Assessment of the safety and performance of the STENTYS self-expanding coronary stent in acute myocardial infarction: results from the APPOSITION I study.
ABSTRACT In the setting of ST-elevation myocardial infarction (STEMI), epicardial vasoconstriction and thrombus load may lead to stent undersizing and malapposition after primary percutaneous coronary intervention (PPCI), which can both be responsible for stent thrombosis or restenosis. Aggressive stent deployment can, on the other hand, cause distal embolisation and the no-reflow phenomenon. The purpose of our study was to evaluate the safety and feasibility of a novel self-expanding stent by assessing the clinical, angiographic and intravascular outcomes after stent deployment at three days and at six months follow-up.
This prospective, multicentre, non-randomised study enrolled 25 STEMI patients undergoing PPCI; a nitinol, self-expanding, coronary stent (STENTYS® stent; STENTYS, Paris, France) was used in all patients. Angiography and intravascular ultrasound (IVUS) or optical coherence tomography (OCT) were performed immediately after stent deployment, after three days and at six months. Primary safety endpoints were mortality, reinfarction, stent thrombosis and stroke at discharge and at six months. The primary feasibility endpoints were technical, device and procedural success, and stent apposition at three days and six months. Secondary endpoints included distal embolisation, binary restenosis, ischaemia-driven target lesion revascularisation (TLR) and late lumen loss (LLL). There were no adverse events at discharge or at six months. Technical, device and procedural success were 100%, 96% and 96%, respectively. IVUS showed a significant vasodilatation distal to the culprit lesion at three-day follow-up (+19%), with a concordant expansion of the implanted stent (+18%), p≤0.001 for both values. One case of distal embolisation was reported. There were no cases of late stent malapposition at six months. In-stent and in-segment LLL were 0.71±0.71 mm and 0.58±0.61 mm. Binary restenosis was 25%, ischaemia-driven TLR was 12%.
This study shows that the use of the STENTYS® self-expanding stent is safe and feasible in STEMI patients. Three days after the procedure, the stent expanded to the same extent as the epicardial vasodilatation and appeared completely apposed to the vessel wall. This could be of benefit in preventing stent thrombosis in the setting of STEMI.
- [show abstract] [hide abstract]
ABSTRACT: As compared with thrombolytic therapy, primary coronary angioplasty results in a higher rate of patency of the infarct-related coronary artery, lower rates of stroke and reinfarction, and higher in-hospital or 30-day survival rates. However, the comparative long-term efficacy of these two approaches has not been carefully studied. We randomly assigned a total of 395 patients with acute myocardial infarction to treatment with angioplasty or intravenous streptokinase. Clinical information was collected for a mean (+/-SD) of 5+/-2 years, and medical charges associated with the two treatments were compared. A total of 194 patients were assigned to undergo primary angioplasty, and 201 to receive streptokinase. Mortality was 13 percent in the angioplasty group, as compared with 24 percent in the streptokinase group (relative risk, 0.54; 95 percent confidence interval, 0.36 to 0.87). Nonfatal reinfarction occurred in 6 percent and 22 percent of the two groups, respectively (relative risk, 0.27; 95 percent confidence interval, 0.15 to 0.52). The combined incidence of death and nonfatal reinfarction was also lower among patients assigned to angioplasty than among those assigned to streptokinase, with a relative risk of 0.13 (95 percent confidence interval, 0.05 to 0.37) for early events (within the first 30 days) and a relative risk of 0.62 (95 percent confidence interval, 0.43 to 0.91) for late events (after 30 days). The rates of readmission for heart failure and ischemia were also lower among patients in the angioplasty group than among patients in the streptokinase group. Total medical charges per patient were lower in the angioplasty group (16,090 dollars) than in the streptokinase group (16,813 dollars, P=0.05). During five years of follow-up, primary coronary angioplasty for acute myocardial infarction was associated with lower rates of early and late death and nonfatal reinfarction, fewer hospital readmissions for ischemia or heart failure, and lower total medical charges than treatment with intravenous streptokinase.New England Journal of Medicine 12/1999; 341(19):1413-9. · 51.66 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Many trials have been done to compare primary percutaneous transluminal coronary