Incidence, Predictors, and Outcome of Plaque Prolapse after Stent Implantation in Patients with Acute Myocardial Infarction: An Intravascular Ultrasound Analysis

1
Incidence, Predictors, and Outcome of Plaque
Prolapse after Stent Implantation in Patients
with Acute Myocardial Infarction An
Intravascular Ultrasound Analysis
Young Joon Hong, MD, PhD Myung Ho Jeong, MD,
PhD, FACC, FAHA, FESC, FSCAI Youngkeun Ahn, MD,
PhD, FACC, FSCAI Doo Sun Sim, MD Jong Won
Chung, MD Jung Sun Cho, MD Nam Sik Yoon, MD
Hyun Ju Yoon, MD Jae Youn Moon, MD Kye Hun Kim,
MD, PhD Hyung Wook Park, MD, PhD Ju Han Kim,
MD, PhD Jeong Gwan Cho, MD, PhD, FACC Jong Chun
Park, MD, PhD Jung Chaee Kang, MD, PhD
The Heart Center of Chonnam National University
Hospital, Chonnam National University Research
Institute of Medical Sciences, Gwangju, Korea
2
Background (I)
? Coronary angiography -- provides only
simple, planar projections of three-
dimensional coronary lumen anatomy. -- is
limited to detect intrastent plaque prolapse
(PP). ? Previous studies have shown that --
PP is not a rare phenomenon. -- PP has been
detected frequently by intravascular
ultrasound (IVUS).
3
Background (II)
? It has been known that several pre-intervention
IVUS factors and aggressive stenting
procedure have been associated with PP. ?
Some studies have demonstrated that PP was
associated with stent thrombosis. ? However,
data on the characteristics of PP in patients
with acute myocardial infarction (AMI) are
lacking.
4
Objectives
? to assess the incidence, predictors, and
outcome of PP after stent implantation for
infarct-related arteries in AMI patients.
5
Patient Population (I)
? a total of 310 patients with a first AMI -
125 ST segment elevation and 185 non-ST segment
elevation MI - From January 9, 2001 to
July 31, 2007 - who underwent
pre-intervention IVUS within 24 hours from
symptom onset - were stented successfully
- had post-intervention IVUS imaging
6
Patient Population (II)
? Identification of infarct-related arteries -
electrocardiographic findings - left
ventricular wall motion abnormalities on left
ventricular angiogram or echocardiogram -
coronary angiographic findings
? Exclusion - prior MI, subacute or late
stent thrombosis, restenosis after
stenting, coronary artery bypass graft failure,
patients studied with IVUS more than 24
hours after symptom onset, and patients in
whom adequate IVUS images could not be
obtained
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Laboratory Analysis
? Venous blood samples were obtained within 24
hours after stenting. ? The blood samples
were centrifuged, and serum was removed and
stored at -70C until the assay could be
performed. ? Absolute creatine kinase-MB (CK-MB)
levels were determined by radioimmunoassay
(Dade Behring Inc., Miami, Florida). ?
Cardiac-specific troponin I (cTnI) levels were
measured by a paramagnetic particle,
chemiluminescent immunoenzymatic assay
(Beckman, Coulter Inc., Fullerton, California).
