This study was the first report from Turkey that analyzed rational guidewire use and procedural success in CTO procedures. We found that rational guidewire usage (1–3 guidewires) was possible, especially in easy and moderately difficult CTO procedures. The crossing of the CTO lesion with the initial guidewire choice decreased both biomaterial use and the cost of the procedure. Classification of the CTO lesion by the J-CTO or EuroCTO score led to a more precise strategy. Polymeric jacketed moderate stiff tip guidewires, particularly the Pilot brand, had superior crossability in the easy and moderately difficult CTO procedures.
Cardiac CTO procedures necessitate special instruments to increase the success rate. Recent advances in medical biotechnology have led to the manufacture of smarter coronary guidewires, which directly affect the procedural success of CTO interventions [12,13,14,15]. The availability of new generation CTO-specific biomaterials is still a concern in most cardiac centers. Most centers use a few brands of CTO-specific materials, including guidewires, microcatheters, and balloon catheters. Moreover, patients have to pay for a certain percentage of the CTO procedure by themselves because of the limited coverage of insurance companies. So, the rational use of such biomaterials is important for sustainable CTO interventions.
Each CTO-dedicated guidewire has a different tip structure, polymer jacket, and tip stiffness [14]. Variations in guidewire structure affect the steerability, crossability, and tactile feedback of the guidewire. Operators should be familiar with the structure of the guidewires, then they should form a strategy for the technique and guidewire choice [13]. The polymer-jacketed guidewire has superior steerability; however, a subintimal course is common, and due to limited tactile feedback, operators should use them very carefully [7, 16]. Non-polymeric guidewires have a better tactile feedback and intraluminal course. However, their steerability is inferior to polymeric guidewires. A stiff tip is important for lesion penetration and wire escalation. A tough stump necessitates more stiff guidewires. Our experience shows that non-polymeric and stiff guidewires are more commonly preferred in complex lesions. Polymeric guidewires are more useful in easy and intermediate difficulty lesions. The presence of microchannels is the optimal indication for soft and moderate stiff tip polymeric guidewires [17,18,19].
Lesion characteristics including length, calcification, tortuosity, stump, distal area, and occlusion duration are all important for defining an optimal strategy [18, 19]. Several CTO scores were proposed to determine the success of a CTO procedure [11]. Instead of evaluating the lesion characteristics one by one, simply totalling the CTO scores may predict the success rate of the procedure. The J-CTO score was developed with the help of the Japan Multicentre CTO registry in 2006. It was approved by investigations that predicted the success rate of antegrade CTO interventions [20]. A lower J-CTO score is usually accepted as an easy or intermediate difficulty case. Higher scores indicate very difficult cases. Our procedures were performed mostly by the antegrade approach. Thus, the J-CTO score is a suitable method to assess our cases. Approximately 80% of the patients had lesions with J-CTO scores of 0–2. So, we can conclude that our results are appropriate to analyze easy, intermediate, and difficult cases. Very difficult cases constituted just 17% of the total cases. There was an inverse correlation between the J-CTO score and success rate, which was in accord with the medical literature [20, 21]. All lesions with a J-CTO of 0 had successful interventions. There was also an inverse relationship between the crossability of the initial guidewire choice and J-CTO score. More than 50% of the lesions with J-CTO scores of 0–1 were crossed with the initial guidewire. This statistic reveals the importance of the initial guidewire choice. Reasonable initial guidewire choice and the single-wire cross strategy would lead to shorter procedural and fluoroscopy times, as well as the use of fewer guidewires, balloons, and stents, which affect the affordability and long-term prognosis of the CTO procedure. Polymeric and moderate stiff tip guidewires showed a superior performance in crossing the CTO segment. The choice of the Pilot brand in lesions with J-CTO scores of 0–1 would increase the probability of crossability with the initial guidewire. In such lesion types, non-polymeric stiff guidewires should not be used as the initial guidewire.
In each CTO procedure, the use of 1–3 guidewires can be accepted as an economical and rational use of guidewires. In each procedure, a standard soft tipped or polymer-jacketed guidewire was used to place the microcatheter. Then, special CTO guidewires replaced the initial standard wire for lesion penetration. In the final stage, the standard wire was exchanged with the CTO wire once again to perform the balloon and stenting procedure. Special CTO wire should be used just for lesion penetration. This strategy necessitates at least 2–3 wires for each procedure. In our cases, the average number of guidewires was < 4 in lesions with J-CTO scores of 0–1. We can conclude that the use of > 4 guidewires with the antegrade technique in lesions with J-CTO scores of 0–1 was not rational, and it can be defined as overuse. The crossability of the polymeric soft and moderate stiff tip guidewires was not so good in lesions with J-CTO scores > 2. For this more complicated lesion, stiff tip non-polymeric guidewires should be used. The Gaia brand showed a more significant crossability performance in lesions with J-CTO scores > 2. The distribution of the Fielder brand was similar between all J-CTO scores. But there was a small detail in the performance of Fielder guidewires. In the lesions with J-CTO scores of 0–1, the crossability of the Fielder guidewire as an initial choice was higher, and the single-wire technique was usually preferred. In the more complex cases, other techniques, particularly the step up and step down strategy, were preferred. Lesions were modified with multiple guidewires, including non-polymer stiff guidewires and Fielder guidewires, that were used to just jump to the true lumen. Thus, a similar distribution of the Fielder brand as a final guidewire did not indicate the strong crossability of lesions with J-CTO scores > 2.
