 3D wiring group than the non-3D wiring group (100% vs. 89.2%, respectively; p = 0.033). Vessel perforation by the antegrade wire tended to be lower in the 3D wiring group than the non-3D wiring group (1% vs. 11%, respectively; p = 0.055). CONCLUSIONS: 3D wiring enables accurate guidewire control, which improves the success rate of antegrade wiring and reduces the antegrade procedure time, resulting in improvement of the overall success rate.

Impact of low tissue backscattering by optical coherence tomography on endothelial function after drug-eluting stent implantation.

This study evaluated the impact of optical coherence tomography (OCT)-derived low-backscattered tissue on mid-term coronary endothelial function after drug-eluting stent (DES) implantation. Although OCT enables detailed in vivo evaluation of neointimal tissue characterization after DES implantation, its association with physiological vascular healing response is unclear. Thirty-three stable angina pectoris patients underwent OCT examination and endothelial function testing with intracoronary infusion of incremental doses of acetylcholine 8-month after DES implantation in a single lesion of the left anterior descending artery. Neointimal tissue was classified into two patterns based on the predominant OCT light backscatter: high backscatter and low backscatter. Although the presence of uncovered or malapposed stent strut was not associated with the degree of vasoconstriction, the degree of vasoconstriction was significantly greater in the DES with low-backscattered neointima than in the DES without low-backscattered neointima (- 32.1 ± 25.7 vs. - 4.1 ± 20.1%, p = 0.003). Moreover, there was an inverse linear relationship between low backscatter tissue index and degree of vasoconstriction after acetylcholine infusion (r = 0.50 and p = 0.003). The endothelium-dependent vasomotor response after 8-month of DES was impaired in patients with low neointimal tissue backscatter on OCT imaging. OCT assessment of low-backscattered tissue may be used as surrogate markers for impairment of endothelial function after DES.

Atherosclerotic Component of the Yellow Segment After Drug-Eluting Stent Implantation on Coronary Angioscopy　- An Ex-Vivo Validation Study.

BACKGROUND: Coronary angioscopy (CAS) is used to comprehensively evaluate vascular responses after drug-eluting stent (DES) implantation. This study sought to evaluate the capability of CAS for evaluating DES strut coverage grade and color grade of the intima compared with histological images in coronary autopsy specimens. Methods and Results: A total of 23 DES extracted from 11 autopsy hearts were imaged by CAS. All stent segments were graded as white or yellow according to the luminal surface color, and thrombus was evaluated according to a previous report. Neointimal coverage over the DES was graded as 0 (stent struts fully visible) to grade 3 (stent struts fully embedded and invisible). Of 76 segments, neointimal coverage was graded as 0 in 35 (46%), 1 in 22 (29%), 2 in 8 (11%), and 3 in 11 (14%). The neointimal thickness increased significantly with increasing neointimal coverage grade on angioscopy. Neointimal color was graded as white in 40 (53%) and yellow in 36 segments (47%). Histological analysis revealed that yellow neointima contained fibroatheroma, foam cells accumulation or superficial calcium deposition. A thrombus was identified in 13 segments. Thrombi adherent around the stent strut were partly intimal erythrocyte accumulation around the strut. CONCLUSIONS: In-stent yellow segment had atherosclerotic components. CAS could evaluate vascular status comprehensively after DES implantation.