Current application and bioavailability of drug-eluting stents

INTRODUCTION

Drug-eluting stents (DES) were developed to reduce the restenosis rate of bare metal stents (BMS) and comprises three main components: i) a metallic scaffold; ii) an antiproliferative drug to reduce or abolish the formation of the neointima; and iii) the polymer, which both enables and controls drug elution into the vessel wall. Over the years, growing evidence has been reported on the safety and efficacy for different indications of DES.

AREAS COVERED

Since the introduction of first-generation DES, the technology has been refined, including changes in the alloy, stent design, polymer, drug and drug dose. In 2014, we will usher in a third generation of DES, which will include biodegradable polymers, polymer-free DES and bioabsorbable scaffolds.

EXPERT OPINION

In recent years, considerable progress has been made in DES development. The BMS platform set the groundwork for the development of metal scaffolds with drug-eluting capability to prevent restenosis. Importantly, extensive research has shown long-term safety and efficacy of the newer generation DES. Available data suggest that DES can be safely and effectively used to treat a complex subset of patients and lesions, including patients presenting with acute myocardial infarction, lesions in saphenous vein grafts, chronic total occlusions, multivessel disease, small vessels, long lesions and bifurcations. One of the safety targets is to eliminate stent thrombosis.

Drug-Eluting Stents Versus Bare Metal Stents in Saphenous Vein Graft Intervention

Percutaneous coronary intervention (PCI) of saphenous vein graft (SVG) is associated with higher adverse event rates, lower procedural success, and inferior longterm patency rates compared with native vessel PCI. The ability to comply with dual antiplatelet therapy, and whether the patient will need an interruption in dual antiplatelet therapy, should be considered when deciding whether to implant a drug-eluting stent (DES) or bare metal stent (BMS) in an SVG. DES should be used for SVG PCI because they seem to reduce target vessel revascularization. This article reviews the evolution and contemporary evidence regarding use of DES versus BMS in SVG PCI.

Late outcomes of drug eluting and bare metal stents in saphenous vein graft percutaneous coronary intervention

AIMS

PCI with drug eluting stents (DES) has been shown to reduce restenosis and major adverse cardiac event (MACE) rates compared to bare metal stents (BMS) in native coronary vessels, although outcomes in saphenous vein graft (SVG) lesions are less clear. We retrospectively studied 388 consecutive patients admitted to our centre for SVG PCI to assess mortality and MACE outcomes (defined as composite endpoint of all-death, stroke, myocardial infarction, stent thrombosis and target lesion (TLR)/vessel (TVR) revascularisation) associated with BMS and DES use.

METHODS AND RESULTS

Two hundred and nineteen (219) patients had BMS and 169 had DES (total 388 patients). Mean follow up was 41.9±23.5 months. No significant differences were observed in mortality (14.2% vs. 11.8%) or MACE (37.6% vs. 35.8%) between the BMS and DES groups at four years follow-up or at other intervening time points studied. Similarly, no differences in TVR/TLR rates were observed over a similar time period (19.8% vs. 21.6%).

CONCLUSIONS

We have observed that DES and BMS use in SVG PCI have comparable mortality and MACE rates, and that in contrast to PCI in native coronary arteries, DES do not reduce revascularisation rates in our study cohort.

Two-year safety and effectiveness of sirolimus-eluting stents (from a prospective registry)

