Natural antioxidants and restenosis after percutaneous transluminal coronary angioplasty

A randomized feasibility study of the effect of ascorbic acid on post-angioplasty restenosis of hemodialysis vascular access (NCT03524846)

Restenosis remains a significant problem after angioplasty of hemodialysis vascular access. Both experimental and clinical studies have shown a protective effect of antioxidants against post-angioplasty restenosis. A prospective, randomized, feasibility study was conducted to investigate the effect of ascorbic acid to prevent restenosis. Ninety-three hemodialysis patients were randomized into three groups after angioplasty: placebo (n = 31), 300 mg ascorbic acid (n = 31), and 600 mg ascorbic acid (n = 31), treated intravenously 3 times per week for 3 months. Eighty-nine completed the clinical follow-up, and 81 had angiographic follow-up. In the angiographic follow-up, the mean (stand deviation) late loss of luminal diameter for the placebo, 300 mg, and 600 mg groups were 3.15 (1.68) mm, 2.52 (1.70) mm (P = 0.39 vs. placebo group), and 1.59 (1.67) mm (P = 0.006, vs. placebo group), with corresponding angiographic binary restenosis of 79%, 67% (P = 0.38 vs. placebo group), and 54% (P = 0.08 vs. placebo group). The post-interventional primary patency rates at 3 months were 47%, 55% (P = 0.59 vs. placebo group), and 70% (P = 0.18 vs. placebo group) for placebo, 300 mg, and 600 mg groups. Our results demonstrated that intravenous 600 mg ascorbic acid was a feasible therapy and might attenuate restenosis after angioplasty; however, its effect on post-interventional primary patency was modest.

Decreased Antioxidant Vitamin Concentration May Be a Risk Factor for Recurrent Carotid Stenosis

Carotid endarterectomy has been found to be associated with a transient increase in systemic oxidative stress, and this has been shown to be a predictor of restenosis. The aim of this study was to determine the incidence of early recurrent stenosis and investigate a possible role of oxidative stress in its development by measuring the concentration of antioxidant vitamins. Patients undergoing carotid endarterectomy between August 2001 and February 2003 were included in the study. A preoperative blood sample was analyzed for antioxidant vitamin concentrations. All patients were followed up by duplex scans 3 and 12 months postoperatively. Ninety-three patients (101 carotid endarterectomies) were recruited. Nine arteries had developed restenosis by 12 months. Those patients who developed recurrent stenosis had significantly lower vitamin C concentrations (19.10 ± 3.69 vs 30.11 ± 19.10, P = .02) than those who did not. This study suggests that low antioxidant vitamin levels may predispose to early restenosis after carotid endarterectomy.

Hyperhomocysteinemia and cardiovascular disease: The nutritional perspectives

Several members of the vitamin B-complex family are known to participate in the normal metabolism of homocysteine (Hcy). Leaving aside the genetic determinants of hyperhomocysteinemia (HHC), the deficiencies of these vitamins can also result in HHC. The situation of sustained and long standing HHC is likely to be prevalent in population groups with low/average socio-economic status, geriatric population and alcohol abusers. If not corrected by supplementation, these population groups certainly are more vulnerable to develop atherosclerosis (AS) and subsequently, cardiovascular disease (CVD). Hyperhomocysteinemia per se and/or HHC-induced oxidative stress result(s) in chronic chemical endothelial injury/dysfunction, smooth muscle proliferation, prothrombotic state and oxidation of low density lipoproteins (LDL) leading to diverse cardiovascular complications. In the first decade of the new millennium, major research efforts would be directed towards understanding the basic mechanism of HHC-induced oxidative stress and the pathophysiology of HHC-induced CVD, culminating in the evolution of hitherto unknown therapeutic strategies such as nutriceuticals and oxidant-antidotes.

Effect of Probucol on Neointimal Thickening in a Stent Porcine Restenosis Model

Restenosis after stent deployment remains a major clinical problem. Antioxidants have been proposed as a promising strategy against restenosis. We tested the antioxidant probucol for its efficacy against neointimal hyperplasia in porcine coronary arteries after stent implantation. Probucol was then tested in vivo in 8 coronary arteries of 4 pigs (1000 mg/day orally beginning 7 days before stenting) and was compared to placebo (10 coronary arteries, 5 pigs) 28 days after stenting. Quantitative intravascular ultrasound (IVUS) revealed 38.8 +/- 4.0 versus 40.1 +/- 3.0% area stenosis in the probucol versus control group. Histopathologic assessment showed that probucol had no beneficial effect on inhibiting the neointimal proliferative response in stent lesions compared to placebo (2.35 +/- 0.26 versus 2.88 +/- 0.25 mm(2)), despite similar injury scores (1.20 +/- 0.12 versus 1.28 +/- 0.14). An edge segment (axially 2-mm proximal to the stent margins) was assessed by IVUS. Remodeling index, which is a good marker of constrictive remodeling, was defined by the ratio of the vessel area in the lesion site (stent edge) to the vessel area in the proximal reference site (6-mm proximal to the stent margins). The remodeling index was significantly larger in the probucol group that in the placebo group (1.18 +/- 0.10 versus 0.90 +/- 0.06, P = 0.0012). In conclusion, probucol reduced constrictive remodeling at the edge of the implant but did not inhibit the tissue response within the stent.

