Percutaneous revascularization of saphenous vein graft (SVG) lesions remains a challenge for interventional cardiologists. Balloon angioplasty in SVG lesions is associated with a high complication rate and a high incidence of restenosis (1- 2). Compared to balloon angioplasty, bare-metal stent (BMS) implantation in SVG lesions has been shown to improve procedural outcomes and reduce major cardiac events (3- 4). However, the incidence of in-stent restenosis remains 20% to 37% (3- 5). Recently, the introduction of drug-eluting stents (DES), either sirolimus-eluting stents (Cypher, Cordis, Johnson & Johnson Company, Warren, New Jersey) or paclitaxel-eluting stents (Taxus, Boston Scientific, Natick, Massachusetts), has shown promising results in selected de novo native coronary artery lesions (6- 10). The safety and efficacy of DES implantation for the treatment of SVG lesions remains uncertain (11). The aim of the present report was, therefore, to evaluate clinical and angiographic outcomes of DES implantation in SVG lesions.

We identified 61 consecutive patients (with 69 lesions) who underwent percutaneous revascularization in SVG lesions using DES from March 2002 to March 2004 (DES group). During this time period, an additional 103 patients were treated for lesions located in SVGs; 25 of them were included in a registry utilizing a covered stent, and others were treated with BMS. The main reasons for utilizing BMS were: 1) a lesion <10 mm in length evaluated to be at low risk of restenosis; 2) a lesion located on an SVG with a reference vessel diameter (RVD) >3.5 mm for which there were no appropriately sized DES available. A control group (BMS group) was composed of 89 consecutive patients (with 120 lesions) who underwent percutaneous treatment in SVG lesions with BMS in the 24 months immediately before the introduction of DES. Patients were excluded if any of the following was present: an acute myocardial infarction (MI) <1 week before the index procedure, implantation of a covered stent, or brachytherapy.

All patients were pretreated with aspirin and either ticlopidine or clopidogrel. A 300-mg loading dose of clopidogrel before the index procedure was administered if patients were not pretreated. During the procedure, patients received intravenous unfractionated heparin (100 IU/kg) to maintain activated clotting time between 250 to 300 s. Platelet glycoprotein IIb/IIIa receptor inhibitors and distal protection devices were used at the discretion of the operator. Stent implantation methods have been described previously (12). All stents were implanted with high deployment pressure (>12 atm). Patients received lifelong aspirin and clopidogrel or ticlopidine for at least three to six months after DES implantation and for at least one month after BMS implantation.

Clinical follow-up was performed by either telephone contact or office visit at 6 months after the index procedure (follow-up window to 210 days). Angiographic follow-up was scheduled for between six and eight months after the procedure unless clinically indicated at an earlier time. The events analyzed in this report included death (cardiac and noncardiac), MI (Q-wave and non–Q-wave), restenosis, stent thrombosis, target lesion revascularization (TLR), and target vessel revascularization (TVR), either percutaneous or surgical.

All deaths were considered cardiac unless otherwise documented. A non–Q-wave MI was defined as creatine kinase-MB enzyme elevation ≥3 × the upper limit of the normal value; when in addition to enzyme elevation there were new pathological Q waves on the electrocardiogram, the event was defined as a Q-wave MI. Target lesion revascularization was defined as repeat revascularization secondary to a stenosis ≥50% within the stent or within the 5-mm borders proximal or distal to the stent at the follow-up angiogram. Target vessel revascularization was defined as repeat revascularization within the treated vessel. Stent thrombosis was defined as any of the following: angiographic documentation of intrastent filling defect or stent occlusion associated with a clinical event, unexplained sudden death, or MI after stent implantation and without concomitant demonstration of a patent stent (13- 14). Major adverse cardiac events (MACE) were defined as cardiac death, MI, TLR, and TVR. Cumulative MACE were defined as the in-hospital and six-month follow-up MACE.

Coronary angiograms were analyzed using a validated edge detection system (CMS, version 5.2, MEDIS, the Netherlands). Minimal lumen diameter (MLD), RVD, and percent diameter stenosis at baseline, post-procedure, and at follow-up were measured, respectively. Acute gain was defined as the difference between the MLD immediately after the procedure and the baseline. Late lumen loss was defined as the difference between the MLD immediately after the procedure and at follow-up (15). Angiographic restenosis was defined as diameter stenosis ≥50% by quantitative coronary angiographic analysis within a previously stented segment (stent and 5 mm proximal and distal) at the follow-up angiogram. No reflow was defined as Thrombolysis In Myocardial Infarction (TIMI) (16) flow grade ≤1 that was not due to dissection or high-grade residual stenosis adjacent to the target lesion (17). Angiographic success was defined as a final residual stenosis <30% with TIMI flow grade 3. Procedural success was defined as the achievement of angiographic success without in-hospital MACE.

