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Chinese Medical Journal 2014;127 (11)
2153
Original article
Nine-month angiographic and two-year clinical follow-up of polymerfree sirolimus-eluting stent versus durable-polymer sirolimus-eluting
stent for coronary artery disease: the Nano randomized trial
Zhang Yaojun, Chen Fang, Takashi Muramatsu, Xu Bo, Li Zhanquan, Ge Junbo, He Qing, Yang Zhijian, Li Shumei,
Wang Lefeng, Wang Haichang, He Ben, Li Kang, Qi Guoxian, Li Tianchang, Zeng Hesong, Peng Jianjun, Jiang Tieming,
Zeng Qiutang, Zhu Jianhua, Fu Guosheng, Christos V. Bourantas, Patrick W. Serruys and Huo Yong
Keywords: Nano stent; polymer-free; sirolimus-eluting stent; clinical outcomes; late lumen loss
Background First generation drug-eluting stents (DES) were associated with a high incidence of late stent thrombosis
(ST), mainly due to delayed healing and re-endothelization by the durable polymer coating. This study sought to assess
the safety and efficacy of the Nano polymer-free sirolimus-eluting stent (SES) in the treatment of patients with de novo
coronary artery lesions.
Methods The Nano trial is the first randomized trial designed to compare the safety and efficacy of the Nano polymer-free
SES and Partner durable-polymer SES (Lepu Medical Technology, Beijing, China) in the treatment of patients with de novo
native coronary lesions. The primary endpoint was in-stent late lumen loss (LLL) at 9-month follow-up. The secondary
endpoint was major adverse cardiac events (MACE), a composite of cardiac death, myocardial infarction or target lesion
revascularization.
Results A total of 291 patients (Nano group: n=143, Partner group: n=148) were enrolled in this trial from 19 Chinese
centers. The Nano polymer-free SES was non-inferior to the Partner durable-polymer DES at the primary endpoint of
9 months (P <0.001). The 9-month in-segment LLL of the polymer-free Nano SES was comparable to the Partner SES
(0.34±0.42) mm vs. (0.30±0.48) mm, P=0.21). The incidence of MACE in the Nano group were 7.6% compared to the
Partner group of 5.9% (P=0.75) at 2 years follow-up. The frequency of cardiac death and stent thrombosis was low for
both Nano and Partner SES (0.8% vs. 0.7%, 0.8% vs. 1.5%, both P=1.00).
Conclusions In this multicenter randomized Nano trial, the Nano polymer-free SES showed similar safety and efficacy
compared with the Partner SES in the treatment of patients with de novo coronary artery lesions. Trials in patients with
complex lesions and longer term follow-up are necessary to confirm the clinical performance of this novel Nano polymerfree SES.
Chin Med J 2014;127 (11): 2153-2158
DOI: 10.3760/cma.j.issn.0366-6999.20133148
Department of Cardiology, Nanjing First Hospital, Nanjing Medical
University, Nanjing, Jiangsu 210006, China (Zhang YJ)
Thoraxcenter, Erasmus Medical Center, Rotterdam, 3015CE, The
Netherlands (Zhang YJ, Muramatsu T, Bourantas CV and Serruys
PW)
Department of Cardiology, Beijing Anzhen Hospital, Capital Medical
University, Beijing 100029, China (Chen F)
Department of Cardiology, Beijing Fuwai Hospital, Beijing 100037,
China (Xu B)
Department of Cardiology, Liaoning Provincial People’s Hospital,
Shenyang, Liaoning 110016, China (Li ZQ)
Department of Cardiology, Zhongshan Hospital, Fudan University,
Shanghai 200032, China (Ge JB)
Department of Cardiology, Beijing Hospital, Beijing 100730, China
(He Q)
Department of Cardiology, Jiangsu Provincial People’s Hospital,
Nanjing, Jiangsu 210029, China (Yang ZJ)
Department of Cardiology, Second Affiliated Hospital of Jilin
University Changchun, Jilin, Jilin 130041, China (Li SM)
Department of Cardiology, Beijing Chaoyang Hospital, Capital
Medical University, Beijing 100020, China (Wang LF)
Department of Cardiology, Xijing Hospital, The Fourth Military
Medical University, Xi’an, Shanxi 710032, China (Wang HC)
Department of Cardiology, Renji Hospital, Shanghai Jiao Tong
University School of Medicine, Shanghai 200127, China (He B)
Department of Cardiology, Beijing Xuanwu Hospital, Capital
Medical University, Beijing 100053, China (Li K)
Department of Cardiology, First Affiliated Hospital of China Medical
University, Shenyang, Liaoning 110001, China (Qi GX)
Department of Cardiology, Beijing Tongren Hospital, Capital Medical
