Understanding Stent Deformation AXIAL Understanding Stent Deformation Keith Dawkins MD FRCP FACC FSCAI Global Chief Medical Officer Senior Vice President Boston Scientific Corporation

Keith D. Dawkins, MD Salary: Boston Scientific Corporation Ownership Interest (Stocks, Stock Options, or other Ownership Interest):

Stent Deformation: Initial Observations

Stent Deformation: Endeavor/Driver 7-Crown Stents Pitney M: EuroIntervention 2011;7:256-262

Stent Deformation: Endeavor/Driver 7-Crown Stents Outcomes in Patients Demonstrating Stent Deformation EVENT N % Angiographic Success 13/14 93% Re-Stent Required 9/14 64% AMI (Tn >1.0) 7/14 50% Stent Thrombosis 0% Early Restenosis 2 14% Usual Restenosis Total Restenosis 4 29% 30-Day MACE 3 21% 6-Month MACE 5 36% 1000 patient, prospective, single-center registry of 2.25-2.75mm Endeavor/Micro-Driver stents Pitney M: EuroIntervention 2011;7:256-262

Hanratty CG: EuroIntervention 2011;7:872-877

Longitudinal Compression Manuscript Three cases of Longitudinal Compression (ELEMENT, RESOLUTE INTEGRITY, BIOMATRIX) ‘In this particular case [Promus Element] the stent at the ostium of the vessel was crushed longitudinally as an Amplatz 1 guide catheter was advanced into the vessel to provide improved guide support. We did not feel this issue was related to the stent platform itself, as a braided guide catheter is capable of deforming any coronary stent’ ‘In this case, the enhanced radiographic visibility of this platform [Element] meant that the complication was immediately apparent’ ‘However we have since observed this phenomenon within our institution with all modern DES platforms from each of the major manufacturers’ Hanratty CG: EuroIntervention 2011;7:872-877

What is Longitudinal Stent Deformation? Longitudinal stent deformation is the axial shortening or lengthening of a stent after implantation, resulting from interaction with an ancillary device such as a guide catheter, post-dilatation balloon, or IVUS catheter AXIAL

Longitudinal Stent Deformation Described with Eight Stent Types Stent Name Material Strut Thickness Connectors BioMATRIX Stainless Steel 112µm 2 or 3  Endeavor Cobalt chromium (MP35N) 91µm 2 or 3 Micro Driver PROMUS Element Platinum chromium 81µm (86µm for ≥4mm diam) 2 Resolute Integrity 1, 2 or 3 TAXUS Element TAXUS Liberté 316L Stainless Steel 97µm 3 Xience V (L605)

Longitudinal Stent Deformation Created in a Model with Malapposed Struts

Ormiston JA: J Am Coll Cardiol Intv 2011;4:1310 –1317

Are these Bench Tests relevant? Ormiston JA: J Am Coll Cardiol Intv 2011;4:1310 –1317

Longitudinal Strength In Perspective Is 0.5 Newtons Relevant? Significant forces can be generated using normal procedural techniques Force (Newtons) 0.5N Embolize a stent Kink a Hypotube Deep-seat a Guide Catheter Catheter tip crossing a deployed stent

Clinically Relevant Stent Compression Test Ormiston Test Relevant Test? Internal Stent supported with a pipe Constrained at base Force applied 360O to full diameter of stent Force value of 1N Constrained by vessel Open ended Malapposed tapered section Point force applied to stent With a 1N load is there a clinical difference in procedural outcome?

16mm WH ELEMENT 16mm WH XIENCE V Pre Post Post Pre

Prabhu S: EuroInterv 2011; published ahead of print

Is the ELEMENT Platform associated with a high rate of MACE Events? PERSEUS Trial PLATINUM Trial MACE (%) 1-year N=320 N=942 N=762 N=768 TAXUS Express TAXUS Element* PROMUS PROMUS Element *ION Kereiakes DJ: J Am Coll Cardiol 2010;56:264-271 Stone GW; J Am Coll Cardiol 2011; 57:1700-1708.

Longitudinal stent deformation: QCA analysis from the PERSEUS & PLATINUM Trials Kereiakes DJ: EuroInterv 2012 (in press)

Platform Innovation Leads to Lower Complaint Rates Improvement in Stent Material & Design  65% Lower Complaint Rate 1.00 Normalized Complaint Rate TAXUS Express TAXUS Liberté PROMUS ELEMENT

PROMUS Element in SCAAR Sarno G: Int J Cardiol 2012; doi.org/10.1016/j.ijcard.2011.12.057

PROMUS Element in SCAAR: Restenosis Follow-up (months) N=13,577 stents (PROMUS Element = 2,724) Sarno G: Int J Cardiol 2012; doi.org/10.1016/j.ijcard.2011.12.057

PROMUS Element in SCAAR: Stent Thrombosis Follow-up (months) N=13,577 stents (PROMUS Element = 2,724) Sarno G: Int J Cardiol 2012; doi.org/10.1016/j.ijcard.2011.12.057

Reducing Risk and Impact of Stent Deformation Similar DFU Verbiage Across Multiple Products Inflation Pressure and Time Care and Precaution Details 1. Care should be taken to control the position of the guide catheter tip during stent delivery, deployment and balloon withdrawal. 2. Care must be exercised when crossing a newly deployed stent with any wire, catheter or ancillary device to avoid disrupting the stent placement, apposition, geometry, and/or coating. Nominal: 11ATM Maintain inflation pressure for 15-30 seconds for full expansion of the stent ION™ Stent 1. Care should be exercised when crossing a newly deployed stent with an intravascular ultrasound (IVUS) catheter, a coronary guidewire, or balloon catheter to avoid disrupting the stent placement, apposition, geometry, and/or coating. 2. …a larger balloon may be used to expand the stent further… If this is required, the stented segment should be recrossed carefully with a prolapsed guidewire to avoid dislodging the stent. Nominal: 9ATM Maintain inflation pressure for 15-30 seconds for full expansion of the stent Endeavor® Stent 1. Care should be taken to control the guiding catheter tip during stent delivery, deployment, and balloon withdrawal. 2. When crossing a newly deployed stent with an intravascular ultrasound (IVUS) catheter, a coronary guide wire, a balloon catheter or delivery system, exercise care to avoid disrupting the stent placement, apposition, geometry, and/or coating. 3. The stent may be further expanded... the stented segment should be recrossed carefully with a prolapsed guide wire to avoid dislodging the stent. Nominal: 8ATM for 2.5 and 2.75mm 9ATM for 3.0, 3.5, 4.0mm’s Maintain pressure for 30 seconds Xience V® (PROMUS®) Stent All verbiage copied directly from U.S. Instructions for Use

Conclusions: Stent Deformation occurs rarely Deformation is not unique to a particular stent: it has been described with 8 stent types In vitro mechanical testing is of questionable relevance to clinical practice Understanding the phenomenon, in particular avoiding the interaction between the stent and ancillary devices, is key Adequately prepare the lesion Initial stent implant at high pressure (≥ 12 atm) Avoid guide-wire bias Care with IVUS crossing Wait for full balloon deflation (NB: Long balloons)