SUOH 03 Guidewire for the Management of Coronary Artery Dissection: Insights from a Multicenter Registry

Background In the setting of coronary artery dissection, both spontaneous and iatrogenic, fixing the intimal tear, usually with stent implantation, can be extremely challenging if the distal wire position has been lost. Common complications are mainly related to the inadvertent subintimal tracking of the guidewire while attempting to gain the distal true lumen. Aims To report the registry results of using the SUOH 0.3 guidewire for managing coronary artery dissection in a real-world multicenter setting. Methods The study population in this retrospective, multicenter, international registry included 75 consecutive patients who underwent PCI and required an antegrade wiring of a dissected coronary artery. Results Successful use of SUOH 0.3 was achieved in 69 (92%) patients. The use of a microcatheter was associated with a significantly higher rate of TIMI 3 flow at the end of the procedure (no microcatheter: n = 17, 81%; microcatheter: n = 52, 96.3%; p = 0.017). The first recanalization attempt was made with the SUOH 03 guidewire in 48 (64%) cases, and it was successful in 42 (87%). The overall PCI success rate was reported in 72 (96%) patients, with no significant differences among patients with different origins, mechanisms, and locations of dissection. Conclusions In this setting, the SUOH 0.3 guidewire provides high procedural success without additional complex techniques.


Introduction
Arterial wall dissection results from mechanical disruption of the endothelium, blood extravasation into the subendothelial space, and subsequent false lumen creation within the tunica media. Te false lumen may compress the true lumen to total occlusion, leading to fow impairment, tissue hypoperfusion, and necrosis [1]. Coronary artery dissection may be spontaneous, traumatic, or iatrogenic [2][3][4]. Spontaneous coronary artery dissection (SCAD) is a rare but potentially life-threatening event, predominantly seen in the young female population, especially postpartum. Te optimal treatment strategy for patients with SCAD is still unclear but is likely based on several clinical and angiographic factors [2]. Iatrogenic coronary artery dissection (ICAD) during coronary angiography or percutaneous coronary intervention (PCI) can be caused by a variety of mechanisms; the most frequent include guide-catheterinduced ostial injury, balloon dilation, aggressive wire manipulation, and the use of atherectomy devices [1,4,5]. Fixing the intimal tear and restoring vessel fow, usually with stent implantation, is easily achieved if a guidewire is already present in the distal true lumen, but it can be extremely challenging if the distal wire position has been lost. One of the main reasons for procedural failure during PCI for spontaneous and iatrogenic coronary artery dissections is the difculty of advancing a guidewire into the distal true lumen. Limited data are available in the published literature regarding the structural properties of guidewires and the manipulation techniques required to maximize the chances of successful coronary wiring. In a previously published hypothesis-generating case series, the results of using the SUOH 0.3 "rope coil" wire (Asahi Intecc, Japan) for coronary dissection tracking were reported [6]. In addition, the "soft wire technique" was described as an efective strategy to regain the true lumen after coronary artery dissection, either before wiring or after wire loss. To our knowledge, this is the only attempt to defne the optimal structural properties and necessary manipulation techniques of a specifc guidewire for managing coronary artery dissection. Te present investigation aims to report the results of using the SUOH 0.3 guidewire for managing coronary artery dissection in a realworld multicenter registry.

Study Design.
Te study population in this retrospective, multicenter, international registry included all consecutive patients from March 2020 to October 2022 in 10 highvolume centers who underwent PCI and in whom antegrade wiring of a dissected coronary artery was clinically required for either spontaneous or iatrogenic dissection. Te inclusion criteria were broad and refected routine clinical practice, including patients with stable CAD and acute coronary syndromes. No limits were set for the number of treated lesions, vessels, or lesion length, and no patients were excluded based on comorbid conditions or age. PCI was performed according to standard techniques, and the devices used were left to operator preference. Each patient provided informed consent for participation in the study. Tis study complies with the Declaration of Helsinki and was approved by the local Ethics Committee.

Device
Description. Te SUOH 0.3 is a composite core, dual coil (Sion Tecc, Asahi Intecc Co, Japan), 0.014″, fat tip guidewire originally developed for tortuous collateral channel tracking. Te "composite core" technology consists of combining a classic linear core wire with a second twisted wire in parallel, conjoined at the tip. Te result is increased and fner torque control (1 : 1) of the tip. "Dual coil technology" consists of a second intertwined inner rope coil, the so-called "ACT ONE," within the classic outer coil allowing optimal and durable shaping of the tip of the wire with improved directional control. Tis wire has a unique combination of technical characteristics: (1) the distal 3 cm of the outer "rope coil" consists of 4 intertwined wires instead of one, resulting in higher tip fexibility, while the proximal 16 cm is made of a conventional single wire rope coil; (2) only the twisted wire of the composite core is connected to the tip in a shaping ribbon tip style, providing tip shape retention and softness; (3) the dual twisted coil structure allows high torqueability and steerability while maintaining good support; and (4) the distal 1 mm tip is preshaped to a 45°a ngle ofering excellent shape memory and retention, with the softest tip load (0.3 gf ) among available contemporary guidewires ( Figure 1).