angioplasty (PTCA) with thrombolytic therapy for acute ST-segment elevation myocardial infarction (AMI). Our aim was to look at the combined results of these trials and to ascertain which reperfusion therapy is most effective. We did a search of published work and identified 23 trials, which together randomly assigned 7739 thrombolytic-eligible patients with ST-segment elevation AMI to primary PTCA (n=3872) or thrombolytic therapy (n=3867). Streptokinase was used in eight trials (n=1837), and fibrin-specific agents in 15 (n=5902). Most patients who received thrombolytic therapy (76%, n=2939) received a fibrin-specific agent. Stents were used in 12 trials, and platelet glycoprotein IIb/IIIa inhibitors were used in eight. We identified short-term and long-term clinical outcomes of death, non-fatal reinfarction, and stroke, and did subgroup analyses to assess the effect of type of thrombolytic agent used and the strategy of emergent hospital transfer for primary PTCA. All analyses were done with and without inclusion of the SHOCK trial data. Primary PTCA was better than thrombolytic therapy at reducing overall short-term death (7% [n=270] vs 9% ; p=0.0002), death excluding the SHOCK trial data (5%  vs 7% ; p=0.0003), non-fatal reinfarction (3%  vs 7% ; p<0.0001), stroke (1%  vs 2% ; p=0.0004), and the combined endpoint of death, non-fatal reinfarction, and stroke (8%  vs 14% ; p<0.0001). The results seen with primary PTCA remained better than those seen with thrombolytic therapy during long-term follow-up, and were independent of both the type of thrombolytic agent used, and whether or not the patient was transferred for primary PTCA. Primary PTCA is more effective than thrombolytic therapy for the treatment of ST-segment elevation AMI.The Lancet 01/2003; 361(9351):13-20. · 39.06 Impact Factor
- Circulation 03/2009; 119(5):657-9. · 15.20 Impact Factor
© Europa Edition 2011. All rights reserved.
*Corresponding author: Erasmus MC, ’s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands.
Assessment of the safety and performance of the STENTYS
self-expanding coronary stent in acute myocardial infarction:
results from the APPOSITION I study
Giovanni Amoroso1, MD, PhD; Robert-Jan van Geuns2*, MD, PhD; Christian Spaulding3, MD, PhD;
Stephane Manzo-Silberman3, MD; Karl E. Hauptmann4, MD; René Spaargaren5, MD;
Héctor M. García-García2, MD, PhD; Patrick W. Serruys2, MD, PhD; Stefan Verheye6, MD, PhD
1. Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands; 2. Erasmus MC, Rotterdam, The Netherlands; 3. Cochin Hospital,
Assistance Publique Hôpitaux de Paris, France and Paris Descartes University and INSERM U 970, Paris, France;
4. Krankenhaus der Barmherzigen Brüder, Trier, Germany; 5. STENTYS SA, Paris, France; 6. ZNA Middelheim, Antwerp,
Aims: In the setting of ST-elevation myocardial infarction (STEMI), epicardial vasoconstriction and throm-
bus load may lead to stent undersizing and malapposition after primary percutaneous coronary intervention
(PPCI), which can both be responsible for stent thrombosis or restenosis. Aggressive stent deployment can,
on the other hand, cause distal embolisation and the no-reflow phenomenon. The purpose of our study was to
evaluate the safety and feasibility of a novel self-expanding stent by assessing the clinical, angiographic and
intravascular outcomes after stent deployment at three days and at six months follow-up.
Methods and results: This prospective, multicentre, non-randomised study enrolled 25 STEMI patients
undergoing PPCI; a nitinol, self-expanding, coronary stent (STENTYS® stent; STENTYS, Paris, France) was
used in all patients. Angiography and intravascular ultrasound (IVUS) or optical coherence tomography
(OCT) were performed immediately after stent deployment, after three days and at six months. Primary
safety endpoints were mortality, reinfarction, stent thrombosis and stroke at discharge and at six months. The
primary feasibility endpoints were technical, device and procedural success, and stent apposition at three
days and six months. Secondary endpoints included distal embolisation, binary restenosis, ischaemia-driven
target lesion revascularisation (TLR) and late lumen loss (LLL). There were no adverse events at discharge
or at six months. Technical, device and procedural success were 100%, 96% and 96%, respectively. IVUS
showed a significant vasodilatation distal to the culprit lesion at three-day follow-up (+19%), with a concord-
ant expansion of the implanted stent (+18%), p≤0.001 for both values. One case of distal embolisation was
reported. There were no cases of late stent malapposition at six months. In-stent and in-segment LLL were
0.71±0.71 mm and 0.58±0.61 mm. Binary restenosis was 25%, ischaemia-driven TLR was 12%.
