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PRO-Kinetic registry
Introduction
The performance of bare metal stents has vastly improved in recent
years. Improvements in three-dimensional geometrical structure
and the use of thinner metals and innovative delivery systems have
enhanced the flexibility and tracking properties (i.e.
manoeuvrability) while optimising the scaffolding of the
atherosclerotic plaque
1
. These properties may translate into
improved long-term clinical outcomes. The search for a better bare
metal stent (BMS) design are of fundamental importance for further
definition of patients that are still eligible for BMS utilisation in the
current era. The PRO-Kinetic stent (Biotronik Corp., Bülach,
Switzerland) is a new generation BMS that combines the properties
of the cobalt chromium metal alloy with thin-struts design to allow
improved stent performances in all procedures.
The primary aim of this single-centre, non-randomised, consecutive
registry was to evaluate the short and intermediate-term clinical
performance of the PRO-Kinetic coronary stent in the treatment of
patients enrolled in every day practice at our institution.
Methods
Patient population
The current study includes 515 patients who were treated at our
institution between January 2006 and March 2008. Patients who
were at least 21 year of age, had stable or unstable angina or
myocardial ischaemia or acute/recent myocardial infarction, and
were undergoing percutaneous coronary intervention (PCI) with bare
metal stents were considered for the study. Patients were excluded if
they had known allergy to aspirin, clopidogrel, ticlopidine, heparin, or
other anticoagulant or anti-platelet therapy as required for PCI.
During the study period, the use of drug eluting stents (DES)
averaged ~40% at our catheterisation laboratories. This pattern of
DES / BMS use is based on guidelines adopted by the Israeli Society
of Cardiology (e.g. recommended DES use primarily in LAD lesions,
proximal segments, long [>20 mm] and in stent restenosis lesions
and/or diabetic patients). Those DES treated patients were obviously
excluded from the current analysis. Only patients with ‘pure’ PRO-
Kinetic utilisation (i.e. no mix of PRO-Kinetic stent with other BMS or
DES stents) were included in the analysis. Written informed consent
was obtained from all patients prior to PCI. Data collection was
approved by the hospital ethical committee.
Coronary angiography and intervention were performed according
to the standard clinical practice at the investigation sites. Dual anti-
platelet therapy with Clopidogrel (75 mg once daily), supplemented
with 100 mg aspirin was recommended for three months for stable
patients and for 6-12 months following acute coronary syndrome
events. Aspirin alone was recommended indefinitely afterwards
(unless contraindicated). Administration of GP IIb/IIIa inhibitors or
bivalirudin (instead of heparin ± GP IIb/IIIa) was optional and was
left to the investigators’ discretion.
The PRO-Kinetic™ stent system
The PRO-Kinetic™ stent system is a cobalt chromium alloy tubular
stent with a unique multi-cellular design, pre-mounted on a semi-
compliant, low profile balloon (Figure 1). The cell structure provides
improved flexibility and tracking properties in tortuous vessels while
radial strength and vessel bend coverage are maintained by the
tubular design. The PRO-Kinetic stent has thin struts
(60 µm/0.0024” per 2.0-3.0 mm stent, 80 µm/0.0031” per 3.5-
4.0 mm stent, and 120 µm/0.0047” per 4.5-5.0 mm stent), a low
profile, high deliverability and a silicon carbide PROBIO
®
passive
coating which may allow properties of utilisation during all PCI
procedures. The PROBIO coating was shown in vitro to reduce the
thrombogenic properties of metal stents, while facilitates
regenerative endothelial coverage
2
.
Endpoints of the registry
The primary endpoint of this registry was a composite of major adverse
cardiac events (MACE, for definition see below) at one and six months
after the procedure. Secondary endpoints were angiographic and
procedural success rates, TLR and TVR rates at six months and
angiographically proven in-stent thrombosis at six months. A pre-
specified sub-analysis was performed for diabetic patients.
Definitions
Angiographic success was defined as final residual stenosis of the
target site <30% using the assigned treatment device alone.
Procedural success was defined as angiographic success without
in-hospital major adverse cardiac events (MACE). MACE is
composed of any death, any myocardial infarction (Q and non
Q MI), or any percutaneous or surgical target vessel
revascularisation (TVR) or target lesion revascularisation (TLR)
Abbreviations and acronyms
BMS:
bare metal stent
DES:
drug eluting stent
CABG: coronary artery bypass surgery
LVEF:
left ventricular ejection fraction
MLD:
minimal lumen diameter
MACE: major adverse cardiac events
PCI:
percutaneous coronary revascularisation
QCA:
quantitative coronary angiography
TVR:
target vessel revascularisation
TLR:
target lesion revascularisation
Figure 1. The Pro-Kinetic stent.