Recanalization of Femoral Artery with the Viabahn Stent Graft
Recanalization of Femoral Artery with the Viabahn Stent Graft
Objective: The treatment of long superficial femoral artery (SFA) chronic total occlusions (CTOs) remains controversial. There are several percutaneous treatment options available for the recanalization of these lesions. Percutaneous transluminal angioplasty (PTA) alone, nitinol stents, and expanded PTFE-lined nitinol stents are all viable treatment alternatives to femoral-popliteal bypass surgery. There are, however, limited data on outcomes of patients with SFA CTOs undergoing endovascular treatment. This study was performed to evaluate the safety, efficacy and 1-year patency rates of the Viabahn (WL Gore and Associates, Flagstaff, Arizona) e-polytetrafluoroethylene (e-PTFE) stent grafts at a major medical center in Phoenix, Arizona.
Methods: Thirty patients (32 limbs) were prospectively treated for activity-limiting claudication after failing medical therapy. These patients received traditional angioplasty and stenting techniques using the Viabahn e-PTFE stent graft. Follow-up ankle-brachial index (ABI) examinations and duplex surveillance were completed at 6 and 12 months in all patients.
Results: The mean age of the patients was 58.4 years. There were 12 women (40%) and 18 men (60%). Five of the patients (16.67%) were diabetics. The procedural success rate was 100%, with no in-hospital morbidity or mortality. The mean preprocedural ABI was 0.54 and the mean SFA occlusion length was 15.4 cm. The mean stented length was 24.6 cm. The median stent diameter was 6 mm. One patient (3.3%) did have subacute stent thrombosis at 4 months. On follow-up testing, the mean post-procedure ABI at 1 year was 0.76 with a primary patency rate of 80% and a primary assisted patency rate of 86%. Silent asymptomatic occlusions were noted in 10% (3/30) of the patients. Restenosis was a prespecified endpoint and was defined as being significant if the proximal peak velocity ratio (PVR) exceeded 2.4 on duplex interrogation. This endpoint was detected in 6.6% of the patient population (2/30) (proximal peak velocity ratio is the ratio of the maximum intrastenotic PSV and the maximum prestenotic PSV).
Conclusions: Percutaneous e-PTFE stent-grafting with the Viabahn stent graft is a viable treatment option for TASC D occlusions in the SFA in claudicants and patients with critical limb ischemia. Primary and primary assisted patency rates at 1 year are comparable to historical surgical outcomes using PTFE grafts as bypass conduits. Long-term data (> 5 years) in a larger patient cohort are necessary before definite conclusions can be drawn.
Atherosclerotic peripheral vascular disease (PVD) is often an underdiagnosed, undertreated and debilitating disease. The 2007 Trans-Atlantic Inter-Society Consensus (TASC) for the Management of Peripheral Arterial Disease document estimates that there are currently 27 million people in Europe and North America who are afflicted with this disease. There are also an estimated 413,000 hospital discharges per year due to chronic PVD. The prevalence of PVD increases progressively with age, beginning after the age of 40, a relationship demonstrated by the National Health and Nutrition Examination Survey. The authors found that PVD was present in 0.9% of those between the ages of 40-49 years, 2.5% of those 50-59 years old, 4.7% in the 60-69 year-old group and 14.5% in those ≥ 70 years. PVD will thus continue to grow in clinical significance as the world's population ages.
The use of percutaneous transluminal angioplasty (PTA) to revascularize the superficial femoral artery (SFA) can result in initial technical success rates > 95%, with a low risk of complications. However, late clinical failure remains an important concern. Restenosis occurs in 40-60% of treated segments after 1 year. The use of angioplasty to treat extensive disease of the SFA has particularly poor results: at 1 year, the rates of restenosis exceed 70% for lesions longer than 10 cm.