Defnitions and Endpoints.
Spontaneous coronary artery dissection was defned as a nontraumatic and noniatrogenic tear in one of the epicardial coronary arteries. Iatrogenic coronary dissection was defned as angiographic evidence of an intimal tear secondary to guidecatheter coronary ostia engagement, forceful injection of contrast medium, wire manipulation, balloon dilation, and use, passage, or deployment of any other interventional device with consequent wire positioning loss. Te grading of dissections was described according to National Heart, Lung, Blood Institute (NHLBI) classifcation: [7].
Type A. Minor radiolucent areas in the lumen without impairment of fow or persistent dye staining after contrast run-of Type B. Luminal fap that is radiolucent and runs parallel to the vessel wall with contrast injection but without impairment of fow or persistent dye staining after contrast run-of Type C. Contrast appears outside of the vessel lumen as an "extraluminal cap" and the staining appears even after contrast clears of the lumen Type D. Spiral radiolucent luminal flling defects, often persistent staining after contrast clears from the vessel Type E. New and persistent flling defects in the vessel lumen. Type F. Lesions that progress to impaired fow or total occlusion.
Te primary endpoint was the successful use of a SUOH 0.3 guidewire, defned as the gain of the true lumen with the guidewire. Te key secondary endpoints were PCI success, defned as achievement of TIMI ≥2 fow at the end of the procedure, and successful use of a SUOH 0.3 guidewire at the frst attempt.

Baseline Clinical and Procedural Characteristics.
Baseline clinical data are reported in Table 1. A total of 75 patients with coronary dissection were included in the present analysis. Te mean age was 64.1 ± 13.6 years, and the female gender was predominant (56% of cases). Cardiovascular risk factors were prevalent, with hypertension and dyslipidemia reported in around 70% of patients. Diabetes was present in one-third of cases. Illicit drug use was rare (less than 2%). Te clinical indication for coronary angiography was acute myocardial infarction in more than half of all cases (NSTEMI: n � 26, 34.7%; STEMI: n � 15, 20%).
No clinical or angiographic diferences were detected depending on dissection etiology although iatrogenic dissection was more common (n � 56, 75%); half of the iatrogenic cases occurred during wiring or predilatation ( Figure 2, Table 2). Ostial catheter dissection occurred in 8 patients (14%). Dissection distribution was uniform between the left anterior descending, circumfex, and right coronary arteries, while 6.7% of dissections involved the left main coronary artery. Te proximal, middle, and distal segments were equally afected by dissection. Flow impairment was present in 49 patients (71%), leading to hemodynamic instability in 14 patients (19%). Even in iatrogenic dissection, vessel occlusion was observed in one-third of cases ("type F″ dissection, Figure 3). No signifcant diferences were observed in TIMI fow among spontaneous and iatrogenic dissections: TIMI fow <2 was reported in 32 patients with spontaneous dissection and 13 with iatrogenic dissection (57% vs. 68%, p � 0.63).

Angiographic and Procedural
Outcomes. Te primary endpoint, successful use of a SUOH 0.3 guidewire, was achieved in 69 (92%) patients ( Figure 4). No signifcant correlation was found with the use of a microcatheter, which was reported in 72% of cases. Conversely, the use of a microcatheter was associated with a signifcantly higher rate of TIMI 3 fow at the end of the procedure (

