Lessons for technique and stent choice

Transcription

1 8 th European Bifurcation Club October Barcelona Session: What are the requirements for using a stent in a bifurcation? Lessons for technique and stent choice October 12 th : 16:45 17:50 Goran Stankovic MD, PhD

2 Lessons for technique and stent choice Interventional cardiologists need to understand limitations and strengths of stent designs; Manufacturers need to understand the trade-offs being made for future iteration design. Ormiston, TCT 2010 cell Connectors Peaks (or Crowns) XIENCE Prime 3.0 mm (6 crowns, 3 cells) N. Foin

3 Requirements for stents in the bifurcation intervention Murasato SB access ability Cell shape Cell expansion area Number of links Stability (durability) during proximal stent expansion (KBT, POT) Strut deformation Cell overdilation Change in radial force, conformability Stability of the polymer in complex procedures Resilience to longitudinal deformation Modified from Murasato 2012

4 Basic stent geometry/design Stents are designed with a succession of rings and connectors: Connectors Hoops/rings provide radial strength Connections hold rings together and provide longitudinal strength Hoop strength (radial strength) and longitudinal strength are independent Connectors play major role in flexibility Connectors control cell size and SB access cell Peaks (or Crowns) XIENCE Prime 3.0 (6 crowns, 3 cells) mm Foin Prime/ Vision Driver Multi- Link Cinatra Element Velocity/ Select Bridges/connectors link hoops/rings Welds link hoops Ormiston

5 Reducing the number of connectors between hoops and thinning struts improves performance characteristics (deliverability/flexibility) but at the cost of reduced longitudinal strength Cypher Select Stainless steel Liberte Stainless steel Vision Xience V Cobalt Chromium MultiLInk 8 Xience Prime Cobalt Chromium Driver Endeavor Cobalt Chromium Integrity Resolute Cobalt Chromium 140µ 100µ 81µ 81µ 91µ 91µ 81µ 6 connectors 3 connectors 3 connectors 3 connectors 2 connectors 2 (3) connectors Omega ION Element Platinum Chromium 2 connectors Ormiston

6 1.Workhorse design selection The optimal selection of stent adjusting to the distal MV according to the vascular branching law and proximal optimization technique can decrease/prevent carina shift. 3.0 Xience Prime with 4.5mm proximal post dilation Culotte 3.0x3.5Xience Prime 3.0 Xience Prime from LCx to LM 3.5 (LWH) Xience Prime with 4.5mm Prox. Dilatation

7 Stent sizing according to the distal reference diameter to avoid risk of carina shift Assessment of strut Apposition Proximal Edge: Achtung! Prox. SB Dist. A B C N. Foin, G.Secco, R.Krams and C. Di Mario, Eurointervention 2011

8 Maximal expansion capacity and workhorse designs Element Xience V Taxus Integrity BioMatrix Cypher 2.25 Very Small WH (2 cells) max exp.: 2.8mm 2.50 Small workshorse (8 crowns, 2 cells) Medium Workhorse (6 crowns, 3 cells) max. expansion: 4.4mm Small workshorse (6 crowns, 2 cells) max expansion: 3.3mm max expansion : 2.75 Medium 3.5mm Workhorse ( Medium Workhorse (8 crowns, 2 cells) max expansion : 4.5mm 3.50 Large workhorse: (9 crowns, 3 cells) max expansion : 5.7mm 4.00 Large workhorse (10 crowns, 2 cells) max expansion: 5.4mm 4.50 crowns, 3 cells) max expansion: 4.7mm Large workhorse (9 crowns, 3 cells) max expansion: 5.75mm Small workhorse (7crowns, 2 cells*) max expansion: 4.0mm *1.5 cell in Resolute Medium workhorse (10 crowns, 2 cells) max expansion : 4.8mm Medium workhorse (6 crowns, 2 cells) max expansion: 4.4mm Large workhorse (9 crowns, 3 cells) max expansion: 5.75mm Medium workhorse (6 crowns, 6 cells) max expansion: 4.75mm Large workhorse (7 crowns, 7 cells) max expansion: 5.7mm 5.00 Maximal stent expansion: inner lumen diameter achieved (MLD) for each workhorse design Foin, Sen, Di Mario, Davies. 2012

9 2. Side branch ostium opening stent cell size: the larger the better? Stent Cell Size *Based on 3mm stent Maximum cell circumference* (mm) Maximum cell diameter* (mm) Endeavor 2.75 mm after KB P. Mortier and manufacturer data 4.0 Most stents can achieve a maximum cell diameter > 3.0 mm Resolute Integrity

10 3. Side branch ostium opening: Importance of cell recrossing location p p d d p d Bifurcation model after Xience V implantation in the Main Branch Views of the SB ostium at 3 different angles Foin, 2012

11 Leaving a balloon deflated in the MV guarantees stent reexpansion after SB dilatation Location of cell recrossing Proximal-Mid Mid After KB Mid-Distal Distal edge B

12 Pre Post KB Proximal versus Distal cell for SB recrossing A. Distal cell B. Proximal cell > 40% malapposed strut toward the SB after KB with angiographic guidance Tzcynski, RevEspCardio 2010 Guidance of cell recrossing location using 3D OCT might improve results of bifurcation stenting in term of strut apposition Alegria, Foin, Di Mario, Eur.J.Cardiovasc.Imag.2012

