Optical coherence tomography and histopathology assessment after implantation of first- and second-generation drug-eluting stents in a porcine coronary model

Impact of Serum Phosphorus Levels on Outcomes After Implantation of Drug-Eluting Stents in Patients on Hemodialysis

BACKGROUND

Elevated serum phosphorus level is an important risk factor for cardiovascular death in general patients on hemodialysis (HD). However, the effect of serum phosphorus levels on outcomes after drug-eluting stent (DES) implantation in HD patients is unknown.Methods and Results:This was a post-hoc study of the OUCH study series, a series of prospective multicenter registries of HD patients who underwent DES implantation comprising 359 patients from 31 centers in Japan. Patients were categorized into 3 groups according to their preprocedural serum phosphorus levels. The 1-year clinical outcomes of the 336 patients treated for de novo lesions were evaluated. Compared with patients with high (>5.5 mg/dL; n=65) or normal (3.5-5.5 mg/dL; n=219) serum phosphorus levels, those with low serum phosphorus levels (<3.5 mg/dL; n=52) had significantly fewer target lesion revascularization events (13.9% vs. 16.9% vs. 1.9%; P=0.0090) and major adverse cardiac and cerebrovascular events (29.2% vs. 31.1% vs. 13.5%; P=0.032). Multivariate logistic regression analysis revealed that low serum phosphorus level was an independent negative predictor for major adverse cardiac and cerebrovascular events (adjusted odds ratio, 0.31; 95% confidence interval, 0.12-0.70; P=0.0036).

CONCLUSIONS

Lowering of serum phosphorus levels beyond the current recommended range may be considered in HD patients who undergo DES implantation.

Early endothelialization associated with a biolimus A9 bioresorbable polymer stent in a porcine coronary model

Although Nobori^®, with a bioresorbable polymer and biolimus A9 abluminal coating, has unique characteristics, few data exist regarding endothelialization early after implantation. Fifteen Nobori^® and 14 control bare-metal stents (S-stent™) were implanted in 12 pigs. Histopathology of stented segments, inflammation, and intimal fibrin content was evaluated on the 2nd and 14th day after implantation. On the 2nd day, endothelial cells were morphologically and immunohistologically confirmed on the surface of both stents, although some inflammatory cells might be involved. Stent surface endothelialization evaluated with a scanning electron microscope showed partial cellular coverage in both stents. On the 14th day, neointimal thickness and percentage of the neointimal area were significantly lower in Nobori^® than in S-stent™ (51.4 ± 4.5 vs. 76.4 ± 23.6 µm, p < 0.05 and 10.8 ± 2.6 vs. 14.1 ± 4.2%, p < 0.01). No significant differences were found in these parameters on the 2nd day (17.3 ± 14.9 vs. 26.7 ± 13.6 µm and 3.7 ± 3.0 vs. 6.7 ± 3.7%), in inflammatory and intimal fibrin content scores. These results demonstrate that endothelialization could occur early after Nobori^® implantation with similar inflammatory reaction to bare-metal stents, probably contributing to low frequency of in-stent thrombosis and restenosis.

Impact of statins therapy on morphological changes in lipid-rich plaques stratified by 10-Year framingham risk score: A serial optical coherence tomography study

The aim of the study was to investigate the impact of statins therapy on morphological changes of lipid-rich plaques by OCT (optical coherence tomography) in patients with known CHD (coronary heart disease), stratified by FRS. Ninety-seven lipid-rich plaques from sixty-nine patients who received statins therapy and underwent serial OCT images (baseline, 6-month and 12-month) were divided into 2 groups according to the FRS (framingham risk score): low risk group A (FRS<10%, N=35, n=45), moderate to high risk group B (FRS≥10%, N=34, n=52). Fibrous cap thickness (FCT) was measured at its thinnest part 3 times. Baseline characteristics were not different between the 2 groups. FCT sustained increased from baseline to 6-month and 12-month follow up in both group A (59.8±20.4μm, 118.3±62.5μm, and 158.8±83.4μm respectively, P<0.001) and group B (62.2±16.8μm, 125.1±78.7μm, 163.8±75.5μm respectively, P<0.001). Lipid index was significantly decreased in both group A (1862.1±1164.5, 1530.3±1108.7, 1322.9±1080.4, P<0.001) and group B (1646.6±958.5, 1535.1±1049.1, 1258.6±1045, P=0.016). The incidence of TCFA was decreased statistically in both group A (P <0.001) and group B (P <0.001). The patients with known CHD can equivalently benefit from statins therapy by stabilizing the lipid-rich plaques. Patients with moderate to high FRS might benefit more within the first year from event time.

Current State of Bioabsorbable Polymer-Coated Drug-Eluting Stents

Drug-eluting stents (DES) have been shown to significantly reduce clinical and angiographic restenosis compared to bare metal stents (BMS). The polymer coatings on DES elute antiproliferative drugs to inhibit intimal proliferation and prevent restenosis after stent implantation. Permanent polymers which do not degrade in vivo may increase the likelihood of stent-related delayed arterial healing or polymer hypersensitivity. In turn, these limitations may contribute to an increased risk of late clinical events. Intuitively, a polymer which degrades after completion of drug release, leaving an inert metal scaffold in place, may improve arterial healing by removing a chronic source of inflammation, neoatherosclerosis, and/or late thrombosis. In this way, a biodegradable polymer may reduce late ischemic events. Additionally, improved healing after stent implantation could reduce the requirement for long-term dual antiplatelet therapy and the associated risk of bleeding and cost. This review will focus on bioabsorbable polymer-coated DES currently being evaluated in clinical trials.