Stents avoid the problems of early recoil and flow-limiting dissection after balloon angioplasty and can thus be used for the treatment of long and complex lesions. Initial studies of stenting of the SFA reported promising results, with patency rates > 85% at 18 months. However, subsequent studies found that exaggerated neointimal hyperplasia frequently leads to in-stent restenosis, and randomized, controlled trials failed to demonstrate any benefit of a stainless-steel stent over angioplasty alone.
Investigation into evaluating efficacy of percutaneous stenting versus angioplasty alone has yielded conflicting results. The VIENNA trial demonstrated a 37% restenosis rate at 12 months in those with SFA stenting versus a 64% restenosis rate for those with angioplasty alone. This was further supported by the RESILIENT trial, which demonstrated superiority with target vessel revascularization (TVR) at 12 months in those with SFA stenting over angioplasty alone. It is important to note that the RESILIENT results were primarily from TASC A and B lesions, with significantly higher crossover than previous studies. In contrast, the FAST trial demonstrated no difference in binary restenosis at 12 months between PTA and stenting compared to PTA alone. This finding was confirmed by a recent meta-analysis, which concluded that while initial procedural success is higher with routine stenting, there was no detectable difference in restenosis or TVR in long-term follow up. Stenting of the SFA for TASC A and B lesions is currently recommended only as a bailout procedure after technical failure of angioplasty.
The last decade has ushered in many new endovascular treatment modalities for PVD including endovascular cryoplasty, cutting-balloon angioplasty, subintimal angioplasty, excisional atherectomy, excimer laser-assisted angioplasty, drug-eluting stents, biodegradable stents and e-PTFE covered self-expanding stents. The TASC II guidelines recommend endovascular treatment for TASC A and B lesions. Surgical revascularization has been the recommendation for TASC D lesions (lesion classifications are provided in Table 1 ). The guidelines are ambiguous as to how TASC C lesions are approached. There remains equipoise, with some recommending a trial of endovascular therapy first, while others suggest open surgical techniques as the frontline therapy. Though the guidelines recommend open surgery for the more severe cases (TASC C and D), many of these patients may benefit from less invasive endovascular treatments because they are not candidates for surgery due to a prohibitively high perioperative cardiovascular risk or other medical comorbidities. Many of these patients are denied any treatment, and thus frequently end up with the catastrophic consequence of limb loss.
Chronic total occlusions (CTOs) of the SFA are a particularly challenging lesion subset. Recanalization rates in CTOs are reported as > 85%. Pooled results also show 1- and 3-year patency rates for CTOs of 65% and 48% for PTA alone, and 73% and 64% for PTA/stent. There are no long-term data for PTA/stent, but the 5-year patency rates of PTA alone for stenosis and occlusion are 55% and 42%, respectively. Because of these success rates, many feel that patients with more extensive disease should be considered for percutaneous treatment and then referred for surgery if this approach fails. Bypass surgery with venous grafts must still be considered the most durable and extensively studied revascularization technique for patients with chronic limb ischemia and extensive disease of the SFA. The Bypass Surgery versus Angioplasty in Severe Ischemia of the Leg trial found that the rates of amputation-free survival after surgery and balloon angioplasty were similar for at least the first 2 years.
Nitinol stents may be an effective alternative to surgical revascularization for longer lesions in patients who are poor candidates for surgery, such as those with severe coexisting cardiovascular conditions. Furthermore, stenting may be an option for patients without available saphenous vein grafts, since the 12-month patency data for stents are similar to those for prosthetic bypass grafts, and stenting has a considerably lower rate of complications. However, the endovascular approach seems justified as long as the rates of complications are low and the surgical target zone for the distal anastomosis of a potential secondary bypass operation remains unaffected by the interventional procedure.
This study, conducted at a major teaching hospital, evaluated the safety, efficacy and 1-year patency rates of the Viabahn expanded-PTFE (e-PTFE) stent grafts (WL Gore and Associates, Flagstaff, Arizona) in patients with SFA disease and Functional Class II and III claudication.