Conclusions: This study shows that the use of the STENTYS® self-expanding stent is safe and feasible in
STEMI patients. Three days after the procedure, the stent expanded to the same extent as the epicardial
vasodilatation and appeared completely apposed to the vessel wall. This could be of benefit in preventing
stent thrombosis in the setting of STEMI.
• bare metal stent
Self-expanding stent in AMI: APPOSITION I
bare metal stent
incomplete stent apposition
late lumen loss
minimal lumen diameter
optical coherence tomography
primary percutaneous coronary intervention
quantitative coronary angiography
reference vessel diameter
ST-elevation myocardial infarction
Thrombolysis In Myocardial Infarction
target vessel revascularisation
Primary percutaneous coronary intervention (PPCI) is considered
the optimal approach for the treatment of ST-elevation myocardial
infarction (STEMI), because of its superior reperfusion outcomes
when compared to thrombolysis1-3.
The presence of thrombus and epicardial vasoconstriction, which
is only partially responsive to nitrates, can lead to an underestima-
tion of the vessel size and consequently to implantation of an under-
sized stent and late stent malapposition. In the acute setting, stent
undersizing is one of the most important predictors of stent throm-
bosis4,5. Studies have shown that both BMS and DES can safely be
used in PPCI for STEMI6-11. However, while the short-term malap-
position rates of BMS and DES appear to be similar (32.7% and
35.2%, respectively, in the HORIZONS-AMI IVUS substudy12),
one study showed a higher rate of late stent malapposition after
DES implantation, raising concerns about the long-term safety of
DES use in patients with STEMI13.
However, aggressive stent deployment and oversizing can lead to
plaque/thrombus disruption and distal embolisation. The subse-
quent occurrence of poor myocardial reperfusion (no-reflow phe-
nomenon) leads to a lack of myocardial salvage with poor short- and
long-term clinical outcomes14.
In vessels with a high thrombus load and major vasoconstriction,
such as in STEMI, the feature of self-expansion could potentially
reduce the occurrence of stent malapposition and distal embolisa-
tion, and thus of stent thrombosis and no-reflow.
The purpose of our study was to evaluate the safety and efficacy
of the STENTYS® self-expanding stent in STEMI patients by
assessing the clinical, angiographic and intravascular outcomes
acutely at three days and at six months post-procedure.
THE STENTYS® STENT
The STENTYS® coronary stent is a self-expanding, nitinol, bare metal
stent with a nominal strut width of 0.0027’’ (68 microns) (Figure 1).
The available stent lengths in the study were 22 and 27 mm with a
diameter suitable for vessels with a reference vessel diameter (RVD)
Figure 1. STENTYS® self-expanding stent.
between 3.0 and 3.5 mm. A 6 Fr compatible, rapid-exchange delivery
system delivers the stent into position over a conventional 0.014”
guidewire, and the stent is deployed by the withdrawal of a retractable
sheath. The stent has a Z-shaped design that is linked together by small
interconnections, which can be disconnected by balloon inflation
between the struts to create side branch access, if needed.
We conducted a multicentre, prospective, non-randomised, single-
arm study. The primary objective was to assess the safety and feasi-
bility of the STENTYS® stent in STEMI patients.
The study protocol was approved by local ethics committees and
competent authorities, and was conducted in accordance with the
Declaration of Helsinki. All serious adverse events were adjudi-
cated by an independent clinical events committee. All angio-
graphic, IVUS and OCT films were analysed by an independent
core lab (Cardialysis, Rotterdam, The Netherlands). All data was
monitored by a monitoring organisation (Medpass, Paris, France)
and entered into a database (double data entry). All patients pro-
vided written informed consent.
