[Beta-radiation as adjuvant treatment of in-stent restenosis in coronary vessels]

INTRODUCTION

The purpose of this study was to describe our initial "real-world" experience with vascular b-radiation for in-stent restenosis using a simple angioplasty approach without stent implantation.

MATERIALS AND METHODS

Thirty-five consecutive patients with in-stent restenosis were treated with balloon angioplasty (n = 28), cutting balloon angioplasty (n = 3), or angioplasty plus stent implantation (only in case of significant dissection: n = 4), followed by catheter-based beta-radiation. Angiographic follow-up was performed after 6 to 10 months.

RESULTS

One patient experienced a left main stem occlusion immediately after beta-radiation, which necessitated an acute coronary bypass operation. No other complications related to the radiation procedure were observed. In-stent restenosis recurred in 6 of the 34 patients (18%).

DISCUSSION

Our results indicate that catheter-based radiation can be safely introduced at centres without previous experience with this treatment modality. Furthermore, the in-stent restenosis recurrence rates after catheter-based radiation which have been obtained in randomised trials can be reproduced in consecutive patients.

[Treatment and prevention of restenosis after percutaneous coronary intervention. Balloons, stents, radioactive rays and drug-releasing stents]

This article briefly reviews the causes of restenosis and the current strategies for preventing and treating restenosis after percutaneous coronary intervention. Interventions such as intracoronary radiation and drug-eluting stents are discussed.

Sirolimus-eluting stent implantation and beta-irradiation for the treatment of in-stent restenotic lesions: comparison of underlying mechanisms of acute gain and late loss as assessed by volumetric intravascular ultrasound

BACKGROUND

The aim of the study was to compare the angioplasty mechanisms of drug (sirolimus)-eluting stent (DES) implantation and vascular brachytherapy (VBT) for the treatment of in-stent restenosis (ISR) as assessed by intravascular ultrasound (IVUS).

METHODS

We performed IVUS in 53 patients (28 DES, 25 VBT) before and after angioplasty of ISR and at 6-month follow-up. Cross-sectional areas of the external elastic membrane, the stent, and the lumen were measured. Plaque + media, peristent plaque, and intimal hyperplasia areas were calculated, respectively.

RESULTS

Clinical and IVUS baseline characteristics did not differ between groups at baseline. After the index procedure, the lumen at the stent site was smaller in the DES group (DES 6.7 +/- 2.0 mm2 vs VBT 7.5 +/- 2.2 mm2, P = .042). Because of less intimal hyperplasia (DES 0.2 +/- 0.5 mm2 vs VBT 0.7 +/- 0.7 mm2, P = .043), the lumen dimensions revealed no difference between groups at follow-up (DES 6.5 +/- 2.3 mm2 vs VBT 6.8 +/- 2.2 mm2, P = .374). At the reference site, the index procedure led to a similar increase of plaque + media (DES 0.9 +/- 0.9 mm2 vs VBT 0.6 +/- 1.2 mm2, P = .150). At follow-up, the plaque + media was significantly smaller in the DES group (DES 8.0 +/- 6.6 mm2 vs VBT 9.9 +/- 7.8 mm2, P = .013).

CONCLUSIONS

Drug-eluting stent for the treatment of ISR more effectively inhibits neointima formation when compared with VBT. Yet insufficient stent expansion might be a reason for device failure and should be avoided. At the reference site, lumen loss by an increased plaque burden, as has been well recognized following VBT, is not present with DES.

Optimizing dosimetry with high-dose intracoronary gamma radiation (21 Gy) for patients with diffuse in-stent restenosis

BACKGROUND

The efficacy of intracoronary gamma radiation (IRT-gamma) in reducing recurrent in-stent restenosis (ISR) is well established using doses of 14-18 Gy. We sought to examine whether an escalation in dose to 21 Gy is safe and confers additional benefit in reducing repeat revascularization and major adverse cardiac events (MACE) in patients with diffuse ISR.

METHODS

Forty-seven patients with diffuse ISR (lesion length 20-80 mm) in native coronary arteries (n=25) and saphenous vein grafts (n=22) underwent percutaneous transluminal coronary angioplasty and/or additional stents followed by IRT-gamma using the Checkmate system (Cordis) with a dose of 21 Gy. All patients were discharged with clopidogrel for 12 months and aspirin indefinitely. Six-month angiographic and 12-month clinical outcomes of these patients were compared to 120 patients treated with 18 Gy using the same system.

