Short- and long-term effects of a novel paclitaxel coated stent in the porcine coronary model

Effect of Interstitial Fluid Flow on Drug-Coated Balloon Delivery in a Patient-Specific Arterial Vessel with Heterogeneous Tissue Composition: A Simulation Study

Angioplasty with drug-coated balloons (DCBs) using excipients as drug carriers is emerging as a potentially viable strategy demonstrating clinical efficacy and proposing additional compliance for the treatment of obstructive vascular diseases. An attempt is made to develop an improved computational model where attention has been paid to the effect of interstitial flow, that is, plasma convection and internalization of bound drug. The present model is capable of capturing the phenomena of the transport of free drug and its retention, and also the internalization of drug in the process of endocytosis to atherosclerotic vessel of heterogeneous tissue composition comprising of healthy tissue, as well as regions of fibrous cap, fibro-fatty, calcified and necrotic core lesions. Image processing based on an unsupervised clustering technique is used for color-based segmentation of a patient-specific longitudinal image of atherosclerotic vessel obtained from intravascular ultrasound derived virtual histology. As the residence time of drug in a stent-based delivery within the arterial tissue is strongly influenced by convective forces, effect of interstitial fluid flow in case of DCB delivery can not be ruled out, and has been investigated by modeling it through unsteady Navier-Stokes equations. Transport of free drug is modeled by considering unsteady advection-reaction-diffusion process, while the bound drug, assuming completely immobilized in the tissue, by unsteady reaction process. The model also takes into account the internalization of drug through the process of endocytosis which gets degraded by the lysosomes and finally recycled into the extracellular fluid. All the governing equations representing the flow of interstitial fluid, the transport of free drug, the metabolization of free drug into bound phase and the process of internalization along with the physiologically realistic boundary and initial conditions are solved numerically using marker and cell method satisfying necessary stability criteria. Simulated results obtained predict that faster drug transfer promotes rapid saturation of binding sites despite perivascular wash out and the concentrations of all drug forms are modulated by the presence of interstitial flow. Such premier attempt of its kind would certainly be of great help in the optimization of therapeutic efficacy of drug.

Drug-eluting stents in preclinical studies: updated consensus recommendations for preclinical evaluation

Coronary drug-eluting stents are commonplace in clinical practice with acceptable safety and efficacy. Preclinical evaluation of novel drug-eluting stent technologies has great importance for understanding safety and possibly efficacy of these technologies, and well-defined preclinical testing methods clearly benefit multiple communities within the developmental, testing, and clinical evaluation chain. An earlier consensus publication enjoyed widespread adoption but is in need of updating. This publication is an update, presenting an integrated view for testing drug-eluting technologies in preclinical models, including novel devices such as bioabsorbable coatings, totally bioabsorbable stents, bifurcation stents, and stent-free balloon-based drug delivery. This consensus document was produced by preclinical and translational scientists and investigators engaged in interventional technology community. The United States Food and Drug Administration (USFDA) recently issued a Draft Guidance for Industry Document for Drug-Eluting Stents. This expert consensus document is consistent with the Food and Drug Administration guidance. The dynamic nature of this field mandates future modifications and additions that will be added over time.

Tacrolimus-eluting carbon-coated stents versus sirolimus-eluting stents for prevention of symptom-driven clinical end points

BACKGROUND

Coating of stents has been shown to minimize the interactions between platelets, stent surface and vascular response following stent implantation. The aim of our study was to compare the tacrolimus-eluting carbon-coated JANUS(®) stent with sirolimus-eluting CYPHER(®) stent for the prevention of symptom-driven clinical end points in a real world clinical setting.

METHODS

This prospective registry with a follow-up period of 24 months was conducted in 90 consecutive patients undergoing coronary artery stenting receiving CYPHER(®) (n = 48) or JANUS(®) (n = 42) stents. The primary end point was a composite of death from cardiovascular causes, nonfatal myocardial infarction and target vessel revascularisation, and the secondary end point was clinically driven in-stent restenosis.

