GE is a rare but severe complication of a PCI. Previous case studies revealed that retained guide wire fragments in the coronary artery may cause various complications, including thrombosis, dissection, vessel occlusion, embolization and even perforation [7,8,9,10]. The most common causes of GE or guidewire fracture are aggressive pulling of the entrapped guidewire, guidewire overrotation, guidewire deformation, atherectomy over a kinked guidewire, and guidewire jailing during stenting [3]. Severe vessel calcification and tortuosity are also associated with a higher risk of GE or guidewire fracture, which is likely attributed to equipment deformation during advancement [3]. Thus, operators should be cautious of device entrapment when dealing with such lesions.

When GE occurs during a PCI, operators should be aware of wire elongation when attempting to extract an entrapped guidewire. This manoeuvre often exacerbates the problem, making extraction more difficult. There are several interventional strategies for the management of GE, such as forceful pulling, guidewire twirling, advancement of a microcatheter/balloon/guide extension over the entrapped guidewire, balloon inflation with parallel guidewire and snaring when the guidewire is fractured [3, 11]. In addition, entering another guidewire in sub-intimal space with knuckle technique with inflating a small balloon in this space may be feasible according to previous study [12]. In rare cases, surgery was considered [13]. The most commonly used technique is the advancement of a microcatheter over the guidewire as close as possible to the site of entrapment and pulling back forcefully on the wire. However, this method may result in wire breakage. In the present case, we attempted all of these methods, except the snaring technique, as the guidewire was not fractured, and the balloon inflation technique, as parallel guidewires were unable to cross the lesion.

An analysis of the PROGRESS CTO online database (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention) revealed that the retrieval of entrapped or fractured guidewires was attempted in 71.4% of the cases, and the success rate was only 26.7% [3]. If the fractured guidewire fragment is located within the coronary tree, leaving the remaining wire in place or covering it with stents may be a viable option that does not result in adverse outcomes [3, 4, 14, 15]. When the intact guidewire is unable to be removed or the fractured guidewire fragment protrudes into the aorta, surgical extraction should be considered. However, a surgical strategy is associated with a high risk of mortality [3]. Our case showed that ELCA was effective for removing entrapped guidewires. ELCA has been proven to be a safe and effective atherectomy strategy in a contemporary PCI [5]. Thus, ELCA may be a preferred option for treating GE, which could prevent the need for a surgical procedure when a traditional interventional strategy fails.

The possible risks of ELCA include laser catheter entrapment, damage to the polymer jacket of the guidewire, vessel dissection, and perforation. Although fluoroscopic view indicated that the polymer sleeve of the guidewire was damaged by rotating and pulling forces before ELCA, we could not exclude that laser energy also melted the polymer, and one should be cautious when using this technique with polymer sleeve guidewires. To validate the effect of laser ablation and reduce the probability of complications, we tried to draw the wire back every 10 rounds of laser treatment. No complications occurred in this case, which indicated that it may be a safe strategy for the retrieval of an entrapped guidewire. However, extraction of adherent plaque tissue from the vessel wall indicated the possibility of vessel damage. The energy and frequency as well as the duration of ELCA use were important for treatment. Therefore, the standard method of ELCA needed more data to establish. Compared with ELCA, the usual methods, including parallel wire technique and the use of microcatheters or balloons, had more evidence and more specific procedures to deal with GE [3, 16]. Insertion of a balloon catheter or a microcatheter over the entrapped wire allow more centering of the force on the wire which was more useful in entrapped side branch wires during bifurcation stenting. Balloon dilation along the entrapped or parallel wire enabled to loosen the plaque tissue around the entrapped guidewire. These traditional methods were more accessible and safer with less complication, which should be prioritised in case of GE. However, the microcatheter and balloon as well as parallel wire failed to pass through the entrapped site after many attempts. Thus, we try to use ELCA. In addition, we recommend pulling back the wire every few rounds of laser treatment and monitoring vital signs and ECG in the process of ELCA, which were more able to avoid complication.

Furthermore, histological findings in our study provide some clues for cause of GE. On one hand, operating factors of GE including excessive and unidirectional rotation of the guidewire during PCI may result in its head being destroyed and embedded in the plaque tissues. One the other hand, the histological examination showed that the dense fibrotic tissue and severe calcified lesion contributed to guidewire compression and damage. While a previous study revealed that heavily calcified lesions may be one cause of GE [17], the present case showed that the plaque tissue causing GE was composed of much more collagen and muscle fiber but less calcified tissue. The hard and calcified lesion lead to the deformation of guidewire and damage of polymer sleeve and spring coils. The dense fibrotic tissue made guidewire difficult to retract once it the has entered. It was difficult to judge which single tissue type resulted in GE. The specific mechanism behind needs further investigation. Although the guidewire was entrapped in the calcified region, we believe that loosening the adjacent collagen fibre during ELCA contributed to the successful removal of the guidewire considering that the collagen tissue was also removed.

Although this case reported the successful removal of entrapped guidewire in CTO lesion by ELCA, more cases should be collected in the future study which validated its efficacy and established a standard process for this method. Particularly, the comparative study for ELCA vs. other method was needed in further investigation. Moreover, long term follow-up is warranted to verify the safety of ELCA.