RESULTS

At baseline, patients in the 21-Gy group had more multivessel, vein graft disease and history of prior myocardial infarctions and coronary artery bypass grafts (P<.001). The use of debulking devices and stents was less in this group (P<.001). Procedural and in-hospital complications were similar. Follow-up at 6 months revealed nonsignificant but lower late loss (in-stent, 0.33+/-0.7 mm; in-lesion, 0.41+/-0.6 mm) in the 21-Gy group compared to the 18-Gy group; follow-up at 12 months revealed a trend toward less overall myocardial infarction, although repeat revascularization and MACE rates were similar.

CONCLUSIONS

IRT-gamma therapy for diffuse ISR lesions with a 21-Gy dose is clinically safe and feasible with marked reduction in late loss but does not confer additional benefit with regard to repeat revascularization and MACE when compared to a dose of 18 Gy.

32P Brachytherapy in the Treatment of Complex Cypher In-Stent Restenosis

Treatment of in-stent restenosis after implantation of a drug-eluting stent is a critical issue. We provide the first report of the use of intravascular radiation therapy for this purpose in a 73-year-old diabetic patient stented for small-vessel bifurcation; treatment of Cypher diffuse in-stent restenosis with (32)P brachytherapy proved successful at clinical and angiographic follow-up at 7 months. This finding should encourage systematic studies on the safety and efficacy of IRT in this problematic setting.

Intracoronary brachytherapy for in-stent restenosis using long sources reduces restenosis

Edge restenosis (candy wrapper effect) and late thrombosis remain a problem in various randomized intracoronary brachytherapy (ICBT) trials for the treatment of in-stent restenosis (ISR). Target vessel revascularization (TVR) due to target lesion revascularization (TLR) and edge restenosis can be decreased with the use of longer ICBT sources and debulking devices and has not been systematically studied. We analyzed 226 patients with ISR (240 vessels of 264 lesions; average lesion length 17.5+/-8.9 mm) who had lesion debulking followed by 90 Strontium (Sr) beta-irradiation using the Novoste Betacath system (30 mm source in 144 vessels and 40 mm source in 96 vessels). Dual antiplatelet therapy was recommended for one year. At follow-up of 12+/-2 months, clinical TVR occurred in 9.7%, with TLR in 7.1% and non-TLR in 2.6% of cases. There was no delayed or late subacute thrombosis. Beta-irradiation using a longer 90Sr source after lesion modification with cutting balloon (CB) and or rotational atherectomy (RA), along with the use of long-term dual antiplatelet therapy is safe and associated with single-digit clinical restenosis.

Intracoronary Brachytherapy for Treatment of In-Stent Restenosis

Randomized, double-blind, placebo-controlled trials have demonstrated that intracoronary brachytherapy is more efficacious than placebo in reducing death, myocardial infarction, and target vessel revascularization at long-term follow up of patients with in-stent restenosis. Intracoronary brachytherapy is efficacious in treating totally occluded in-stent restenotic lesions, in treating de novo and in-stent restenotic lesions in saphenous vein grafts, in treating diffuse in-stent restenosis, in treating native coronary ostial in-stent restenotic lesions, in treating patients with diabetes with in-stent restenosis, in treating patients at high-risk for recurrence of restenosis, in treating elderly patients, and in treating patients who failed intracoronary radiation. Beta and gamma intracoronary brachytherapy are equally effective in treating in-stent restenosis. Long-term aspirin and clopidogrel should be administered for at least 1 year to reduce late vessel thrombosis. Inadequate radiation may cause edge stenosis.