University, Beijing 100730, China (Li TC)
Department of Cardiology, Affiliated Tongji Hospital, Huazhong
University of Science and Technology, Tongji School of Medicine,
Wuhan, Hubei 430032, China (Zeng HS)
Department of Cardiology, Beijing Millennium Monument Hospital,
Capital Medical University, Beijing 100038, China (Peng JJ)
Department of Cardiology, Tianjin Armed Policemen Hospital,
Tianjin 300162, China (Jiang TM)
Department of Cardiology, Affiliated Union Medical Hospital of
Huazhong University of Science and Technology, Tongji School of
Medicine, Wuhan, Hubei 430022, China (Zeng QT)
Department of Cardiology, First Affiliated Hospital of Zhejiang
University, Hangzhou, Zhejiang 310003, China (Zhu JH)
Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang
University School of Medicine, Hangzhou, Zhejiang 310016, China
(Fu GS)
Department of Cardiology, Peking University First Hospital, Beijing
100034, China (Huo Y)
Correspondence to: Dr. Huo Yong, Department of Cardiology,
Peking University First Hospital, Beijing 100034, China (Tel: 86-1083575727. Fax: 86-10-66551383. Email: [email protected]).
Zhang Yaojun and Chen Fang contributed equally to this study.
This study was sponsored by Lepu Medical Technology, Beijing,
China.
Chin Med J 2014;127 (11)
2154
F
irst generation drug-eluting stents (DES) with controlled
release of anti-proliferative drugs from durablepolymers have markedly reduced restenosis compared
with bare-metal stents. 1,2 However, hypersensitivity
reactions and delayed vessel healing induced by the
durable polymers used in these first-generation DES
resulted in a high frequency of late stent thrombosis
(LST).3-5 Recent advances in stent technology, with the
introduction of biocompatible or biodegradable polymers,
have minimized the risk of this complication.6,7 However,
there are still concerns about durable polymers in the newgeneration DES, such as delayed vascular healing and reendothelialisation.8 Recently, the polymer-free DES were
tested in several studies and proved to be a feasible and
efficacious method to inhibit neointimal cell proliferation
without the potential of late polymer-related adverse
effects.9-11
The Nano (Lepu Medical Technology, Beijing, China)
sirolimus-eluting stent (SES) is a polymer-free stainless
steel DES, with nanoporous cavities as drug carriers.
The average diameter of the nanopore is around 400
nm. These nanopores have the capability of controlling
antiproliferative drug release and maintaining inherited
mechanical properties of stent struts. The present study was
designed to investigate the safety and efficacy of this novel
polymer-free SES compared with the durable-polymer SES
(Lepu Medical Technology) in the treatment of patients
with de novo coronary artery lesions.
METHODS
Study design and patient population
The Nano trial is a prospective, single-blinded, multicentre,
randomized clinical trial which was designed to investigate
the safety and efficacy of the Nano polymer-free DES
compared with the Partner durable-polymer SES (Lepu
Medical Technology), which is widely used in China. A
total of 291 patients with up to two de novo native coronary
artery lesions were enrolled in the study at 19 high-volume
Chinese medical centers. The study protocol was approved
by all institutional ethics committees of all participating
centers. All patients provided written informed consent for
participation in the study. The primary investigators had full
access to and take full responsibility for the integrity of the
data. All authors have read, and agreed to, the manuscript
as written.
The inclusion criteria for the present study include: age ≥18
years old, maximum two de novo native coronary artery
lesions, the target lesion with a diameter stenosis ≥70%,
visual reference vessel diameter (RVD) in 2.5–4.0 mm and
a visual lesion length ≤40 mm. The major exclusion criteria
were as follows: acute myocardial infarction within one
week, left main coronary artery disease, true bifurcation
lesion with side branch diameter ≥2.25 mm, chronic total
occlusion, in-stent restenosis, NYHA classification >class
3 or LVEF ≤40%, prior PCI within 12 months, or renal
dysfunction (serum creatinine concentration ≥3.0 mg/dl).
