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Non-ST-Elevation Myocardial Infarction (NSTEMI), unstable angina
pectoris, creatine kinase values, as well as reference coronary
diameters of treated coronary vessels, clinical presentation,
angiographic findings, procedural success, balloon angioplasty
procedure, adjunctive therapy, acute results, procedural
complications and hospital course. All events were recorded and
maintained in a central cohort database. Stenosis morphology was
classified as type A, B1, B2, or C stenosis according to AHA/ACC
guidelines
29
. Angiograms were initially evaluated by the
investigators, using visual assessment at baseline, immediately after
balloon angioplasty respectively following stent placement. The
morphology of the target lesion, presence and degree of calcium,
degree of plaque burden, percent of diameter stenosis and
thrombolysis in myocardial infarction (TIMI) grade flow were
documented. Throughout the study, adverse cardiac and cerebral
events were recorded, including death, cerebrovascular accident,
abrupt or late vessel closure, re-infarction, perforation, dissection,
distal embolisation or no-reflow phenomena as encountered during
the procedure and hospitalisation.
Angioplasty protocol
A dose of 100 mg of aspirin was administered before angioplasty
and daily thereafter. Heparin was given intravenously in an initial
bolus of 7.500-10.000 U, followed by incremental bolus doses to
maintain an activated clotting time during the procedure.
Intracoronary nitroglycerin was administered before and during the
procedure at the operator’s discretion. The size of the balloon and
stent (PRO-Kinetic Cobalt Chromium Coronary Stent with PROBIO
®
silicon carbide coating, BIOTRONIK AG, Switzerland) was selected
according to an estimated ratio 1:0 for diameter of stent/reference
artery. The length of the stent was chosen on the basis of the length
of the target stenosis. In case of non-sufficient deployment of the
stent, post-dilatation with a non-compliant balloon was carried out.
Study endpoints and definitions
The primary study endpoint was the rate of target lesion
revascularisation (intention-to-treat) and late loss at 6-month follow-
up. The secondary combined endpoint was the procedural success
and the rate of major adverse cardiac events (MACE). MACE was
defined as: 1) cardiovascular death; or, 2) unstable or stable angina
pectoris with need for target lesion revascularisation (intention-to-
treat); or, 3) myocardial infarction (ST- or non ST-elevation
myocardial infarction (STEMI, NSTEMI) with elevation of creatine
kinase (CK) levels greater than twice normal laboratory values with
any abnormal MB fraction during the follow-up period.
Procedural success was defined as the ability to insert the stent into
the target lesion, to achieve final reduction of lumen diameter
stenosis to < 30% (after stent deployment), and to obtain TIMI 3
flow in the absence of major in-laboratory and in-hospital
complications (death, emergency bypass surgery, development of a
new non-ST-elevation myocardial infarction, or ST-elevation
myocardial infarction and target vessel revascularisation).
Perforation was defined as persistent extra vascular collection of
contrast medium beyond the vessel wall with or without associated
clinical complications.
30
Dissection was considered to be major if it
was flow-limiting or associated with death, myocardial infarction, or
the need for bypass surgery - and minor if it did not lead to clinical
complication.
31
Acute closure was defined as reduced antegrade
flow (TIMI < l) caused by acute occlusion of the target lesion. Intra
coronary thrombus was defined as an intra-luminal lucency, filling
defect, or staining consistent with angiographic appearance of
thrombus.
32
ST-elevation myocardial infarction was diagnosed as
the development of ST-elevations on the electrocardiogram and
elevation of creatine kinase-MB above laboratory normal values.
Non-ST-elevation myocardial infarction was defined as creatine
kinase determination of twice the normal, with a positive MB with or
without persistent ST-segment or T-wave changes on the post-
procedural electrocardiogram. Groin site complications included
need for blood transfusion or surgical intervention.
Statistical analysis
Statistical analysis was performed at the Data Management Centre
of Genae Associates in Antwerp, Belgium using the SPSS platform
(SPSS Inc, Chicago, IL, USA). Categorical variables, described
using absolute numbers and frequency of characteristics or event,
were assessed by chi-square or Fisher’s test. For comparison of
continuous measures described by means with standard deviations,
Student’s t-test was used. Changes in TIMI grade, target lesion
revascularisation, and percent of diameter stenosis were tested
using a Wilcoxon sign rank test. A p < 0.05 was considered
significant.
Angiographic analysis
Coronary angiography was performed in a routine manner. We
obtained measurements of the interpolated reference diameter,
lesion length and diameter, diameter stenosis, and minimal luminal
diameter (MLD) before and after the intervention and at follow-up,
from angiograms performed after intra coronary administration of
nitroglycerin in all patients, where follow-up angio was available.
Coronary angiograms were obtained in a routine manner by
experienced cardiologists, who had limited information about
patients including their laboratory results or previous angioplasty
treatment. Quantitative coronary arteriography (QCA) was
performed by independent interventionists at the core laboratories
of Genae Associates in Antwerp, Belgium using the QAngioXA
platform (Medis Medical Imaging Systems B.V., Rotterdam, the
Netherlands) with previously stipulated and validated edge-
detection algorithms using a catheter for calibration
33,34
.
Results
Clinical characteristics
Silicon Carbide coated cobalt chromium stent angioplasty was
performed on a total of 161 lesions in 145 patients with a mean age of
69.0±13.8 (range 41-92, 69.0% males). Further baseline
characteristics of the total population are shown in Table 1. The
baseline morphologic characteristics of the target vessel are
expressed in Table 2.
Low recurrent stenosis after coronary silicon carbide coated cobalt chromium stent