[Investigations of beta-dosimetry at two different sources for the cardiovascular brachytherapy]

The intracoronary brachytherapy is used at the Hamburg University Hospital as a method to treat in-stent restenosis. Two different radiochromic film types were applied to obtain dosimetric information of the beta-sources used (32P and 90Sr/90Y). First, these films were analyzed for their suitability for dosimetry. Within the investigated dose range (MD-55-2: 0 to 33 Gy, HD-810: 0 to 105 Gy), both films showed a linear behavior between the dose and the optical density (OD). Because radiochromic films are subject to time-based changes in OD, a method for colour stabilization was investigated (RCS-method). This method allowed to greatly shorten the time between irradiation and evaluation from 24 hours (time necessary for the film to reach a quasi-stable status) to 2.5 hours. Colour-stabilized films can also be stored for a long time and reanalyzed with almost the same results. Within the limits of the measurements error, both film types showed an energy independent response. Within the dose profiles, analyses of the two source types resulted in differences of 13.5% (32P) and 21% (90Sr/90Y). These inhomogenities are consistent with the fabrication tolerances given by the manufactures.

Two-year clinical follow-up of 90Sr/90 Y beta-radiation versus placebo control for the treatment of in-stent restenosis

BACKGROUND

It is an ongoing concern that intracoronary brachytherapy may possibly just delay the problem of in-stent restenosis ("late catch up"). For gamma-radiation, 3 placebo-controlled studies have shown the maintenance of the initially positive effect after 2 years, but similar data do not exist for beta-radiation. STents And Restenosis Trial (START) was the first placebo-controlled randomized trial for in-stent restenosis with beta-radiation; herein, we report the 2-year clinical follow-up.

METHODS AND RESULTS

Two hundred and forty-four patients were randomized to active treatment, 232 patients to placebo (nonactive source train) treatment. The primary end point of efficacy was target vessel revascularization (TVR); primary safety end point was any major adverse cardiac event (MACE) at 8 months and 2 years. Two-year clinical outcome in patients receiving brachytherapy was based on 195 of 244 original patients (79.9%) and in the placebo arm on 183 of 232 original patients (78.9%). TVR was significantly reduced by 25%; from 36.6% (placebo) to 27.5% (brachytherapy) remained significant after 2 years (RR .7 [.57-.98], 95% CI -9.2 [-17.5-0.8]). The Kaplan-Meier analysis for TVR and MACE showed improvement beginning approximately 90 days after radiation and remained almost constant for the 2 following years. Freedom from TVR was significantly increased from 62.4% +/- 3.8% to 71.6% +/- 3.3% (P = .027) and freedom from MACE from 58.9% +/- 3.7% to 68.0% +/- 3.4% (P = .035).

CONCLUSIONS

The START trial shows for the first time that the initial beneficial effects of intracoronary brachytherapy with beta-radiation using 90 Sr/ 90 Y are maintained at 2-year clinical follow-up period.

Evolution of vascular brachytherapy over time: Data from the RENO-registry analysis

OBJECTIVE

To study the evolution of procedural variations in vascular brachytherapy (VBT) and their relationship to medium-term outcome.

METHODS AND RESULTS

The RENO (European Surveillance Registry with Novoste Beta-Cath) prospectively collected procedural and clinical outcome data on 1098 patients treated with VBT. Patients were divided for this analysis into Group-I, the first 50% registered, and Group-II, the last 50% registered. Shorter 30-mm source trains were more commonly used in Group-I (p<0.001) while longer 40-mm (p=NS) and 60-mm (p<0.001) source trains were more commonly used in Group-II. Mean dwell time for radiation seeds was longer in Group-II compared to Group-I (4.20+/-1.48 min vs. 4.14+/-1.44 min; p<0.05). Mean radiation dose was higher in Group-II (19.73+/-3.33 Gy vs. 17.92+/-2.68 Gy; p<0.001). Cutting balloons were more frequently used in Group-II (p<0.001). There was significant drop in the incidence of geographic miss in Group-II (3.2% vs. 9%; p<0.00005). There were nonsignificant trends towards reduction in angiographic restenosis, target vessel (TV) revascularisation, death and major adverse cardiac events (MACE).

CONCLUSION

There has been a learning curve and evolution of VBT techniques over time. In general, there has been an increase in radiation source length, use of cutting balloons, dwell time and radiation dose. This has resulted in significant reduction of geographic miss and a trend towards improve clinical outcomes. Continued development may result in further improvement in the treatment of patients with in-stent restenosis (ISR).

