During 2011 and 2012, the study included 135 patients with bifurcation lesions treated with the provisional stenting technique. The patients met the following inclusion criteria: a) irrespective of its length, morphology or angulation, MV lesion > 50% located at a bifurcation point; b) MV diameter ≥ 2.5mm; c) SB diameter ≥ 2.25mm; and d) length of the stenosis in the SB < 10mm. Exclusion criteria: a) contraindications to dual antiplatelet therapy; b) acute phase of myocardial infarction (direct or rescue angioplasty), and c) cardiogenic shock. All patients gave written informed consent.

All interventions were performed using the femoral approach. All patients were treated using a stepwise provisional stenting strategy.16 A first stent was implanted in the MV and a guidewire was jailed between the stent mesh and the SB vessel wall. At this point, the SB ostium was evaluated. If the SB was compromised, another guidewire was advanced into the SB, the jailed guidewire was extracted, and the SB was simultaneously or sequentially dilated. After this maneuver, the SB ostium was again evaluated and a second stent was implanted in the SB at the discretion of the operator. The operator also chose the type of guidewire to be jailed. Two types were available: “nonpolymer-coated” BMW [Balance MiddleWeight] and Floppy II models; Abbot Vascular, Illinois, United States) and “polymer-coated” (Pilot 50 or Whisper MS models; Abbott Vascular). Procedural success was defined as TIMI (Thrombolysis In Myocardial Infarction) grade 3 flow in both the MV and SB and residual stenosis visually estimated as ≤ 20% in the MV. At the time of percutaneous coronary intervention, all patients were receiving dual antiplatelet therapy with acetylsalicylic acid and clopidogrel. Procedural anticoagulation was achieved with unfractionated heparin (100 U/kg intravenous bolus). Glycoprotein IIb/IIIa inhibitors were administered at the discretion of the operator. After the intervention, all patients received combined anticoagulant and dual antiplatelet therapy for 12 months and were instructed to continue aspirin indefinitely. After percutaneous coronary intervention, all patients underwent an electrocardiogram and troponin and creatine levels were measured at 6hours and 24hours. If clinically indicated, further electrocardiograms and enzyme tests were ordered. Non-Q-wave myocardial infarction was defined as an increase in the creatine kinase level up to 3 times the upper limit of the normal range.

The Medina classification was used to assess the anatomy of the bifurcation at baseline.17 All patients underwent angiograms before and after percutaneous coronary intervention, and the MV and SB reference diameters, minimal lumen diameters, and percentages of stenosis were measured. Data were obtained on a group of variables that could influence subsequent damage to the guidewire, such as the type of bifurcation, tortuosity, and calcification.

During the study period, coronary guidewires were consecutively collected that had been used to treat the bifurcation lesions using the jailed guidewire technique. After the guidewires were withdrawn, they were cleaned with an aqueous solution and allowed to dry before analysis. The microscopic study was performed using an SMZ-800 stereomicroscope (Nikon Instruments, Inc.; Melville, New York, United States). This microscope is mounted with a parallel double lens and interchangeable objectives with a magnification range of 1.0× to 6.3× and a standard visual field of 3.5 mm to 22.0 mm. Microphotographs were acquired using a DS-Fi1 color camera (two-thirds inch, high-density CCD; 5.24 million pixels; Nikon Instruments). Recorded image sizes range from 2560×1920 pixels (maximum 10 frames per second) to 1280×960 pixels (maximum 21 frames per second). A 100-W P-ICI2 coaxial episcopic illuminator (Nikon Instruments) was used to improve image quality. This device controls power and light intensity via an external transformer coupled by optical fiber.

Low magnification was used to evaluate the first 40cm of the distal end of the coronary guidewire and higher magnification was used to examine areas with suspected damage in more detail. The external and internal covers were examined for changes. Images were acquired of damage, which was graded into 5 categories:

• 1.

  No damage: the guidewire suffered no loss of integrity over its entire length (Figure 2).

  
  

  Figure 2.

  Images of new guidewires obtained by stereo microscopy. A: nonpolymer-coated guidewire. B: polymer-coated guidewire.

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• 2.

  Slight damage (Figure 3A): the external cover suffered loss of integrity ≤ 2mm.

  
  

  Figure 3.

  Different degrees of damage in nonpolymer-coated guidewires after using the jailed guidewire technique. A: mild damage. B: moderate damage. C: severe damage.

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• 3.

  Moderate damage (Figure 3B): the external cover suffered loss of integrity > 2mm.

• 4.

  Severe damage (Figure 3C): visible changes to the inner cover of the guidewire.

• 5.

  Fracture: discontinuity at some point along the guidewire.

Dichotomous variables are expressed as numbers and percentages of the total. Quantitative variables are expressed as mean±standard deviation. The chi-square test or Fisher's exact test was used to analyze differences between proportions. The Student-Fisher t test for unpaired data was used to compare continuous variables in both groups of patients. A P value of < .05 was used as a cutoff for statistical significance. All analyzes were performed using the SPSS 20 0.0 software package.