Uncertainty exists about the long-term safety and efficacy outcomes of sirolimus-eluting stents (SESs) in unselected patients. The present study was performed to evaluate the safety and efficacy of the SES in treatment of patients with coronary artery disease in an unselected population. Over a 2-year period, 1,504 consecutive patients undergoing percutaneous coronary intervention with ≥1 SES were enrolled. The primary end point was the occurrence of target vessel failure (TVF; a composite of cardiac death, myocardial infarction, or clinically driven target vessel revascularization). An independent clinical event committee adjudicated all adverse events up to 2-year follow-up. Dual antiplatelet therapy was recommended for ≥1 year throughout the study period. Mean age was 65 ± 11 years; 75% were men, and 34% were diabetics. SESs were implanted for off-label indications in 86% of cases. TVF rates were 3.3%, 6.9%, 11.5%, and 15.5% at 30-day, 6-month, 1-year, and 2-year follow-ups, respectively. The 2-year cumulative rate of definite/probable stent thrombosis was 0.9%; 0.2% was very late thrombosis, occurring from 1 year to 2 years. Patients off dual antiplatelet therapy at 6 months had a significantly increased rate of subsequent death from noncardiac causes. Patients off dual antiplatelet therapy at 1 year had a significantly decreased rate of subsequent clinically driven target lesion revascularization. In conclusion, use of SESs in unselected patients with coronary artery disease was associated with a low TVF rate at 2 years with an acceptable incidence of stent thrombosis.

Drug-eluting or bare metal stents for the treatment of saphenous vein graft disease: a Bayesian meta-analysis

BACKGROUND

Observational studies and randomized, controlled trials have yielded uncertain results regarding the benefits of drug-eluting stents (DES) for the treatment of saphenous vein graft (SVG) disease. The objective of this meta-analysis was to assess the cumulative evidence regarding the efficacy and effectiveness of DES to treat SVG compared with bare metal stent (BMS).

METHODS AND RESULTS

We conducted a bayesian hierarchical meta-analysis of all randomized, controlled trials and observational studies that compared clinical outcomes after DES or BMS placement in SVG disease. Our search resulted in 25 studies, cumulating 5755 patients. DES implantation was not associated with an increased risk of death (odds ratio [OR], 0.85; 95% credible intervals (CrI) [CrI], 0.62 to 1.21) or myocardial infarction (OR, 0.83; 95% CrI, 0.56 to 1.32), but wide CrIs preclude definitive conclusions. Target vessel revascularization (OR, 0.55; 95% CrI, 0.39 to 0.76) and target lesion revascularization (OR, 0.58; 95% CrI, 0.37 to 0.87) were both reduced by approximately 45% with DES. When combining these outcomes, the OR for major adverse cardiac events was reduced in patients treated with DES (OR, 0.62; 95% CrI, 0.46 to 0.81). Finally, the relative risk of stent thrombosis appeared lower with DES, although again the CrIs were very wide (OR, 0.54; 95% CrI, 0.13 to 1.39).

CONCLUSIONS

In this study-level meta-analysis, the largest ever reported and the first using bayesian methods, the use of DES for the treatment of SVG disease reduces target vessel revascularization and target lesion revascularization procedures compared with BMS. Although there is no evidence to date to suggest increased rates of mortality, myocardial infarction, or stent thrombosis, further data are needed to address this safety issue.

Comparison of drug-eluting and bare metal stents for saphenous vein graft lesions (from the National Heart, Lung, and Blood Institute Dynamic Registry)

The effectiveness and safety of drug-eluting stents (DES) compared with bare-metal stents (BMS) in saphenous vein graft (SVG) disease remains unclear. In particular, there is a paucity of data on long-term outcomes. In this study, 395 patients enrolled in the National Heart, Lung, and Blood Institute Dynamic Registry who underwent stenting of SVG lesions with BMS (n = 192) from 1999 to 2006 or DES (n = 203) from 2004 to 2006 were analyzed. Patients were followed prospectively for the occurrence of cardiovascular events and death at 3 years. Patients treated with DES were more likely to have diabetes mellitus and other co-morbidities and previous percutaneous coronary intervention. Treated lesions in DES patients were more complex than those in BMS patients. At 3 years of follow-up, the adjusted risk for target vessel revascularization (hazard ratio 1.03, 95% confidence interval 0.65 to 1.62, p = 0.91) and death or myocardial infarction (hazard ratio 0.72, 95% confidence interval 0.49 to 1.04, p = 0.08) was similar in patients treated with DES and those treated with BMS. The combined outcome of death, myocardial infarction, or target vessel revascularization excluding periprocedural myocardial infarction was also similar (adjusted hazard ratio 0.82, 95% confidence interval 0.62 to 1.09, p = 0.16). In conclusion, this multicenter nonrandomized study of unselected patients showed no benefit of DES in SVG lesions, including no reduction in target vessel revascularization, compared with BMS at 3 years. An adequately powered randomized controlled trial is needed to determine the optimal stent type for SVG percutaneous coronary intervention.