Superiority of sirolimus eluting stent compared with intracoronary beta radiation for treatment of in-stent restenosis: a matched comparison

OBJECTIVE

To compare acute and follow up clinical and angiographic results after treatment of in-stent restenosis (ISR) by sirolimus eluting stents (SES) with results obtained after intracoronary radiation therapy (IRT).

DESIGN

Matched pair analysis.

METHODS

62 consecutive ISR lesions (< 30 mm lesion length, reference diameter < 3.5 mm) in 62 patients were treated with SES. From a database of 174 lesions (n = 141 patients) treated for ISR by intracoronary beta radiation, 62 lesions (62 patients) were pair matched with the SES group for diabetes mellitus, lesion length, vessel size, and pattern of ISR. Six month angiographic and 12 month clinical follow up results were obtained.

RESULTS

Baseline clinical and angiographic characteristics were similar between the groups (not significant). SES implantation resulted in significantly lower postprocedural in-lesion diameter stenosis than did IRT (mean (SD) 14.2 (9.5)% v 21.1 (10.6)%, p = 0.001), significantly higher minimum lumen diameter at follow up (1.91 (0.58) v 1.55 (0.72) mm, p = 0.005), and a higher net gain (1.16 (0.55) v 0.77 (0.70) mm, p = 0.002). Angiographic binary in-lesion restenosis rate at six months was 11% in the SES group and 29% in the IRT group (p = 0.046). In 16 ISR lesions SES were used after failed IRT and in 46 lesions for first time ISR. In-lesion late loss was higher after use of SES for failed IRT than after use of SES for first time ISR (0.61 (0.67) mm v 0.24 (0.41) mm, p = 0.018). In a multivariate analysis prior failed IRT was the only independent predictor for recurrent restenosis after SES for ISR (p = 0.052, odds ratio 5.8). Six patients (10%) in the SES group and 17 patients (27%) in the IRT group underwent target lesion revascularisation during the 12 months of follow up (p = 0.022).

CONCLUSIONS

In this non-randomised matched cohort SES achieved acute and follow up results superior to IRT for treatment of ISR even if cases of failed IRT are included. Failed IRT is a predictor of impaired SES effectiveness.

Intracoronary brachytherapy--clinical state and pathophysiological considerations

In-stent restenosis remains the limitation of coronary stent implantation despite numerous efforts of its prevention by catheter-based techniques or by drug therapy. Today, only intravascular irradiation has proven to effectively reduce neointima formation, restenosis rate and major adverse cardiovascular events by approximately 50%. Its efficiency is demonstrated for high-risk subsets like long lesions, lesions in saphenous venous bypass grafts or diabetic patients, indicating the extraordinary potential of vascular irradiation. Yet vascular irradiation has some limitations. Edge effect describes the phenomenon of excessive neointimal proliferation at the edges of an irradiated segment and is likely due to axial dose fall-off and/ or barotrauma by the angioplasty procedure. Geographic miss, the combination of dose fall-off and vessel injury may be deleterious, especially if a new stent is implanted. The use of appropriate radiation source lengths to avoid geographic miss substantially reduces the incidence of edge effect. Late thrombosis, occurring even years after irradiation, had significantly diminished the benefit of vascular irradiation in initial clinical trials, but extension of ntiplatelet therapy up to 12 months after irradiation has reduced its rates to placebo levels. Vascular brachytherapy is of considerable clinical benefit in the prevention of restenosis and the only proven option for the treatment of in-stent restenotic lesions. This review will focus on the mechanisms of action of vascular irradiation, on the pathophysiological reasons for its complications and therapeutic options. Both angiographic and clinical results of randomised and observational studies will be updated in detail.

Improving patient-specific dosimetry for intravascular brachytherapy

PURPOSE

Accurate patient-specific dosimetry in intravascular brachytherapy (IVBT) is generally difficult due to the extremely high-dose gradient, complexity of treatment device, and patient-specific geometry (e.g., calcification, stent, curvature, movement of target). The purpose of this study is to analyze quantitatively and systematically the dose effects of calcification, stent, guidewire, and source curvature on clinical dosimetry in an IVBT procedure, and propose a method that can be used to assess these effects in routine clinical practice.

