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Biomedical subjects

Ron Waksman

Publications and source records attributed to Ron Waksman.

At least 73 records · Page 4Linked to original sources
PubMed2005

Contemporary Use of Drug-eluting Stents.

Since the era of balloon angioplasty, stents have been a revolutionary advance in the treatment of severe coronary artery disease. However, one of the major limitations is in-stent restenosis. Although brachytherapy was found to be an effective treatment, the goal remains to develop a kind of stent that will not restenose. The emergence of drug-eluting stents provided a novel solution for the reduction of restenosis. The currently approved indication for drug-eluting stents by the US Food and Drug Administration is for discrete, de novo lesions in native vessels with reference vessel diameters of 2.5 to 3.5 mm. However, in the worldwide daily practice, there have been numerous off-label uses of drug-eluting stents, and their long-term follow-up and experience in more complex lesions are accumulating. This article reviews the current off-label uses of drug-eluting stents. The majority of the supporting data are from registry and observational studies, yet many studies are limited by small sample sizes. Therefore, large, prospective, randomized, double-blind, and controlled trials are definitely warranted to further support current practice. Nevertheless, the "real world" unrestricted uses of drug-eluting stents seem to be the current trend in the interventional field.

Journal Article↗
PubMed2005

Brachytherapy and bivalirudin evaluation study.

BACKGROUND: Bivalirudin is shown to be a competent substitute for heparin in percutaneous coronary intervention (PCI). The safety and efficacy of bivalirudin in patients undergoing PCI and vascular brachytherapy (VBT) are not known. This study aimed to assess the safety and efficacy of bivalirudin as a single antithrombotic agent in patients undergoing PCI and VBT. METHODS: A total of 152 patients enrolled in the Brachytherapy and Bivalirudin Evaluation Study underwent PCI and VBT with either gamma (n = 8) or beta radiation (n = 144). The main outcome measures were in-hospital events and 30-day clinical outcomes. All patients were treated with bivalirudin (0.75 mg/kg bolus and 1.75 mg/kg per hour infusion for beta radiation, 1 mg/kg bolus and 2.5 mg/kg per hour infusion for gamma radiation) as a single antithrombotic agent during the entire procedure. RESULTS: Baseline clinical and angiographic characteristics were similar between the 2 groups. More than 90% of the patients received beta radiation. In-hospital events showed a higher prevalence of acute procedural intracoronary thrombosis in patients treated with gamma- vs beta radiation (25% vs. 0.7%, P < .001). Thirty-day outcomes including death, Q-wave, and non-Q-wave myocardial infarctions, subacute stent thromboses, and repeat revascularizations were similar in both groups. CONCLUSION: Bivalirudin, as a single antithrombotic agent during PCI and VBT with beta emitters, may be used safely, but its use in the setting of PCI and gamma radiation may not be acceptable due to an increased incidence of acute procedural intracoronary thrombosis.

Angioplasty, Balloon, Coronary↗
PubMed2005

Rapamycin attenuates atherosclerotic plaque progression in apolipoprotein E knockout mice: inhibitory effect on monocyte chemotaxis.

Rapamycin has been shown to reduce neointimal thickening in the setting of balloon angioplasty and chronic graft vessel disease. This study was designed to test the effect of oral rapamycin on atherosclerotic plaque progression and the possible mechanism involved. Apolipoprotein E (apoE) knockout mice were fed either a diet supplemented with cholesterol or with cholesterol and rapamycin. At 4 and 8 weeks, quantitative analyses of plaque area and macrophage numbers were determined. Plasma cholesterol, triglyceride, and whole-blood rapamycin levels were measured. Rapamycin could be detected in the blood of mice (117+/-7 pg/mL). In mice fed with rapamycin, atherosclerotic lesions covered 22% of the aortic arch as compared with 41% in cholesterol-fed mice. The macrophage count was significantly lower in the rapamycin-fed mice as compared with cholesterol-fed mice. Rapamycin, in a dose-dependent manner, inhibited monocyte chemotaxis elicited by stromal cell-derived factor-1. Lesions in the cholesterol-fed mice had complex atherosclerotic plaque with acellular core, cholesterol clefts, and an abundant collection of monocytes/macrophages. Lesions in the rapamycin-fed mice were mainly composed of monocytes/macrophages. Oral rapamycin is effective in slowing the progression of atherosclerosis. Along with its multitude actions, attenuation of monocyte chemotaxis may be one more way by which rapamycin attenuates plaque progression.

