Importance of Adjunct Delivery Techniques to Optimize Deployment Success of Distal Protection Filters During Vein Graft Intervention

Abstract: Objectives. This study assessed the impact of adjunct delivery techniques on the deployment success of distal protection filters in saphenous vein grafts (SVGs). Background. Despite their proven clinical benefit, distal protection devices are underutilized in SVG interventions. Deployment of distal protection filters can be technically challenging in the presence of complex anatomy. Techniques that facilitate the delivery success of these devices could potentially improve clinical outcomes and promote greater use of distal protection. Methods. Outcomes of 105 consecutive SVG interventions with attempted use of a FilterWire distal protection device (Boston Scientific) were reviewed. In patients in whom filter delivery initially failed, the success of attempted redeployment using adjunct delivery techniques was assessed. Two strategies were utilized sequentially: (1) a 0.014˝ moderate-stiffness hydrophilic guidewire was placed first to function as a parallel buddy wire to support subsequent FilterWire crossing; and (2) if the buddy-wire approach failed, predilation with a 2.0 mm balloon at low pressure was performed followed by reattempted filter delivery. Results. The study population consisted of 80 men and 25 women aged 73 ± 10 years. Mean SVG age was 14 ± 6 years. Complex disease (American College of Cardiology/American Heart Association class B2 or C) was present in 92%. Initial delivery of the FilterWire was successful in 82/105 patients (78.1%). Of the 23 patients with initial failed delivery, 8 (35%) had successful deployment with a buddy wire alone, 7 (30%) had successful deployment with balloon predilation plus buddy wire, 4 (17%) had failed reattempt at deployment despite adjunct maneuvers, and in 4 (17%) no additional attempts at deployment were made at the operator’s discretion. Deployment failure was reduced from 21.9% initially to 7.6% after use of adjunct delivery techniques (P<.01). No adverse events were observed with these measures. Conclusions. Deployment of distal protection devices can be technically difficult with complex SVG disease. Adjunct delivery techniques are important to optimize deployment success of distal protection filters during SVG intervention.

J INVASIVE CARDIOL 2017;29(2):54-58. Epub 2016 December 15.

Key words: coronary artery bypass graft, distal embolization, embolization protection devices, no-reflow phenomenon, percutaneous coronary intervention, saphenous vein graft

Percutaneous coronary intervention (PCI) of saphenous vein grafts (SVGs) is fraught with a high risk of complications due to distal embolization and no-reflow.^1-5 Distal protection devices have been demonstrated to significantly reduce these risks.^6,7 Use of these devices in SVG interventions is a class I recommendation in the American College of Cardiology (ACC)/American Heart Association (AHA)/Society of Cardiac Angiography and Interventions (SCAI) PCI guidelines.⁸ Despite their proven clinical benefit, distal protection devices are underutilized in SVG procedures.^9-11

Placement of distal protection filters can be technically challenging in the presence of significant tortuosity or complex high-grade lesions.¹² Such technical difficulties result in deployment failure and likely contribute to the reluctance of some operators to use these devices more routinely.^13,14 Accordingly, techniques to facilitate the delivery success of distal filters could potentially improve clinical outcomes while promoting greater usage of the devices. The goal of this study was to assess the impact of adjunctive delivery techniques on the deployment success of distal protection filters in SVG intervention. 

Methods

A retrospective angiographic and medical record chart review was performed to identify procedural outcomes of 105 consecutive SVG interventions with attempted use of a FilterWire distal protection device (Boston Scientific). Patients with a totally occluded SVG or with an inadequate landing zone for a FilterWire were excluded. Patients with unsuccessful initial filter delivery underwent two sequential adjunct strategies to reattempt deployment. The initial adjunct strategy was placement of a 0.014˝ moderate-stiffness hydrophilic guidewire into the SVG to function as a parallel buddy wire to support subsequent FilterWire crossing. If there was failure to deliver the FilterWire with use of the buddy wire alone, predilation of the lesion at low pressures with a 2.0 mm balloon was performed followed by reattempted delivery of the FilterWire with the original buddy wire in place. Procedural angiograms were analyzed using quantitative and qualitative analyses to evaluate SVG characteristics associated with failure of FilterWire delivery. Success rates of filter placement before and after use of adjunct delivery techniques were compared using Chi² analysis. A P-value <.05 was considered statistically significant.  

Results

Baseline clinical characteristics are summarized in Table 1. The patient population consisted of 80 men and 25 women. Mean patient age was 73 ± 10 years. Diabetes was present in 42%. Clinical presentation was an acute coronary syndrome in 71%. Detailed anatomic features by qualitative and quantitative coronary analyses are presented in Table 2. Mean SVG age was 13.7 ± 5.9 years. Complex SVG disease (ACC/AHA lesion class B2 or C) was present in 92% of patients. 