METHODS AND MATERIALS

Monte Carlo techniques were used to calculate 3-D dose distribution in both homogeneous and inhomogeneous media for three most commonly used IVBT sources: (90)Sr beta (Novoste), (192)Ir gamma (Cordis/Best), and (32)P beta (Guidant). Dosimetric perturbations in the presence of metallic stents, calcified plaques, metallic guide wires, and source curvature were studied for situations commonly encountered in the clinic. The importance of each of these perturbations and their practical influence on patient-specific dosimetry were analyzed. Factors (plaque, stent, guidewire, and curvature) that may be used to correct/reduce these perturbations were introduced to prevent dosimetric cold spots during IVBT. Practical methods of using these correction factors are proposed.

RESULTS

Dose perturbations are significant due to the presence of source curvature, metallic stents, calcified plaques, and metallic guide wires, especially for beta sources. These perturbations can be as high as 30% under normal clinical conditions, although they can be much higher in extreme situations. Empirical relationships of plaque factor with the thickness of calcified plaque, stent factor with stent metallic surface area, guidewire with guidewire thickness, and curvature factor with the bending angle are derived. These relationships are found to be useful in improving clinical dose accuracy in IVBT treatment planning or dose evaluation after treatment.

CONCLUSIONS

Significant dose perturbations due to the presence of source curvature, metallic stents, calcified plaques, and guide wires have been found in IVBT for in-stent restenosis. Because it has been reported that, with the current prescriptions for IVBT, higher doses consistently improve treatment outcomes, the empirical method derived from this work can be used to assess cold spots dosimetrically, thus improving patient-specific dosimetry for IVBT.

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.

Intracoronary brachytherapy following drug-eluting stent failure. It's still not time to hang up the spikes!

Drug-eluting stents (DES) have significantly reduced the incidence of restenosis. Although the results obtained with these novel antiproliferative devices are encouraging, recent reports have shown that DES are not completely immune from restenosis. Therefore, the broad use of DES has inevitably led to a major issue: treatment of DES failure. Intracoronary brachytherapy (IBT) represents an important advancement for treatment of in-stent restenosis (ISR) and has led to important pathophysiological insight on the restenotic process. To date, IBT, when properly used, still represents the gold standard for treatment of ISR. However, experience with IBT is for treatment of ISR occurring with bare metal stents (BMS). Whether IBT may be used with the same safety and efficacy profile as an adjunctive treatment for ISR following DES implantation is still unknown. In this article, we report the outcome of a series of patients with DES failure treated with IBT. IBT for treatment of DES failure was shown to be both safe and efficient and, therefore, until ISR exists, IBT still remains an important player in this growing and even more challenging setting.

Long-term clinical and angiographic outcome of patients with occlusive in-stent restenosis treated with (32P) beta-brachytherapy

The objective of this study was to determine the safety and efficacy of (32)P beta-brachytherapy in totally occlusive in-stent restenosis (ISR). Patients with occlusive ISR were generally excluded from the randomized clinical trials on intracoronary brachytherapy (utilizing either gamma- or beta-sources) that have shown reductions in restenosis rate and need for revascularization procedures. We analyzed short- and long-term effects of (32)P beta-brachytherapy (20 Gy) in 27 patients (28 lesions) with occlusive ISR and 84 (99 lesions) patients with nonocclusive high-risk ISR. The primary outcome measure was frequency of in-lesion angiographic binary restenosis at 7 months. Secondary endpoints were rates of major adverse cardiac events (MACE), target vessel revascularization (TVR), clinically driven TVR, and target lesion revascularization (TLR). (32)P beta-brachytherapy was feasible and safe and provided similar postprocedural angiographic results in the two clinically comparable groups. However, the 7-month binary restenosis rate was higher in the occlusive group, as were the MACE and late total occlusion rates. Multivariate logistic analysis of the overall population indicated occlusive pattern to be the only independent predictor of angiographic restenosis. In both groups, recurrent lesions most often showed a focal pattern with significant reduction of length. Although safe and effective in high-risk ISR, (32)P brachytherapy at 20 Gy does not appear to be sufficient to avoid long-term restenosis in patients with occlusive lesions. Further studies should determine the most suitable source and dosage of brachytherapy for patients with occlusive ISR.