Animals↗
PubMed2005

Effect of antioxidants on atherosclerotic plaque formation in balloon-denuded and irradiated hypercholesterolemic rabbits.

The oxidative modification of low-density lipoprotein (LDL) hypothesis implies that antioxidants should be effective in suppressing atherosclerosis. This study is designed to test the potential of antioxidants to inhibit atherosclerotic plaque progression in balloon-denuded and irradiated hypercholesterolemic rabbits. Rabbits were fed with a 1% cholesterol diet supplemented with or without a mixture of antioxidants (vitamin E, vitamin C, selenium, zinc, copper, manganese, N-acetylcysteine, glutamine). At 7 days both iliac arteries were balloon denuded, and 4 weeks later, 1 iliac artery underwent endovascular irradiation (n=12), while the contralateral was sham treated (n=12). Four weeks after irradiation, animals were euthanized, and arteries were fixed and processed for histo- or immunohistochemistry for determining the plaque area, macrophage count, and oxidized LDL-positive areas. Plasma antioxidant levels were significantly higher in the animals fed with antioxidant diet. Plasma (thiobarbituric acid-reactive substances) and arterial tissue oxidized LDL (immunoreactive to specific oxidized LDL antibody) levels were significantly higher in the irradiated as compared with nonirradiated animals (0.69+/-0.09 and 31.05+/-4.21 versus 0.24+/-0.04 and 18.42+/-4.62, P<0.001 and 0.05), and antioxidants partially lowered the oxidized LDL levels (0.35+/-0.14 and 25.41+/-4.82, P<0.001 and 0.01). Plaque area in the irradiated animals was 175% greater than in nonirradiated animals (P<0.05). Antioxidant supplementation resulted in a 50% decrease in plaque area of both control and irradiated animals. Antioxidants reduced both the cholesterol-induced and radiation-enhanced circulating and tissue oxidized LDL levels, resulting in reduced plaque.

Animals↗
PubMed2005

Impact of continued hospitalization in patients pre-treated with clopidogrel prior to coronary angiography and undergoing coronary artery bypass grafting.

Pre-treatment of patients with clopidogrel prior to coronary angiography (CAG) and possible percutaneous coronary intervention (PCI) is a standard practice. Candidates for coronary artery bypass surgery (CABG) are discharged or remain in the hospital until CABG after clopidogrel is discontinued. We investigated whether any differences exist in the rates of surgical complications and outcomes between these two groups of patients. We conclude that continued hospitalization of clopidogrel pre-treated patients does not confer any safety benefit with regard to post-operative complications and 30-day mortality. Discharging these patients after CAG may reduce hospitalization costs.

Aged↗
PubMed2005

Drug-eluting stents versus repeat vascular brachytherapy for patients with recurrent in-stent restenosis after failed intracoronary radiation.

Recurrent in-stent restenosis (ISR) following intracoronary radiation therapy (IRT) continues to be a therapeutic challenge. The present study aims to evaluate the clinical outcomes of patients who were treated with drug-eluting stent (DES) implantation versus repeat IRT for recurrent ISR after brachytherapy failure. A cohort of 88 patients who were previously treated with brachytherapy for ISR and presented with angina and recurrence of angiographic restenosis were evaluated for treatment with either DES [sirolimus-eluting stents (SES) or paclitaxel-eluting stents (PES); n = 34] or percutaneous coronary intervention (PCI) and repeat radiation (gamma or beta radiation; n = 54). The two groups had similar baseline clinical and angiographic characteristics. The in-hospital outcomes were similar between both groups. At long-term follow-up of 9.7 +/- 4.1 months for the DES group and 10.3 +/- 3.5 months for the repeat IRT group, there were no deaths or myocardial infarctions (MI). There was a trend toward more target vessel revascularization-major adverse cardiac events (TVR-MACE) in the DES group (p = 0.09). In addition, the patients in the DES group had a significantly lower survival rate compared to those in the repeat IRT group (p = 0.018). For patients who had recurrent ISR following IRT, either DES implantation or repeat radiation is safe and is associated with excellent immediate outcomes. Yet, at long-term follow-up, repeat IRT was associated with less recurrences and need for repeat revascularization when compared to DES implantation. Therefore, repeat IRT should be considered as an option for this difficult patient subset.