Drug-eluting versus bare-metal stent for treatment of saphenous vein grafts: a meta-analysis

BACKGROUND

Saphenous vein grafts develop an aggressive atherosclerotic process and the efficacy of drug eluting stents (DES) in treating saphenous vein graft (SVG) lesions has not been convincingly demonstrated. The aim of this study was to review and analyze the current literature for controlled studies comparing DES versus bare metal stents (BMS) for treatment of SVG stenoses.

METHODOLOGY/PRINCIPAL FINDINGS

We searched several scientific databases and conference proceedings up to March 15, 2010 for controlled studies comparing target vessel revascularization (TVR) between DES and BMS. Summary odds ratios (OR) for the primary endpoint TVR and secondary endpoints infarction, stent thrombosis and death were calculated using random-effect models. A total of 29 studies (3 randomized controlled trials RCT) involving 7549 (202 in RCT) patients were included. The need for target vessel revascularization in the DES group tended to be lower compared to BMS for the 3 RCT (OR 0.50 [0.24-1.00]; p = 0.051) and for observational studies (0.62 [0.49-0.79]; p<0.001). There was no significant difference in the risk for myocardial infarction in the RCT (OR 1.25 [0.22-6.99]; p = 0.250) but a lower risk for DES based on the observational studies 0.68 [0.49-0.95]; p = 0.023. The risk for stent thrombosis was found to be non-different in the RCT (OR 0.78 [0.03-21.73], p = 0.885) while it was in favor of DES in the observational studies (0.58 [0.38 - 0.84]; p<0.001). The mortality was not significantly different between DES and BMS in the RCT's (OR 2.22 [0.17 - 29.50]; p = 0.546) while the observation studies showed a decreased mortality in the DES group (0.69 [0.55-0.85]; p<0.001).

CONCLUSION

DES may decrease TVR rate in treatment of SVG stenoses. No differences in reinfarction rate, stent thrombosis or mortality was found between the DES and BMS groups in the RCT's while the observational data showed lower risk for myocardial infarction, stent thrombosis and death in the DES group. This may be a result of patient selection bias in the observational studies or represent a true finding that was not the detected in the RCT analysis due to limited statistical power.

Effectiveness and safety of drug-eluting stents in vein grafts: a meta-analysis

BACKGROUND

The use of drug-eluting stents (DES) in degenerative vein grafts is currently an off-label indication. Recent studies have had conflicting results regarding the effectiveness and safety of this practice. The objective of this meta-analysis was to compare DES to bare-metal stents for the treatment of vein graft stenosis.

METHODS

PubMed and the Cochrane clinical trials database were systematically searched to identify all randomized controlled trials (RCTs) and observational studies examining DES for vein graft stenosis published in English between 2003 and 2009. Inclusion criteria included follow-up duration > or =6 months. Data were stratified by study design and pooled using random effects models.

RESULTS

Twenty studies were found to meet our inclusion criteria. Eighteen studies were observational and 2 were RCTs. In observational studies, DES were associated with a reduction in major adverse cardiac events (MACE) (odds ratio [OR] 0.50, 95% CI 0.35-0.72), death (OR 0.69, 95% CI 0.53-0.91), target vessel revascularization (TVR) (OR 0.54, 95% CI 0.37-0.79), and target lesion revascularization (TLR) (OR 0.54, 95% CI 0.37-0.78). The incidence of myocardial infarction was similar between groups. In the RCTs, pooled results were inconclusive because of small sample sizes.

CONCLUSIONS

Although data from observational studies suggest that the use of DES for vein graft stenosis has favorable effects on MACE, death, TVR, and TLR, these data should be interpreted with caution due to their observational nature. Corresponding RCT data are inconclusive. There remains a need for large multicenter RCTs to address the effectiveness and safety of DES for vein graft stenosis.