[The effects of intracoronary brachytherapy on long-term patency of previously chronically occluded bypass graft--a case report]

A case of a 70-year-old female who underwent CABG (four grafts) 12 years earlier, is presented. Following surgery, the patient suffered from two reinfarctions. Coronary angiography revealed total occlusion of the graft implanted to the right coronary artery which was treated by coronary angioplasty. Because of restenosis, the patient underwent successful intracoronary brachytherapy.

Two-year clinical follow-up results of intracoronary radiation therapy with rhenium-188-diethylene triamine penta-acetic acid-filled balloon

We investigated the 2-year clinical follow-up results as well as 6-month angiographic and clinical follow-up results of intracoronary radiation therapy using a rhenium-188-diethylene triamine penta-acetic acid ((188)Re-DTPA)-filled balloon system. The study comprised of 161 patients with significant de novo (83%) or in-stent restenosis (17%) lesions. Irradiation to deliver 17.6 Gy at a depth of 1.0 mm into the vessel wall was carried out after successful intervention. At 6-month follow-up, binary restenosis developed with significantly lower frequency in the radiation group than in the control group (24.3% vs. 46.3%; P = 0.009), although target lesion revascularization rate did not show significant benefit. At 2-year follow-up, cumulative target lesion revascularization rate was not significantly different between radiation group (n = 86) and control group (n = 75; 20.0% vs. 26.0%; P = 0.368). The rate of major adverse cardiac events including death, myocardial infarction, and target lesion revascularization did not show significant difference between two groups either (22.3% vs. 30.1%; P = 0.266). In conclusion, although significant reduction in restenosis rate was noted at 6-month angiographic follow-up, intracoronary radiation therapy mostly in patients with de novo lesion did not show significant clinical benefit in 6-month and 2-year follow-up results. The benefit was noted only in a small subgroup of patients with in-stent restenosis.

Pseudoperforation during kissing balloon angioplasty

We describe a case of apparent perforation during kissing balloon angioplasty of a bifurcation lesion. There was no evidence of perforation on follow-up angiography or via intravascular ultrasound. Possible etiologies include minimal perforation that immediately sealed postdeflation or forced contrast into the microvascular bed via a proximal side branch.

Two-year outcomes of repeated brachytherapy in patients with restenosis after intracoronary radiation therapy

This study compared the 2-year outcomes of repeat brachytherapy (n = 10) and conventional percutaneous intervention (n = 14) in patients with restenosis after intracoronary brachytherapy with a rhenium-188-filled balloon system. The short-term target lesion revascularization rate was significantly lower in the repeat brachytherapy group (0% vs 36%, p = 0.038), and additional target lesion revascularization was required in 2 patients with repeat brachytherapy during 2-year follow-up. There were no vascular complications related to repeat brachytherapy.

Relation of clinical success in coronary brachytherapy to dose

Intravascular brachytherapy is the primary treatment for coronary in-stent restenosis. Variations in dose in the treated artery may represent a potential cause of treatment failure. We compared dose distributions in patients who had developed recurrent restenosis (treatment failure) with those in patients who remained event free at 9 months (treatment success). We followed 140 patients who were receiving brachytherapy for in-stent restenosis with 4 radiation delivery devices to identify treatment failures and successes. Through a nested case-control construct, treatment failures (n = 14) were compared 1:2 with treatment successes (n = 28) matched by radiation delivery system and in-stent restenosis lesion pattern. The dose absorbed by 90% of the artery encompassed by the external elastic membrane (D(90)EEM) was calculated by applying intravascular ultrasound at 2-mm intervals along the treated lesion. Dose calculations were performed using dose kernel integration techniques generated from Monte Carlo simulations. The mean minimum D(90)EEM in treatment failures was 7.46 +/- 1.98 Gy, and that in treatment successes was 8.87 +/- 1.13 Gy (p = 0.007). Using a minimum dose threshold of 8.4 Gy, a minimum D(90)EEM <or=8.4 Gy occurred in 13 patients (93%) whose treatment failed but only in 9 patients (32%) whose treatment was a success (p <or=0.001). No confounding variables were found to be statistically significant between treatment failures and successes. In conclusion, current brachytherapy dose prescriptions allow for inter- and intralesion variations in dose. Arteries that receive <or=8.4 Gy at any point along the external elastic membrane are more likely to result in treatment failures. Dosimetry guided by intravascular ultrasound may be critical to ensure adequate dose delivery and outcomes.