L-ascorbic acid stimulates expression of smooth muscle-specific markers in smooth muscle cells both in vitro and in vivo

The dedifferentiation of vascular smooth muscle cells (VSMCs) plays a critical role in the progression of atherosclerosis and restenosis after angioplasty. Thus, factors that stimulate smooth muscle cell differentiation should be useful for therapy for these diseases. Previously, we found that l-ascorbic acid (L-Asc) induces the expression of smooth muscle-specific genes in a pluripotent bone marrow stromal cell line, TBR-B. This finding suggests that l-Asc stimulates the differentiation of smooth muscle cells. In the present study, we investigated the effects of l-Asc and its derivatives on the differentiation state of VSMCs in vitro and in vivo. l-Asc and its long-lasting derivatives stimulated the production of smooth muscle-specific myosin heavy chain-1 (SM1) and calponin 1 in a dose-dependent manner in rat cultured VSMCs, and the elevated production of SM1 and calponin 1 was maintained for at least 2 weeks. Moreover, oral administration of 3 g/kg of l-Asc to the balloon-injured rats induced a higher expression of SM1 and calponin 1 in the injured arteries compared with that from administration of the delivery vehicle alone. These data demonstrated new biologic activity, such as the stimulation of VSMC differentiation, of l-Asc and its long-lasting derivatives. In addition, these compounds may serve as useful tools for analysis of the differentiation of VSMCs and for therapy for vascular diseases.

Saiko-ka-Ryukotsu-Borei-To inhibits intimal thickening in carotid artery after balloon endothelial denudation in cholesterol-fed rats

Oral administration of Saiko-ka-Ryukotsu-Borei-To (SRB), a traditional Chinese formulation, dose dependently inhibited intimal thickening in carotid artery injured by balloon endothelial denudation in cholesterol-fed rats. SRB also inhibited vascular smooth muscle cell (VSMC) proliferation, which is assessed by counting the VSMCs immunoreactive with antiproliferating cell nuclear antigen (PCNA) antibody in the intimal area. VSMC proliferation is considered to play a central role in the development of intimal thickening. SRB slightly, but not significantly, reduced serum total cholesterol and low-density lipoprotein cholesterol. These results indicate that the suppressive effect of SRB on intimal thickening may result from its inhibitory effect against VSMC proliferation, but does not depend on lowering of lipid levels. The balloon injury model used in this study has similar pathological processes to restenosis after percutaneous coronary intervention (PCI). Therefore the present results may provide a new therapeutic strategy using SRB to reduce restenosis after PCI in the treatment of patients with ischemic coronary artery disease. Furthermore, since it is considered that artery restenosis after balloon injury in PCI is "accelerated atherosclerosis, " SRB may have beneficial effects in atherosclerosis that develops over a long clinical course in hyperlipidemia, diabetes, etc.

Effect of the final coronary arterial diameter after coronary angioplasty on heart rate variability responses

BACKGROUND

Autonomic nervous system dysfunction and reduced heart rate variability (HRV) after percutaneous transluminal coronary angioplasty (PTCA) were reported in patients with coronary artery disease. However, factors related to reduced HRV are not clearly demonstrated. The aim of the present study was to assess the relationship between HRV indices and the final coronary arterial luminal diameter after PTCA.

METHODS

Twenty-seven patients (23 male, 4 female, mean age: 52.5 +/- 7.1 years) with single vessel disease were included in the study. PTCA was performed in all patients. Low-frequency power (LFP), high-frequency power (HFP), and total power (TP) were calculated by using frequency-domain analysis of HRV. All examinations were performed 24 hours before, and 24 hours, 10 days, and 30 days after PTCA. The patients were divided into groups according to the PTCA restenosis risk score, the degree of dilatation, and revascularization after coronary angioplasty.