13 More serious stent deformation in 2-link stent with the GW crossed through the extremely distal cell Driver stent Central cell Distal cell

14 Which is more suitable, 2-link or 3-link? Cross sectional view Balloon overlapping changed from lateral to longitudinal position. Wide opening for the SB Endeavor 3.0/24 KBI ( /20, 8atm) 3D, Y-shape model Murasato Y, Euro PCR 2010

15 Which is suitable, 2-link or 3-link? Murasato Y, Euro PCR 2010 Cross sectional view Stent structure was maintained in the KBI site. Balloon overlapping changed from lateral to longitudinal position. ML Zeta 3.5/28 KBI ( /20, 8atm) 3D, Y-shape model

16 Which is suitable, 2-link or 3-link? Murasato Y, Euro PCR 2010 SB orifice ML Zeta 3.5/28 KBT ( /20, 8atm) When the vertical link was in the SB ostium, the jailed strut remained at the site where the SB balloon crossed over the MV balloon.

17 Malapposition remains a major issue after bifurcation stenting Quantification of strut apposition in 31 bifurcations assessed by OCT showed that: > 11.8 % struts remained malapposed in proximal MV > High rate of struts (>45%) found malapposed toward the SB ostium despite KB Post-Dilatation OCT after Culotte technique in the LAD/D1 branch Tzcynski et al. Simple Versus Complex Approaches to Treating Coronary Bifurcation Lesions. RevEspCardio 2010 Consistent use of FKI is still insufficient to ensure complete apposition in majority of cases

18 Sequential SB-MV 2 Step dilatation can be used instead of Kissing Balloon after Provisional Stenting of Bifurcations MV stent A MV stent A SB dilatation B SB dilatation B Conventional Kissing C D C Conventional Kissing SB-MV 2-Step Sequence 2-Step Series of 3.0 Drug Eluting Stents (Xience, Biomatrix, Taxus, Endeavour, Promus Element) Identical platforms in each group, n= 13 x 2 D

19 Results KB vs SB-MV sequence Ostial stenosis is considerably reduced after dilatation of the SB % SB area stenosis was 69.2 % without post-dilatation, significantly reduced after KB (20.9 %) and after 2- KB Step (25.6 %) Strut malapposition in the bifurcation is reduced with SB dilatation followed by KB or SB-MV Rate of malapposition in the ostium after KB and 2-Step was respectively 22.1 % and 26.6 %, a significant reduction compared to simple stenting across (47.0 %, p<0.0005) No proximal malapposition risk with sequential SB-MV 2-Step approach 36.4 % vs. 3.8 % for 2-step, p= Step Avg. of n= 2x 13 stents (Xience, Biomatrix, Element, Taxus, Resolute)

20 Wall strain Finite Element Analysis KB vs 2 step KB A High strain SB-MV B Courtesy P. Mortier M. De Beule, FEops N. Foin, R. Torii, P. Mortier et al. JACC Interventions. In press 2011

21 Importance of Cell Size with Culotte Technique. This is only partially true as it is an oversimplification of the anatomy of the SB origin. Obstruction occurs in MB and SB Y x X= 3/sinY 3mm 3.5mm 6mm 90 O 60 O 30 O 3mm 3mm 3mm

22 Bench Deployments Steep Distal Angles (110 o eg L Main) Four different stenting strategies T stenting has best expansion at the carina Kissing post-dilatation does not fully expand the stents in the ostium T stenting Crush Culotte SKS stenting

23 Crush stenting KBT Gap still remained after KBT Ormiston JA et al. Catheter Cardiovasc Interv. 2004; 63: 332-6

24 Ormiston JA. Euro PCR 2010

25 Ormiston JA. Euro PCR 2010

26 Stent designs and longitudinal strength Longitudinal strength is determined by: 1) the number of connectors, 2) connectors alignment, 3) strut alloy + thickness Compression test Weakness: 1. Element 2. Driver 3. Liberte, Integrity 4. ML8, Vision 5. Cypher Stretch test Ormiston J. JACC Int, Dec 2011 Weakness: Prabhu, Eurointervention, Nov Element, Driver 2. Liberte, Integrity 3. ML8, Vision 4. Cypher Ormiston JA, JACC Interv. 2011, 4, 1310

27 Polymer injury of DES after bifurcation stenting SB ostium after crush and kissing with large balloons and multiple inflations at 20 atm Ormiston J, AP summit 2005 Does polymer injury limit the efficacy of DES?

28 Conclusions (1) Stent design (connector/strut design) determines: 1) flexibility, 2) deliverability and 3)conformability; Best design depends on which properties you are looking for and the lesion you want to treat (distal tortuous vs. Left Main shaft) The optimal selection of stent adjusting to the distal MV according to the vascular branching law and proximal optimization can prevent carina shift. The available stents have good access to the SB and well-expansion can be obtained by 2-step KBT. This is more likely in the 2-link stents, however, KBT in high-angled bifurcation or POT has a risk of cell deformation, overdilation, and polymer damage.

29 Conclusions (2) Although there is a possibility of remaining jailed struts even after KBT in the 3-link stent, it keeps its structure and has less risk of cell deformation in the proximal MV. Longitudinal deformation is likely to occur in the 2- link stents. Special attention should be paid in the cases with the 2-link stents used in the LMT or the bifurcation which requires complex procedures such as recurrent KBT and IVUS.