Patient doses in gamma-intracoronary radiotherapy: the Radiation Burden Assessment Study

PURPOSE

To determine accurately the radiation burden of both patients and staff from intracoronary radiotherapy (IRT) with (192)Ir and to investigate the importance of IRT in the patient dose compared with interventional X-rays.

METHODS AND MATERIALS

The Radiation Burden Assessment Study (RABAS) population consisted of 9 patients undergoing gamma-IRT after percutaneous transluminal coronary angioplasty and 14 patients undergoing percutaneous transluminal coronary angioplasty only as the control group. For each patient, the dose to the organs and tissues from the internal and external exposure was determined in detail by Monte Carlo N-particle simulations. Patient skin dose measurements with thermoluminescence dosimeters served as verification. Staff dosimetry was performed with electronic dosimeters, thermoluminescence dosimeters, and double film badge dosimetry.

RESULTS

With respect to the patient dose from IRT, the critical organs are the thymus (58 mGy), lungs (31 mGy), and esophagus (27 mGy). The mean effective dose from IRT was 8 mSv. The effective dose values from interventional X-rays showed a broad range (2-28 mSv), with mean values of 8 mSv for the IRT patients and 13 mSv for the control group. The mean dose received by the radiotherapist from IRT was 4 microSv/treatment. The doses to the other staff members were completely negligible.

CONCLUSION

Our results have shown that the patient and personnel doses in gamma-IRT remain at an acceptable level. The patient dose from IRT was within the variations in dose from the accompanying interventional X-rays.

A novel method of brachytherapy using local delivery of 99mTc-HMPAO for coronary stent restenosis

BACKGROUND

Restenosis after percutaneous coronary intervention (PCI) is a matter that still remains to be resolved. Herein, the inhibitory effect of locally delivered 99mTc-HMPAO (hexamethyl propylene amine oxime) on neointimal hyperplasia after coronary stenting was examined in a pocine model, and its safety and efficacy observed in patients with coronary stent restenosis.

METHODS

After a stent overdilation injury, local radioisotope delivery using 99mTc-HMPAO was applied to one coronary artery (Group I) and control therapy to another (Group II) in each of 10 pigs. Follow-up coronary angiogram (CAG) and histopathologic assessment were performed 4 weeks after stenting. Eleven patients (10 males and one female, 62.4 +/- 5.7 years of age) underwent local administration of 30 mCi/ 2 mL 99mTc-HMPAO shortly after PCI, via a Dispatch Catheter, followed by a whole body scan to evaluate the distribution of the 99mTc-HMPAO, as well as a thallium-201 (TI-201) myocardial scan to evaluate myocardial perfusion. The major adverse cardiac events (MACE) were assessed during a one-year clinical follow-up.

RESULTS

On histopathological analysis, the neointimal areas were 1.2 +/- 0.6 and 2.7 +/- 0.4 mm2 (p=0.002), and the histopathological areas of stenosis were 27.16.3 and 53.4 +/- 5.2% in Groups I and II (p=0.001), respectively. In the clinical study, there was no in-hospital MACE. On a quantitative coronary angiographic analysis, the minimal luminal diameter was increased from 0.4 +/- 0.3 to 2.9 +/- 0.2 mm, and diameter stenosis decreased from 84.2 +/- 9.5 to 16.3 +/- 11.0% following PCI. Follow-up CAG was performed in 9 cases (81.8%) and restenosis occurred in 2 (22.2%). On a follow-up CAG, the minimal luminal diameter, diameter stenosis rate, lumen loss and loss index were 2.0 +/- 0.8 mm, 27.7 +/- 2.9%, 0.7 +/- 0.7 mm and 0.2 +/- 0.3, respectively. During the one-year clinical follow-up there were no cases of death or acute MI, but two cases of target vessel revascularization (18.2%).

CONCLUSION

Local delivery of 99mTc-HMPAO, a novel radiotherapy, can be used safely and effectively for coronary stent restenosis.