8
IVUS Imaging
? All IVUS examinations were performed before PCI
after intracoronary administration of 200
µg nitroglycerin ? Commercially available IVUS
system (Boston Scientific
Corporation/SCIMed, Minneapolis, MN) ? IVUS
catheter was advanced distal to the target
lesion, and imaging was performed
retrograde to the aorto-ostial junction at
an automatic pullback speed of 0.5 mm/sec
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IVUS Analysis (I)
? according to the American College of Cardiology
Clinical Expert Consensus Document on
Standards for Acqusition, Measurement and
Reporting of Intravascular Ultrasound
Studies ? using planimetry software
(TapeMeasure, INDEC Systems Inc., Mountain
View, CA) -- external elastic membrane (EEM)
cross-sectional area (CSA) -- lumen
CSA -- plaque plus media (PM) CSA EEM CSA
minus lumen CSA -- plaque burden PM CSA
divided by EEM CSA
10
Proximal Reference
Lesion Site
Distal Reference
EEM
Lumen
PM
Min PM Thickness
Max PM Thickness
Ca
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IVUS Analysis (II)
? The lesion was the site with the smallest lumen
CSA -- if there were multiple image slices
with the same minimum lumen CSA ? the
image slice with the largest EEM and PM was
measured ? Plaque morphology --
Hypoechoic plaque less bright compared with the
reference adventitia
-- Hyperechoic, noncalcified as bright as or
brighter than the reference
adventitia without acoustic shadowing --
Calcified plaque hyperechoic with shadowing
lesion contained
gt90 of circumferential
calcium
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IVUS Analysis (III)
? Coronary artery remodeling -- was assessed
by comparing the lesion site to the
reference EEM CSA ? Remodeling index (RI) the
lesion site EEM CSA divided by the
average of the proximal and distal reference EEM
CSA -- Positive remodeling RI gt1.05 --
Intermediate remodeling RI between 0.95 and
1.05 -- Negative remodeling RI lt0.95
? Thrombus -- an intraluminal mass --
having a layered or lobulated appearance --
evidence of blood flow (microchannels) within the
mass -- speckling or scintillation
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IVUS Analysis (IV)
? A ruptured plaque -- contained a cavity that
communicated with the lumen with an
overlying residual fibrous cap fragment. -- a
fragmented and loosely adherent plaque without a
distinct cavity and without a fibrous cap
fragment was not considered a plaque
rupture. -- rupture sites separated by a
length of artery containing smooth lumen
contours without cavities were considered
to represent different plaque ruptures. --
plaque cavity was measured and extrapolated to
the ruptured capsule area.
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Example of Plaque Rupture with Thrombus
Ruptured plaque cavity
Thin fibrous cap
Thrombus
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IVUS Analysis (V)
? At post-intervention -- minimum stent CSA
-- Percent stent expansion minimum stent CSA
divided by
mean reference lumen CSA -- PP was
defined as tissue extrusion through the stent
strut at post-intervention -- Volume
of PP subtracting lumen volume from stent
volume
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Baseline Characteristics (I)
Plaque Prolapse (n85) No Plaque Prolapse (n225) p value
Age (yrs) 6513 6511 1.0
Male gender, () 49 (58) 130 (58) 1.0
Clinical presentation, ()     0.081
  Non-ST segment elevation MI 44 (52) 141 (63)  
  ST segment elevation MI 41 (48) 84 (37)  
Diabetes mellitus, () 31 (37) 80 (36) 0.9
Hypertension, () 64 (75) 154 (68) 0.2
Smoking, () 30 (35) 75 (33) 0.7
Family history of coronary artery disease, () 18 (21) 34 (15) 0.2
Previous percutaneous coronary intervention, () 3 (10) 9 (8) 0.8
Thrombolytic therapy, () 11 (13) 21 (9) 0.4
Glycoprotein IIb/IIIa inhibitors, () 20 (24) 44 (20) 0.4
Use of distal protection devices, () 12 (14) 12 (5) 0.010
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Baseline Characteristics (II)
Plaque Prolapse (n85) No Plaque Prolapse (n225) p value
Aspirin at admission, () 11 (13) 21 (9) 0.4
