2.1

Patient population

This was an observational, prospective, single centre study. Between 2006 and 2009 the 3921 PCI were performed in our centre, including the implantation of 900 EUPES and 3944 SES. The study consecutively included patients with at least 70% de novo coronary lesions in one or two native coronary arteries and who had undergone the coronary stenting using either EUPES or SES. The exclusion criteria were acute coronary syndrome less than 3 months before the intervention, heart failure III–IV (NYHA), diabetes mellitus (DM) type 1 or de-compensated DM type 2, familial hypercholesterolemia, hepatic or renal failure, the lesion type C (ACC/AHA definition), occlusive and bifurcation coronary lesions and length of lesions more than 28 mm.

Before and after PCI, patients received standard treatment of CAD with aspirin, β-blockers and statins, as well ACE-inhibitors and calcium antagonists, if needed. During angioplasty every patient was given an intra-arterial injection of 70 U/kg of heparin and intracoronary injection of 250 μg of nitroglycerin. Patients received clopidogrel for 3–5 days before stent implantation and for 12 months after stenting. All patients were fully informed about the possible procedure-related risks. The study was approved by the Institutional Review Board and written informed consent was obtained for participation in the study.

2.2

Endpoints

To assess the long term outcomes of coronary stenting, patients were followed for 2 years. Telephone contacts were conducted every three months, patients with the resumption complaints had additional examination including coronary angiography, if needed. Follow-up coronarography was performed in patients with recurrent angina and/or documented myocardial ischemia by non-invasive examinations (exercise tests with or without imaging). We evaluated a predefined follow-up: the incidence of MACE which included total death (cardiac or non-cardiac), MI (Q-wave or non-Q wave), TLR, ST (acute [within 24 h], sub-acute [from 24 h to 30 days], late [from 30 days to 12 months] or very late [after 12 months]). MI was defined as ECG changes and an increase of creatinine kinase-MB and/or cardiac troponins above the 99th percentile upper reference limit. TLR was defined as follow-up revascularisation within the stent or within the 5-mm borders proximal and distal to the stent. Stent thrombosis was defined as definite thrombosis according to the Academic Research Consortium .

2.3

Angiographic analysis

Coronarography was performed according to standard method using “COROSCOP 33” and “AXIOM ARTIS”, (Siemens, Germany) equipments. EUPES were available in 2.25, 2.5, 2.75, 3.0, 3.25, 3.5, and 4.0 mm diameters, and 8, 10, 13, 16, 18, 23, 28, 33 and 38 mm lengths. The full range of manufactured SES was available, ranging from 2.25 to 3.5 mm in diameter and from 8 to 33 mm in length. Allocation of stents type was the decision of the operator. Stents were implanted following mandatory predilatation. The nominal stent diameter corresponded to the reference diameter at the site of stenosis. Stent length was selected sufficient to cover approximately 3 mm of non-diseased tissue on either side of the lesion. Post-dilatation was used to optimize the results of the intervention. After the last dilatation and removal of balloon catheter and coronary guidewire from artery, the contrast-enhanced visualization of the dilated vessel using at least 2 orthogonal scans for the better imaging was performed.

The analysis of all obtained angiograms was performed using quantitative computer analysis (QCA) “AXIOM ARTIS” equipment, (Siemens, Germany). QCA measurements were performed by two independent operators: the first one — during the procedure; the second — after the procedure blinded to the stent type. Variation between measurements was less than 5%. The parameters used for analysis of the angiographic data were as follows: the diameter and length of implanted stent; reference diameter; minimal lumen diameter at the side of maximal stenosis baseline, immediately after PCI and during follow-up coronarography; diameter stenosis (%) at baseline, immediately after PCI (residual stenosis) and during follow-up coronarography; late lumen loss (the difference between minimal lumen diameters immediately after PCI and follow-up).

2.4

Evaluation of lipid panel

Blood samples were collected after 12-h fasting from the cubital vein before the PCI. Serum levels of total cholesterol (TC), triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) were determined by enzymatic method using the biochemical blood analyzer «ARCHITECT» (Abbott Laboratories, USA) and reagents of the same producer. Low-density lipoprotein cholesterol (LDL-C) was calculated from the Friedewald formula. The obtained data were presented in mmol/l.

2.5

Statistical analysis

Statistical analysis of results was performed using STATISTICA 6.0 software package (StatSoft Inc., USA), with significance set at the 2-tailed 0.05 level. Continuous variables were reported as Median and Lower and Upper Quartiles (Med (LQ-UQ)) and compared with Student’s t-test and Mann–Whitney U test, when appropriate. Categorical variables were compared with χ ² criterion and Fisher’s exact test (for binary variables). Clinical events were analysed on a per-patient basis, and quantitative coronary angiography data were analysed on a per-lesion basis. Event-free survival during follow-up at 2 years was evaluated according to the Kaplan–Meier analysis and survival among groups was compared using Cox’s F-test. Univariate and multivariate Cox regression analyses were performed to evaluate stents-associated outcomes. In multivariate analyses, the following variables were entered into the model: age, gender, diabetes mellitus (DM), smoking, prior MI, the reference artery diameter, length of implanted stent and degree of residual stenosis immediately after intervention. The final results are presented as adjusted hazard ratio (HR), with the associated 95% confidence intervals (95% CI).

