Drug-Eluting Stents Are Safe and Effective

Nanotexture and crystal phase regulation for synergistic enhancement in re-endothelialization on medical pure titanium surface

Re-endothelialization has been recognized as a promising strategy to address the tissue hyperplasia and subsequent restenosis which are major complications associated with vascular implant/interventional titanium devices. However, the uncontrollable over-proliferation of smooth muscle cells (SMCs) limits the clinical application of numerous modified strategies. Herein, a novel modified strategy involving with a two-step anodic oxidation and annealing treatment was proposed to achieve rapid re-endothelialization function regulated by regular honeycomb nanotexture and specific anatase phase on the titanium surface. Theoretical calculation revealed that the presence of nanotexture reduced the polar component of surface energy, while the generation of anatase significantly enhanced the polar component and total surface energy. Meanwhile, the modified surface with regular nanotexture and anatase phase produced positive effect on the expression of CD31, VE-Cadherin and down-regulated α-SMA proteins expression, indicating excellent capacity of pro-endothelial regeneration and inhibition of SMCs proliferation and migration. One-month in vivo implantation in rabbit carotid arteries further confirmed that modified tube implant surface effectively accelerated confluent endothelial monolayer formation and promoted native-like endothelium tissue regeneration. By contrast, original titanium tube implant induced a disorganized tissue proliferation in the lumen with a high risk of restenosis. Collectively, this study opens us an alternative route to achieve the function that selectively promotes endothelial cells (ECs) growth and suppresses SMCs on the medical titanium surface, which has a great potential in facilitating re-endothelialization on the surface of blood-contacting titanium implant.

Surface biomimetic modification with laminin-loaded heparin/poly-l-lysine nanoparticles for improving the biocompatibility

Late thrombus and restenosis caused by delayed endothelialization and insufficient biocompatibility of polymer coating continue to be the greatest limitations of drug-eluting stents. In this study, based on the specific structure of vascular basement membrane, a novel biomimetic nano-coating was constructed by incorporating laminin into electrostatic-assembled heparin/poly-l-lysine nanoparticles. Alteration of heparin and poly-l-lysine concentration ratio in a certain range has no significantly influence nanoparticle size, uniformity and stability, but may affect the chemical property and subsequently the binding efficiency to dopamine-coated titanium surface. By use of this feature, four different nanoparticles were synthesized and immobilized on titanium surface for creating gradient nanoparticle binding density. According to in vitro biocompatibility evaluation, the nanoparticle modified surfaces were found to effectively block coagulation pathway and reduce thrombosis formation. Moreover, NP10L and NP15L modified surface with relatively low heparin exposing density (4.9 to 7.1μg/cm2) showed beneficial effect in selective promoting EPCs and ECs proliferation, as well as stimulating cell migration and NO synthesis.

Is there delayed restenosis in patients with coronary artery disease treated with sirolimus-eluting stent?

BACKGROUND

Although long-term follow-up after sirolimus-eluting stent implantation shows a sustained clinical benefit in several randomized and registered trials, little is known about the pattern of neointimal growth beyond the first 6 to 9 months. In this study, we therefore evaluated the possible delayed restenosis in patients with coronary artery disease treated with sirolimus-eluting stent.

METHODS

A total of consecutive 333 patients with 453 lesions were enrolled in this study (among 782 consecutive patients with 1023 lesions). Lesions were subjected to follow-up by quantitative coronary angiography, and patients were divided into two groups according to the time of follow-up by quantitative coronary angiography: early group (< or =270 days, n=270 with 369 lesions) and late group (>270 days, n=63 with 84 lesions). Binary restenosis was defined as stenosis of more than 50% of the lumen diameter in the target lesion.

RESULTS

Baseline clinical, demographic or angiographic characteristics were well balanced between the two groups. The in-stent restenosis rate was not significant between the early group and the late group (3.5 vs. 6.0%; P>0.05). The late loss and target lesion revascularization appeared higher in late group but there were no significant differences (0.15+/-0.38 mm vs. 0.24+/-0.44 mm; and 4.9 vs. 9.5%, P>0.05, respectively). Similarly, overall thrombosis rate was also same in both groups. In-segment restenosis was, however, higher in late group compared with that in early group (7.9 vs. 16.7%, P=0.013).

CONCLUSION

In this unrestricted population, the beneficial effects of sirolimus-eluting stent implantation extend out more than 1 year in real world practice, that has been confirmed by the results of the large randomized clinical trials. The late in-segment restenosis could, however, be found, suggesting that a prolonged clinical and angiographic surveillance in this subset of patients seems to be warranted.