Patients admitted for STEMI with an onset of chest pain of less than
12 hours were screened for enrolment in the study. The inclusion
criteria were: >20 minutes of chest pain and ≥1 mm of ST-segment
elevation in at least two contiguous leads or new left bundle branch
block; age between 18 and 80 years; a de novo native coronary
lesion suitable for PCI with primary stent implantation; RVD
≥3.0 mm and ≤3.5 mm; target lesion length ≤ 21 mm (visually esti-
mated) in order to be covered by a single study stent.
The exclusion criteria were: prior thrombolytic therapy; myocar-
dial infarction caused by in-stent restenosis or restenosis; cardio-
genic shock; contra-indication to aspirin or clopidogrel; uncertain
neurological outcome after cardiopulmonary resuscitation; patients
under mechanical ventilation; renal failure (creatinine >2.5 mg/dl
or 150 µmol/l); known hypersensitivity to nickel-titanium; uncor-
rected bleeding disorders; previous stenting of the target vessel;
unprotected left main coronary disease with >50% stenosis; trifur-
cation lesions; excessive tortuosity of the target vessel; coronary
artery bypass graft surgery (CABG) planned for the target or
another vessel; participation in another investigational drug or
device study where the follow-up period was incomplete.
STUDY PROCEDURE AND MEDICATION
Patients were treated according to the current daily practice in each
of the participating centres. Thrombo-aspiration was recommended,
while predilatation was left to the discretion of the investigator.
Intracoronary nitroglycerine was systematically administered after
thrombus aspiration in order to properly evaluate vessel size. Stent
disconnection to allow side branch access was recommended if the
diameter of the side branch was >2.25 mm with TIMI flow <3, and/
or stenosis >50%, and/or dissection >grade B. The use of post-dila-
tation was recommended if there was a residual stenosis >30%.
Before the procedure, patients received anticoagulation therapy
according to local practice. The protocol recommended a 500 mg
bolus of aspirin, 300-900 mg clopidogrel, a heparin bolus of
5,000 IU IV and the use of glycoprotein IIb/IIIa inhibitors. Use of
bivalirudin was accepted. After the procedure, patients received
aspirin (at least 75 mg/day indefinitely) and clopidogrel (75 mg/
day for at least one month after the procedure).
Clinical data was collected before and after the procedure, at dis-
charge and at six months. Angiographic and IVUS assessments
were performed immediately after stent implantation, at three days
after the procedure, and at six months post-procedure. In a sub-
group of patients, OCT was performed instead of IVUS for optimal
assessment of the presence of thrombus and for stent apposition.
Primary safety endpoints were all-cause mortality, reinfarction, stent
thrombosis and stroke at discharge and at six months. Primary effi-
cacy endpoints were technical, device and procedural success after
stent placement, and apposition of the stent at three days and six
months. Secondary efficacy endpoints were angiographic signs of
distal embolisation after stent placement (investigator assessment),
binary angiographic restenosis, late lumen loss (LLL), and ischae-
mia-driven target lesion revascularisation (TLR) at six months.
All deaths were considered cardiac unless a non-disputed non-car-
diac cause was present. A TLR was considered clinically indicated
if angiography at follow-up showed both a diameter stenosis ≥50%
(core lab QCA assessment) and one of the following: (1) a positive
history of recurrent angina pectoris, presumably related to the target
vessel; (2) objective signs of ischaemia at rest (ECG changes) or
during exercise test (or equivalent), presumably related to the target
vessel; (3) abnormal results of any invasive functional diagnostic
test (e.g., Doppler flow velocity reserve, fractional flow reserve);
(4) a TLR or target vessel revascularisation (TVR) with a diameter
stenosis ≥70% even in the absence of the above-mentioned ischae-
mic signs or symptoms. Technical success was defined as the ability
to cross with the device and deploy the stent as intended at the tar-
get lesion. Device success was defined as technical success with
achievement of a final diameter stenosis <30%, and with TIMI flow
2 or 3 by quantitative coronary angiography (QCA). Procedural
success was defined as technical success without the occurrence of
death, reinfarction or repeat revascularisation of the target lesion
during the hospital stay.
Quantitative coronary angiography (QCA) was performed using
the CAAS5 analysis system (Pie Medical BV, Maastricht, The
Netherlands)15. In each patient, the stented segment and the peri-
stent segments (defined by a length of 5 mm proximal and distal to
the stent edge) were analysed. Repeat angiography was scheduled
at three-days and six-month follow-up.