Comparison of Plaque Sealing With Paclitaxel-Eluting Stents Versus Medical Therapy for the Treatment of Moderate Nonsignificant Saphenous Vein Graft Lesions

Background— The presence of moderate saphenous vein graft (SVG) lesions is a major predictor of cardiac events late after coronary artery bypass grafting. We determined the effects of sealing moderate nonsignificant SVG lesions with paclitaxel-eluting stents (PES) on the prevention of SVG atherosclerosis progression.

Methods and Results— Patients with at least 1 moderate SVG lesion (30% to 60% diameter stenosis) were randomized either to stenting the moderate SVG lesion with a PES (n=30, PES group) or to medical treatment alone (n=27, medical treatment group). Patients had an angiographic and intravascular ultrasound evaluation of the SVG at baseline and at 12-month follow-up. The primary end points were (1) the ultrasound SVG minimal lumen area at follow-up and (2) the changes in ultrasound atheroma volume in an angiographically nondiseased SVG segment. Mean time from coronary artery bypass grafting was 12±6 years, and mean low-density lipoprotein cholesterol level was 73±31 mg/dL. A total of 70 moderate SVG lesions (39±7% diameter stenosis) were evaluated. Significant disease progression occurred in the medical treatment group at the level of the moderate SVG lesion (decrease in minimal lumen area from 6.3±3.0 to 5.6±3.1 mm 2 ; P <0.001), leading to a severe flow-limiting lesion or SVG occlusion in 22% of the patients compared with none in the PES group ( P =0.014). In the PES group, mean minimal lumen area increased ( P <0.001) from 6.1±2.2 to 8.6±2.9 mm 2 at follow-up ( P =0.001 compared with the medical treatment group at 12 months). There were no cases of restenosis or stent thrombosis. No significant atherosclerosis progression occurred at the nonstented SVG segments. At 12-month follow-up, the cumulative incidence of major adverse cardiac events related to the target SVG was 19% in the medical treatment group versus 3% in the PES group ( P =0.091).

Conclusions— Stenting moderate nonsignificant lesions in old SVGs with PES was associated with a lower rate of SVG disease progression and a trend toward a lower incidence of major adverse cardiac events at 1-year follow-up compared with medical treatment alone, despite very low low-density lipoprotein cholesterol values. This pilot study supports further investigation into the role of plaque sealing in SVGs.

Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT002289835.

Drug-eluting versus bare-metal stents for treating saphenous vein grafts

BACKGROUND

Current data show conflicting results regarding safety and efficacy of drug-eluting stents (DES) versus bare-metal stents (BMS) for treating saphenous vein grafts (SVG). Our objective was to compare DES with BMS for SVG intervention.

METHODS

Patients undergoing stenting with DES or BMS to SVG from January 2000 to June 2007 were included. To eliminate any unobserved bias regarding stent selection, the BMS cohort was divided into pre- and post-2003 when DES became available. Adjusted Cox analysis compared DES with pre- and post-2003 BMS patients. The primary end point was a composite of all-cause mortality, myocardial infarction, or target lesion revascularization.

RESULTS

Of the total 566 patients, 217 (38%) received DES, 110 (20%) received BMS post-2003, and 239 (42%) received BMS pre-2003. Median follow-up was 2.9 years (interquartile range 1.4-4.9 years). There was a trend toward lower primary end point with DES compared to post-2003 BMS (91 events, adjusted hazard ratio 0.61, 95% CI 0.35-1.07, P = .08). However, despite 179 events, DES use was not associated with lower primary end point compared with pre-2003 BMS (adjusted hazard ratio 0.61, 95% CI 0.28-1.35, P = .23).

CONCLUSIONS

Although DES showed a trend toward a lower primary end point when compared with BMS post-2003, this association was no longer present when DES was compared to pre-2003 BMS. These results are consistent with the preponderance of available data and indicate that unobserved bias in observational registries may explain the reported benefit of DES over BMS for treating SVG.