Statin at admission, () 10 (12) 20 (9) 0.4
Ejection fraction () 4613 4313 0.11
White blood cells (103/mm3) 8.93.1 9.23.6 0.6
Hemoglobin (g/dl) 12.22.0 12.32.2 0.7
Platelet count (103/mm3) 22090 23186 0.4
Creatinine clearance (ml/min) 6031 6635 0.15
Total cholesterol (mg/dl) 18147 16542 0.029
Triglyceride (mg/dl) 13267 12765 0.6
LDL cholesterol (mg/dl) 11043 10037 0.091
HDL cholesterol (mg/dl) 4512 4213 0.11
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Coronary Angiographic Findings
Plaque Prolapse (n85) No Plaque Prolapse (n225) p value
Infarct-related artery, () 0.024
Left main 0 (0) 5 (2)
LAD 36 (42) 131 (58)
LCX 14 (17) 28 (12)
RCA 35 (41) 61 (27)
Lesion location, () 0.8
Ostium 1 (1) 3 (1)
Proximal 31 (37) 90 (40)
Middle 46 (54) 109 (48)
Distal 7 (8) 23 (10)
Multivessel disease, () 41 (48) 112 (50) 0.8
Thrombus, () 14 (16) 22 (10) 0.10
Calcium, () 7 (8) 23 (10) 0.6
TIMI flow grade 0, () 19 (22) 30 (13) 0.052
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Procedural Results
Plaque Prolapse (n85) No Plaque Prolapse (n225) p value
Stent type, () 0.15
Sirolimus-eluting stent 35 (41) 103 (46)
Paclitaxel-eluting stent 19 (22) 30 (13)
Bare-metal stent 31 (37) 92 (41)
No. of deployed stents, () 1.50.6 1.10.3 lt0.001
Stent diameter (mm) 3.280.40 3.240.46 0.7
Stent length (mm) 3113 218 lt0.001
Inflation pressure (mmHg) 15.32.9 14.12.6 0.001
Reference diameter (mm) 3.320.85 3.270.72 0.5
Pre-MLD (mm) 0.630.32 0.680.51 0.18
Lesion length (mm) 2312 158 0.001
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Intravascular Ultrasound Findings
Plaque Prolapse (n85) No Plaque Prolapse (n225) p value
Reference
EEM CSA (mm2) 12.84.6 12.94.7 1.0
Lumen CSA (mm2) 8.33.0 8.33.1 0.9
PM CSA (mm2) 4.62.6 4.52.6 1.0
Plaque burden () 3511 3411 0.7
Minimum lumen site
EEM CSA (mm2) 13.14.1 12.34.8 0.2
Lumen CSA (mm2) 2.51.5 2.81.3 0.063
PM CSA (mm2) 10.64.2 9.44.3 0.040
Plaque burden () 79.513.0 75.210.6 0.003
IVUS lesion length (mm) 2812 188 lt0.001
Calcium arc (º) 11476 19581 lt0.001
Calcium length (mm) 3.62.7 5.53.7 0.008
Superficial calcium, () 51 (60) 158 (70) 0.087
Minimum stent CSA (mm2) 8.142.99 7.252.27 0.029
Stent expansion () 9825 8729 0.014
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Plaque Rupture
Multiple Plaque Rupture
()
()
P0.001
P0.089
22
Plaque Cavity Area
(mm2)
P0.008
23
Thrombus
()
P0.001
24
Plaque Morphology
()
P0.044
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Remodeling Index
P0.017
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Incidence of Plaque Prolapse according to the
Stent Length
plt0.001
(42/84)
Plaque prolapse ()
(23/89)
(20/137)
18
gt18, 28
gt28
Stent length (mm)
27
Incidence of Plaque Prolapse according to the
Presence/Absence of Plaque Rupture
p0.001
(43/112)
Plaque prolapse ()
(42/198)
Plaque rupture ()
Plaque rupture (-)
28
Incidence of Plaque Prolapse according to the
Remodeling Pattern
p0.011
(41/113)
(21/75)
Plaque prolapse ()
(23/122)
Positive remodeling
Intermediate remodeling
Negative remodeling
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Changes of Cardiac Enzymes at FU
Plaque prolapse
No plaque prolapse
? CK-MB
? cTnI
30
30-Day Stent Thrombosis Rate
p0.3
Stent thrombosis ()
(2/85)
(2/225)
Plaque prolapse ()
Plaque prolapse (-)
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Multivariate Predictors of Post-PCI CK-MB
Elevation
Plaque prolapse (OR7.34, 95 CI 3.55-15.19,
plt0.001)
Plaque rupture (OR1.95, 95 CI 1.10-3.46,
p0.023)
Thrombus (OR1.84, 95 CI 1.08-3.13, p0.026)
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Multivariate Predictors of PP
Stent length (OR2.39 95 CI 1.17-3.89, p0.003)
Plaque rupture (OR1.96 95 CI 1.14-3.37,
p0.015)
Positive remodeling (OR1.72 95 CI 1.01-2.92,
p0.044)
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Conclusions
The incidence of PP after stenting for
infarct-related artery was 27.
Pre-intervention IVUS lesion characteristics
plaque rupture and positive remodeling and
longer stent length predict PP, and PP is
associated with myonecrosis after stenting for
infarct-related artery in patients with AMI.