==== Front JACC Asia JACC Asia JACC Asia 2772-3747 Elsevier S2772-3747(23)00056-X 10.1016/j.jacasi.2023.03.003 Cutting-Edge Technology Efficacy of Intravascular Ultrasound–Based 3D Wiring Using the Tip Detection Method for CTO Intervention Suzuki Satoshi MD a Okamura Atsunori MD, PhD a_okamura@watanabe-hsp.or.jp @Aokamura5 a∗ Nagai Hiroyuki MD a Ishikawa Masato MD b Kameda Satoshi MD c Tanaka Kota MD a Watanabe Heitaro MD, PhD a Nakazawa Gaku MD, PhD d Sakata Yasushi MD, PhD c Shiojima Ichiro MD, PhD e a Cardiovascular Center, Sakurabashi Watanabe Hospital, Osaka, Japan b Department of Cardiology, Fujita Health University, Aichi, Japan c Division of Cardiology, Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Osaka, Japan d Division of Cardiology, Kindai University Faculty of Medicine, Osaka, Japan e Department of Medicine II, Kansai Medical University, Osaka, Japan ∗ Address for correspondence: Dr Atsunori Okamura, Cardiovascular Center, Sakurabashi Watanabe Hospital, 2-4-32 Umeda, Kita-ku, Osaka 530-0001, Japan. a_okamura@watanabe-hsp.or.jp@Aokamura5 09 5 2023 6 2023 09 5 2023 3 3 526530 12 1 2023 1 3 2023 6 3 2023 © 2023 The Authors 2023 https://creativecommons.org/licenses/by/4.0/ This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). To perform intravascular ultrasound (IVUS)–based real-time 3-dimensional wiring in chronic total occlusion percutaneous coronary intervention, we devised a tip detection method and developed AnteOwl WR (AO)-IVUS, which is an upgraded version of Navifocus WR (Navi)-IVUS with an added pull back transducer system. We compared the procedural outcomes of AO-IVUS–based 3-dimensional wiring using the tip detection method (n = 30) and Navi-IVUS–based conventional wiring (n = 17) in chronic total occlusion percutaneous coronary intervention. The success rate of IVUS-guided wiring was markedly improved in the AO-IVUS group compared with the Navi-IVUS group (93% vs 59% of cases, respectively; P = 0.007). In cases of successful IVUS-guided wiring, the IVUS-guided wiring time was markedly improved in the AO-IVUS group compared with the Navi-IVUS group (9 ± 8 minutes vs 24 ± 26 minutes, respectively; P = 0.001). There were 2 successful cases of tip detection-antegrade dissection and re-entry in the AO-IVUS group. Key Words chronic total occlusion coronary intervention IVUS-based 3D wiring tip detection method Abbreviations And Acronyms 3D 3-dimensional ADR antegrade dissection and re-entry AO AnteOwl WR AWE antegrade wire escalation CTO chronic total occlusion IVUS intravascular ultrasound Navi Navifocus WR PCI percutaneous coronary intervention RWE retrograde wire escalation TD tip detection ==== Body pmcOver the past decade, we have tried to standardize intravascular ultrasound (IVUS)–guided wiring as the key to maximizing the accuracy of guidewire manipulation in chronic total occlusion (CTO) percutaneous coronary intervention (PCI). In 2012, we developed Navifocus WR (Navi)-IVUS, the first CTO-specific IVUS, with a small profile and a short distance from the tip to the transducer in collaboration with Terumo Corp.1 The success rate could likely not be greatly improved. However, observation of the movement of the guidewires in the CTO lesions indicated the importance of 3-dimensional (3D) manipulation of the guidewires. Therefore, in 2014, we devised the 3D imaging rule and established angiography-based 3D wiring.2 Subsequently, to perform 3D wiring in real time even with IVUS-guided wiring, we devised a tip detection (TD) method and developed AnteOwl WR (AO)-IVUS (Terumo Corp), which is an upgraded version of Navi-IVUS with an added pull back transducer system.3 As AO-IVUS was launched in Japan in 2019, AO-IVUS–based real-time 3D wiring using the TD method has achieved the high success rate.4,5 While performing this wiring, we first found in August 2021 that the TD method allows for antegrade dissection re-entry (ADR) because the wall between the subintima and the true lumen can be punctured at the intended part in an exactly vertical direction using the IVUS observation. We named this method “tip detection antegrade dissection re-entry (TD-ADR).”6 In the present study, we compared the procedural results of Navi-IVUS–based conventional wiring and AO-IVUS–based real-time 3D wiring using the TD method in CTO-PCI. Methods Study population We compared the procedural outcomes for the first 2 years after approval of each IVUS catheter at Sakurabashi Watanabe Hospital (Osaka, Japan). Between August 2012 and July 2014 after Navi-IVUS was first launched, 17 CTO-PCI patients underwent Navi-IVUS–based conventional wiring (Navi-IVUS group) among 171 consecutive CTO-PCI cases (96% success rate; the first operator was A.O. in 71% of cases, S.K., H.N., T.Y., or A.S. in the others). Between October 2019 and September 2021 after the launch of AO-IVUS, 30 patients undergoing CTO-PCI were treated with AO-IVUS–based real-time wiring (AO-IVUS group) among 168 consecutive CTO-PCI cases (97% success rate; the first operator was A.O. in 80% of cases, S.S., M.I., H.N., or K.T. in the others). These 47 patients (Navi-IVUS group; n = 17; AO-IVUS group; n = 30) were retrospectively enrolled in the present study. The review board of our institution approved the study protocol. All patients provided written informed consent to participate in this clinical study. The study was approved by the Central Medical Ethics Committee of Sakurabashi Watanabe Hospital, Osaka, Japan (approval #20-40). Interventional procedure, including methodology of NAVI-IVUS– and AO-IVUS–based wiring in CTO-PCI We have already reported the specifications of Navi-IVUS (short-tip IVUS)1 and AO-IVUS (short-tip and pull back IVUS).3 Among the 4 major CTO revascularization strategies—antegrade guidewire escalation (AWE), retrograde guidewire escalation (RWE), ADR using the Stingray system (Stingray-ADR, Boston Scientific),4 and IVUS-guided wiring—we performed AWE followed by IVUS-guided wiring as often as possible instead of parallel wiring while following the CTO algorithms for CTO crossing. Stingray-ADR was not performed in the period of Navi-IVUS because we started it in 2018. In antegrade wiring, the tip shape of CTO stiff wires was a 1-mm curve at an angle of 45°. A Corsair microcatheter (Asahi Intecc Co, Ltd) was mainly used because of sufficient backup support for the guidewires. When the antegrade first guidewire was advanced to around the CTO exit but could not be passed through the CTO lesion, it was highly probable that the first guidewire was advanced into the subintimal space. We moved on to using IVUS-guided wiring as much as possible instead of parallel wiring. The Corsair microcatheter was advanced through the guidewire around the CTO exit to create a space for the IVUS catheter, and if the guidewire was a tapered wire, it was changed to a 0.014-inch moderately stiff CTO wire to obtain good support for advancing the IVUS catheter. Using a double-chamber catheter, the second guidewire was then advanced and the microcatheter was advanced through this second wire, and the IVUS catheter was advanced through the first guidewire. When the IVUS catheter could not be advanced after the Corsair’s bougie, balloon dilatation was performed with a small-diameter balloon. We performed the following 2 steps: positional information of vascular structures, such as the intimal space and exit lumen, was transferred from the IVUS image to the angiographic image as we reported previously4; and IVUS-based wiring was performed to advance the second guidewire to the target. In the Navi-IVUS group, the image-delayed IVUS-guided wiring was performed. The IVUS transducer was placed just beyond the transition site between the intimal space and subintimal space. The second guidewire was advanced to the position that was