Quantitative analysis of all angiographic data was performed
offline by an independent core laboratory (Cardialysis, Rotterdam,
The Netherlands). The following QCA parameters were deter-
mined: computer-defined minimal luminal diameter (MLD), refer-
ence diameter obtained by an interpolated method, and percentage
diameter stenosis. Binary restenosis was defined in every segment
as diameter stenosis ≥50% at follow-up. Late loss was defined as the
difference between MLD post-procedure and MLD at follow-up16.
Intravascular ultrasound images were acquired by motorised pull-
back at a constant speed of 0.5 mm/s. A computer-based contour
detection program (Curad BV, Wijk bij Duurstede, The Nether-
lands) was used for automated three-dimensional reconstruction of
the coronary segment beginning 5 mm distal and extending 5 mm
proximal to the stented segment. Feasibility, reproducibility and
inter- and intra-observer variability of this system have been vali-
dated in vivo17,18.
Quantitative analysis of all IVUS data was performed offline by
an independent core laboratory (Cardialysis BV, Rotterdam, The
Netherlands). The lumen, stent boundaries and external elastic
membrane (vessel boundaries) were detected using a minimum cost
algorithm. The stent volume (SV) and lumen volume (LV) were
calculated by multiplying length by mean areas. The intra-stent
neointimal volume was calculated as the difference between SV
and LV. The percentage obstruction of the stent volume was calcu-
lated as the intra-stent neointimal volume/stent volume*100.
Incomplete stent apposition (ISA) was defined as one or more
stent struts separated from the vessel wall with evidence of blood
speckles behind the strut on ultrasound. Late incomplete stent appo-
sition was defined as ISA at follow-up that was not present
OPTICAL COHERENCE TOMOGRAPHY ACQUISITION OCT acqui-
sition was carried out in five patients with the C7-XR™ Fourier-
domain system (LightLab Imaging, Westford, MA, USA) using the
These acquisitions were performed by first advancing a conven-
tional wire distal to the segment of interest, and then advancing the
OCT imaging catheter (RX ImageWire II; LightLab Imaging) dis-
tally towards the treated region. Pullback was performed while con-
Self-expanding stent in AMI: APPOSITION I
trast medium (3 mL/s, Iodixanol 370, Visipaque; GE Healthcare,
Cork, Republic of Ireland) was injected continuously into the guide
catheter using an injection pump. In this case, the automated pull-
back rate was 20 mm/s and the frame rate was 100 images/s.
OPTICAL COHERENCE TOMOGRAPHY ANALYSIS OCT measure-
ments were performed by an independent core lab (Cardialysis,
Rotterdam, The Netherlands) with proprietary software for offline
analysis (LightLab Imaging). The analysed region comprised the
stented segment as well as the segments 5 mm proximal and distal
to the stent. The lumen and stent areas were measured at 1 mm
In order to determine apposition of the struts, the following was
performed: (1) the distance from the middle point of the endolumi-
nal side of each strut to the lumen contour was measured; (2) if this
distance was greater than the strut thickness, this was considered a
malapposed strut; (3) in the frames with malapposed struts, the dif-
ference between the lumen and stent areas was measured, as this
represented the incomplete stent apposition area.
Analyses were conducted on an intention-to-treat basis. Continuous
variables were summarised by mean and standard deviation.
Descriptive statistics were provided for all variables considered in
the analysis. Categorical variables are presented as counts and per-
centages. Continuous variables are presented as mean, standard
deviation, and number of observations. Statistical analysis was per-
formed using Statistical Analysis System (SAS) for Windows (ver-
sion 9.1; SAS Institute Inc., Cary, NC, USA). Paired analysis
(comparisons of results for individual patients immediately post-
stent placement and at follow-up) was performed for IVUS data.
A total of 25 patients (mean age 58 years; 60% males) were enrolled
between March and October 2009 at five European sites. In 20/25
patients, IVUS was performed following stent placement, while in
the remaining five patients, OCT was performed.
PROCEDURAL AND IN-HOSPITAL RESULTS
Table 1 summarises the subject and lesion characteristics at base-
line. TIMI flow 0 at baseline was present in 68% of all subjects.
Thrombo-aspiration before stent implantation was performed in
17/25 patients (68%), and 14/25 patients (56%) required predilata-
tion of the culprit lesion. Ten patients received GPIIb/IIIa inhibitors.