RESULTS

The groups were comparable for age, gender, and coronary artery risk factors. HRV was found to be reduced in 76% of patients. Reduction in HRV after PTCA was significantly related to the PTCA risk score and the degree of revascularization (r = 0.48, P < 0.01 and r = 0.50, P < 0.008). Reduction in HRV was more significant in patients with previous myocardial infarction (P < 0.05). Recovery of HRV occurred on the tenth day after PTCA.

CONCLUSION

Transient and rapidly recovered, especially parasympathetically modulated HRV reduction occurred after PTCA in patients with single-vessel disease. HRV reduction is associated with PTCA restenosis risk score and the degree of revascularization as invasive feature of angioplasty, hence it may be related to reperfusion.

Haptoglobin phenotype and the risk of restenosis after coronary artery stent implantation

We recently demonstrated that an allelic polymorphism in the haptoglobin gene is a major determinant of susceptibility to a number of vascular disorders. We set out to determine if haptoglobin phenotype was predictive of the development of restenosis in a consecutive series of patients, all of whom underwent stent implantation followed by repeat angiography with quantitative coronary angiography analysis 6 months later. This study included 214 consecutive patients undergoing stent implantation for de novo lesions between 1998 and 1999 in Aalst, Belgium. All underwent follow-up quantitative coronary angiography analysis 6 months after the procedure. The haptoglobin phenotype was determined by electrophoresis. No significant differences were found between patients segregated by phenotype with respect to clinical, procedural, and angiographic factors previously suggested to influence the development of restenosis. None of the diabetic patients homozygous for the haptoglobin 1 allele developed restenosis compared with a >50% restenosis rate for diabetic patients with at least 1 haptoglobin 2 allele (p <0.02). In all patients (diabetic and nondiabetic), we observed a trend toward a lower incidence of restenosis in patients homozygous for the 1 allele (21% vs 33%, p <0.09). Moreover, we found a graded risk relation to the number of haptoglobin 2 alleles. The risk of developing restenosis was greater in subjects with 2 haptoglobin 2 alleles (36%) than in those with 1 haptoglobin 2 allele (31%) or no haptoglobin 2 alleles (21%). Thus, knowledge of the haptoglobin phenotype may be useful in assessing and utilizing new therapies that attempt to reduce restenosis, and may have important implications for the risk stratification algorithm used in managing diabetic patients with coronary artery disease.

Long-term retention of a novel antioxidant sulphur-substituted fatty acid analogue after local delivery in porcine coronary arteries

OBJECTIVE

Antioxidants have been suggested to reduce restenosis after balloon angioplasty. A novel sulphur-containing fatty acid, tetradecylthioacetic acid (TTA), with antioxidant properties, is efficiently incorporated into cellular phospholipids. We have determined the uptake and retention of TTA after local coronary artery delivery in 20 pigs.

DESIGN

Radiolabelled TTA was delivered to 40 main coronary arteries via a multiporous coronary angioplasty balloon catheter inflated before, after, or without overstretch vessel injury. The animals were killed at intervals of up to 6 weeks post-procedure. The radioactivity of the tissue sections was determined as nmol TTA/g tissue.

RESULTS

Concentrations of TTA in the coronary arteries were 1.84 +/- 0.45 nmol/g up to 24 h, 1.50 +/- 0.96 nmol/g at 2 weeks, 0.22 +/- 0.11 nmol/g at 4 weeks and a trace was present at 6 weeks (p-value for trend <0.01). The arterial wall uptake at the delivery site was higher than distal to delivery (1.84 +/- 0.37 vs 0.55 +/- 0.13 nmol/g, p = 0.006) and perivascular fat (p < 0.01) but not higher than in the myocardium. Infusion before, after or without vessel injury was not important for tissue concentration.

CONCLUSIONS

After local coronary artery delivery, the antioxidant TTA is taken up by the arterial wall in which it is retained for at least 4 weeks.

Haptoglobin phenotype as a predictor of restenosis after percutaneous transluminal coronary angioplasty

We have demonstrated that a genetic polymorphism in the antioxidant protein haptoglobin is important in determining which patients develop restenosis after percutaneous transluminal coronary angioplasty. Knowledge of the haptoglobin phenotype may be useful in the assessment and utilization of new therapies to reduce restenosis, particularly in patients who are homozygous for the haptoglobin 2 allele.

