OCT Assessment of Late Stent Malapposition after DES Department of Cardiology The 2nd affiliated hospital of HMU Jingbo Hou

Late stent malapposition -- What is it? Certain distance between vascular wall and at least one stent strut. 支架贴壁不良是指至少一个以上支架小梁与血管壁之间存在一定的空隙（距离）； SM include instant stent malapposition late stent malapposition： continuous malapposition after stent implantation. Acquired stent malapposition.

Acquired LSM Follow-up Baseline No remodeling Positive remodeling Explain late incomplete apposition: at baseline, the vessel is fully opposed; however, at follow-up one of two conditions occur: 1. No remodeling: Intimal tissue decreases in size and causes a dissociation between the struts and vessel wall. 2. Aneurysmal remodeling: the vessel wall (media and adventia) pulls away from the stent struts. Emphasize LIA upon discontinuation of clopidogrel has been associated with a high thrombosis rate. Be sure to transition to the Cypher case (in the re-print) to give a real world example of LaST (next slide) * Study by Dr. Abizaid, presented at TCT 2005. Positive remodeling

Mechanism for LSM Vascular wall positive remodelling Absorption of thrombus or plaque component (in ACS) Chronic retraction of stent Unclear for exact pathologic mechanism Delayed healing Chronic inflammation Hypersensitive reaction

Stent strut neointimal coverage J Am Coll Cardiol Img, 2010; 3:76-84

Malapposition Which is better?

Long-term follow-up of LSM

Frequency of ISA ---in BMS and DES Trial SIRIUS IVUS TAXUS II IVUS BMS SES N=80 Post-procedure ISA 9 (14.8%) 13 (16.3%) Resolved ISA 3 (4.9%) 7 (8.7%) Persistent ISA 6 (9.8%) 6 (7.5%) Late-acquired ISA ISA at follow-up BMS n=240 TAXUS N=229 19 (7.9%) 16 (7.0%) 11 (4.6%) 11 (4.8%) 8 (3.3%) 5 (2.2%) 13 (5.4%) 20 (8.7%) 21 (8.8%) 25 (10.9%) Ako J, et al. JACC. 2005; 46(6):1002-1005. Tanabe K, et al. Circulation. 2005; 111(7):900-905.

Metal strut thickness(μm) Polymer thickness(μm) OCT assessment of LSM Late stent malapposition is defined when the distance between its inner surface reflection and the vessel wall is more than strut thickness plus polymer thickness plus OCT resolution. Stent type Metal strut thickness(μm) Polymer thickness(μm) Malapposition (μm) Cypher Select 140 7 ≥160 Taxus Liberte 97 15 ≥130 Firebird Ⅰ 100 10 ≥125 Partner 114 6

OCT assessment of LSM Measurement of MSA and MSD. Double-headed red arrow is MSD. Dotted area is MSA.

LSM in our center LSM in 126 DES stents in 68 patients at least 1 year after implantation were evaluated by OCT in our department； MSD, MSA, RLA and RSA were examined by OCT.

Clinical data Patient number 68 Stent number 126 Age(years) 60.1±10.2 Male gender, n (%) 57(83.8) Hypertension, n (%) 40(58.8) Hyperlipidemia, n (%) 23(33.8) Diabetes Mellitus, n (%) 21(30.9) Smoking 31(45.6) Target vessels, n (%) LAD 65(51.6) LCX 22(17.4) RCA 39(31.0) Stent type, n (%) Cypher select, n (%) 26(20.6) Taxus Liberte, n (%) 15(11.9) Partner, n (%) 51(40.5) Firebird Ⅰ, n (%) 34(27.0) Average stent diameter (mm) 3.1±0.5 Average stent length (mm) 25.1±6.8

Quantitative analysis Patient vessel RSA (mm2) RLA MSA MSD (μm) /RSA(%) DES time (years) 1 LAD 7.2 6.4 5.6 1050 77.8 1.1 2 RCA 7.1 7.0 1.2 310 16.9 1.5 3 13.1 12.1 1.7 460 13.0 1.9 4 6.5 4.7 0.9 520 13.9 5 5.7 800 21.1 1.3 6 10.3 10.8 1.8 320 17.5 7 5.5 5.1 650 23.6

Late stent thrombosis— DES: Factors to consider Discontinuation of antiplatelet therapy Late incomplete apposition Late stent thrombosis Delayed endothelialization Polymer hypersensitivity/ inflammation Late Stent Thrombosis (“LST”) is a well known, potentially life threatening complication of PCI/stenting. There are four widely suspected underlying causes of LST: discontinuation of antiplatelet therapy, late incomplete apposition, polymer hypersensitivity/inflammation and delayed endothelialization. As you will see in the following slides, Endeavor effectively reduces the risk of each of these causes of LST. This is reflected in the excellent Endeavor clinical program results with 0% LST after 10 days in more than 1200 patients.

Clinical information Male，43-year-old； 2008-4-18: Selective PCI for subacute anterior MI，2 DES stents were implanted along LAD； Long smoking and drinking history. No hypertension and diabetic history.

Clinical information 2009-7-30： After stopping using of clopidogrel for 2 months, the patient had acute anterior MI again. Thrombolytic therapy was given to him in local hospital. 2009-8-12：CAG.

2008-4-18

2008-4-18

2008-4-18 2009-8-18

2009-8-18 2008-4-18 2009-8-18

Possible reason for late thrombus and recurrent MI Comparison of CAG of two times of PCI, we found obvious coronary positive remodel. The change of vascular wall induce late stent malapposition. Late stent malapposition and stop using of dual antiplatelet therapy were probable reasons for very late stent thrombosis.

What can we get from this case? How to prevent late stent malapposition？ Choose suitable type of stent in ACS (BMS or others). New type stents without polymer or biodegradable polymer to induce reendothelization. Drug therapy to prevent vascular wall positve remodelling??

Treatment to LSM…… Prolonged dual antiplatelet treatment. How long?? Implantation for another stent. BMS or covered stent?