assumed to correspond to the target (intraplaque, exit lumen of the CTO, and so on) on angiographic images. On the other hand, in the AO-IVUS group, AO-IVUS–based real-time 3D wiring was performed.3 The TD method was performed to accurately navigate the guidewire to the target. During guidewire navigation, the tip and its direction were always visualized by moving the IVUS transducer back and forth at the tip part to visually construct the 3D image of the guidewire inside the vessel. In addition, the guidewire tip was accurately guided to the target under direct visualization while the transducer was always advanced in accordance with the advancement of the guidewire tip. From August 2021, we also performed TD-ADR to pass the re-entry routes. Study definition CTO was defined as totally occluded lesion with an estimated duration of at least 3 months with thrombolysis in myocardial infarction grade 0. The J-CTO (Multicenter CTO Registry of Japan) score was applied to grade the difficulty of CTO lesions. The angiographic classifications, such as collateral connection grade, CTO entry type, calcification, bending, and lesion length, were defined as reported previously.7 Procedural success was defined as when both the guidewire and balloon crossed the occluded lesion completely, successfully dilating the occluded artery, and achieving restoration of antegrade flow (Thrombolysis In Myocardial Infarction grade flow score 3) with <50% residual stenosis on final angiography. In-hospital major adverse cardiac and cerebrovascular events consisted of cardiac and noncardiac death, Q-wave myocardial infarction, non–Q-wave myocardial infarction, target vessel failure followed by emergent target vessel revascularization with PCI or coronary artery bypass grafting, and stroke. Myocardial infarction was defined as an increase in creatine kinase level to more than twice the normal upper limit. Complications during the procedure consisted of vessel perforations without tamponade by the guidewire at the CTO site and perforations leading to cardiac tamponade. Statistical analysis Numerical data are expressed as the median (IQR), whereas categorical values are expressed as percentages. Continuous data were compared using the Mann-Whitney U test because of the nonparametric nature of the data. Frequency functions were assessed using the Fisher exact test and the chi-square test. In all analyses, P < 0.05 was taken to indicate statistical significance. All statistical analyses were performed using commercially available software, EZR (Saitama Medical Center, Jichi Medical University). Results Table 1 presents a summary of patient and lesion characteristics. Compared with the AO-IVUS group, the Navi-IVUS group has more patients with a history of coronary artery bypass grafting (18% vs 0%), fewer smokers (12% vs 57%), and more patients treated with hemodialysis (18% vs 0%). Table 2 shows the outcomes of the procedures. The success rate of IVUS-guided wiring was markedly improved in the AO-IVUS group compared with the Navi-IVUS group (93% vs 59%, respectively; P = 0.007). In the Navi-IVUS group, before Navi-IVUS–based wiring, the primary AWE was performed in all cases, followed by the rescue RWE in 53% (n = 9 of 17). The success rate of Navi-IVUS based wiring was 59% (n = 10 of 17). In the AO-IVUS group, before AO-IVUS–based wiring, the primary AWE was performed in 83% (n = 25 of 30) followed by the rescue RWE in 8% (n = 2 of 25), and the primary RWE was performed in 17% (n = 5 of 30) followed by Stingray-ADR in 80% (n = 4 of 5). After the failure of Stingray-ADR (n = 4), we then succeeded using AO-IVUS–based wiring in all of the 4 cases, which included the 2 cases recanalized by TD-ADR. The success rate of AO-IVUS–based wiring was 93% (n = 28 of 30).Table 1 Demographic and Angiographic Characteristics Navi-IVUS Group (n = 17) AO-IVUS Group (n = 30) P Value Demographic