Optimal anti-platelet therapy : duration of anti-platelet therapy with drug-eluting and bare-metal stents

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How to approach drug-eluting stent restenosis

Drug-eluting stents (DES) have been a major advance in percutaneous coronary intervention reducing restenosis and repeat revascularization. The application of DES to the treatment of complex lesion and patient subsets has resulted in significant rates of DES restenosis or failure. Though predominantly focal, substantial rates of non-focal DES restenosis are being observed. Non-focal disease most likely represents a resistant process that will remain a therapeutic challenge. An understanding of the causative mechanical and biological factors is essential for the prevention and treatment of DES restenosis. Robust data relating to the treatment efficacy for this problem is lacking. At present, repeat DES or vascular brachytherapy appear to the best available options. Evidence from randomized controlled trials and large registries is required to establish a formal treatment approach. We provide guidelines based on current available evidence.6 page(s

Intravascular ultrasound guidance in drug-eluting stent deployment

The role of routine intravascular ultrasound (IVUS) guidance during percutaneous coronary intervention (PCI) in the bare metal stent era remains controversial. The potential to reduce revascularization was reported without impacting non-fatal myocardial infarction and death. Drug-eluting stents (DES) have realized improved clinical results in patients undergoing PCI but are not free of restenosis and are limited by thrombosis, particularly in more complex lesion types. Stent under-expansion, malposition, and incomplete lesion coverage have been identified as the key mechanisms of DES failure. The identification of these features on IVUS and their subsequent treatment may lead to improved clinical outcomes. Though a clinical benefit is intuitive, results from randomized trials are still needed to justify routine IVUS guided DES implantation. The Authors provide a review of the currently available evidence pertaining to the potential clinical benefit of IVUS guidance in DES implantation.11 page(s

DC resistivity of alumina and zirconia sintered with TiC

Pure alumina and zirconia powders were sintered separately with increasing amount of TiC up to similar to 65 vol. %, as a conducting second phase with an aim to prepare conducting structural ceramics which can be precisely machined by EDM technique. TiC did not help in sintering the parent phase but it decreased the d.c. resistivity of the composite to 1 ohm.cm at similar to 30 vol.% loading. The conductivity is explained by the effective media and percolation theories

Percutaneous treatment of a giant coronary aneurysm using a Symbiot stent

Percutaneous treatment of coronary aneurysms has been proven to be a safe and effective alternative to surgery. We report the successful treatment of a giant proximal left circumflex artery aneurysm with distal occlusion in a 76-year-old man using the new generation of covered stent, Symbiot, a polytetrafluoroethylene-covered self-expandable stent (Boston Scientific, Natick, MA).2 page(s

Investigation of various magnetic features of spinel type cobalt ferrite (CoFe2O4) nanoparticles tuned by annealing temperature

Cobalt ferrite (CoFe2O4) nanoparticles synthesized by chemical co-precipitation method were studied to see the effect of annealing temperatures on the structural parameters and magnetic properties of the sample. X-ray powder diffraction (XRD), transmission electron microscope (TEM) and SAD pattern demonstrated that single face (fcc) spinel structure of CoFe2O4 has been formed showing particles in completely crystalline state which was further confirmed by the lattice parameter and the unmixed hkl values. The particle size is in the range of about 5-10 nm depending on the annealing temperature from 200°C to 400°C. The grain growth occurred monotonically with the increase of annealing temperature. The magnetic properties demonstrated a strong dependence on particle size. The saturation magnetization Ms, remanent ratio Mr/Ms and coercivity Hc increased with the increase of particle size. The hysteresis curves for samples of different grain size showed the ferrimagnetic behavior which is completely analogous to the slow relaxation sextet peaks of Mössbauer spectroscopy. Other parameters such as chemical shift, quadruple splitting and hyperfine field and site occupancy of Fe3+ were determined by Mössbauer spectroscopy. Ferrimagnetic to superparamagnetic transition temperature known as blocking temperature TB was determined from the temperature dependent magnetization curves. With the increase of grain size, Blocking temperature also increases. Maximum entropy changes due to magnetic phase transition were also observed for mentioned annealing temperatures in the context of Magnetocaloric effect

Successful treatment of a coronary cameral fistula secondary to elective sirolimus-eluting stent implantation

Coronary cameral fistulae, communications between the coronary tree and the chambers of the heart, are a rare complication of percutaneous coronary intervention. The functional significance and management of these fistulae remain uncertain. We report such a case in a patient undergoing elective sirolimus-eluting stent implantation and provide a review of the literature.3 page(s

Intravascular ultrasound-guided percutaneous coronary interventions in contemporary practice

Intravascular ultrasound imaging has been pivotal in the understanding of coronary artery disease and the development of percutaneous coronary intervention. The ability to analyse vessel walls and measure atherosclerotic lesions more accurately has enabled the field of invasive cardiology to overcome the limits of angiography. In fact, intravascular ultrasound measurements correlate with functional measurement of coronary blood flow, as a result interest in their use for the diagnosis of lesion severity in ambiguous lesions and for left main trunk analysis has grown. On the interventional side, intravascular ultrasound is used to determine the major predictors of restenosis and stent thrombosis, which are the main pitfalls of percutaneous coronary intervention. In the bare-metal stent era, intravascular ultrasound-guided percutaneous coronary intervention was associated with a reduction in restenosis rates because it enabled identification and treatment of the risk factors for complications. Although drug-eluting stents have provided a great technological advance in percutaneous coronary intervention, further reducing the rate of in-stent restenosis, they have not abolished restenosis completely; intravascular ultrasound has also been used in this setting to identify the mechanisms responsible for drug-eluting stent restenosis. As in the bare-metal stent era, identification of the predictors of restenosis and stent thrombosis and their subsequent treatment may offer the promise of improved outcome in the drug-eluting stent era. This review focuses on the potential benefit of intravascular ultrasound-guided percutaneous coronary intervention with regard to restenosis and stent thrombosis in the bare-metal stent and drug-eluting stent eras.9 page(s

The clinical outcome of restricting drug-eluting stents to patients at highest risk of restenosis

AIMS: To assess the clinical outcomes of patients where drug eluting stents (DES) were restricted to those at highest risks of restenosis, we compared three different strategies for stent implantation: bare metal stents (BMS) only, DES only and a group where DES use was restricted (RES). METHOD AND RESULTS: Initial comparison was made between BMS only (279 patients, 316 lesions) and DES only (272 patients, 302 lesions). The endpoints of death, non-fatal myocardial infarction and target lesion revascularisation (TLR) [MACE] were assessed at 12 months. The incidence of MACE in the BMS only and DES only groups were 14% and 7% (p=0.002) and TLR was 8% and 1% (p<0.0001). Comparison was then made between these results and a third group where DES was restricted to patients at highest risk of restenosis. The restricted group (RES) comprised 249 patients (271 lesions) of which 53% received DES. RES remained significantly better than BMS, MACE (14% vs. 8%, p=0.02) and TLR (8% vs. 3%, p=0.02). When RES was compared with DES only, there was no significant difference in MACE (8% vs. 7% p=0.42), but there was a significantly lower TLR rate in the DES only group (1% vs. 3% p=0.04). CONCLUSIONS: The overall incidence of events in patients where DES use was restricted to 53% of patients remains low and this may be an acceptable treatment strategy to reduce costs.6 page(s