Technical success was 100% (25/25 patients). In five patients, an
additional, non-study stent was used (one BMS and four DES); in
four cases, this second stent was placed to treat a second lesion, and
in one case because of insufficient lesion coverage. Final TIMI 3
flow after stent implantation was achieved in 24/25 patients (96%);
there was one angiographic finding of distal embolisation and
TIMI 2 flow. This patient presented with a 99% stenosis in the LAD
with TIMI 0 flow; thrombectomy, pre- and post-dilatation were
performed and IIB/IIIA inhibitors were administered.
Table 1. Baseline data.
Male gender 15 (60%)
Congestive heart failure 0 (0%)
Previous stroke0 (0%)
Previous myocardial infarction1 (4%)
Previous CABG 0 (0%)
Previous PCI1 (4%)
Former smoker 4 (16%)
Current smoker13 (52%)
Diabetes mellitus 5 (20%)
Peripheral arterial disease2 (8%)
RCA 10 (40%)
TIMI flow 0 at baseline17 (68%)
Mean lesion length (mm) 14.82±11.86
Mean lesion diameter stenosis before stent
Minimum lumen diameter (mm)0.28 ±0.44
Reference vessel diameter (mm)2.76±0.32
Mean lumen diameter (mm)2.33±0.43
LAD: left anterior descending coronary artery; LCX: left circumflex
coronary artery; RCA: right coronary artery
In 20/25 patients (80%), postdilatation was performed: in 11
patients at pressures ≤15 ATM; in nine patients at high pressures
(above 15 ATM).
Device success was 96% (24/25 patients) as one patient had a
residual stenosis of 52% due to a heavily calcified lesion. Procedural
success was 96% (24/25 patients) with no stent thromboses or
adverse events prior to discharge.
SIX-MONTH CLINICAL AND ANGIOGRAPHIC RESULTS
Clinical follow-up at six months was available in 25/25 patients.
No death (cardiac or non-cardiac), reinfarction or stent thrombo-
sis was reported at six months post-procedure. One patient expe-
rienced a reversible ischaemic neurological deficit 140 days
Angiographic follow-up was available for 20/25 patients. Five
patients, all free of symptoms, refused to undergo the scheduled
There were no late stent thromboses or total occlusions; 5/20
patients (25%) showed angiographic binary restenosis. Three of
them had clinically-driven TLR (12%), while two patients had non-
clinically driven TLR (restenosis <70% with no symptoms of
In-stent LLL was 0.71±0.71 mm and in-segment LLL 0.58±0.61 mm.
No stent fractures were detected. QCA results are shown in Table 2.
IVUS was performed after stent implantation, at three days, and at
six months after the procedure in 20/25, 16/25 and 15/25 patients,
respectively. Table 3 shows the results of those IVUS controls.
Three-day, paired IVUS results showed a non-significant
increase of the proximal segment (+5%), but a significant increase
of the mean reference area distal to the stent (+19%; p<0.001).
Mean stent area and minimum lumen area also significantly
increased (+18% and +19%, respectively; p<0.001 for both).
Table 4 provides the mean changes in MLA of the patients who had
IVUS follow-up; Figure 2 gives an overview of the MLA changes
of individual patients.
Incomplete stent apposition (ISA) was present in one patient
(5%) post-stent placement. None of the patients had ISA at six-
month follow-up. An example of stent expansion is illustrated in
OCT was performed after stent implantation, at three days, and at six
months after the procedure in 5/25, 4/25 and 3/25 patients, respectively.
Table 2. QCA results post-stent and at six months.
RVD (mm) 2.86±0.372.84±0.62
MLD in-stent (mm)
MLD in-segment (mm)2.14±0.461.69±0.67
% DS in-stent14.47±10.1537.64±21.61
% DS in-segment 23.03±10.1040.50±18.98
LLL in-stent NA0.71±0.70
LLL in-segment NA 0.58±0.61
Angiographic restenosis*NA 25% (5/20)
*Defined as >50% in-stent restenosis
Table 3. IVUS measurements post-stent and at three days and six
Vessel volume, mm3
Lumen volume, mm3
Stent volume, mm3
Plaque behind stent, mm3
225±99 244±109 169±60
Intimal hyperplasia, mm3
Minimum lumen area, mm2
Minimum lumen diameter, mm2.54±0.35 2.78±0.352.32±0.52
Patients with ISA120
Mean ISA area, mm2
Maximum ISA area, mm2
Minimum ISA area, mm2
Table 4. Paired IVUS analysis (N=16).