Abstract and Introduction
Abstract
Objective: The treatment of long superficial femoral artery (SFA) chronic total occlusions (CTOs) remains controversial. There are several percutaneous treatment options available for the recanalization of these lesions. Percutaneous transluminal angioplasty (PTA) alone, nitinol stents, and expanded PTFE-lined nitinol stents are all viable treatment alternatives to femoral-popliteal bypass surgery. There are, however, limited data on outcomes of patients with SFA CTOs undergoing endovascular treatment. This study was performed to evaluate the safety, efficacy and 1-year patency rates of the Viabahn (WL Gore and Associates, Flagstaff, Arizona) e-polytetrafluoroethylene (e-PTFE) stent grafts at a major medical center in Phoenix, Arizona.
Methods: Thirty patients (32 limbs) were prospectively treated for activity-limiting claudication after failing medical therapy. These patients received traditional angioplasty and stenting techniques using the Viabahn e-PTFE stent graft. Follow-up ankle-brachial index (ABI) examinations and duplex surveillance were completed at 6 and 12 months in all patients.
Results: The mean age of the patients was 58.4 years. There were 12 women (40%) and 18 men (60%). Five of the patients (16.67%) were diabetics. The procedural success rate was 100%, with no in-hospital morbidity or mortality. The mean preprocedural ABI was 0.54 and the mean SFA occlusion length was 15.4 cm. The mean stented length was 24.6 cm. The median stent diameter was 6 mm. One patient (3.3%) did have subacute stent thrombosis at 4 months. On follow-up testing, the mean post-procedure ABI at 1 year was 0.76 with a primary patency rate of 80% and a primary assisted patency rate of 86%. Silent asymptomatic occlusions were noted in 10% (3/30) of the patients. Restenosis was a prespecified endpoint and was defined as being significant if the proximal peak velocity ratio (PVR) exceeded 2.4 on duplex interrogation. This endpoint was detected in 6.6% of the patient population (2/30) (proximal peak velocity ratio is the ratio of the maximum intrastenotic PSV and the maximum prestenotic PSV).
Conclusions: Percutaneous e-PTFE stent-grafting with the Viabahn stent graft is a viable treatment option for TASC D occlusions in the SFA in claudicants and patients with critical limb ischemia. Primary and primary assisted patency rates at 1 year are comparable to historical surgical outcomes using PTFE grafts as bypass conduits. Long-term data (> 5 years) in a larger patient cohort are necessary before definite conclusions can be drawn.
Introduction
Atherosclerotic peripheral vascular disease (PVD) is often an underdiagnosed, undertreated and debilitating disease. The 2007 Trans-Atlantic Inter-Society Consensus (TASC) for the Management of Peripheral Arterial Disease document estimates that there are currently 27 million people in Europe and North America who are afflicted with this disease. There are also an estimated 413,000 hospital discharges per year due to chronic PVD. The prevalence of PVD increases progressively with age, beginning after the age of 40, a relationship demonstrated by the National Health and Nutrition Examination Survey. The authors found that PVD was present in 0.9% of those between the ages of 40-49 years, 2.5% of those 50-59 years old, 4.7% in the 60-69 year-old group and 14.5% in those ≥ 70 years. PVD will thus continue to grow in clinical significance as the world's population ages.
The use of percutaneous transluminal angioplasty (PTA) to revascularize the superficial femoral artery (SFA) can result in initial technical success rates > 95%, with a low risk of complications. However, late clinical failure remains an important concern. Restenosis occurs in 40-60% of treated segments after 1 year. The use of angioplasty to treat extensive disease of the SFA has particularly poor results: at 1 year, the rates of restenosis exceed 70% for lesions longer than 10 cm.