Continuous variables are presented as mean values ± SD and categorical variables as frequency (%). Continuous variables were compared using independent sample t test. Categorical variables were compared with chi-square statistics. Survival free of MACE was estimated using the Kaplan-Meier method, and the differences between the two survival curves were compared with the log-rank test. The Cox proportional hazards regression model was used to identify the independent predictors of MACE at six-month follow-up. The results are presented as hazard ratios (HR) with 95% confidence interval (CI). A p value of <0.05 was considered statistically significant, and all reported p values are two-sided. Statistical analysis was performed using SPSS Version 11.5 (SPSS Inc., Chicago, Illinois).

The baseline clinical characteristics were similar between the two groups, except for a trend toward a higher incidence of hypercholesterolemia in the DES group (65.6% vs. 49.4%, p = 0.07) (Table 1).

Angiographic and procedural characteristics are shown in (Table 2). The percentage of restenotic lesions were significantly higher in the DES group than in the BMS group (34.8% vs. 6.7%, p < 0.001). In the DES group, sirolimus-eluting stents were implanted in 35 patients (57.4%) and paclitaxel-eluting stents in 26 patients (42.6%). Compared to the BMS group, the DES group had a smaller mean maximum balloon diameter (3.35 mm vs. 3.83 mm, p < 0.001) and a longer stent length per lesion (29.4 mm vs. 20.4 mm, p < 0.001).

Serial quantitative coronary angiographic analyses are shown in (Table 3). The mean MLD was 1.01 mm for the DES group and 1.24 mm for the BMS group (p = 0.009). The DES group had a trend toward smaller RVD compared to the BMS group (p = 0.08). Post-procedure RVD and MLD were significantly larger in the BMS group.

Angiographic follow-up was available in 43 patients (71%) (with 50 lesions) in the DES group and 61 patients (69%) (with 86 lesions) in the BMS group. The mean time to angiographic follow-up was not statistically different between the two groups (6.9 ± 3.2 months vs. 6.2 ± 2.1 months, respectively, p = 0.3). Compared to the BMS group, late lumen loss was significantly smaller in the DES group (0.37 ± 0.97 mm vs. 1.09 ± 1.10 mm, p = 0.003). In-segment restenosis occurred less frequently in the DES group (10.0% vs. 26.7%, p = 0.03). There was no statistical difference regarding the incidence of late occlusion during six-month follow-up (6.0% vs. 8.1%, p = 0.90).

In-hospital results and clinical follow-up outcomes are shown in (Table 4). The incidence of in-hospital MACE was similar between the two groups (6.6% vs. 5.6%, p = 1.0). Non–Q-wave MI occurred in four patients (6.6%) of the DES group and in five (5.6%) of the BMS group (p = 1.0). Among those who suffered a non–Q-wave MI in the BMS group, one patient (1.1%) died two days after the procedure.

Six-month clinical follow-up was available in all patients. The cumulative MACE at six months was 11.5% in the DES group and 28.1% in the BMS group (p = 0.02). There were no statistically significant differences in the cumulative incidence of death and MI between the two groups. Compared to the BMS group, the rates of TLR and TVR were significantly lower in the DES group (TLR: 3.3% vs. 19.8%, p = 0.003; TVR: 4.9% vs. 23.1%, p = 0.003, respectively). The rate of MACE-free survival was 88.5% in the DES group and 71.9% in the BMS group (p = 0.03) (Figure 1).

Cox regression analysis was used to identify independent predictors of MACE at six months follow-up. Variables entered into analysis included: age of patient, age of SVG, diabetes, hypercholesterolemia, unstable angina, left ventricular ejection fraction, usage of distal protection devices, administration of glycoprotein IIb/IIIa inhibitors, duration of dual antiplatelet therapy, restenotic lesions, occluded lesions, stent type, baseline RVD, lesion length, post-procedural MLD, maximal balloon inflation pressure, and stent length. By Cox regression analysis, diabetes (HR: 3.03; 95% CI: 1.33 to 6.90; p = 0.008), usage of BMS (HR: 2.53; 95% CI: 1.07 to 5.97; p = 0.03), and age of SVG (HR: 1.10; 95% CI: 1.02 to 1.19; p = 0.02) were identified as predictors of MACE during six-month follow-up.