Study devices
The Nano stent has a backbone composed by 316L
stainless steel with abluminal nanoporous cavities as drug
carriers that contain the anti-proliferative drug sirolimus
(2.2 μg/mm2) (Figure 1). Kinetic release data indicate that
about 85% of the drug releases within 1 month after stent
implantation. The available stent lengths are 12, 15, 18, 24,
29 and 36 mm with diameters of 2.50, 2.75, 3.00, 3.50 and
4.00 mm.
Randomization, procedures and adjunct drug therapy
Immediately after successful passage of the guidewire
through the target lesion, the patients were randomly
assigned to receive either a Nano or Partner stent, by
a computer-generated allocation sequence. Lesions
were treated by standard interventional techniques, and
post-balloon dilation after the device implantation was
recommended. In case a bailout procedure and additional
stent were required, the stent had to be the same as the
initial stent allocated. The procedure was considered
successful when stent placement had a residual stenosis of
<20% and Thrombolysis in Myocardial Infarction flow was
grade 3.
All patients received a loading dose of 300 mg clopidogrel
at least two hours prior to the procedure and intravenous
heparin during the procedure. After the intervention, all
patients received 100 mg/d of aspirin indefinitely, as well as
75 mg/d of clopidogrel for at least 12 months.
Study endpoints, definitions, and follow-up
The primary endpoint of the study was in-stent late lumen
loss (LLL) at 9-month follow-up. The secondary endpoints
included in-segment LLL, binary restenosis at angiographic
follow-up, major adverse cardiac event (MACE, defined
as a composite of cardiac death, myocardial infarction
Figure 1. Nano polymer-free sirolimus-eluting stent. The Nano stent has a backbone composed by 316L stainless steel with nanoporous
cavities as abluminal drug carriers, containing the anti-proliferative drug sirolimus. The scanning electron microscopy images of nanoporous
before (A) and after (B) antiproliferative drug loaded, before (C) and after (D) device inflation.
Chinese Medical Journal 2014;127 (11)
(MI), or target lesion revascularization (TLR)), all-cause
death, and stent thrombosis at 2 years follow-up. Death
was considered to be from cardiac causes unless a noncardiac cause could be identified. MI was defined as rise
in plasma level of creatine kinase (CK)-MB/troponin
≥3 times the upper limit of normal, with or without new
pathological Q-waves on the electrocardiogram. Stent
thrombosis (definite and probable) was defined according
to the Academic Research Consortium classification.
Clinical follow-up was scheduled at 30, 90, 180, 365 days,
and two years. Adverse events were monitored throughout
the follow-up period, and adjudicated by an independent
clinical events committee.
Angiograms were recorded before and immediately after
the procedure as well as at 9 months follow-up. Standard
quantitative coronary angiography (QCA) methodology
was used, including analysis of in-stent and peri-stent
segments (5 mm proximal and distal to the stent edge).
Binary restenosis was defined as a diameter of the stenosis
≥50% at angiographic follow-up. LLL was calculated
as the difference of minimal lumen diameter between
post-procedure and follow-up. Operators of the core
angiographic laboratory (China Cardiovascular Research
Foundation (CCRF), Beijing, China) were blinded to the
assigned stent groups with the aid of the automated edgedetection system CAAS II V5.0 (Pie Medical Imaging, The
Netherlands).
Statistical analysis
The study was designed to test the equivalence between
the polymer-free and durable polymer stents regarding the
endpoint of LLL. The non-inferiority margin was set to 0.25
mm. The null hypothesis stated that the difference in LLL
between polymer-free and polymer stent would be ≥0.25
mm. The alternative hypothesis stated that the difference
in LLL between rough-surface stents and smooth-surface
stents would be <0.25 mm. We chose a power of 80% and
a-level of 0.05. For this purpose, 77 patients with follow-up
angiography in each group were needed. To accommodate
for possible losses during follow-up, we included 100
patients in each group. The analyses were performed on an
intention-to-treat basis.
Data are expressed as mean±standard deviation (SD) or
as proportions (%). The differences between groups were
assessed by χ2 test or Fisher’s exact test for categorical
data and t-test for continuous data. Comparisons of twoyear clinical outcomes were conducted with the KaplanMeier method and the log-rank tests. A P value less than
0.05 was considered statistically significant (two-sided). All
statistical analyses were performed by SAS version 9.1.3
(SAS Institute, Cary, NC, USA).
RESULTS
Baseline characteristics and procedural results
A total of 291 patients were enrolled in this study and
randomized to receive a Nano stent (n=143) or Partner stent
2155
(n=148). As shown in Table 1, the baseline clinical and
lesion features were well matched between the two groups
(diabetes 15.4% vs. 18.2% and hyperlipidemia 26.9% vs.