Edge Vascular Response After Resorption of the Everolimus-Eluting Bioresorbable Vascular Scaffold - A 5-Year Serial Optical Coherence Tomography Study

BACKGROUND

The edge vascular response (EVR) has been linked to important prognostic implications in patients treated with permanent metallic stents. We aimed to investigate the relationship of EVR with the geometric changes in the everolimus-eluting bioresorbable scaffold using serial optical coherence tomography (OCT) analysis.

METHODS AND RESULTS

In the first-in-man ABSORB trial, 28 patients (29 lesions) underwent serial OCT at 4 different time points (Cohort B1: post-procedure, 6, 24, and 60 months [n=13]; Cohort B2: post-procedure, 12, 36, and 60 months [n=15]) following implantation of the scaffold. In Cohort B1, there was no significant luminal change at the distal or proximal edge segment throughout the entire follow-up. In contrast, there was a significant reduction of the lumen flow area (LFA) of the scaffold between post-procedure and 6 months (-1.03±0.49 mm(2)[P<0.001]), whereas between 6 and 60 months the LFA remained stable (+0.31±1.00 mm(2)[P=0.293]). In Cohort B2, there was a significant luminal reduction of the proximal edge between post-procedure and 12 months (-0.57±0.74 mm(2)[P=0.017]), whereas the lumen area remained stable (-0.26±1.22 mm(2)[P=0.462]) between 12 and 60 months. The scaffold LFA showed a change similar to that observed in Cohort B1.

CONCLUSIONS

Our study demonstrated a reduction in the scaffold luminal area in the absence of major EVR, suggesting that the physiological continuity of the lumen contour is restored long term. (Circ J 2016; 80: 1131-1141).

Everolimus-eluting bioresorbable stent vs. durable polymer everolimus-eluting metallic stent in patients with ST-segment elevation myocardial infarction: results of the randomized ABSORB ST-segment elevation myocardial infarction-TROFI II trial

AIMS

Patients with ST-segment elevation myocardial infarction (STEMI) feature thrombus-rich lesions with large necrotic core, which are usually associated with delayed arterial healing and impaired stent-related outcomes. The use of bioresorbable vascular scaffolds (Absorb) has the potential to overcome these limitations owing to restoration of native vessel lumen and physiology at long term. The purpose of this randomized trial was to compare the arterial healing response at short term, as a surrogate for safety and efficacy, between the Absorb and the metallic everolimus-eluting stent (EES) in patients with STEMI.

METHODS AND RESULTS

ABSORB-STEMI TROFI II was a multicentre, single-blind, non-inferiority, randomized controlled trial. Patients with STEMI who underwent primary percutaneous coronary intervention were randomly allocated 1:1 to treatment with the Absorb or EES. The primary endpoint was the 6-month optical frequency domain imaging healing score (HS) based on the presence of uncovered and/or malapposed stent struts and intraluminal filling defects. Main secondary endpoint included the device-oriented composite endpoint (DOCE) according to the Academic Research Consortium definition. Between 06 January 2014 and 21 September 2014, 191 patients (Absorb [n = 95] or EES [n = 96]; mean age 58.6 years old; 17.8% females) were enrolled at eight centres. At 6 months, HS was lower in the Absorb arm when compared with EES arm [1.74 (2.39) vs. 2.80 (4.44); difference (90% CI) -1.06 (-1.96, -0.16); Pnon-inferiority < 0.001]. Device-oriented composite endpoint was also comparably low between groups (1.1% Absorb vs. 0% EES). One case of definite subacute stent thrombosis occurred in the Absorb arm (1.1% vs. 0% EES; P = ns).

CONCLUSION

Stenting of culprit lesions with Absorb in the setting of STEMI resulted in a nearly complete arterial healing which was comparable with that of metallic EES at 6 months. These findings provide the basis for further exploration in clinically oriented outcome trials.

The Potential of Minipigs in the Development of Anticancer Therapeutics: Species Comparison and Examples of Special Applications

Minipigs are increasingly being used as an alternative to dog or monkey in nonclinical safety testing of pharmaceuticals since they share similar anatomical and physiological characteristics to humans. Integrative assessment of pharmacodynamic and pharmacokinetic data sets of drug candidates fromin silico,in vitro, andin vivoinvestigations form the basis for selecting the most relevant nonrodent species for toxicology studies. Developing anticancer therapeutics represents a special challenge for species selection due to their effects on multiple organ systems. The toxicological profile of anticancer drugs can be associated with steep dose-response curves, especially due to dose-limiting toxicity on the alimentary, hematopoietic, and immune systems. Selection of an appropriate species for toxicology studies is of importance to avoid an inappropriately low (without benefit for the late-stage cancer patient) or high clinical starting dose (with a risk of unexpected adverse reactions). Although the minipig has been the preferred species to develop drugs applied topically, it is only rarely used in anticancer drug development compared to dog and monkey. In this context, we discuss the potential of minipigs in anticancer drug development with examples of programs for oral and dermal administration, intravascular application in drug-eluting stents, and local chemotherapy (chemoembolization).