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

2. 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.

3. 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

4. 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

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

6. Malapposition
Which is better?

7. Long-term follow-up of LSM

8. 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):
Tanabe K, et al. Circulation. 2005; 111(7):

9. 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

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

11. 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.

12. 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

13. 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

14. 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.

15. 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.

16. 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.
：CAG.

24. 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.

25. 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??

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