Pathology of drug-eluting versus bare-metal stents in saphenous vein bypass graft lesions

OBJECTIVES

The purpose of this study was to assess the pathological responses of atherosclerotic saphenous vein bypass grafts (SVBGs) to drug-eluting stents (DES) versus bare-metal stents (BMS).

BACKGROUND

Repeat bypass surgery is typically associated with a high rate of morbidity and mortality. Percutaneous coronary interventions have emerged as the preferred treatment; however, only limited data are available on SVBGs pathological responses to DES and BMS.

METHODS

Formalin-fixed SVBG of >2 years duration (n = 31) were collected to histologically characterize advanced atherosclerotic lesions in native SVBG. In a separate group, SVBGs treated with DES (n = 9) and BMS (n = 9) for >30 days duration were assessed for morphological and morphometric changes.

RESULTS

Necrotic core lesions were identified in 25% of SVBG sections, and plaque rupture with luminal thrombosis was observed in 6.3% of histological sections (32% [10 of 31] vein grafts examined). Morphometry of DES demonstrated reduction in neointimal thickening versus BMS (0.13 mm [interquartile range: 0.06 to 0.16 mm] vs. 0.30 mm [interquartile range: 0.20 to 0.48 mm], p = 0.004). DES lesions also showed greater delayed healing characterized by increased peristrut fibrin deposition, higher percentage of uncovered struts, and less endothelialization compared with BMS. Stent fractures (DES 56% vs. BMS 11%, p = 0.045) and late stent thrombosis (DES 44% vs. BMS 0%, p = 0.023) were more common in DES versus BMS.

CONCLUSIONS

Advanced SVBG atherosclerotic lesions are characterized by large hemorrhagic necrotic cores. Stenting of such lesions is associated with delayed vascular healing and late thrombosis particularly following DES implantation, which may help explain the higher rates of cardiovascular events observed in SVBG stenting as compared with native coronary arteries.

Percutaneous revascularization strategies in saphenous vein graft lesions: long-term results

AIMS

Although half of saphenous vein grafts (SVGs) present obstructive atherosclerotic disease 10 years after implantation, controversy remains concerning the ideal treatment. Our aim was to compare percutaneous revascularization (PCI) options in SVG lesions, according to intervention strategy and type of stent.

METHODS

A retrospective single-center analysis selected 618 consecutive patients with previous bypass surgery who underwent PCI between 2003 and 2008. Clinical and angiographic parameters were analyzed according to intervention strategy - PCI in SVG vs. native vessel vs. combined approach - and type of stent implanted - drug-eluting (DES) vs. bare-metal (BMS) vs. both. A Cox regressive analysis of event-free survival was performed with regard to the primary outcomes of death, myocardial infarction (MI) and target vessel failure (TVF).

RESULTS

During a mean follow-up of 796±548 days the rates of death, MI and TVF were 10.9%, 10.5% and 29.5%, respectively. With regard to intervention strategy (74.4% of PCI performed in native vessels, 17.2% in SVGs and 8.4% combined), no significant differences were seen between groups (death p=0.22, MI p=0.20, TVF p=0.80). The type of stents implanted (DES 83.2%, BMS 10.2%, both 3.2%) also did not influence long-term prognosis (death p=0.09, MI p=0.11, TVF p=0.64). The implantation of DES had a favorable impact on survival (p<0.001) in the subgroup of patients treated in native vessels but not in SVG.

CONCLUSIONS

Among patients with SVG lesions, long-term mortality, MI and TVF were not affected by intervention options, except for the favorable impact on survival of DES in patients treated in native vessels.

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.

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.

Comparison of percutaneous coronary intervention in native coronary arteries vs. bypass grafts in patients with prior coronary artery bypass graft surgery

OBJECTIVE

To compare the procedural and clinical outcomes of prior coronary artery bypass graft surgery (CABG) patients undergoing percutaneous coronary intervention (PCI) in native arteries vs. bypass grafts.

METHODS

The medical and catheterization records and the angiograms of 142 consecutive prior CABG patients who underwent 165 PCI of 247 lesions at our institution between January 1, 2003, and December 31, 2006, were retrospectively reviewed.

RESULTS

Mean age was 66+/-10 years and 99% were men: 79 and 63 patients underwent native coronary or bypass graft PCI, respectively. Compared to patients undergoing bypass graft PCI, those undergoing native coronary artery PCI were younger (mean age 64+/-10 vs. 68+/-10 years, P=.008), more likely to present with stable angina (29% vs. 8%, P=<.001), and presented earlier after CABG (after a mean of 9+/-6 vs. 12+/-5 years, P<.01). Compared to bypass graft PCI, native coronary PCI was more likely to be performed with drug-eluting stents (88% vs. 57%, P<.001) and was associated with lower risk of no-reflow (3% vs. 24%, P<.001). After a mean follow-up of 2.5+/-1.1 years, both groups of patients had similar but high incidence of myocardial infarction, repeat PCI, and death.

CONCLUSIONS

Prior CABG patients undergoing native coronary artery PCI have lower procedural risk, but similar postprocedural clinical outcomes compared to patients undergoing bypass graft PCI. If feasible, native coronary arteries may be the preferred PCI target in prior CABG patients.