New Re-Entry Device for Revascularization of Chronic Coronary Total Occlusions: Preliminary Single Japanese Center Experience

Abstract: Background. Although retrograde approach for coronary chronic total occlusion (CTO) has been introduced, the procedure is still time and resource consuming. A simplified antegrade approach might be another resort. The aim of this study was to evaluate a new device designed to facilitate guidewire re-entry into the true lumen of a CTO from the adjacent subintimal space. Methods. Patients with CTO were entered into a prospective registry regardless of lesion characteristics. A new metal-tip catheter was used initially in primary use cases. If it created subintimal tracking, a new re-entry tool (a flat balloon with 2 exit ports offset by 180 degrees) was used as a platform to attempt guidewire penetration into the distal true lumen. In rescue use cases after unsuccessful conventional wiring, the re-entry procedure was subsequently attempted. Results. In 11 CTO lesions attempted, device success was achieved in 8 cases (72.7%). Re-entry procedure success rate was higher in primary use cases (80%) compared to rescue use cases (33.3%). Retrograde approach was conducted immediately after unsuccessful antegrade procedure using this device in the other 3 cases and successful recanalization was achieved in all cases. All lesions were stented, resulting in TIMI 3 flow without major complications. Conclusion. A new coronary re-entry device may provide another strategic option in the antegrade approach to recanalize CTOs.

J INVASIVE CARDIOL 2012;24(8):396-400

Key words: chronic total occlusion, percutaneous coronary intervention, subintimal tracking

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Successful recanalization of coronary chronic total occlusions (CTO) reduces angina,^1,2 improves impaired left ventricular function,^3,4 decreases the need for subsequent coronary artery bypass graft surgery,¹ and possibly improves long-term survival.^5,6 Although the introduction of the retrograde approach and dedicated new devices has improved the initial procedural success in percutaneous coronary intervention (PCI) of CTO,^7-10 the overall success rate remains unsatisfactory mainly because of antegrade subintimal wire trapping without available retrograde collateral channels.

Some specific CTO devices other than dedicated CTO guidewires have been introduced outside Japan;^11-13 however, the efficacy seems to be still generally limited. A new re-entry CTO device system was introduced (BridgePoint Medical, Inc) and the clinical potential has been shown in both  PCI and peripheral intervention.^14,15 This paper describes the initial clinical results and a sub-analysis of the intravascular ultrasound (IVUS) findings associated with the use of the BridgePoint device in Japanese patients.

Methods

Device description. The BridgePoint device system consists of 3 items: (1) the CrossBoss (CB), a new crossing metal catheter with a 1 mm blunt tip, which is used to create the space inside the occlusion by manual high-speed clockwise or counterclockwise rotation (Figure 1); (2) the Stingray re-entry balloon catheter (SB), which is an over-the-wire system with a flat balloon and two wire exports for puncture (Figure 2); and (3) the Stingray dedicated re-entry guidewire (SG), which is used for puncture from the Stingray balloon catheter (Figure 2). All components of the system are compatible for use in a 6 Fr guiding catheter.

Patient selection and procedure. Patients were recruited for this study if they had a previous coronary angiogram demonstrating a CTO in one of their native coronary arteries. A CTO was defined as an obstruction with Thrombolysis in Myocardial Infarction (TIMI) flow grade 0 and the estimated occlusive duration was unknown or >3 months. Although no patient in this series was turned down for an attempt at recanalization because of adverse angiographic features, such as severe calcification, tortuosity, lack of a visible entry point, or excessive lesion length, the patient selection highly depended on the availability of this device. All subjects provided informed consent for the procedure using this device.