characteristics  Age, y 67 (61-73) 68 (55-72) 0.706  Male 15 (88) 28 (93) 0.613  Clinical presentation  Asymptomatic 8 (47) 16 (53) 0.766  Stable angina 9 (53) 14 (47)  History of CABG 3 (18) 0 (0) 0.042  Coronary risk factors  Hypertension 15 (88) 26 (87) 1.000  Diabetes mellitus 7 (33) 10 (59) 0.753  Dyslipidemia 14 (82) 27 (90) 0.653  Smoker 2 (12) 16 (57) 0.004  PAD 3 (12) 2 (11) 1.000  eGFR (<45 mL/min/1.73 m2) 4 (24) 1 (3) 0.051  Hemodialysis 3 (18) 0 (0) 0.042  LVEF <35% 3 (18) 3 (10) 0.889 Angiographic characteristics  Target vessel  RCA 5 (29) 6 (20) 0.588  LAD 6 (35) 15 (50)  LCX 6 (35) 9 (30)  LMT 0 (0) 0 (0)  CABG 0 (0) 0 (0) 1.000  Collateral filling grade  CC 0 1 (6) 2 (7) 0.276  CC 1 9 (53) 22 (73)  CC 2 7 (41) 6 (20)  CTO entry types  Blunt 10 (59) 21 (70) 0.528  Severe calcification 4 (24) 13 (43) 0.218  Bending (>45°) 5 (29) 8 (27) 1.000  Occluded Length (>20 mm) 14 (82) 20 (67) 0.321  Reattempted lesion 2 (12) 10 (33) 0.165  ISR 2 (12) 1 (3) 0.544  J-CTO score 2 (1-3) 3 (1-3) 0.223  0 3 (18) 1 (3)  1 2 (12) 7 (23)  2 7 (41) 6 (20)  3 3 (18) 11 (37)  4 1 (6) 3 (10)  5 1 (6) 2 (7) Values are median (IQR) or n (%). AO-IVUS = AnteOwl WR intravascular ultrasound; CABG = coronary artery bypass grafting; CC = collateral connection grade; CTO = chronic total occlusion; eGFR = estimated glomerular filtration rate; ISR = in-stent restenosis; J-CTO score = Japanese chronic total occlusion score; LAD = left anterior descending coronary artery; LCX = left circumflex coronary artery; LVEF = left ventricular ejection fraction; Navi-IVUS = Navifocus WR intravascular ultrasound; PAD = peripheral arterial disease; RCA = right coronary artery. Table 2 Procedure Outcomes, MACCE, and Complications Total Cases of IVUS-Guided Wiring Navi-IVUS Group (n = 17) AO-IVUS Group (n = 30) P Value Frequency of use of computed tomography information 9 (53) 18 (60) 0.647 Frequency of use of 8-F guide catheter for antegrade approach 16 (94) 26 (87) 0.640 Frequency of use of the parallel wire technique before IVUS guide wiring 5 (29) 0 (0) 0.004 Predilatation to advance IVUS catheter  Corsair's bougie only 6 (35) 17 (57) 0.176  Addition of balloon dilatation with a small-diameter balloon 11 (65) 11 (37)  Rotablation 0 (0) 2 (7) Microcatheter in IVUS-guided wiring  Corsair 7 (41) 23 (77) 0.026  Finecross 10 (58) 7 (23) 0.002 IVUS-guided wiring time, min 27 (15-45) 8 (5-12) 0.002 Total procedure time, min 208 (156-266) 143 (110-180) 0.002 Fluoroscopic time, min 113 (80-13) 72 (60-98) 0.002 RAD, mGy 6,627 (5,109-8,217) 3,172 (2,040-3,930) < 0.001 Contrast dose, mL 220 (200-300) 130 (111-160) < 0.001 Success rate of IVUS-guided wiring 10 (59) 28 (93) 0.007 Success rate throughout the procedure 15 (88) 29 (98) 0.170 MACCE  Cardiac death 0 (0) 0 (0) 1.000  Noncardiac death 0 (0) 0 (0) 1.000  QMI 0 (0) 0 (0) 1.000  Non-QMI 0 (0) 0 (0) 1.000  Emergent target vessel revascularization with PCI or CABG 0 (0) 0 (0) 1.000  Stroke 0 (0) 0 (0) 1.000 Complications during the procedure  Vessel perforation by the guidewire 0 (0) 0 (0) 1.000  Cardiac tamponade 0 (0) 0 (0) 1.000 Successful cases of IVUS-guided wiring 10 28 Crossing wire in IVUS guided wiring  Confianza 9g 0 (0) 4 (14) 0.562  Confianza 12g 9 (90) 16 (57)  Confianza 20g 1 (10) 6 (21)  Others 0 (0) 2 (7) IVUS-guided wiring time, min 16 (7-25) 8 (5-9) 0.067 Values are n (%) or median (IQR). IVUS = intravascular ultrasound; MACCE = major adverse cardiac and cerebrovascular event(s); PCI = percutaneous coronary intervention; QMI = Q-wave myocardial infarction; RAD = radiation absorbed dose; other abbreviations as in Table 1. The total procedure time, fluoroscopic time, radiation absorbed dose, and amount of contrast were significantly reduced in the AO-IVUS group than the Navi-IUVS group. In cases of successful IVUS-guided wiring, the IVUS-guided wiring time tended to be improved in the AO-IVUS group compared with the