Stents avoid the problems of early recoil and flow-limiting dissection after balloon angioplasty and can thus be used for the treatment of long and complex lesions. Initial studies of stenting of the SFA reported promising results, with patency rates > 85% at 18 months. However, subsequent studies found that exaggerated neointimal hyperplasia frequently leads to in-stent restenosis, and randomized, controlled trials failed to demonstrate any benefit of a stainless-steel stent over angioplasty alone.
Investigation into evaluating efficacy of percutaneous stenting versus angioplasty alone has yielded conflicting results. The VIENNA trial demonstrated a 37% restenosis rate at 12 months in those with SFA stenting versus a 64% restenosis rate for those with angioplasty alone. This was further supported by the RESILIENT trial, which demonstrated superiority with target vessel revascularization (TVR) at 12 months in those with SFA stenting over angioplasty alone. It is important to note that the RESILIENT results were primarily from TASC A and B lesions, with significantly higher crossover than previous studies. In contrast, the FAST trial demonstrated no difference in binary restenosis at 12 months between PTA and stenting compared to PTA alone. This finding was confirmed by a recent meta-analysis, which concluded that while initial procedural success is higher with routine stenting, there was no detectable difference in restenosis or TVR in long-term follow up. Stenting of the SFA for TASC A and B lesions is currently recommended only as a bailout procedure after technical failure of angioplasty.
The last decade has ushered in many new endovascular treatment modalities for PVD including endovascular cryoplasty, cutting-balloon angioplasty, subintimal angioplasty, excisional atherectomy, excimer laser-assisted angioplasty, drug-eluting stents, biodegradable stents and e-PTFE covered self-expanding stents. The TASC II guidelines recommend endovascular treatment for TASC A and B lesions. Surgical revascularization has been the recommendation for TASC D lesions (lesion classifications are provided in Table 1 ). The guidelines are ambiguous as to how TASC C lesions are approached. There remains equipoise, with some recommending a trial of endovascular therapy first, while others suggest open surgical techniques as the frontline therapy. Though the guidelines recommend open surgery for the more severe cases (TASC C and D), many of these patients may benefit from less invasive endovascular treatments because they are not candidates for surgery due to a prohibitively high perioperative cardiovascular risk or other medical comorbidities. Many of these patients are denied any treatment, and thus frequently end up with the catastrophic consequence of limb loss.
Chronic total occlusions (CTOs) of the SFA are a particularly challenging lesion subset. Recanalization rates in CTOs are reported as > 85%. Pooled results also show 1- and 3-year patency rates for CTOs of 65% and 48% for PTA alone, and 73% and 64% for PTA/stent. There are no long-term data for PTA/stent, but the 5-year patency rates of PTA alone for stenosis and occlusion are 55% and 42%, respectively. Because of these success rates, many feel that patients with more extensive disease should be considered for percutaneous treatment and then referred for surgery if this approach fails. Bypass surgery with venous grafts must still be considered the most durable and extensively studied revascularization technique for patients with chronic limb ischemia and extensive disease of the SFA. The Bypass Surgery versus Angioplasty in Severe Ischemia of the Leg trial found that the rates of amputation-free survival after surgery and balloon angioplasty were similar for at least the first 2 years.
Nitinol stents may be an effective alternative to surgical revascularization for longer lesions in patients who are poor candidates for surgery, such as those with severe coexisting cardiovascular conditions. Furthermore, stenting may be an option for patients without available saphenous vein grafts, since the 12-month patency data for stents are similar to those for prosthetic bypass grafts, and stenting has a considerably lower rate of complications. However, the endovascular approach seems justified as long as the rates of complications are low and the surgical target zone for the distal anastomosis of a potential secondary bypass operation remains unaffected by the interventional procedure.
This study, conducted at a major teaching hospital, evaluated the safety, efficacy and 1-year patency rates of the Viabahn expanded-PTFE (e-PTFE) stent grafts (WL Gore and Associates, Flagstaff, Arizona) in patients with SFA disease and Functional Class II and III claudication.
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