Using the Viabahn for SFA In-Stent Restenosis

The application of a covered stent to treat nitinol stent restenosis in the SFA has so far proven to be a promising approach.

By Gary M. Ansel, MD; Charles F. Botti, Jr, MD; and Mitchell J. Silver, DO
 

Although nitinol stents appear to be improving the results of endovascular treatment of the superficial femoral artery, restenosis still occurs in a significant number of patients. Focal restenosis may be easily treated by balloon angioplasty; however, effective long-term treatment of diffuse stent restenosis has yet to be defined. This case study and the text that follows describes our institution’s early experience of debulking and stent grafting these lesions.

CASE PRESENTATION

A 72-year-old woman presented with recurrent, symptomatic right-calf claudication. She had undergone placement of a self-expanding stainless steel stent in the right superficial femoral artery (SFA) 6 months previously at an outside institution. The patient reported that recurrent symptoms started approximately 3 months after the procedure, but they had worsened to the point that she could not function at her work place. The patient had a history of coronary artery disease with stable angina that was being treated medically. Her resting ankle-brachial index (ABI) was .49. Repeat peripheral angiography showed total occlusion of the right SFA. After review of the initial angiogram, it was believed that the proximal vessel was not adequately treated.

The patient underwent repeat balloon angioplasty with adjunctive nitinol stent placement of the proximal vessel. The postprocedure ABI improved to .94, and she was asymptomatic. Three months later, the patient again developed recurrent symptoms. Noninvasive duplex scanning again showed recurrent closure of the SFA. A trial of oral cilostazol was attempted; however, the patient developed significant headache and gastrointestinal intolerance. The dosage was lowered but still not tolerated. Two months later, the patient underwent laser atherectomy and repeat balloon angioplasty with resolution of her symptoms.

Six months later, the patient again developed recurrent symptomatic occlusion. She was then entered into a randomized radiation versus balloon angioplasty trial. However, the patient was randomized to no radiation, and 3 months later, symptoms recurred. She was offered repeat intervention with polytetrafluoroethylene (PTFE)-covered Viabahn stents (Figure 1). To allow for the fullest expansion of this graft stent combination, debulking with laser atherectomy was used prior to balloon angioplasty and stenting.

The final angiographic result was excellent (Figure 2). No residual pressure gradient across the stented area was present, and the patient’s postprocedure ABI was .96. She continued to be asymptomatic, with documented patency both by noninvasive duplex scanning and angiography 18 months later (Figure 3). Her ABI was .93.

SFA TREATMENT OPTIONS

Symptomatic lower-limb ischemia commonly results from atherosclerotic disease of the SFA. Currently, more than 100,000 patients undergo invasive treatment of the SFA each year, and this number is expected to continue to escalate. Although 5-year primary patency rates with surgical venous bypass of 80% or more have been reported, other controlled trials have shown much poorer results with primary 2-year patency rates closer to 66%.1,2 Given the significant morbidity and mortality rates associated with open surgery, endovascular procedures, which present lower risk and are repeatable, have begun to flourish and are more frequently offered as a primary treatment option. The use of stand-alone balloon angioplasty has been shown to have acceptable results in short lesions but randomized trial data have shown stenting to be associated with significantly lower patient risk.3

The historical results of stenting in the SFA have been mixed, and early results with self-expanding stainless steel stents appeared to be dismal. However, these data are confounded by poor study designs. Large-diameter stents were commonly utilized in small-diameter vessels and antiplatelet regimens were suboptimal; assisted and secondary patency were rarely addressed.4,5 More contemporary data using these stents appear to show improved clinical results. Gordon et al evaluated their use of the Wallstent (Boston Scientific Corporation, Natick, MA) in long SFA occlusions. Although the primary patency of 29.9% was very poor, the secondary patency of 63% at 3 years certainly challenges the results of prosthetic surgical bypass grafts.6

SELF-EXPANDING STENTS AND RESTENOSIS

The more contemporary self-expanding stent market has gradually moved to the use of nitinol stents. Although diffuse restenosis still occurs in a significant number of patients, anecdotally we have found the pattern of restenosis to be more focal than that commonly seen with stainless steel stents. This experience is supported by the improved short and midterm results with these stents.7,8 However, unlike other vascular beds in which the stent result at approximately 9 months may be maintained, progression of disease and restenosis appears to lead to a continuing decrease in stent patency in the SFA.9 Although repeat balloon angioplasty is effective for focal restenosis, in our experience, diffuse long-segment nitinol stent restenosis has a high failure rate when treated by angioplasty alone.

THE ADVANTAGES OF COVERED STENTS

Review of the available literature studying utilization of PTFE self-expanding covered stents in the SFA suggests that it may offer an excellent option for the treatment of diffuse in-stent restenosis. PTFE graft material is inert with a very small pore size that does not allow for significant tissue ingrowth. There are currently eight retrospective and one randomized published studies.10-18 The average lesion length in these studies is 14 cm, and 61% of the lesions were total occlusions. A closer look at these studies offers some valuable insight. In the three studies with poor results (1-year primary patency <50%), deficiencies in techniques are obvious.10-12 These deficiencies included poor antiplatelet therapy, not stenting the entire angioplasty site, and not following study protocol and enrolling patients with unacceptable tibial runoff. Studies without these deficiencies have shown very good results (2-year primary patency >74%).13-18

As in the case presented, our early experience in a small number of patients has been very favorable. Ten patients with diffuse nitinol stent restenosis treated with Viabahn stents have been followed prospectively for a minimum of 1 year. Vessel and lesion characteristics include a mean lesion length of >26 cm, femoral vessel diameter ≥5 mm, and at least one tibial artery is patent to the foot. Duplex-defined primary, assisted primary, and secondary patency (<2 cm/sec) were 70%, 80%, and 90%, respectively. The one patient that thrombosed the Viabahn stent had previously experienced early femoropopliteal bypass thrombosis less than 1 year postprocedure. These results appear to be far superior to our experience with repeat balloon angioplasty, debulking, and restenting in this group with diffuse in-stent disease.

CONCLUSION

When considering the use of covered stents in the SFA, several issues must be considered. As in surgically placed grafts, several variables that affect patency may come into play. These variables include vessel diameter, inflow, and outflow. Thus, the vessel should be dilated to the true vessel diameter, and inflow or outflow obstructions should be addressed if possible. Because progression of disease is significant in the SFA, spot stenting is to be discouraged. The complete length of previously stented SFA, plus any area of progressing disease should be covered. Caution should be utilized if important collateral vessels are to be covered because acute limb-threatening ischemia may occur if the stent graft should close. In summary, stent grafting of diffuse nitinol stent restenosis appears to be a promising approach that should be further studied. 

Gary M. Ansel, MD, is Clinical Director for Peripheral Vascular Intervention, MidOhio Cardiology and Vascular Consultants, MidWest Research Foundation, Riverside Methodist Hospital, Columbus, Ohio. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Ansel may be reached at (614) 262-6772; gansel@mocvc.com.
Charles F. Botti, Jr., MD, is a cardiovascular interventionist/peripheral vascular interventionist at MidOhio Cardiology and Vascular Consultants, MidWest Cardiology Research Foundation, Riverside Methodist Hospital, Columbus, Ohio. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Botti may be reached at (614) 262-6772; cbotti@mocvc.com.
Mitchell J. Silver, DO, is a cardiovascular interventionist/ peripheral vascular interventionist at MidOhio Cardiology and Vascular Consultants, MidWest Cardiology Research Foundation, Riverside Methodist Hospital, Columbus, Ohio. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. He may be reached at (614) 262-6772; msilver@mocvc.com.

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