After successful arterial access with one or two 6-8 Fr sheaths was accomplished, heparin bolus was given to achieve an activated clotting time (ACT) >250 seconds. Bilateral coronary injections to visualize collateral circulation were utilized unless antegrade collaterals provided excellent details of the distal lumen. In the primary use of this device, a CB catheter was advanced ahead of the occlusion using a traditional 0.014˝ coronary wire. Then the CB catheter alone was pushed into the occlusion with a manual high-speed clockwise or counterclockwise rotation. An intermediate wire was used to probe the occlusive segment when the CB catheter migrated into side branches or stopped at the bend inside the occlusion. When the CB catheter successfully created the channel into a distal lumen, a soft wire was advanced there through the inner lumen, and the subsequent procedure was then performed in a conventional PCI manner. If the CB catheter created subintimal space beyond the occlusive segment, it was changed to the SB catheter by using a soft wire. The SB catheter was positioned at the potential re-entry site and then inflated to 3-4 atm. Coronary angiography in appropriate angles was next utilized to determine the orientation of the subintimal re-entry balloon exit ports above or below, right or left of the true lumen re-entry target. The SG was next used to attempt penetration into the true lumen. After successful wire positioning in the distal true lumen was confirmed by angiography, the re-entry balloon catheter was deflated and removed, leaving the wire in place. When the SG could not be advanced into the distal true lumen even after successful puncture, the wire was changed to a slippery soft wire to navigate the distal channel. Subsequent standard balloon dilation was performed, followed by drug-eluting stent placement to complete revascularization. In some cases, this device was used as a rescue alternative after unsuccessful antegrade wiring with a 0.014˝ conventional wire. In those cases, the CB catheter was not used to advance the SB catheter. In cases of unsuccessful antegrade revascularization by using this system, the retrograde approach was then applied to achieve procedural success. ACT was checked every hour and kept >250 seconds in the antegrade approach and >300 seconds in the retrograde approach with additional heparin until the end of procedure.

Patients were hospitalized overnight and discharged the next day if there was no major adverse cardiac event (MACE). MACE included all death, emergent bypass surgery, repeated revascularization, Q-wave or non-Q wave myocardial infarction (MI), any vascular complications, and contrast-induced nephropathy (CIN). Documentation of new, pathological Q waves in 2 or more contiguous leads in an electrocardiogram associated with any elevation of creatine kinase-MB was required for a diagnosis of Q-wave myocardial infarction. Non-Q wave myocardial infarction was defined as the elevation of creatine kinase to more than twice the upper limit associated with any elevation of creatine kinase-MB without the appearance of Q waves. CIN was defined as either >25% increase of serum creatinine or an absolute increase in serum creatinine of 0.5 mg/dL. Device success and procedural success rates were examined as well as procedural complications. Device success was defined as successful revascularization using this device system. Re-entry procedure success was defined as successful puncture using SB catheter and SG. Procedural success was defined as an achievement of final TIMI flow grade 3 without residual stenosis >50%.

Quantitative coronary angiography was conducted with the Cardiovascular Measurement System (CMS-MEDIS Medical Imaging Systems). Occlusion length was assessed from the start of the occlusion to distal antegrade or retrograde vessel filling from bridging collaterals or collaterals provided by a coronary artery other than the target vessel, and using simultaneous contrast medium injection in both right and left coronary arteries, if necessary.

IVUS sub-analysis. IVUS examination was routinely used as much as possible. To investigate the influence of the intimal thickness on re-entry procedure with SB catheter and SG, it was measured by an independent IVUS expert in recorded images with auto-pull back by 0.5 mm/second. In cases with successful re-entry procedure, IVUS recording was done after 1.5 mm balloon dilatation beyond the puncture site. Puncture site was carefully determined by IVUS image and procedural angiogram, and intimal thickness was then measured in 3 segments: puncture site, and 1 mm distal and proximal to the puncture site. In cases with successful retrograde approach after unsuccessful re-entry procedure, IVUS recording was done after antegrade 1.5 mm balloon dilatation. In those cases, puncturing was attempted several times before retrograde approach, so that intimal thickness was measured in 3 segments at each attempted site. Attempted puncturing direction was carefully identified by side-branch direction in IVUS and procedural angiogram. The data were expressed as mean ± standard deviation. Student’s t-test or non-parametric analysis by the Mann-Whitney U-test were used for comparison.

