Hypothesis: When compared to conventional balloon angioplasty, cryoplasty post-dilation decreases the risk of SFA nses in-stent restenosis

Transcription

1 Cryoplasty or Conventional Balloon Post-dilation of Nitinol Stents For Revascularization of Peripheral Arterial Segments Background: Diabetes mellitus is associated with increased risk of in-stent restenosis after superficial femoral artery (SFA) stenting with nitinol self-expanding stents (nses) 1 Hypothesis: When compared to conventional balloon angioplasty, cryoplasty post-dilation decreases the risk of SFA nses in-stent restenosis 1 Bakken et al, Journal of Vasc Surgery; 2007

2 Design DESIGN: Prospective, randomized, multi-center clinical evaluation of the PolarCath system vs. conventional balloon post-dilation of nses implanted in the SFA of patients with DM, presenting with life-style limiting claudication 121 patients with DM consented between August 2008 and December 2010 in 4 clinical sites in U.S. 90 SFA nses implanted (74 patients/16 B/L) nses Post-dilation Randomization 1:1 47 (39%) patients not stented OBJECTIVE: To compare the rates of binary restenosis, at 12 months, as determined by duplex ultrasound (DUS) 2.5 times increase in Doppler peak systolic velocity (PSV) in the stented segment and 10mm beyond its proximal and distal edges Cryoplasty Group (N=45) DUS and clinical follow-up at 12 months in 91.1% (N=41) nses: nitinol self-expanding stents *Excluded from stent based primary analysis 4 (8.9%) Deaths* Conventional Balloon Group or CBA (N=45) 2 (4.4%) Deaths* DUS and clinical follow-up at 12 months in 95.5% (N=43)

3 Inclusion Criteria 1. Diabetics, insulin or non-insulin dependent above 21 years of age 2. Severe intermittent claudication (RB stage 3), chronic critical limb ischemia with rest pain (RB stage 4), or chronic critical limb ischemia with ischemic ulcers (RB stage 5) 3. SFA nses length 60 mm 4. SFA nses diameter 5 mm Exclusion Criteria 1. Serum creatinine 2.0 mg/dl 2. Absence of at least 1 vessel brisk infra-popliteal run-off to the foot 3. LV ejection fraction 25% 4. Allergy to iodinated contrast 5. Allergy to aspirin or clopidogrel 6. Relative or absolute contraindication to anticoagulation 7. WBC < 3,000K/UL; platelet count < 100,000K/UL; Hgb < 10 g/dl Sample size calculation: assuming 65% and 35% restenosis with conventional balloon and cryoplasty treatments and 10% attrition, for an alpha = 0.05 and power =80%, 43 vascular segments would be needed in each treatment arm 1 1 Banerjee et al, Am J of Cardiology; 2009

4 Cryoplasty n = 45 Conventional balloon n = 45 p Value Age (years ± SD) ± ± Male 82% 93% 0.11 Hypertension 98% 96% 0.16 Hyperlipidemia 96% 93% 0.32 Diabetes mellitus 100% 100% 1.00 Tobacco use 56% 60% 0.76 Chronic kidney disease Coronary artery disease Baseline Characteristics 9% 13% % 64% 0.70 Prior MI 24% 18% 0.44 MI: myocardial infarction

5 Baseline Characteristics Cryoplasty n = 45 Conventional balloon n = 45 p Value Hemoglobin A1C 7.43 ± ± Insulin requiring DM 16% 22% 0.39 Serum creatinine 1.14 ± ± Aspirin 69% 60% 0.38 Clopidogrel 40% 53% 0.21 Warfarin 13% 4% 0.14 Statin 89% 76% 0.10 ACEI/ARB 80% 69% 0.23 Beta blocker 62% 71% 0.38 Proton pump inhibitor 24% 20% 0.66 ACEI: angiotensin converting enzyme inhibitor ARB: angiotensin receptor blocker

6 Procedural Characteristics Cryoplasty n = 45 Conventional balloon n = 45 p Value Mean Rutherford stage Baseline ABI 0.59 ± ± Lesion length (mm) ± ± No. of run-off vessels 2.1 ± ± Chronic total occlusions 56% 44% 0.06 Total stent length (mm) ± ± Stent diameter (mm) 6.09 ± ± Debulking 36% 27% 0.45 Post-dilations Balloon length (mm) ± ± Balloon diameter (mm) 5.23 ± ± Number of dilations 2.51 ± ± ABI: ankle-brachial index

7 Primary endpoint: 12m binary restenosis 60% 40% p= % 55.8% 29.3% Conventional Balloon Post-dilation n=43 Cryoplasty Balloon Post-dilation n=41

8 Cumulative hazard of restenosis Cumulative hazard of restenosis Conventional Cryoplasty HR=2.39, 95% CI p<0.01 Time (in days) Cryoplasty Conventional ACT: activated clotting time UFH: unfractionated heparin

9 Change in ABI from baseline at 12m p=0.66 p=0.004 ABI ± ± ± ± Baseline 12m Conventional Balloon Post-dilation Baseline 12m Cryoplasty Balloon Post-dilation ABI: ankle-brachial index

10 Change in WIQ* from baseline at 12m p=0.005 p=0.002 WIQ Score Baseline 12m Baseline 12m Conventional Balloon Post-dilation Cryoplasty Balloon Post-dilation *Walking impairment questionnaire score

11 90% SFA Chronic total occlusion 12m binary restenosis 60% p= % 70.0% 36.0% Conventional Balloon Post-dilation n=20 Cryoplasty Balloon Post-dilation n=25

12 Cumulative hazard of restenosis (Non-CTO vs. CTO) HR=3.61, 95% CI ; p=0.05* Cumulative hazard of restenosis Conventional CTO Conventional non-cto Cryoplasty CTO Cryoplasty non-cto HR=2.69, 95% CI ; p=0.13* HR=2.65, 95% CI ; p=0.15* Reference Group Time (in days) *Comparedto reference group

13 90% Bilateral SFA nses Implants 12m binary restenosis 60% p= % 66.7% 26.7% Conventional Balloon Post-dilation n=15 Cryoplasty Balloon Post-dilation n=15 Analysis excludes 1 patient with same treatment to B/L LE

14 Cryoplasty or Conventional Balloon Post-dilation of Nitinol Stents For Revascularization of Peripheral Arterial Segments Conclusions In patients with diabetes mellitus presenting with life-style limiting claudication, post-dilation of nitinol self-expanding stents in the SFA using PolarCath cryoplasty significantly reduced 12-month in-stent restenosis compared to conventional balloon post-dilation