Increased systemic oxidative stress after elective endarterectomy: relation to vascular healing and remodeling

It has been reported that systemic and local redox state may have an important role in the functional and organic changes characterizing the process of vascular response to injury. Carotid endarterectomy to remove atherosclerotic plaque is followed by a long lasting healing and remodeling process that can be carefully followed over time with noninvasive ultrasonography. Plasma vitamin C concentration and native LDL (n-LDL) content in lipid peroxides, vitamin E, beta-carotene, and lycopene as well as LDL susceptibility to peroxidation were assessed in 45 patients undergoing elective endarterectomy for internal carotid stenosis, at baseline, 24 hours, 3 and 15 days, and 1 month after surgery. Serial duplex scans were performed in all patients postoperatively and 3, 6, and 12 months. The changes in far wall thickness (FW) and % renarrowing from postoperatively to 12 months were used as remodeling indices. Plasma antioxidant vitamins and lag-phase showed a sharp and significant decrease during the first 24-hours after surgery remaining unchanged until the third day, whereas, an opposite trend was evidenced for n-LDL content in lipid peroxides and serum ceruloplasmin. After the third day all the parameters returned progressively to baseline within one month from endarterectomy. Interestingly, the n-LDL lipid peroxide content, the serum ceruloplasmin and the plasma vitamin C concentration, measured at 24 and 3 days from surgery, were significantly associated to the change in % renarrowing from postoperatively to 12 months. The higher the LDL content in lipid peroxides, the higher the serum level of ceruloplasmin, the lower the plasma content in vitamin C and the higher the % of vessel renarrowing. In conclusion, carotid endarterectomy with atherosclerotic plaque removal is associated with an acute and prolonged increase in systemic oxidative stress that influences vascular healing and late luminal loss.

Diet enriched with procyanidins enhances antioxidant activity and reduces myocardial post-ischaemic damage in rats

Aim of this work was to study the efficacy of procyanidins from Vitis vinifera seeds, a standardized mixture of polyphenol antioxidants, on cardiac mechanics following ischemia/reperfusion stunning in the rat, after 3 weeks supplementation. Young and aged male rats were fed a diet enriched with procyanidins complexed (1:3 w/w) with soybean lecithin (2.4%); control animals (CTR-young and CTR-aged) received an equal amount of lecithin and 2 additional groups of animals the standard diet. At the end of the treatment, the total plasma antioxidant defense (TRAP), vitamin E, ascorbic acid and uric acid were determined in plasma and the hearts from all groups of animals subjected to moderate ischemia (flow reduction to 1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min). In both young and aged rats supplemented with procyanidins the recovery of left ventricular developed pressure (LVDP) at the end of reperfusion was 93% (p < 0.01) and 74% (p < 0.01) of the preischemic values and the values of coronary perfusion pressure (CPP) were maintained close to those of the preischemic period. Also creatine kinase (CK) outflow was restrained to baseline levels, while a 2-fold increase in prostacyclin (6-keto-PGF1alpha) in the perfusate from hearts of young and aged rats was elicited during both ischemia and reperfusion. In parallel, procyanidins significantly increased the total antioxidant plasma capacity (by 40% in young and by 30% in aged rats) and the plasma levels of ascorbic acid, while tend to reduce vitamin E levels; no significant differences were observed in uric acid levels. The results of this study demonstrate that procyanidins supplementation in the rat (young and aged) makes the heart less susceptible to ischemia/reperfusion damage and that this is positively associated to an increase in plasma antioxidant activity.

Phosphorylcholine-coated metallic stents in rabbit iliac and porcine coronary arteries

The arterial wall reaction to phosphorylcholine-coated metal stents was examined in rabbits and pigs. Compared to non-coated stents, no significant difference was found by angiography and histology. We conclude that although phosphorylcholine-coating does not provoke arterial neointima formation or decrease luminal diameter compared to stainless steel stents, the coating does not seem to reduce restenosis.

Effectiveness of an antioxidant in preventing restenosis after percutaneous transluminal coronary angioplasty: the Probucol Angioplasty Restenosis Trial

OBJECTIVES

The Probucol Angioplasty Restenosis Trial was a prospective, randomized, controlled study that investigated the effectiveness of probucol therapy in reducing the rate of restenosis after percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Antioxidants have an inhibitory effect on smooth muscle cell growth in experiments in vitro and in vivo, which suggests a possible pharmacologic effect on restenosis after PTCA.

METHODS

One hundred one patients were randomly assigned to receive 1,000 mg/day of probucol or control (no lipid-lowering) therapy 4 weeks before PTCA. After 4 weeks of premedication, both groups underwent PTCA. Probucol was continued until follow-up angiography 24 weeks after PTCA. Angiographic results were analyzed at a core laboratory by quantitative coronary angiography.