Post-stent placement3 days∆
Mean reference area (mm2)
Proximal (5 mm)
Distal (5 mm)6.24±2.057.41±3.2219%p<0.02
Mean lumen area (mm2)7.57±1.918.88±2.1817%p<0.001
Mean stent area (mm2)7.62±1.929.01±2.2718%p=0.001
Minimum lumen area (mm2)5.19±1.456.25±1.5319%p=0.001
Figure 2. Paired IVUS analysis: MLA post-procedure compared to
MLA at three days for individual patients.
Self-expanding stent in AMI: APPOSITION I
Paired OCT results showed a significant increase of minimal
lumen area at three days (5.52±1.46 mm2 to 7.50±0.73 mm2; +28%).
The percentage of malapposed stent struts immediately after the pro-
cedure was 2.27% and decreased to 0.11% three days later. Figure 4
demonstrates that some malapposition immediately after stent
implantation has resolved at three-day follow-up. This full apposition
is the consequence of an increase of the stent area following resolu-
tion of vessel constriction in the setting of acute MI.
Figure 3. IVUS images at baseline (A and A’) and at three-day follow-up (B and B’), showing an 18% increase in stent area. In panel C, the
two stent contours are overlapped. Arrows indicate the increase in stent size over three days.
Figure 4. OCT images immediately after stent implant (left) and after three-day follow-up (right). Malapposition area between 8 and 10
o’clock (white arrow) present after stent implant has resolved three days later.
This study shows that the use of the self-expanding STENTYS®
stent is safe and feasible in the setting of PPCI for STEMI. This
stent also displays the distinctive feature of positively adapting to
the changes in coronary anatomy (vasodilatation, thrombus dissolu-
tion), which occur during the first few days after the procedure.
Stent thrombosis is one of the major unresolved issues in PPCI.
In this setting, stent thrombosis rates are two to three times higher
than in the case of elective procedures. The HORIZONS-AMI
study13 demonstrated a 3.3% stent thrombosis rate (definite/proba-
ble) at one year. Its occurrence was associated with various factors,
both patient and procedure-related.
Epicardial coronary vasoconstriction due to systemic adrenergic
activation during PPCI can lead to an underestimation of the refer-
ence vessel diameter with subsequent implantation of an undersized
stent. Furthermore, residual intracoronary thrombus after throm-
boaspiration may later dissolve, leaving a gap between the stent and
the vessel wall. Stent undersizing and malapposition are both
potential causes of stent thrombosis5,6.
To our knowledge, this is the first study in the setting of STEMI
with IVUS examinations performed both immediately after stent
implantation and at three days. We demonstrated a significant
vasodilatation distal to the culprit lesion at three days after the pro-
cedure (+19%). Our results confirm the occurrence of severe epi-
cardial vasoconstriction in the acute setting of STEMI and
underscore the need for developing techniques or devices to avoid
stent undersizing. The concordant increase in the STENTYS® stent
area (+19%) at three days and the absence of malapposed stents
seen at six months suggest that this device follows the growth of the
vessel lumen while vasoconstriction and thrombus are resolving.
Studies have suggested that neointimal proliferation after stent
implantation is proportional to vessel wall injury caused by the
force exerted on the arterial segment20. Vessel wall injury with self-
expanding stents is different from that of balloon-expandable stents.
A nitinol self-expanding stent tends to take its original memory
shape. The radial force of self-expanding stents decreases when the
stent diameter increases, reaching an equilibrium when the outward
force of the stent equals the inward force of the vessel. The
STENTYS® stent has a memory diameter more than one millimetre
beyond the size of the vessel that it is intended for; this means that
the self-expanding stent automatically adapts to the size of the
At six-month follow-up, this is translated into regression of the
plaque behind the struts together with an increased growth of the
neo-intima. Therefore, with self-expanding stents, late stent expan-
sion and vessel growth is offset by larger intimal proliferation. The
net result is that balloon-expandable and self-expanding stents
result in similar values for mean and minimal lumen diameters, and
have equivalent LLL at long-term follow-up.