The main findings of this report are that utilization of DES for treatment of SVG lesions appears safe and feasible and DES implantation in SVG lesions seems effective in reducing the incidence of restenosis and improves MACE-free survival at six months.

It is estimated that at least 50% of SVG lesions will develop stenosis or occlusion within 10 years of implantation (18). Due to the higher mortality and morbidity associated with repeat bypass surgery, percutaneous revascularization is the preferred approach for treatment of SVG lesions (19). Early results using balloon angioplasty alone to treat SVG lesions were disappointing (20). Although the introduction of stents achieved more predictable results and higher success rates, the incidence of restenosis remained still as high as 37% (3- 4).

In comparison with previous studies (3- 4), the present report enrolled patients with more challenging lesion characteristics, including 18.8% ostial lesions, 4.3% total occlusion, and 34.8% restenotic lesions. These subgroups are known to be associated with less favorable outcomes (1,21- 22). However, these lesions treated with DES had a significant improvement in late lumen loss (0.37 ± 0.97 mm vs. 1.09 ± 1.10 mm, p = 0.003), resulting in lower in-segment restenosis rate (10.0% vs. 26.7%, p = 0.03). Compared to the studies using DES implanted in de novo native coronary artery lesions, late lumen loss obtained in the present report appears larger (6- 7). It is worth noting that three of the five restenotic lesions in the DES group were found to be total occlusions, and this fact may have influenced the quantification of the late loss. Late occlusion is a known problem associated with stenting of SVG lesions. It is reported that late occlusion occurs in 4% to 7% of the cases that received BMS (23- 24). However, to date, no data are available about the rate of late occlusion in SVG lesions after DES implantation. It is also unclear whether the pattern of restenosis after DES implantation in SVG lesions is different from the one found in native coronary arteries (25).

Compared to the BMS group, MACE-free survival rates at six months in the DES group were higher (88.5% vs. 71.9%, p = 0.03). By Cox regression analysis, diabetes, usage of BMS, and age of SVG were identified to be the predictors of MACE during six-month follow-up. It has been shown that diabetes is an independent risk factor for worse clinical and angiographic outcomes in native coronary arteries and SVG lesions (26- 28). Compared to the stenting in SVG lesions of nondiabetic patients, diabetics have higher TLR and late mortality (27). Marked intimal abnormalities and more rapid progression of the atherosclerotic disease in diabetic subjects may contribute to unfavorable outcomes (29). Graft age was described as one of the risk factors for less favorable results in previous studies (30- 31). In the present report, the mean graft age was 9.4 years.

Despite the encouraging findings of this report, we cannot ignore that 30% to 50% of late cardiac events (after one year) in patients with SVG lesions are due to disease progressions at different sites rather than the target one (3,32). This knowledge is important when evaluating the clinical impact of reducing restenosis in SVG lesions after DES implantation. For these reasons the long-term clinical benefit of DES in SVG lesions remains to be determined. Adjunctive therapies (e.g., treatment of the concomitant diseases associated with coronary heart disease, extended antithrombotic therapy) may be important to impact on late events, which may occur independently of restenosis.

The present report has some limitations: 1) it is a retrospective study; 2) the DES group included two different types of DES; 3) not all patients performed angiographic follow-up; and 4) clinical follow-up is limited to seven months. Despite these limitations, this report represents a large cohort of patients treated on SVG by DES implantation with complete clinical follow-up.

Some patients with SVG lesions were treated by BMS between March 2002 and March 2004. This fact may be perceived as a selection bias. If anything, these patients had very focal lesions or lesions located in large SVGs for which no appropriately sized DES were available; this group represents a lower-risk cohort for TLR. Despite the limitations in this study design, a conclusive randomized trial comparing DES to BMS appears progressively less feasible due to ethical difficulties with treating high-risk cohorts with BMS.

Percutaneous revascularization in SVG lesions with DES appears feasible with a high procedural success rate. Compared to BMS implantation, DES implantation in SVG lesions is associated with a reduction in the restenosis rate and a beneficial effect on MACE-free survival at six-month follow-up.