Discussion
Coronary artery dissection treatment remains a major issue. Gaining the distal true lumen with the guidewire is the most challenging step when indicated in SCAD or in cases of ICAD when the distal wire position has been lost.    In this context, intravascular ultrasound (IVUS) can visualize the dissection entry point, confrm the presence of the wire in the true lumen, and provide useful information regarding dissection length and vessel diameter that can guide stent selection. However, this maneuver carries potential risks, such as extending the coronary dissection with the imaging catheter. Optical coherence tomography imaging, although previously described, is not recommended due to the need for contrast injection. If antegrade wiring cannot be readily accomplished, alternative techniques derived from chronic total occlusion (CTO) interventions to gain distal true lumen have been described, including subintimal tracking and reentry (STAR), antegrade fenestration and reentry (AFR), limited antegrade subintimal tracking (LAST), subintimal reentry using the Stingray balloon, and whenever possible retrograde recanalization through collateral channels [8,9]. However, some of the techniques mentioned above are timeconsuming, others require dedicated devices (i.e., the stingray system), and all are intended for experienced and CTO-PCI-trained operators. Moreover, IVUS-guided subintimal reentry, also described as a possible technique during acute vessel closure, requires signifcant expertise in IVUS interpretation. Given the high complexity of the technique and the possibility of widening the antegrade dissection, it should only be considered a "bailout" procedure. Antegrade wiring of the true lumen should be the frst-line strategy in patients presenting with coronary artery dissection. Crossing or recrossing the dissected segment can be accomplished with a soft workhorse guidewire with a low tip load. Soft workhorse guidewires provide enhanced tactile and visual feedback,  Type of iatrogenic dissection 0% Figure 3: Types of iatrogenic dissection in the overall cohort. Type A minor radiolucent areas in the lumen without impairment of fow or persistent dye staining after contrast run-of; type B luminal fap that is radiolucent and runs parallel to the vessel wall with contrast injection, but without impairment of fow or persistent dye staining after contrast run-of; type C contrast appears outside the vessel lumen as an "extraluminal cap," and the staining appears even after contrast clears of the lumen; type D spiral radiolucent luminal flling defects, often persistent staining after contrast clears of the lumen; type E new and persistent flling defects in the lumen; type F lesions that progress to impaired fow or total occlusion. Journal of Interventional Cardiology increasing the chance of successfully fnding the true lumen. It is imperative to avoid creating new dissection planes or causing acute vessel occlusion when attempting to gain wire access into the true lumen. Limited data are available regarding the structural properties of the guidewires and the manipulation techniques to maximize the chance of success. Among the wide range of available coronary guidewires, the SUOH 03 guidewire has certain structural features that make it ideal for gaining the true lumen into, or distally to, the dissected segment, thereby minimizing the risk of enlargement and extension of the dissection. Te shaping ribbon tip style, the hydrophilic coating, and the soft and low-weight tip load combined with the "rope coil" technology ensure a nontraumatic advancement, high torque control, and durable preservation of the tip shape. Observing the advancement of the guidewire is crucial in discriminating between endoluminal and subintimal tracking, therefore limiting the propagation of dissection during advancement into the diseased segment. Te tip curling in the subintimal culde-sac is an immediate sign of subintimal tracking, while wire progression without tip defection ("straight tip progression") stands for true lumen tracking [6]. Such visual feedback combined with high directional control allows repeating gentle and nontraumatic attempts to move from the false into the true lumen, with no need for contrast dye injections. Moreover, we observed that a guidewire's ability to facilitate spontaneous intraluminal tracking during cardiac motion is mainly related to tip fexibility. In case of tortuosity, the use of a microcatheter improves the wire control and allows confrmation of endoluminal position with blood backfow. In this multicenter registry, we analyzed 75 consecutive cases of coronary artery dissections, both ICAD and SCAD, treated with PCI in 10 mid-to-high-volume centers worldwide. Our data reveal a high success rate (92%), which is not comparable with other results due to the paucity of published data in such clinical scenarios. In their 302 consecutive SCAD cases, Mori et al. reported 100 patients who underwent ad hoc PCI (33.1%), 78% of which were classifed as successful [10]. Common complications included false lumen stenting and proximal and distal dissection propagation, mainly related to the inadvertent subintimal tracking of the guidewire during the attempts to gain the distal true lumen [10]. In our series, the high success rate is constant between ICAD and SCAD, irrespective of dissection mechanism or location. Tis result is even more relevant considering that dissections in proximal or midcoronary segments were about 62%, and the prevalence of fow impairment was 71%, two elements with potential relevant clinical implications in case of unsuccessful treatment. In tortuous vessels, using a microcatheter results in better wire control, reducing hematoma enlargement and increasing the chance of gaining the distal true lumen. In our study, microcatheter used to tackle tortuosity and improve wire control was the only predictor of fnal TIMI III fow. No variability between the participating centers has been revealed, supporting the reproducibility and predictability of this technique.

Conclusions
Despite the potentially unfavorable clinical impact of coronary artery dissection and the need for complicated treatments, the "soft tip wire technique" based on using the SUOH 0.3 guidewire has proven to provide high procedural success without the need for additional complex techniques. Larger studies, including results from non-CTO PCI centers, would further clarify the role of this technique in the treatment of coronary artery dissection.

Data Availability
Underlying data are not publicly available due to concerns for patient privacy and commercial confdentiality.

Additional Points
Te absence of a control group precludes a direct comparison with unselected workhorse guidewires. Te lack of a prespecifed CAD PCI protocol may represent an important source of bias. Moreover, all the participating centers have an active and robust CTO program, with related complex PCI skills and mid-to-high procedure volumes. Tese elements may represent bias due to the operators' CTO and complex PCI skills and their previous experience using the SUOH 0.3 guidewire in complex settings other than CAD.

Conflicts of Interest
All authors declare that there are no conficts of interest.