The ability of a self-expanding stent to grow in volume in the
first hours to days after the procedure allows gentle deployment
with less trauma, but also reduces plaque disruption/thrombus dis-
lodgement and thus could lead to less distal embolisation21,22. In our
study we observed one case of angiographically visible distal
embolisation, and a very high percentage of patients achieved final
TIMI 3 flow (96%). Animal studies have also confirmed that this
stent does not need to be deployed at high pressures as it continues
to expand after implantation23.
The STENTYS® stent differs from other self-expanding and
nitinol stents in several ways. While the WALLSTENT® (Boston
Scientific, Natick, MA, USA) was a self-expanding stent, it was not
made of nitinol but a braided, cobalt-alloy wire. It had clinical and
mechanical shortcomings including difficulties in precise position-
ing as a result of foreshortening of up to 20% on expansion, and
sharp wire ends that could lead to vessel trauma24.
Unlike the WALLSTENT® but similar to the STENTYS® stent,
the Radius™ stent (Boston Scientific) was a nitinol stent, laser-
cut from a tube. However, the Radius stent had a completely dif-
ferent design compared with the STENTYS® stent, resulting in
different mechanical properties such as different radial and
chronic outward forces, thicker and longer struts, and a larger cell
size that is not optimised for conformability to vessel wall varia-
tions21,22. As a result of these technical shortcomings and poor out-
come, clinical use of previous self-expanding stents has been
The STENTYS® stent showed favourable behaviour in terms of
LLL. The binary restenosis rate was 25%, compared to the 22.9%
restenosis at 13-month follow-up reported in the BMS arm of the
HORIZONS trial in similar lesions of similar lengths and compara-
ble RVDs13. The clinically-driven TLR rate was low, thus support-
ing the hypothesis that the use of drug-eluting stents, taking into
account their potential long-term caveats, is not mandatory in the
case of PPCI.
Bifurcation lesions remain a challenge and have been reported
in over 20% of patients treated with PPCI25. Outcome data for
PPCI of bifurcation lesions is limited, since STEMI is a common
exclusion criterion in randomised bifurcation studies26. In one
observational study, the presence of bifurcation lesions in the set-
ting of PPCI caused a slight excess of MACE23, while in the
NORDIC study, PPCI with DES stenting of bifurcation lesions
resulted in a trend towards an excess of stent thrombosis27. The
larger CADILLAC trial confirmed a higher incidence of stent
thrombosis in bifurcation lesions following PPCI (29% vs. 5% in
non-bifurcations; p=0.002)28. In the APPOSITION I study, only
one patient required treatment of a bifurcation. One of the features
of the STENTYS® stent is the possibility of disconnecting struts
to create access to a side branch. This was done with good results
in one study patient. Although a dedicated feasibility study has
shown the potential benefits of the use of the STENTYS® stent in
bifurcation lesions29, it remains to be demonstrated whether this
also applies to the treatment of bifurcation lesions in the setting of
This was a non-randomised, controlled feasibility study with a
small number of patients and strict selection criteria. Thus, these
Self-expanding stent in AMI: APPOSITION I
results cannot be extrapolated to broader patient groups with wider
selection criteria. As it was a feasibility study, the trial was not
intended to enable firm conclusions on the safety and efficacy of
the device to be drawn.
This APPOSITION I feasibility study shows that the use of the
STENTYS® self-expanding stent is safe and feasible in the treat-
ment of STEMI patients. Three days after the procedure, the stent
expands further to match the vasodilatation occurring distal to the
culprit lesion, and shows excellent apposition at six months.
Whether these findings could result in a lower late stent thrombosis
remains to be determined by further studies.
The authors would like to acknowledge all the cardiologists
involved in the PCI procedures of APPOSITION I. The authors
would also like to acknowledge the contribution of the Clinical
Event Committee consisting of P. Agostoni, Department of Cardiol-
ogy, University Medical Centre, Utrecht, The Netherlands and E.
Kedhi, Department of Cardiology, Maasstad Ziekenhuis, Rotter-
dam, The Netherlands.
Conflict of interest statement
R. Spaargaren is an employee of Stentys. The other authors have no
conflicts of interest to declare.
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