35.1% in the Nano and Partner groups). Although a greater
prevalence of prior MI was found in the Nano group,
the difference is not statistically significant (P=0.06).
The lesion characteristics were comparable between the
Nano and Partner groups as well (RVD 3.00±0.45 mm
vs. 3.05±0.49 mm and lesion length 23.7±13.3 mm vs.
23.6±13.8 mm, Table 2).
Angiographic results
In total, 234 patients experienced angiographic follow-up
at 9-month follow-up (Nano n=112 and Partner n=122).
The QCA results are shown in Table 3. Although the instent LLL in the Nano group is significantly higher than
seen in the Partner group (0.37±0.40 mm vs. 0.26±0.40
mm, P=0.03), the Nano polymer-free SES was non-inferior
to the Partner durable-polymer SES for this primary
Table 1. Baseline and lesion characteristics
Characteristics
Age (years)
Male
Diabetes mellitus
Hypertension
Hypercholesterolemia
Current smoker
Family history of CAD
Prior MI
Prior PCI
Unstable angina
Target vessel
LAD
LCX
RCA
Reference vessel diameter (mm)
Lesion length (mm)
Minimal lumen diameter (mm)
Diameter stenosis (%)
Nano group
(n=143)
55.3±10.7
106 (74.4)
22 (15.4)
81 (56.4)
38 (26.9)
77 (53.9)
6 (3.9)
53 (37.2)
18 (13.4)
78 (54.5)
Partner group
(n=148)
59.5±9.8
117 (79.2)
27 (18.2)
75 (50.7)
52 (35.1)
73 (49.4)
4 (2.6)
35 (23.4)
22 (16.1)
89 (60.1)
62 (43.2)
30 (21.2)
48 (33.9)
3.00±0.45
23.7±13.3
0.80±0.48
86.2±9.6
60 (40.5)
28 (19.0)
54 (36.4)
3.05±0.49
23.6±13.8
0.89±0.43
83.9±9.8
P values
0.54
0.47
0.64
0.47
0.27
0.58
1.00
0.06
0.54
0.20
0.68
0.79
0.77
0.36
0.90
0.15
0.53
Data are expressed as mean±SD or n (%). AHA/ACC: American Heart
Association/American College of Cardiology; CAD: coronary artery disease;
LAD: Left anterior descending artery; LCX: left circumflex artery; MI:
myocardial infarction; PCI: percutaneous coronary intervention; RCA: right
coronary artery.
Table 2. Procedural results
Variables
Pre-dilation
Post dilatation
Maximum pressure (atm)
Treated lesion per patient
Total stent length per lesion (mm)
Reference vessel diameter (mm)
Minimal lumen diameter (mm)
In-stent
In-segment
Diameter stenosis
In-stent
In-segment
Late lumen loss (mm)
In-stent
In-segment
Device success (%)
Lesion success (%)
Nano group
(n=179)
135 (75.4)
80 (44.7)
13.9±2.9
1.25±0.55
23.4±6.84
3.05±0.49
Partner group
(n=188)
145 (77.1)
91 (48.4)
14.3±3.2
1.27±0.63
22.8±7.1
3.08±0.50
2.33±0.61
2.11±0.66
2.44±0.58
2.13±0.58
0.16
0.80
14.91±5.68
21.67±9.66
14.84±4.83
20.70±8.24
0.90
0.31
0.37±0.40
0.34±0.42
100
100
0.26±0.40
0.30±0.48
100
100
<0.01
0.21
1.00
1.00
P values
0.70
0.48
0.24
0.76
0.25
0.64
Data are expressed as mean±SD, % or n (%). 1 atm=101.325 kPa.