Navi-IVUS group (P = 0.067). The crossing wires in IVUS-guided wiring were mainly Confianza family wires in both groups. There were no in-hospital major adverse cardiac and cerebrovascular events or complications during the procedure in either group. Discussion AO-IVUS–based 3D wiring has made it possible to perform high-precision guidewire manipulation in CTO lesions. In addition, the risk of tip hardness has been reduced, resulting in the easier step-up of the guidewires when needed. Therefore, the success rate of AO-IVUS–based 3D wiring exceeded 90% in short IVUS-guided wiring time. The 2 failure cases were true bifurcation cases in which there was a risk of the side branch occlusion caused by hematoma. In one patient when rescue RWE was performed, it resulted in successful recanalization, and in the other patient when primary RWE was performed at a later date, it resulted in successful recanalization. The absorbed radiation dose and amount of contrast were significantly reduced in the AO-IVUS group compared with the Navi-IVUS group. The main reasons were that the cine-angiography had been replaced with fluoroscopy in most of the PCI procedures and the coronary artery images created by computed tomography had been able to be moved in conjunction with the movement of the angiography detector to allow it to assume the vessel course in the CTO lesions. While performing AO-IVUS-based 3D wiring, we succeeded in the intentional creation of the re-entry with an exact vertical directional puncture using the TD method (TD-ADR) in 2 cases even after the failure of Stingray-ADR. Compared with Stingray-ADR, TD-ADR enables the puncture to be at a more proximal region with greater accuracy because the target is clearly visible on IVUS images.5 AO-IVUS–based 3D wiring using the TD method ensures accurate and reliable guidewire navigation not only through the intraplaque routes but also through re-entry in CTO-PCI. Study limitations The present study was based on retrospective data analysis of a relatively small number of patients from a single center. Conclusions AO-IVUS–based real-time 3D wiring using the TD method markedly increased the success rate of IVUS-guided wiring in CTO-PCI compared with conventional IVUS-guided wiring. Funding Support and Author Disclosures Dr Okamura has received speaker fees from Terumo Corp (Tokyo, Japan). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center. ==== Refs References 1 Okamura A. Iwakura K. Date M. Nagai H. Sumiyoshi A. Fujii K. Navifocus WR is the promising intravascular ultrasound for navigating the guidewire into true lumen during the coronary intervention for chronic total occlusion Cardiovasc Interv Ther 29 2014 181 186 24101093 2 Tanaka T. Okamura A. Iwakura K. Efficacy and feasibility of the three-dimensional wiring technique for chronic total occlusion percutaneous coronary intervention: first report of outcomes of the three-dimensional wiring technique J Am Coll Cardiol Intv 12 2019 545 555 3 Okamura A. Iwakura K. Iwamoto M. Tip detection method using the new IVUS facilitates the 3-dimensional wiring technique for CTO intervention J Am Coll Cardiol Intv 13 2020 74 82 4 Suzuki S. Okamura A. Iwamoto M. New CTO-specific IVUS: AnteOwl success in previously failed CTO case treated with Navifocus IVUS J Am Coll Cardiol Case Rep 2 2020 961 965 5 Suzuki S. Okamura A. Iwakura K. Initial outcomes of AnteOwl IVUS-based 3D wiring using the tip detection method for CTO intervention J Am Coll Cardiol Intv 14 2021 812 814 6 Suzuki S. Okamura A. Nagai H. Iwakura K. Tip detection-antegrade dissection and reentry using intravascular ultrasound in chronic total occlusion intervention: first human case report Eur Heart J Case Rep 6 2022 1 5 7 Suzuki Y. Muto M. Yamane M. Independent predictors of retrograde failure in CTO-PCI after successful collateral channel crossing Catheter Cardiovasc Interv 90 2017 E11 E18 27651224