A flow diagram summarizing the outcomes of attempted FilterWire delivery is depicted in Figure 1. Initial delivery of a distal protection filter was successful in 82 patients without adjunct techniques. Of the 23 patients with initial failed delivery, 8 (35%) had successful deployment with a buddy wire alone, 7 (30%) had successful deployment with balloon predilation plus buddy wire, 4 (17%) had failed reattempt at deployment despite adjunct maneuvers, and in 4 (17%), no additional attempts at deployment were made at the operator’s discretion. With use of adjunct delivery techniques, the deployment failure rate decreased from 21.9% initially to only 7.6% (P<.01) (Figure 2). All patients with an initial unsuccessful filter deployment had two or more of the following features: SVG degeneration score of at least 50%, minimum lumen diameter of <1 mm, severe vessel tortuosity, and total lesion length >20 mm. Angiograms from an illustrative case are shown in Figure 3. 

PCI was successful in all 105 patients. One patient had a non-fatal periprocedural myocardial infarction. There were no in-hospital deaths or other major adverse cardiac events. Importantly, there were no complications or adverse cardiac events in patients in whom buddy wire or predilation techniques were used to facilitate FilterWire delivery. 

Discussion

PCI of older venous bypass grafts is associated with a high risk of ischemic complications due to distal embolization and no-reflow.^1-5 Distal protection devices have been shown to significantly reduce the risk of procedural complications during SVG intervention. In the landmark SAFER trial, use of distal protection resulted in a 42% relative reduction in major adverse cardiac events.⁶ Accordingly, ACC/AHA/SCAI PCI guidelines confer a class I recommendation for use of distal protection devices during SVG intervention.⁸ 

Despite the evidence of clinical benefit and current guideline recommendations, distal protection devices continue to be underutilized. Two large series from the National Cardiovascular Data Registry have reported that distal protection is used in <25% of vein graft PCI.^9,11 While anatomic factors may prohibit use of distal protection devices in some patients, the reluctance of operators to use them routinely likely also relates to the perception that the devices are cumbersome and complicated to use.^13,14

The currently available distal protection filters, FilterWire EZ (Boston Scientific) and SpiderFX embolic protection device (Covidien), have deployment sheaths with 3.2 Fr outer diameters. Because of the crossing profile and stiffness of these devices, placement of distal protection filters can be technically challenging in the face of severe tortuosity or tight stenoses. Accordingly, techniques that facilitate the delivery success of distal protection devices could potentially improve clinical outcomes and foster greater adoption of these devices by interventionalists. 

In the initial clinical study of the first-generation FilterWire, Popma and colleagues reported successful deployment of the device in 86% of vein grafts.¹² In the event of initial failure of the filter to cross the stenosis, the authors described use of a second wire as a buddy wire and, if needed, using an undersized balloon dilation to permit passage of the device. However, the frequency with which these adjunctive techniques were used was not reported. In the randomized FIRE trial, FilterWire deployment was successfully achieved in over 90% of cases, but the use of additional deployment tricks was not discussed.⁷ Therefore, it remains possible, if not probable, that the utility of these relatively simple adjunctive delivery techniques go underappreciated by many operators.

In this consecutive series of SVG interventions, initial delivery of the FilterWire failed in approximately 22% of attempts. Among patients with initially failed delivery, repeat attempts at deployment with the described techniques were successful in 79%. These maneuvers reduced delivery failure from 21.9% to 7.6% (P<.01). Special note should be made that balloon predilation prior to stenting can result in distal embolization in vein grafts.¹⁵ In order to facilitate the passage of filter delivery catheters but avoid distal embolization, we specifically used undersized 2.0 mm balloon catheters inflated at low pressures. Importantly, there were no ischemic or embolic complications related to these auxiliary delivery techniques. While this study focused on delivery of the FilterWire, these techniques may theoretically be used in the delivery of alternative types of distal protection filters. 

Conclusion

Deployment of distal protection devices can be technically difficult with complex SVG disease. Adjunctive delivery techniques are important to optimize deployment success of distal protection filters during SVG intervention. Interventionalists must be aware of the technical challenges of distal protection filter delivery and how to overcome them in order to adhere to best practice guidelines during SVG interventions.

References

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From ¹MedStar Heart and Vascular Institute, Union Memorial Hospital, Baltimore, Maryland; ²Easton Hospital, Easton, Pennsylvania; ³Thomas Jefferson University Hospital, Philadelphia, Pennsylvania; and ⁴Northwell Health, Manhasset, New York.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Fischman reports stock options in Medtronic and Boston Scientific (unrelated to this manuscript). The remaining authors report no conflicts of interest regarding the content herein.

Manuscript submitted August 5, 2016, provisional acceptance given on August 9, 2016, accepted on August 23, 2016.

Address for correspondence: Michael P. Savage, MD, FACC, FSCAI, FACP, Jefferson Angioplasty Center, Thomas Jefferson University Hospital, 111 South 11th Street, Gibbon Building, Suite 6210, Philadelphia, PA 19107. Email: michael.savage@jefferson.edu.