Chin Med J 2014;127 (11)
2156
Table 3. Angiographic results at 9 months follow-up
Variables
Angiographic follow-up rate
Reference vessel diameter (mm)
Minimum lumen diameter (mm)
In-stent
Proximal edge
Distal edge
In-segment
Diameter stenosis
In-stent
Proximal edge
Distal edge
In-segment
Binary restenosis (n (%))
In-stent
Proximal edge
Distal edge
In-segment
Late lumen loss (mm)
In-stent
Proximal edge
Distal edge
In-segment
Nano group
(n=112)
78.3
3.04±0.49
Partner group
P values
(n=122)
82.4
3.08±0.50
0.64
2.33±0.61
2.77±0.68
2.36±0.64
2.11±0.66
2.44±0.58
2.76±0.68
2.27±0.61
2.13±0.58
0.16
0.91
0.28
0.81
24.1±14.6
15.2±12.7
18.4±13.7
30.4±17.3
14.7±4.7
16.6±15.6
18.6±13.1
28.0±13.9
0.80
0.47
0.88
0.52
5 (4.5)
3 (2.7)
4 (3.6)
10 (8.9)
4 (3.3)
4 (3.3)
3 (2.5)
8 (6.6)
0.64
0.79
0.62
0.50
0.37±0.40
0.28±0.45
0.20±0.26
0.34±0.42
0.26±0.40
0.31±0.56
0.22±0.44
0.30±0.48
0.03
0.57
0.59
0.21
Data are expressed as mean±SD, % or n (%).
Table 4. Clinical outcomes at 2 years follow-up (n (%))
Indice
Major adverse cardiac event*
All-cause death
Cardiac death
Myocardial infarction
Target vessel revascularization
Stent thrombosis
Nano group
(n=132)
10 (7.6)
1 (0.8)
1 (0.8)
2 (1.5)
8 (6.1)
1 (0.8)
Partner group
(n=136)
8 (5.9)
1 (0.7)
1 (0.7)
1 (0.7)
7 (5.3)
2 (1.5)
P values
0.59
1.00
1.00
0.62
0.75
1.00
*
A composite of cardiac death, myocardial infarction and target vessel
revascularization.
endpoint (P <0.001). The 9-month in-segment LLL of the
polymer-free Nano SES was comparable to the Partner
SES (0.34±0.42 mm vs. 0.30±0.48 mm, P=0.21). The rates
of in-segment and in-stent binary restenosis were similar
between the two groups.
Clinical outcomes
At 2-year follow-up, a total of 268 patients (92.4%)
completed clinical follow-up (Nano n=132 and Partner
n=136). Clinical outcomes are summarized in Table 4. The
incidence of MACE in patients who underwent Nano and
Partner stent implantation was similar (7.6% vs. 5.9%,
P=0.59). There were no significant differences in cardiac
death (0.8% vs. 0.7%, P=1.00), MI (1.5% vs. 0.7%,
P=0.62), and TLR (6.1% vs. 5.3%, P=0.75). Only three
cases of stent thrombosis (definite/probable) were observed
in the two groups (0.8% vs. 1.5%, P=1.00).
DISCUSSION
The present study is an early prospective, multicenter,
randomized clinical trial investigating the use of Nano
polymer-free SES in treating patients with de novo coronary
artery lesions in China. The findings of this study showed
that the Nano polymer-free SES had similar safety and
efficacy compared with the Partner durable-polymer SES.
Stent thrombosis was rarely observed in both the Nano and
Partner groups.
Metallic DES has become widely used in patients with
coronary artery disease, and significantly reduces restenosis,
compared with bare metal stent.12,13 However, delayed
vascular healing and impaired endothelialization, potentially
caused by polymer-related inflammation, hypersensitivity,
and toxicity in first generation DES, increased the risk
of late and very late stent thrombosis.4,5 Recently, several
newer generation DESs with biocompatible polymer
coatings have been introduced to reduce the risk of this
complication. In the RESOLUTE all-comers trial, the
incidence of ST in the Xience V group was only 0.8% at
one-year follow-up.14 Alternatively, a recent meta-analysis
showed that the median target lesion revascularization rate
was only about 3% with everolimus eluting stent at 1 year
follow-up, and a significant lower rate of revascularization
over 1 year. 15 However, most of available studies did
not have angiographic or invasive imaging follow-up at
long term. Thus, there is little information on the “catchup” phenomenon following the newer generation durable
polymer DESs implantation. In a small randomized study of
the SPIRIT II trial, the in-stent LLL after EES implantation
was (0.17±0.32) mm at 6-month follow-up, and increased
to (0.33±0.37) mm at two years.16 The potential clinical
importance and exact mechanisms of this phenomenon still
need further investigation.17
To avoid the potential adverse effect of permanent presence
of polymer coatings to coronary artery, DESs with
biodegradable-polymer and polymer-free designs were
introduced. The clinical performance of the biodegradable
polymer technology has been extensively evaluated in
several all-comers trials, showing promising results at shortand long-term follow-up. However, controversial results
regarding this technology have been recently reported. In
the SORT OUT V trial, Christiansen et al demonstrated that
the biodegradable polymer-coated biolimus-eluting stents
did not show non-inferiority in the assessment of clinical
safety and efficacy compared with a durable polymer
sirolimus-eluting stent (Cypher) at one-year follow-up.18,19
The polymer-free DES as an emerging technology has
been specially designed to offer long term safety.10 In the
past decade, old fashion polymer-free DESs however did
not prove to be efficacious of inhibiting neointimal cell
proliferation, resulting in a high risk of restenosis.20 The
problem of these devices might be attributed to the fact
that the modified process of coatings through microporous
surfaces impaired the loading dose of the drug to be eluted.