2.1

Patient population

This was an observational, prospective, single centre study. Between 2006 and 2009 the 3921 PCI were performed in our centre, including the implantation of 900 EUPES and 3944 SES. The study consecutively included patients with at least 70% de novo coronary lesions in one or two native coronary arteries and who had undergone the coronary stenting using either EUPES or SES. The exclusion criteria were acute coronary syndrome less than 3 months before the intervention, heart failure III–IV (NYHA), diabetes mellitus (DM) type 1 or de-compensated DM type 2, familial hypercholesterolemia, hepatic or renal failure, the lesion type C (ACC/AHA definition), occlusive and bifurcation coronary lesions and length of lesions more than 28 mm.

Before and after PCI, patients received standard treatment of CAD with aspirin, β-blockers and statins, as well ACE-inhibitors and calcium antagonists, if needed. During angioplasty every patient was given an intra-arterial injection of 70 U/kg of heparin and intracoronary injection of 250 μg of nitroglycerin. Patients received clopidogrel for 3–5 days before stent implantation and for 12 months after stenting. All patients were fully informed about the possible procedure-related risks. The study was approved by the Institutional Review Board and written informed consent was obtained for participation in the study.

2.2

Endpoints

To assess the long term outcomes of coronary stenting, patients were followed for 2 years. Telephone contacts were conducted every three months, patients with the resumption complaints had additional examination including coronary angiography, if needed. Follow-up coronarography was performed in patients with recurrent angina and/or documented myocardial ischemia by non-invasive examinations (exercise tests with or without imaging). We evaluated a predefined follow-up: the incidence of MACE which included total death (cardiac or non-cardiac), MI (Q-wave or non-Q wave), TLR, ST (acute [within 24 h], sub-acute [from 24 h to 30 days], late [from 30 days to 12 months] or very late [after 12 months]). MI was defined as ECG changes and an increase of creatinine kinase-MB and/or cardiac troponins above the 99th percentile upper reference limit. TLR was defined as follow-up revascularisation within the stent or within the 5-mm borders proximal and distal to the stent. Stent thrombosis was defined as definite thrombosis according to the Academic Research Consortium .

2.3

Angiographic analysis

Coronarography was performed according to standard method using “COROSCOP 33” and “AXIOM ARTIS”, (Siemens, Germany) equipments. EUPES were available in 2.25, 2.5, 2.75, 3.0, 3.25, 3.5, and 4.0 mm diameters, and 8, 10, 13, 16, 18, 23, 28, 33 and 38 mm lengths. The full range of manufactured SES was available, ranging from 2.25 to 3.5 mm in diameter and from 8 to 33 mm in length. Allocation of stents type was the decision of the operator. Stents were implanted following mandatory predilatation. The nominal stent diameter corresponded to the reference diameter at the site of stenosis. Stent length was selected sufficient to cover approximately 3 mm of non-diseased tissue on either side of the lesion. Post-dilatation was used to optimize the results of the intervention. After the last dilatation and removal of balloon catheter and coronary guidewire from artery, the contrast-enhanced visualization of the dilated vessel using at least 2 orthogonal scans for the better imaging was performed.

The analysis of all obtained angiograms was performed using quantitative computer analysis (QCA) “AXIOM ARTIS” equipment, (Siemens, Germany). QCA measurements were performed by two independent operators: the first one — during the procedure; the second — after the procedure blinded to the stent type. Variation between measurements was less than 5%. The parameters used for analysis of the angiographic data were as follows: the diameter and length of implanted stent; reference diameter; minimal lumen diameter at the side of maximal stenosis baseline, immediately after PCI and during follow-up coronarography; diameter stenosis (%) at baseline, immediately after PCI (residual stenosis) and during follow-up coronarography; late lumen loss (the difference between minimal lumen diameters immediately after PCI and follow-up).

2.4

Evaluation of lipid panel

Blood samples were collected after 12-h fasting from the cubital vein before the PCI. Serum levels of total cholesterol (TC), triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) were determined by enzymatic method using the biochemical blood analyzer «ARCHITECT» (Abbott Laboratories, USA) and reagents of the same producer. Low-density lipoprotein cholesterol (LDL-C) was calculated from the Friedewald formula. The obtained data were presented in mmol/l.

2.5

Statistical analysis

Statistical analysis of results was performed using STATISTICA 6.0 software package (StatSoft Inc., USA), with significance set at the 2-tailed 0.05 level. Continuous variables were reported as Median and Lower and Upper Quartiles (Med (LQ-UQ)) and compared with Student’s t-test and Mann–Whitney U test, when appropriate. Categorical variables were compared with χ ² criterion and Fisher’s exact test (for binary variables). Clinical events were analysed on a per-patient basis, and quantitative coronary angiography data were analysed on a per-lesion basis. Event-free survival during follow-up at 2 years was evaluated according to the Kaplan–Meier analysis and survival among groups was compared using Cox’s F-test. Univariate and multivariate Cox regression analyses were performed to evaluate stents-associated outcomes. In multivariate analyses, the following variables were entered into the model: age, gender, diabetes mellitus (DM), smoking, prior MI, the reference artery diameter, length of implanted stent and degree of residual stenosis immediately after intervention. The final results are presented as adjusted hazard ratio (HR), with the associated 95% confidence intervals (95% CI).