The EuroCTO or CASTLE score was defined with the help of the prospective EuroCTO registry [11]. This novel scoring chart was compared with the J-CTO score, and it was found to be superior in more complex cases. We performed a J-CTO score-like analysis also for the EuroCTO score. Our result was comparable for both scoring methods. Lesions with EuroCTO scores of 0–1 showed a result similar to lesions with J-CTO scores of 0–1. The average guidewire number was < 4, and more than 50% of the lesions were crossed with the initial guidewire. Polymeric moderate stiff tip guidewires showed a superior performance in crossing the CTO segment as an initial guidewire choice. However, final wire brand, composition, and stiffness did not differ among the EuroCTO score group. Nonetheless, we can state that stiffer tip guidewires were preferred with higher EuroCTO scores. As a limitation, there were just four lesions with EuroCTO scores of 5–6, which significantly reduced the statistical analysis for very complex lesions. Non-polymeric moderate stiff tip guidewires were used more commonly in lesions with EuroCTO scores 1–4 as a final guidewire compared to the initial wire type. Our data confirmed that the polymeric moderate stiff tip Pilot brand was a good choice for lesions with EuroCTO scores 0–1.
Our results strongly confirmed that the use of CTO scoring would influence our technique in a favorable way, which directly affect the initial guidewire choice. Single-wire escalation is associated with the use of fewer guidewires. For the easy and intermediate difficulty CTO lesions, single-wire crossing should be the initial choice for rational guidewire usage. Other techniques including parallel wire, step up-step down, and dissection and re-entry were associated with a very low probability of penetration of the lesion with the initial guidewires. However, the parallel wire technique offered more rational guidewire use. The average number of guidewires used was lower when comparing to step up-step down and dissection and re-entry techniques. Polymeric guidewires were more successful in single-wire escalation. Non-polymeric guidewires should be chosen in the other techniques. According to lesion modification during wire escalation and drilling, optimal guidewire exchange should be performed. For the dissection and re-entry technique, polymeric guidewires should be preferred to jump into the true lumen.
The use of new generation guidewires would increase the success rate. However, the affordability of new generation guidewires would limit their optimal preference. The Fielder brand is one of the most commonly preferred soft polymeric guidewires. We usually preferred the Fielder XT series rather than the new generation Fielder XT-A. This choice may overshadow the crossability of the Fielder brand. The new generation Fielder XT-A series has an additional composite core technology in the guidewire tip, which enhances crossability. We used Fielder XT-A series in only four cases, which did not show statistically significant superiority. On the other hand, the new generation non-polymeric guidewires are preferred compared to the older series. The Miracle brand is a well-known non-polymeric guidewire from Asahi Intecc. The new generation Gaia brand with composite core technology has replaced the Miracle series. In our experience, the Gaia brand was preferred over the Miracle series, which would directly affect the success rate. On the other hand, we used first-generation Gaia 1-2-3 brands. The newly released Gaia Next series, which has Xtrand coil technology, was not used in any of the cases. For more complex lesions that necessitate a stiff tip load, Confianza 9 was preferred over the Confianza Pro series, which possesses a thinner tip and has a more slippery hydrophilic coating. Moreover, we also used Gladius guidewires as a last resort in certain cases. The Gladius brand is a new generation peripheral guidewire, which has a durable balanced tip composition. It has relatively superior crossability for intermediate and difficult CTO lesions. Although it is designed for peripheral interventions, it can be used for coronary CTO procedures in selected cases (as a rescue solution). On the other hand, the newly released Gladius MG guidewire series was not used due to its unavailability.
Preference for new generation guidewires would lead to more successful procedural results [21, 22]. However, the experience of the operator was also just as important as technology [23]. Our case series, newly released guidewires were used in a few cases. Nonetheless, our procedural success rate was above the average (approximately 90%). Each operator has a special relationship with guidewires, and each has their favourite guidewire for different occasions. Experienced operators can predict the behavior of the guidewire in each of the different lesion compositions. Indeed, all operators want to perform CTO procedures with newly released technology. Unfortunately, it is not possible in most cardiac centres located in Turkey. For this reason, the operator should know the composition and behavior of all the guidewire brands to choose guidewires in a rational manner.
Limitations
The first limitation is a relatively small sample size. For assessing newly released biotechnology, we analyzed the recent past period of time. So, our case sample is relatively small. All the procedures were performed by the same CTO team, which raises a question about the personal preference of the guidewires. Although the procedures were performed by the same team, the cases were collected from different hospitals, which have their own catheter laboratory and independent purchasing department. So, the CTO operators preferred the guidewire according to its availability in the catheter laboratory.