RESULTS

Dilation was successful in 46 of 50 patients in the probucol group and 45 of 51 in the control group. At follow-up angiography 24 weeks after angioplasty, angiographic restenosis occurred in 9 (23%) of 40 patients in the probucol group and 22 (58%) of 38 in the control group (p = 0.001). Minimal lumen diameter was 1.49 +/- 0.75 mm (mean +/- SD) in the probucol group and 1.13 +/- 0.65 mm in the control group (p = 0.02). Percent diameter stenosis at follow-up angiography in the probucol group was significantly lower than that in the control group (43.9% vs. 56.4%, p = 0.009). The late loss was 0.37 +/- 0.69 mm in the probucol group and 0.60 +/- 0.62 mm in the control group (p = 0.13). The loss/gain ratio was 0.32 +/- 0.74 in the probucol group and 0.56 +/- 0.81 in the control group (p = 0.059). Net gain was greater in the probucol group than in the control group (0.77 +/- 0.70 vs. 0.48 +/- 0.59 mm, p = 0.053).

CONCLUSIONS

Probucol administered beginning 4 weeks before PTCA appears to reduce restenosis rates.

Effects of trimetazidine on heart rate variability and left ventricular systolic performance in patients with coronary artery disease after percutaneous transluminal angioplasty

Fifty-one patients (mean age 51.6 +/- 7.1 years) with angiographically proven coronary artery disease (CAD) entered the study. In 26 patients (Group I), trimetazidine treatment started twenty-four hours after percutaneous transluminal coronary angioplasty (PTCA). Another 25 patients (Group II) without trimetazidine treatment were kept as controls. The groups were comparable by age, gender, risk factors of CAD, coronary anatomy, left ventricular performance, and heart rate variability indices at baseline state. Power spectral analysis of heart rate variability and two-dimensional and Doppler echocardiographic examinations were performed before PTCA, and twenty-four hours, ten days, thirty days, and three months after PTCA. A statistically significant improvement of left ventricular systolic performance (P < 0.001), augmentation of the parasympathetic band of heart rate variability (P < 0.001), and decline of P1/P2 ratio (P < 0.01) were evident in patients treated with trimetazidine, while no apparent changes were observed in controls. The intergroup analysis also showed marked difference between groups as recorded on the day 30 and month 3 of observation (P < 0.001). During follow-up period recurrences of angina pectoris and ischemia were registered in Group II, while no evidence of ischemia was discerned in Group I patients. In conclusion, trimetazidine modulates the autonomic control of heart rate, ie, reduces sympathetic overactivity and augments vagal influences, improves left ventricular contractility, and diminishes the clinical manifestations of ischemia in patients with CAD after PTCA.

Possible prevention of postangioplasty restenosis by ascorbic acid

In this preliminary study to assess the possibility of using ascorbic acid to prevent post-percutaneous transluminal coronary angiography (PTCA) restenosis, the incidence of restenosis was significantly less in 50 patients receiving 500 mg/day of oral ascorbic acid than in 51 control patients. Thus, ascorbic acid, a potent natural antioxidant, appeared to be possibly effective in attenuating post-PTCA restenosis.

The lack of effect of beta-carotene on restenosis in cholesterol-fed rabbits

The success of percutaneous transluminal coronary angioplasty is limited by restenosis in 30-50% of cases. Cellular production of reactive oxygen species at the site of injury has been implicated as a contributing factor in the process of restenosis. beta-Carotene is a lipid-soluble antioxidant whose effects on this process have not been previously investigated. We attempted to elucidate whether beta-carotene treatment was capable of reducing restenosis. Femoral artery stenoses were produced by nitrogen-desiccation in rabbits fed a high-cholesterol diet. The animals were randomized to receive either a parenteral bolus of beta-carotene immediately prior to angioplasty, followed by 5 days of subcutaneous treatment (Acute Treatment); 5 days of subcutaneous pretreatment with beta-carotene followed by a parenteral bolus immediately prior to angioplasty and then another 5 days of subcutaneous treatment (Pretreatment); or vehicle only (Control). Angiography was performed immediately before and after angioplasty, and 28 days after angioplasty. The animals were then sacrificed, and the femoral arteries were harvested for histopathology. By quantitative angiography, the late loss of luminal diameter between angioplasty and final angiography was not significantly different between the acute treatment group, the pretreatment group and the control group. By histopathology, the area of intimal hyperplasia and the percent cross-sectional area stenosis were also not significantly different. The late loss in luminal diameter after angioplasty correlated significantly with the acute gain in luminal diameter produced by angioplasty. The amount of intimal hyperplasia correlated significantly with the arterial injury score assessed by histopathology. In summary, in this animal model of restenosis, parenteral beta-carotene failed to significantly reduce the amount of either intimal hyperplasia or late loss in luminal diameter after angioplasty.