Table 1 shows the baseline clinical and angiographic data. Most patients were admitted for acute coronary syndrome. The distributions by age, sex, risk factors, and clinical characteristics were similar in both groups (Table 1) except for that of diabetes mellitus, which was significantly higher in the polymer-coated guidewire group (50% vs 27%; P<.01). The most frequently affected bifurcation was the anterior descending artery/diagonal branch without significant differences between groups (Table 2). Table 3 shows the characteristics of the interventions. Lesions in both groups were treated in a similar manner. However, in the polymer-coated stent group significantly more stents were needed (1.45±0.60 vs 1.06±0.25 stents; P<.001) and the use of SB postdilation was significantly higher (70% vs 45%; P=.02). A second stent was rarely used in the SB and its use was almost identical in both groups (9%). There were no significant differences between groups regarding other technical aspects or the use of glycoprotein IIb/IIIa platelet inhibitors. Both groups were similar regarding bifurcation location, MV size, SB size, stenosis severity, and the type of bifurcation lesion according to the Medina classification (Tables 2 and 4). The prevalence of coronary calcification was significantly higher in the polymer-coated guidewire group (79% vs 53%; P<.002).

Table 4 shows the quantitative angiographic data. The minimal lumen diameter, percentage of stenosis in the treated segments, and the immediate postintervention reduction in this percentage was similar in the MV of both groups. However, lesions in the origin of the SB were more severe in the polymer-coated guidewire group; the percentage of stenosis in the origin of the SB was higher (53%±32% vs 31%±31%; P<.003) and the minimum luminal diameter was smaller (1.04±0.7mm vs 1.70±0.8mm; P<.002). There were no significant differences between the 2 types of guidewires regarding the development of complications. There was 1 death in each group. One patient in the nonpolymer-coated guidewire group died of ventricular fibrillation 48hours after the procedure, and 1 patient in the polymer-coated guidewire group died after a compassionate revascularization procedure.

Some type of microscopic damage was observed in 25 of the guidewires analyzed (18%). Damage was more frequent in nonpolymer-coated guidewires (53.0% vs 1.1%; P<.001). However, severe damage was observed in only 2 guidewires (1.5%), both of which were nonpolymer-coated. There were no cases of complete fracture. Table 5 shows the results of the microscopic analysis of the guidewires.

The implantation of a stent in the MV can displace the carina, which may affect or occlude the origin of the SB. In these situations, the jailed guidewire helps to keep the SB open and, in the event of occlusion, the guidewire is the only marker of its position. It also facilitates access to the SB by favorably changing the angle of the bifurcation. An additional advantage is that it anchors the guidewire, thus facilitating the intubation of the guidewire catheter and providing firmer support for the balloon to cross the origin of the SB. Finally, in extreme situations, it can be used to introduce a low-profile balloon and dilate the SB, and to conclude the intervention using the inverted crush technique or to redilate the stent crushed in the MV once the branch occlusion has been resolved.19

Given that the MV stent is retained under pressure against the arterial wall, the guidewire jailed between these 2 structures may suffer damage and even fracture at the time of withdrawal. Although rare, the guidewire can fracture during withdrawal, which is a severe procedural complication that may require its urgent surgical removal.7–15 However, preventative measures exist, which include avoiding the following: the use of polymer-coated guidewires, locating the distal portion of the guidewire in small-caliber secondary vessels, using high pressures during stent release, covering a large portion of the jailed guidewire with stents, and postdilation of the MV with balloon, which should only be done if needed and only with short “noncompliant” balloons.9

Currently, a wide variety of coronary guidewires are available with different properties that make them suitable for various indications. According to their external coating, guidewires can be classified as polymer-coated or nonpolymer-coated (Figure 2). Although there are no randomized studies that have determined the most suitable guidewire in the jailed guidewire technique, expert recommendations advise against the use of polymer-coated guidewires during this technique based on the argument that that they are more susceptible to fracture than nonpolymer-coated guidewires.6,8,20 Given that the fracture rate is very low, it would be difficult to design a randomized study to identify which type of guidewire is more resistant to fracture during this technique.

This pilot study used microscopic damage to the guidewire as a surrogate variable of fracture. It was found that a non-negligible percentage of nonpolymer-coated guidewires suffered some type of external damage and even inner damage, whereas only 1 polymer-coated guidewire showed moderate damage to the external coating (Figure 4). Microscopic damage was not associated with clinical events and there were no fractures. The use of polymer-coated guidewires was not associated with an increased number of complications. Thus, the relevance of this study lies in its technical aspects, rather than in its clinical aspects.

Figure 4.

Moderate damage to a polymer-coated guidewire after use of the jailed guidewire technique.

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This study was an observational study. In addition, the choice of guidewire was left to the operator's discretion, once the coronary anatomy and characteristics of the bifurcation had been assessed. The operators chose polymer-coated guidewires for more complex, more calcified, and more severe bifurcations. Although this situation may have led to negative bias regarding the polymer-coated guidewire group, paradoxically these guidewires suffered the least damage (despite their not being recommended for this use).

The study also has 3 methodological limitations. Firstly, the choice of only 2 types of guidewire per group could hinder the extrapolation of the results to other types of guidewires. Secondly, a traditional stereomicroscope was used to evaluate damage. The optical resolution of this instrument is limited, which we sought to overcome by the use of a coaxial episcopic illuminator. Thirdly, the proposed classification for assessing the damage was arbitrary and the use of > 2mm in length as a cutoff point for damage was chosen on the basis of our own observations that the use of a shorter length makes it difficult to identify damage by visual inspection. It would be of little relevance to identify only minor damage by the use of sophisticated technology.

Since no articles have been published on the present topic, we believe that the results of this study can provide a basis for future research using larger randomized trials.