Results

This device system was used in 11 CTO cases; primary use for 8 cases and rescue use for the other 3 cases. Table 1 summarizes the baseline patient and lesion demographics. Figure 3 shows a flow chart of procedural results and Table 2 summarizes the procedural results in detail. Five of the cases were re-attempted cases that were previous failures. Among 8 cases for primary use, the CB catheter successfully crossed the entire occlusion in 3 cases; CB catheter success rate was thus 37.5% (3/8). However, in 2 of those cases, an intermediate wire (Miracle 3, Asahi Intecc) was required to change the direction of CB catheter inside the occlusion. In the other 5 cases, after subintimal passage of CB catheter, a puncture by using SB catheter and SG was attempted. Although the SB catheter was successfully advanced in all of the cases, successful re-entry was achieved in 4 cases. The reason for unsuccessful re-entry in 1 case was the balloon rupture of the SB catheter, which caused expansion of subintimal dissected space. In the 3 cases in which the SB was used for rescue use after subintimal tracking with conventional wire, the Corsair microcatheter (Asahi Intecc) was used for the successful advancement of SB catheter; however, the re-entry procedure was successful in only 1 case. Therefore, the overall re-entry procedural success rate by using SB catheter and SG was 62.5% (5/8). In 2 of those cases, the SG was changed to a slippery wire (Fielder XT, Asahi Intecc) in order to navigate the distal true lumen. For all 3 cases with an unsuccessful re-entry procedure, the retrograde approach was attempted immediately and was successful in all cases. Therefore, procedural success with drug-eluting stent implantation was achieved in all 11 cases without any MACE, and the patients were discharged the next day. Fluoroscopy time was 41.3 ± 28.2 minutes in the primary use group and 88.7 ± 35.2 minutes in the rescue use group. Contrast volume was 181 ± 115 mL in the primary use group and 307 ± 61 mL in the rescue use group. Postprocedural reference diameter was 3.37 ± 0.39 mm, minimal lumen diameter was 3.05 ± 0.36 mm, and diameter stenosis was 8.9 ± 3.9%.

The overall device success rate was 72.7% (8/11): 87.5% (7/8) in the primary and 33.3% (1/3) in the rescue use group. Re-entry procedure success rate was 80% (4/5) in the primary and 33.3% (1/3) in the rescue use group. A case example is shown in Figure 4.

Adequate IVUS examination could be done in 4 cases with successful and in 1 case with unsuccessful re-entry procedure after 3 puncturing attempts. Therefore, the intimal thickness was measured in 12 segments in successful cases and 9 segments in unsuccessful cases. The thickness was significantly thinner in the successful case group compared to the unsuccessful case group with the re-entry procedure (0.33 ± 0.18 mm vs 1.32 ± 0.36 mm; P=.001). Both case examples are shown in Figure 5.

Discussion

Initial procedural success rate of PCI of CTO has been improved by the introduction of dedicated guidewires and development of new wiring techniques. The retrograde approach has significantly improved the overall success rate.^7-10 However, it requires a high level of operator experience⁹ and always carries the risk of a critical event during the procedure caused by donor artery trouble. Also, this bilateral approach for CTO requires longer fluoroscopy and procedure times.^7-9 Therefore, the strategy facilitating antegrade recanalization without retrograde approach should be considered as another strategic goal. Although some new devices to enhance antegrade recanalization other than conventional wiring technique have been introduced over the years, those success rates were not satisfactory.^11-13 This report describes that a new re-entry device system has the potential to facilitate antegrade approach in PCI of CTO.