Moreover, the pattern of drug release kinetics of polymerfree DES was likely to be different with those of durable
polymer DES.
Several new polymer-free DESs combining novel coating
technologies or post-treatment techniques with different
drugs have been pre-clinically or clinically evaluated.21-23 In
a small study comparing the parameters of optical coherent
Chinese Medical Journal 2014;127 (11)
tomography imaging in 19 patients undergoing Cre8
polymer-free DES implantation and 19 patients undergoing
bare metal stents, no difference in the stent strut coverage
was observed (99.8% at three months vs. 99.6% at one
month, P non-inferiority <0.01).9 This result may provide
an opportunity to shorten the duration of dual antiplatelet
therapy after the device implantation. The Nano polymerfree SES presented in the current study has its unique
design, providing longer term follow-up information after
the stent implantation. However, no invasive imaging
examinations were planned, which did not allow us to
evaluate the vascular response of the device at follow-up
after percutaneous coronary intervention.
Device related ST is mainly associated with several
components of device, such as antiproliferative drug, stent
surface, and especially polymers. The unique design of
the Nano stent, without polymer coatings, may provide
the opportunity to minimize the risk of ST. The low
incidence of ST in the current study can be due to the
low risk patients with simple de novo lesions enrolled.
Of note, the proof of lower device-related ST rate after
the Nano stent implantation can only come from daily
clinical data. Thus the current study is not enough to make
any definitive conclusions on this. Apart from safety, it is
also important to ensure that the use of this nanoporous
polymer-free technology does not adversely affect efficacy.
It may be disappointed that the in-stent LLL of the Nano
stent is significantly higher than seen in the Partner group.
Surprisingly, similar clinical efficacy endpoints were
observed between the 2 studied devices. Theoretically, the
technology of nanopores used in the Nano stent has strong
drugs adhesion power that can effectively control antiproliferative drug release, the in vivo performance may still
partially rely on device’s well-expansion after procedure.
Thus, post-balloon dilation was recommended in clinical
practice to achieve a high percentage of complete stent
strut apposition to eliminate the impact of blood flush
on drug release. Based on the encouraging results of
the present study, at least, it supports the concept of this
novel technology with nanoporous cavity as drug carrier
to effectively control drug release and sufficiently inhibit
neointimal hyperplasia.
The manufacture has improved the technology,
incorporating several innovative technologies, such as
dual-coating, coupling, and cold isostatic post-treatment
techniques. Preclinical evaluation of the “Nano plus” stent
indicated that the fracture strain significantly increase to 5%
through dual-coating technology, which can mostly avoid
coating fracture during stent deployment. Currently, the
Nano plus OCT study using optical coherent tomography
imaging has started at five European medical centers, to
evaluate the extent of neointimal hyperplasia and early
arterial healing at 3 months (Clinicaltrials.gov Identifier:
NCT01925027).
The limitations of the study are as follows. First, the
sample size was calculated to assess a difference in LLL,
2157
which is only a surrogate endpoint for clinical efficacy.
Second, lack of intracoronary imaging examinations
provided limited insights on vascular response after the
device implantation.24 Third, patients enrolled in the present
study only had de novo coronary artery lesions, thus larger
randomised trials with longer term follow-up in patients
with complex lesions are required.
The results of this study showed that the Nano polymerfree SES had similar clinical safety and efficacy compared
with the Partner durable-polymer SES in the treatment of
patients with de novo coronary artery lesions. Appropriate
powered randomized all-comers trials in patients with
clinical and lesional complexities are necessary to confirm
the reported findings.
Acknowledgements: We are grateful to the clinical research
coordinators in the Nano randomized trial organization and
participating centers for their great effort.
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(Received December 7, 2013)
Edited by Wang Mouyue and Liu Huan