Aged↗
PubMed2004

Angiographic and clinical outcomes of late total occlusion versus treatment failure without late total occlusion in patients after intracoronary radiation therapy for in-stent restenosis.

This study aimed to compare the outcomes of patients with late total occlusion (LTO) versus patients with recurrence in the absence of LTO after intracoronary radiation therapy for in-stent restenosis. LTO, especially in the context of acute myocardial infarction, after intracoronary radiation therapy for in-stent restenosis, is associated with negative clinical outcomes after 6 and 12 months compared with in-stent restenosis without LTO.

Brachytherapy↗
PubMed2004

Bivalirudin versus heparin as an antithrombotic agent in patients treated with a sirolimus-eluting stent.

Bivalirudin (Angiomax) is increasingly used as a substitute for heparin in a variety of percutaneous coronary interventions. This retrospective, observational study aimed to evaluate the efficacy and safety of bivalirudin compared with heparin as an antithrombotic regimen in patients treated with sirolimus-eluting stents (Cypher) and found that bivalirudin is clinically safe and feasible, with fewer vascular and ischemic complications compared with heparin.

Anticoagulants↗
PubMed2004

Oral rapamycin to inhibit restenosis after stenting of de novo coronary lesions: the Oral Rapamune to Inhibit Restenosis (ORBIT) study.

OBJECTIVES: The aim of this study was to establish safety and feasibility of oral Rapamycin at two doses-2 mg and 5 mg-in achieving low rates of repeat target lesion revascularization (TLR) in de novo native coronary artery lesions. BACKGROUND: Drug-eluting stents have shown the ability to limit restenosis. Oral Rapamycin is an alternative strategy that can target multiple coronary lesions suitable for treatment with any approved metal stent and at potentially lower cost. METHODS: The Oral Rapamune to Inhibit Restenosis (ORBIT) study is an open-label study of 60 patients with de novo lesions treated with bare metal stents in up to two vessels. After a loading dose of 5 mg, patients received a daily dose of 2 mg (n = 30) and 5 mg (n = 30) for 30 days. Six-month angiographic, intravascular ultrasound (IVUS), and clinical follow-up were conducted. RESULTS: Baseline clinical and procedural characteristics were similar: 10% of patients in the 2-mg group and 30% in the 5-mg group did not complete the course; 43% in the 2-mg group and 66% in the 5-mg group had side effects. At six-month follow-up, late loss (0.6 +/- 0.5 mm vs. 0.7 +/- 0.5 mm; p = NS), in-stent binary restenosis (7.1% vs. 6.9%; p = NS), in-stent percent volume obstruction by IVUS (29% vs. 24%; p = NS), and clinically driven TLR (14.3% vs. 6.9%; p = NS) were similar in 2-mg and 5-mg groups. CONCLUSIONS: Oral Rapamycin for the prevention of restenosis is safe, feasible, and associated with low rates of repeat revascularization. Although associated with certain side effects, it may be considered for patients undergoing multivessel stents if proven in larger randomized studies.

Administration, Oral↗
PubMed2004

Value of monitoring activated clotting time when bivalirudin is used as the sole anticoagulation agent for percutaneous coronary intervention.

Anticoagulation during percutaneous coronary intervention (PCI) requires the monitoring of activated clotting time (ACT) to protect from periprocedural ischemic and bleeding complications; however, the optimal ACT values have not been established when PCI is performed with bivalirudin. After 495 consecutive patients treated for coronary artery disease with PCI received bivalirudin as a single anticoagulation agent, it was found that ACT is reproducible when bivalirudin is used during PCI and does not correlate with clinical events.

Aged↗
PubMed2004

Clinical, angiographic, and intravascular ultrasound characteristics of early saphenous vein graft failure.