The blunt tip of the CB catheter easily creates antegrade lumen inside the occlusion. However, the true channel tracking by this catheter alone is not promising (37.5% in this report). Also, to control the direction inside the occlusion, an intermediate CTO wire is frequently required. However, the CB catheter itself may play a crucial role to minimize the antegrade dissected space for successful re-entry procedure. Considering the results from our experience and another operator reports, it’s basically important to minimize the antegrade subintimal space in order to achieve successful re-entry by using the SB catheter and SG. In 1 unsuccessful re-entry case in primary use, unexpected balloon rupture of the SB catheter created a huge subintimal space. Among 3 cases in rescue use after failed conventional wiring causing the expansion of subintimal space, successful re-entry was achieved in only 1 case. Werner et al also reported a higher success rate in primary use (71%) compared to rescue use (50%) in their first European experience of this device system.¹³ Therefore, for a successful re-entry procedure, it’s mandatory to minimize the subintimal platform and stabilize the SB catheter for puncturing by SG.

Another determinant of a successful re-entry procedure may be the target position for puncture. The number was quite limited; however, IVUS examination in this series showed that the intima was significantly thinner at successful puncture site compared to unsuccessful puncture site. Because the vertical penetration depth created by SG puncture toward the true lumen is inevitably limited, a thicker intima may prohibit a successful re-entry procedure. Therefore, the target position should be selected at a healthy-looking distal true lumen. In other words, cases with a diffuse narrowing distal true lumen may not be good candidates for this device system. In addition to angiographic information and the anatomical conditions during the procedure, the images of a preprocedural multi-detective computed tomography may be helpful for making reentry decisions during the procedure.¹⁶

Clinical implications. There are considerable device-specific procedural complications or risks: (1) migration of CB catheter into side branch with or without branch vessel perforation; (2) wire perforation caused by SG puncture to a wrong direction; and (3) loss of big side branches due to a long subintimal passage beyond the occlusion. The first issue could be overcome by using an intermediate wire to probe the correct direction. Decision-making of puncture direction should be carefully done by orthogonal contralateral injection. CTOs involving a big side branch, such as a distal right coronary occlusion up to posterior bifurcation, are not indicated for this device.

We suggest the following rationale for use of this device system in our current Japanese practice. It is recommended that antegrade conventional wiring should be attempted first in each case. Considering that the availability of collateral channel is an independent predictor of procedural success regardless of CTO morphology,¹⁷ the retrograde approach should be considered secondly after antegrade wiring failure when a feasible collateral channel is identified and there isn’t high risk of donor artery trouble. If a collateral channel could not be identified or is unavailable, the re-entry procedure by using this device should be applied secondly except in cases with a diffuse narrowing distal true lumen or a big side branch. To minimize the subintimal platform for puncturing, the procedure must be commenced before aggressive parallel wiring or IVUS-guided penetration technique, because these types of wiring technique easily expand the subintimal space, which does not enable the SB catheter to be stabilized at the SG puncture.¹⁸ Therefore, if the case is re-attempted, direct use of the CB catheter should be considered. In cases without available collateral channel for retrograde approach, this device system provides a new methodology for rescue alternatives in the antegrade manner.

Study limitations. Since this is a preliminary single-center experience, the number included in this study is quite limited. Also, patient selection highly depended on the availability of the device unit, which was personally imported from the United States, as well as patient informed consent. Therefore, there was no consecutive lesion selection, which may cause some selection bias. Further study with a large number of patients in a multicenter registry is warranted and eventually a full randomized study would be helpful.

Conclusion

This new coronary re-entry device may provide another strategic option in the antegrade approach to recanalize CTOs.

References

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From the ¹Department of Cardiology, Toyohashi Heart Center, Toyohashi, Aichi, Japan and ²Cardiovascular Interventional Research, Torrance Memorial Medical Center, Torrance, California.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Tsuchikane is a consultant for Abbott Vascular, Boston Scientific, and Asahi Intecc.
Manuscript submitted February 8, 2012, provisional acceptance given March 12, 2012, final version accepted April 9, 2012.
Address for correspondence: Etsuo Tsuchikane, MD, PhD, Department of Cardiology, Toyohashi Heart Center, 21-1 Gobudori, Oyama, Toyohashi, Aichi, 441-8530 Japan. Email: dokincha@aioros.ocn.ne.jp