Final Results of the Protected Superficial Femoral Artery Trial Using the Filter Wire EZ System

Abstract

Conclusion: A distal protection device during femoral popliteal interventions reduces distal migration of debris. Summary: The study evaluated the safety and efficacy of a single distal protection device (Filter Wire EZ Embolic Protection System, Boston Scientific, Mountain View, Calif) for capturing debris during superficial femoral artery (SFA) percutaneous interventions. An additional aim was to define the incidence of distal embolization during SFA interventions. This was a prospective, single-center registry. The study included 30 patients suitable for percutaneous transluminal angioplasty (PTA). Primary end points were occurrence of distal embolization, decreased runoff, improvement in ankle-brachial index (ABI), and number of filters containing emboli. Secondary end points included procedural or device-related death and/or clinical target lesion revascularization, device delivery, deployment success, and incidence of embolic recovery. Procedural success was defined as <30% residual stenosis, with no worsening of distal runoff as determined by angiography. The study enrolled 29 patients with 30 treated limbs, suitable for PTA, between February 2007 and March 2008. Claudication was the indication for intervention in 26 patients and critical limb ischemia in 3. One patient underwent treatment in both legs. The average degree of stenosis was 86% ± 7%, and stenosis length ranged from 8 to 88 mm. No procedural or device-related complications occurred. Average degree of residual stenosis was 10 % ± 10%. ABI improved from 0.56 ± 0.16 to 0.92 ± 0.19 (P < .05). At 1 month, there was no ultrasound-detected waist stenoses or dissections. Microscopic debris was found in 27 of the 30 filters used. Particle size was 1200 ± 640 μm (range, 90-2000 μm). Histologic analysis indicated debris consisted of platelets, erythrocytes, inflammatory cells, extracellular matrix, and cholesterol. There was no correlation between lesion morphology and type of debris. Comment: This is a small, single-center, nonrandomized commercially sponsored study with the first author having a consulting arrangement with the study sponsor. The study is obviously good marketing material for the manufacture of the FilterWire EZ System. However, assuming the author's observations are accurate, the study should bring some measure of concern to all who perform catheter-based SFA interventions, because these interventions seem to be nearly uniformly associated with distal embolization. Long-term clinical implications of these distal emboli remain to be defined, but as someone once said, they may not be bad, but they can't be good! The true clinical utility of embolic protection devices in all vascular beds remains an intriguing, and certainly a potentially profitable, avenue of research.