RESULTS

The primary combined endpoint occurred in 38% of patients (n = 16) in the JANUS(®) group compared to 10% (n = 5) in the CYPHER(®) group. The relative risk increase of the composite end point was therefore 63% higher in patients receiving JANUS(®) stents compared to the CYPHER(®) stents (crude HR = 1.63, 95% CI = 1.17-2.28, p = 0.004; adjusted HR = 1.79, CI = 1.26-2.55, p = 0.001). Interestingly, 75% of events in the JANUS(®) group occurred during the first 6 months after stent implantation. Similarly, the rate of clinically driven in-stent restenosis was higher in patients receiving JANUS(®) stent (n = 10, 2%) compared to the CYPHER(®) stent (n = 2, 4%). Concordantly, the relative risk for clinically driven in-stent restenosis was 81% higher in the JANUS(®) group compared to the CYPHER(®) group (crude HR = 1.81, 95% CI = 1.08-3.02, p = 0.02; adjusted HR = 2.24, CI = 1.26-3.96, p = 0.006).

CONCLUSION

The use of tacrolimus-eluting carbon coated JANUS(®) stent was associated with worse clinical outcome compared to the sirolimus-eluting CYPHER(®) stent in clinical routine use.

Azithromycin does not prevent six-month myointimal proliferation but attenuates the transient systemic inflammation occurring after coronary stenting

OBJECTIVES

Stent implantation produces a systemic increase of inflammatory markers that correlates with Chlamydophila pneumoniae infection in atherosclerotic plaque. We performed a clinical intervention study to investigate the effect of antibiotic treatment on 6-month follow-up angiographic minimal luminal diameter after stenting.

METHODS

Ninety patients were randomly assigned to oral azithromycin or placebo in a double-blinded and randomized fashion. Medication was initiated 2 weeks before a pre-scheduled stenting procedure and maintained 12 weeks thereafter. Angiographic outcomes were evaluated by a six-month follow-up angiography and laboratorial parameters were accessed by blood sampling 2 weeks before stenting, within the first 24 h after procedure and additional samples after four weeks and 6 months.

RESULTS

Minimal luminal diameter (1.76 +/- 0.56 mm Vs. 1.70 +/- 0.86 mm; P = 0.7), restenosis rate, diameter stenosis, late loss, and binary restenosis rates were comparable in placebo and azithromycin group in the 6 months follow-up. Serum levels of C-reactive protein presented a three fold significant increase in the control group one day after stenting but did not change in the azithromycin group (8.5 [3.0;16.4] Vs. 2.9 [1.7;6.6]-median [25;75 percentile] P < 0.01).

CONCLUSIONS

Azithromycin does not improve late angiographic outcomes but attenuates the elevation of C-reactive protein levels after stenting, indicating an anti-inflammatory effect.

Two year follow-up after treatment of coronary in-stent restenosis with a paclitaxel-coated balloon catheter

BACKGROUND

We are presenting an extension of a previously published trial on the efficacy and safety of a paclitaxel-coated balloon in coronary ISR in a larger patient population and after a complete follow-up of 2 years.

METHODS

Hundred eight patients were enrolled in two separately randomized, double-blind multicenter trials on efficacy and safety using an identical protocol. Patients were treated by the paclitaxel-coated (3 microg/mm(2) balloon surface; Paccocath) or an uncoated balloon. The main inclusion criteria were a diameter stenosis of >or=70% and <30 mm length with a vessel diameter of 2.5-3.5 mm. The primary endpoint was angiographic late lumen loss in-segment. Secondary endpoints included binary restenosis rate and major adverse cardiovascular events (MACE).

RESULTS

Quantitative coronary angiography revealed no differences in baseline parameters. After six months in-segment late lumen loss was 0.81 +/- 0.79 mm in the uncoated balloon group vs. 0.11 +/- 0.45 mm (P < 0.001) in the drug-coated balloon group resulting in a binary restenosis rate of 25/49 vs. 3/47 (P < 0.001). Until 12 months post procedure 20 patients in the uncoated balloon group compared to two patients in the coated balloon group required target lesion revascularization (P = 0.001). Between 12 and 24 only two MACE were recorded, a stroke in the uncoated and a target lesion revascularization in the coated balloon group.

CONCLUSION

Treatment of coronary ISR with paclitaxel-coated balloon catheters persistently reduces repeat restenosis up to 2 years. (ClinicalTrials.gov Identifier: NCT00106587, NCT00409981).