Direct stenting limits sirolimus-eluting stent edge neointimal thickening

Does direct stenting with drug-eluting stents improve outcome? A meta-analysis of 10,900 patients

OBJECTIVES

The aim of this study is to summarize the outcomes of patients undergoing direct stenting (DS) with drug-eluting stents (DES) compared to those who underwent balloon predilatation.

BACKGROUND

DS has been associated with improved outcomes in the bare-metal stent era. Although DS with DES implantation has been increasingly adopted in clinical practice, its safety and effectiveness remain controversial.

METHODS

The search criteria identified 546 studies in the Medline/PubMed, Cochrane, and EMBASE databases from 2001 to July 2014. From these, seven studies totaling 10,900 patients were selected. Summarized estimates [odds ratio (OR) and 95% confidence intervals] were obtained using a random-effects model. The primary outcomes were a composite of major adverse cardiac events (MACE), including all-cause death, myocardial infarction (MI), and repeat revascularization. The secondary outcomes included a composite of death and MI and the rates of target lesion revascularization (TLR).

RESULTS

Overall, 4101 (38%) and 6799 (62%) patients underwent DS with DES and balloon pre-dilatation, respectively. DS with DES reduced the likelihood of MACE (OR: 0.81 [0.71-0.93]). Additionally, DS with DES was associated with reduced rates of death/MI (OR: 0.76 [0.62-0.92]), and TLR (OR: 0.66 [0.44-0.98]).

CONCLUSIONS

DS with DES is safe and may be associated with better outcomes in selected patients. © 2016 Wiley Periodicals, Inc.

MicroRNA-21 mediates the rapamycin-induced suppression of endothelial proliferation and migration

Rapamycin suppresses endothelial proliferation and migration, which leads to delayed re-endothelialization in the rapamycin-eluted stents that are used in coronary heart disease patients. Because microRNAs (miRs) play important roles in endothelial angiogenesis, we tested the hypothesis that rapamycin induces endothelial suppression, partly through pathways that involve miRs. Rapamycin treatment increased the expression of miR-21 in HUVECs. The downregulation of miR-21 by inhibitors abolished the negative effects of rapamycin on endothelial cell growth and mobility. RhoB was confirmed as a direct target gene of miR-21. Knockdown of Raptor by siRNA mimicked the effects of rapamycin on miR-21 expression. Our study provides a new explanation of the mechanism of rapamycin-mediated inhibition of endothelial proliferation and migration.

SERCA2a gene transfer prevents intimal proliferation in an organ culture of human internal mammary artery

Coronary restenosis, a major complication of percutaneous balloon angioplasty, results from neointimal proliferation of vascular smooth muscle cells (VSMCs). The sarco/endoplasmic reticulum calcium ATPase isoform 2a (SERCA2a), specific to contractile VSMCs, has been reported previously to be involved in the control of the Ca²⁺-signaling pathways governing proliferation and migration. Moreover, SERCA2a gene transfer was reported to inhibit in vitro VSMC proliferation and to prevent neointimal thickening in a rat carotid injury model.

The aim of this study was to evaluate the potential therapeutic interest of SERCA2a gene transfer for prevention of in-stent restenosis using a human ex vivo model of left internal mammary artery (hIMA) intimal thickening.

Left hIMAs, obtained at the time of aorto-coronary bypass surgeries, were subjected to balloon dilatation followed by infection for 30 min with adenoviruses encoding either human SERCA2 and GFP or control gene (beta-galactosidase) and GFP. Proliferation of subendothelial VSMCs and neointimal thickening were observed in balloon-injured hIMA maintained 14 days in organ culture under constant pressure and perfusion. SERCA2a gene transfer prevented vascular remodeling and significantly (p<0.01, n=5) reduced neointimal thickening in injured arteries (intima/media ratio was 0.07 ± 0.01 vs 0.40 ± 0.03 in βGal-infected arteries).

These findings could have potential implications for treatment of pathological in stent-restenosis.

Inhibition of neointimal hyperplasia after stent placement with rhenium 188-filled balloon dilation in a canine iliac artery model

PURPOSE

To evaluate the efficacy of beta-irradiation therapy with rhenium 188 ((188)Re) mercaptoacetyltriglycine (MAG3)-filled balloon dilation to prevent neointimal hyperplasia after stent placement in a canine iliac artery model.

MATERIALS AND METHODS

A total of 15 stents were implanted into the iliac arteries of eight dogs (one or two stents in each dog). Rhenium 188 MAG3-filled balloon dilation was performed immediately after placement of 10 bare stents-20 Gy in group II (n = 5) and 40 Gy in group III (n = 5)-and conventional balloon dilation was performed immediately after placement of the remaining five bare stents (group I). A follow-up angiogram was obtained 8 weeks after the procedure, and percentage of luminal stenosis was calculated for the proximal and distal ends of each stent. Neointimal thickening (expressed as the neointimal area divided by the sum of neointimal area and media area) was assessed for microscopic examination.

RESULTS

All eight dogs survived until they were euthanized 8 weeks after the procedures. The mean luminal stenosis measurements at 8-week follow-up angiography in groups I, II, and III were 26.63%, -0.44%, and 10.53%, respectively. The mean neointimal thickening measurements in groups I, II, and III were 0.77, 0.21, and 0.34, respectively. The mean percentage of luminal stenosis and neointimal thickening differed significantly among the three groups (P < .05).

CONCLUSIONS

beta-Irradiation with (188)Re-MAG3-filled balloon dilation has the potential to reduce neointimal hyperplasia secondary to stent placement in a canine iliac artery model. A dose of 20 Gy may be preferable versus a dose of 40 Gy to reduce neointimal hyperplasia.

Drug-Eluting Stents in Bifurcations

Background— The use of a drug-eluting stent (DES) has strongly limited the incidence of in-stent restenosis in bifurcation lesions; nevertheless, restenosis still remains a problem at the origin of the bifurcation side branch. The aim of this study is to analyze the consequences of the kissing postdilatation technique on 5 DESs, using microfocus x-ray computerized tomography and scanning electron microscopy.

Methods and Results— Five different DESs (Cypher, Cypher Select, Endeavor, Taxus Express, and Taxus Liberté) were deployed using kissing postdilatation protocols in a bench-top model. For all types of DES, microfocus x-ray computerized tomography analysis showed that (1) kissing postdilatation of the stent by 2 coaxial balloons caused elliptic deformation in the proximal segment and (2) kissing postdilatation technique reduced the ratio of potential metal to artery (manufacturer’s data/calculated ratio [%]: Cypher, 12.7/8.8; Cypher Select, 13.5/10.2; Endeavor, 19.0/13.3; Taxus Express, 20.5/4.7; Taxus Liberté, 17.9/12.5) and the potential drug application to area in the proximal segment, including the ostial struts (struts adjacent to and lying around the side branch ostium) (manufacturer’s data/calculated drug application [μg/mm 2 ]: Cypher, 1.4/1.0; Cypher Select, 1.4/1.1; Endeavor, 1.6/1.1; Taxus Express, 1.0/0.7; Taxus Liberté, 1.0/0.7). Scanning electron microscopy analysis showed a significantly greater coating damage to the ostial struts in all stents evaluated ( P <0.05).

Conclusions— Commercially available DESs subjected to simultaneous kissing balloon postdilatation in an unconstrained model may contribute to side branch ostial restenosis by proximal segment elliptic deformation and damage to the polymer coating.