Drug‐eluting coronary stents — a note of caution

There are two types of coronary stents: bare-metal stents (BMS) that cost about $800 each, and drug-eluting stents (DES) that cost about $3,300 each. DES reduce the rate of restenosis but have a higher incidence of late stent thrombosis, particularly if dual antiplatelet therapy with aspirin and clopidogrel is interrupted. Stent thrombosis has a myocardial infarction rate of 70% and a mortality rate of 31%-45%. Randomised studies of BMS versus DES show no increase in myocardial infarction or death with DES in simple coronary lesions, but in clinical practice, DES are mainly used in complex coronary disease where the rate of stent thrombosis is higher. Registry data suggest an increased rate of death and myocardial infarction of 0.5%-1.0% per annum with DES. Clinicians need to be aware of the risks associated with prematurely ceasing dual antiplatelet therapy in patients with DES.

Comparison of drug-eluting versus bare metal stents on later frequency of acute myocardial infarction and death

In clinical trials of highly selected patients, drug-eluting stents (DESs) decreased restenosis but not the rate of acute myocardial infarction (AMI) or death. Whether DES use has an affect on the rate of AMI or death in unselected patients is uncertain. Bare metal stents (BMSs) were placed in 1,164 consecutive patients in the year before the introduction of DESs. DESs were subsequently placed in 1,285 consecutive comparable patients at Wake Forest Baptist Medical Center. Early and late clinical outcomes were compared. Propensity score analysis was used to adjust outcomes for baseline differences. Patient and procedural characteristics of the 2 groups were similar, with an overall incidence of 72% for acute coronary syndromes (p = NS). At 9 months, target vessel revascularization (2.8% vs 8.6%, p <0.001), AMI (3.7% vs 4.7%, p = 0.257), and death (4.9% vs 7.1%, p = 0.030) were lower in the DES group than in the BMS group. Propensity score-adjusted Cox proportional hazard ratios for DES versus BMS at 9 months were 0.71 (95% confidence interval 0.42 to 1.19) for AMI, 0.56 (95% confidence interval 0.36 to 0.87) for death, and 0.60 (95% confidence interval 0.42 to 0.86) for the combined end point of AMI or death. In conclusion, in this single-center observational study, use of DESs in consecutive unselected patients, most of whom would not have been eligible for inclusion in the randomized trials of DES versus BMS, was associated with lower AMI and death rates than in a comparable group of patients treated with BMSs in mid-term (9-month) follow-up.

Is late stent thrombosis in drug-eluting stents a real clinical issue? A single-center experience and review of the literature

BACKGROUND

Randomized studies have not found an increased rate of late stent thrombosis (LAST) in drug-eluting stents (DES) compared with bare metal stents (BMS) but those studies were statistically not powered to show such a difference. At the same time there is an increasing number of reports of LAST in DES patients in the current literature.

PATIENTS AND METHODS

We tried to describe the incidence of LAST in an unselected DES and BMS patient population. All patients who underwent stenting in our hospital between October 2003 and March 2006 were included in the study (n=1377). A total of 424 (30.1%) patients were treated with only BMS stents, 520 (37.8%) with paclitaxel-eluting stents (PES), 384 (27.9%) with sirolimus-eluting stents (SES) and 49 (3.6%) with BMS and DES. Long-term follow-up of all patients was used to determine the incidence of LAST as defined by angiographically proven stent thrombosis associated with acute symptoms more than 30 days after stent implantation. Followup was between 1 month and 2 years 7 months (mean 12 months). Patients treated with DES were younger (66+/-11 years) than BMS patients (72+/-10 years; p<0.001) and more often had diabetes (24.2% vs 17.4%; p < 0.001). A previous PCI had been performed in 27.1% of DES patients vs 13.9% of BMS patients (p < 0.001).

RESULTS

There were 9 cases of LAST: 2 with SES (at 6 and 11 months after implantation), 6 with PES (at 6, 9 (2x), 10, 16 and 26 months), and one with BMS (at 22 months). All patients with LAST presented with STEMI and without an angina history that suggested restenosis. Two cases were related to complete cessation of antiplatelet therapy, one because of patient non-compliance (SES), one after aspirin was stopped for orthopedic surgery (BMS). Two cases occurred within 1 month of cessation of clopidogrel therapy and while these patients were on aspirin therapy. Five cases occurred on aspirin monotherapy 2, 3, 4, 10 and 20 months, respectively after planned cessation of clopidogrel. None of the cases occurred under dual antiplatelet therapy. All patients underwent primary PCI; none died.

CONCLUSION

Angiographically proven LAST occurred in our unselected patient population with an incidence of 0.84% in patients treated with DES and 0.21% in BMS patients within a mean follow-up of 12 months (p = 0.36). LAST may indeed occur in clinically stable patients while on aspirin monotherapy. Since LAST led in all patients to STEMI it seems to be a serious clinical issue that prompts further investigation and discussion of length of dual platelet therapy.