OBJECTIVES: We sought to examine saphenous vein graft (SVG) lesions that fail within the first year after operation. BACKGROUND: Saphenous vein grafts remain patent for approximately 10 years; however, up to 15% to 20% of SVGs become occluded within the first year. METHODS: We studied 100 patients who underwent percutaneous coronary intervention (PCI) for early (<1 year post-implantation) SVG failure lesions and compared them with a diabetes- and hypercholesterolemia-matched cohort of late SVG failures (>1 year). Coronary angiography and intravascular ultrasound images were analyzed. RESULTS: The majority of patients in both groups were males who presented with unstable angina; 36% were diabetic. Graft ages were 6.0 +/- 2.9 months and 105.4 +/- 50.8 months, respectively. The early SVG failure lesion location was more often ostial or proximal (62% vs. 42%, respectively). Early SVG failures were angiographically smaller than late failures (reference: 2.47 +/- 0.86 mm vs. 3.26 +/- 0.83 mm, p < 0.001) but had similar lesion lengths. Intravascular ultrasound showed that early failure lesions had smaller proximal and distal reference lumen areas (7.3 +/- 6.8 mm2 vs. 10.6 +/- 3.8 mm2, p = 0.026) and greater reference plaque burden than late failures (52.3% vs. 36.1%, p < 0.001). After PCI, 20.6% of early and 30.6% of late failure lesions had creatine kinase-myocardial band (CK-MB) greater than twice normal. CONCLUSIONS: Early SVG failure is mostly proximal or ostial, lesions appear focal, and early SVGs appear smaller than late SVGs. Intravascular ultrasound shows significant reference segment plaque burden, suggesting more severe, diffuse SVG disease.

Aged↗
PubMed2004

Impact of major side branch on periprocedural enzyme elevation and long-term outcome in patients undergoing percutaneous coronary intervention and brachytherapy for in-stent restenosis.

Side branch occlusion is 1 mechanism for the increase of creatine phosphokinase-MB after percutaneous coronary intervention and is associated with long-term adverse events. We studied 248 patients who underwent brachytherapy for in-stent restenosis with and without side branches, compared levels of creatine phosphokinase-MB with procedural, in-hospital, and long-term clinical outcomes, and found that patients with side branches have increased levels of creatine phosphokinase-MB after percutaneous coronary intervention and higher rates of restenosis, target vessel, and target lesion revascularization at 6-month follow-up.

Angioplasty, Balloon, Coronary↗
PubMed2004

Comparison of baseline characteristics and one-year outcomes between African-Americans and Caucasians undergoing percutaneous coronary intervention.

The objectives of this study were to determine whether there are race-based differences in baseline characteristics and in short- or long-term outcomes after percutaneous coronary intervention (PCI). African-Americans have a higher incidence of coronary artery disease but are less likely to undergo coronary revascularization than Caucasians. Little is known about the profiles and outcomes of African-Americans who undergo PCI. Consecutive series of 1,268 African-Americans and 10,561 Caucasians with symptomatic coronary artery disease who underwent PCI between January 1994 and June 2001 were analyzed. Patients hospitalized for acute myocardial infarction were excluded. African-Americans were older, were more likely to be women, and had more co-morbid baseline conditions compared with Caucasians. Preprocedure lesion characteristics were similar with regard to vessel size, length, and complexity. The rate of clinical success did not differ between the groups. African-Americans experienced more in-hospital combined events of death and Q-wave myocardial infarction (p = 0.03). After propensity score adjustment, African-American race was not an independent predictor for in-hospital events. At 1 year, African-Americans had a slightly lower rate of target lesion revascularization and a 50% higher rate of death (9.8% vs. 6.4%, p <0.001), with a relative risk of 1.52 (95% confidence interval 1.22 to 1.89). In multivariate analysis, African-American race remained a significant predictor of increased 1-year mortality (hazard ratio 1.35, 95% confidence interval 1.06 to 1.71, p = 0.01). African-Americans undergoing angioplasty have more co-morbid baseline conditions than Caucasians. Despite similar clinical success, 1-year outcomes are impaired in African-Americans.

Aged↗