PVD CHILL Study Summary

PolarCath® Peripheral Dilatation System Safety Registry 9 Month Results

Objective To determine the safety and performance of the PolarCath Peripheral Dilatation System for the endovascular treatment of femoropopliteal stenoses.The PolarCath Peripheral Dilatation System uses rapid cold therapy dilatation for simultaneous dilation and cooling of the vessel wall for the treatment of complex peripheral lesions.   Design Prospective, multi-center study using the PolarCath Peripheral Dilatation System. Enrolled patients met all the inclusion and exclusion criteria and signed a written, informed consent. Eligible patients presented with: exercise-induced claudication, target lesion with RVD between 5 mm and 7 mm (inclusive), lesion stenoses between 50%and 100%(inclusive), at least one run-off vessel, and a total lesion length of up to 10 cm.   Primary Endpoints Technical and procedural success Technical success is defined as the ability to cross and dilate the lesion and achieve ≤30%residual angiographic stenosis by visual estimate, and <50%residual stenosis by core laboratory duplex scan analysis, with antegrade flow to the target vessel. Patency rate Clinical patency is defined as freedom from clinically driven repeat percutaneous intervention of the target lesion or bypass surgery of the target vessel due to re-occlusion of the target lesion. Primary patency is defined as binary restenosis less than 50%, equal to a finding of less than a 2.0 SVR (systolic velocity ratio) on duplex ultrasound.   Secondary Endpoints • Serious adverse event rates • Maintenance of blood flow at 3 and 9 months as determined by ABI and lower extremity arterial duplex scan   Enrollment One hundred two (102) patients were enrolled at 15 U.S. sites and one European site.   IDE Registry Conclusions1 • Primary clinical patency was 82.2% at 9 months • TLR* rate at 9 months was 17.8% • Technical success was 85.3% and procedural success was 94.1% • Flow-limiting dissection rate was 7% • PolarCath Peripheral Dilatation System safely dilates stenotic and occluded lesions in the superficial femoral and popliteal arteries • Primary patency was 70% (duplex ultrasound SVR < 2.0) *TLR is calculated per patient rather than per lesion.

In vitro studies have demonstrated that application of cryo therapy can modulate the neointimal response that leads to restenosis through induction of smooth muscle cell apoptosis.2-4

Long-Term Results

Follow-up of study subjects was performed at up to 3.4 years after treatment to provide additional information
about the long-term durability of CryoPlasty® Therapy outcomes.

• Mean follow-up time (months): 31.3 +/- 6.3
• Of 102 subjects enrolled, 70 study subjects were available for extended follow-up

*Kaplan-Meier estimate: a common statistical tool

used to generate a probability curve of how

long it would take for something being measured

or studied to occur. In this case it is clinical

patency (freedom from TLR). It is calculated

using actual data from the study.

References
1. Data on file at Boston Scientific Corporation.
2. Tatsutani KN, Joye JD, Virmani R, Taylor MS. In vitro evaluation of vascular endothelial and smooth muscle cell survival and apoptosis in response to hypothermia and freezing. CryoLetters. 2005;26(1):55-64.
3. YiuW, Cheng SWK, Sumpio BE. Direct comparison of endothelial cell and smooth muscle cell response to supercooling and rewarming. J Vasc Surg. 2007;46(3):557-564.
4. YiuW, Cheng SWK, Sumpio BE. Vascular smooth muscle cell apoptosis induced by “supercooling” and rewarming. J Vasc Intervent Radiol. December 2006;17(12):1971-1977.