The role of brachytherapy and Cutting BalloonTM angioplasty in the current treatment of stent restenosis

The Gamma I, START and INHIBIT trials conclusively demonstrate the feasibility, safety and efficacy of intracoronary radiation as the treatment of choice for stent restenosis. Further reports confirm this finding and extend the indications. Vascular brachytherapy should be made available for all patients with diffuse stent restenosis. Specific devices such as cutting balloons may improve the procedure but does not seem to have an impact alone on the evolution.

Optimization of dose distributions for bifurcated coronary vessels treated with catheter-based photon and beta emitters using the simulated annealing algorithm

The dose distributions in the bifurcated vessels treated with a catheter-based delivery system are complicated by the geometry of bifurcation consisting of a main and a branch vessel at different angles, and it is difficult to generate satisfactory dose distributions. We hypothesize that increasing the number of dwell positions can result in better dose distributions. An optimization method based on the simulated annealing was developed to demonstrate the validity of this idea. In this method, the source in the branch treatment was allowed to take up to five dwell positions. A cost function was constructed to deliver the prescription dose to the planning targets with penalties for both overdosing and underdosing. By using the optimization algorithm, it was found that for 90 degrees to 60 degrees bifurcated vessels an optimized single dwell position treatment scheme can be as effective as the schemes that include up to five dwell positions. As the bifurcation angle becomes smaller than 60 degrees, the dose distributions generated with the single dwell position scheme become less satisfactory than the more complicated treatment schemes with multiple dwell positions. By using a three-dwell-position treatment scheme for the 192Ir source, the overdosing can be kept under 166% even at a bifurcation angle of 20 degrees.

Delayed restenosis after gamma brachytherapy for in-stent restenosis

Intracoronary brachytherapy is a promising modality for inhibition of in-stent restenosis. However, there is a concern of late progression after brachytherapy. This case report describes delayed restenosis after brachytherapy.

Intracoronary brachytherapy with ??-radiation for the treatment of long diffuse in-stent restenosis

OBJECTIVE

To assess the efficacy of intracoronary brachytherapy with beta-radiation (Sr/Y) for the treatment of long diffuse in-stent restenosis (ISR).

METHODS

As recurrent ISR depends on intimal injury after coronary angioplasty, long in-stent restenotic lesions were defined as lesions with a treatment length >26 mm (lesion length >20 mm plus a treatment margin of 3 mm at each end). Seventy-eight patients with long ISR were treated at our institution with beta-brachytherapy after coronary angioplasty. Patients were irradiated with either an approximate dose of 12 Gy at 1 mm vessel wall depth or with 18 Gy at 1 mm vessel wall depth. Clinical follow-up was available for 69 patients and angiographic follow-up for 65 patients. Late lumen loss (LLL), binary restenosis (stenosis >50%), target lesion revascularization (TLR) and major adverse cardiac events (MACE) were assessed for a follow-up time of 6.6+/-2.2 months.

RESULTS

Mean interventional treatment length was 46+/-18 mm. TLR was performed in all 23 patients with binary restenosis (33%). Death of cardiac cause was reported for two patients, one of whom did not undergo TLR. Thus, overall MACE rate was 35%. Recurrent ISR was significantly more frequent in patients with geographic miss. Comparison of the different radiation dose regimens revealed significantly lower LLL in patients irradiated with the higher dose (0.20+/-0.68 mm compared with 0.65+/-0.96 mm, P=0.03).

CONCLUSION

Intracoronary brachytherapy with beta-radiation (Sr/Y) is a safe and effective therapeutic option for the reduction of recurrent ISR in long diffuse lesions. We recommend a high-dose irradiation with 18 Gy at 1 mm vessel wall depth.

Deleterious Effect of Coronary Brachytherapy on Vasomotor Response to Exercise

BACKGROUND

Intracoronary radiotherapy (brachytherapy) has been proposed as treatment option for in-stent restenosis. Long-term results of brachytherapy with regard to vascular integrity and vasomotor responsiveness are unknown. The purpose of the present study was to determine the vasomotor response after brachytherapy and to assess its influence on vasomotion during exercise.

METHODS AND RESULTS

Biplane quantitative coronary angiography was performed at rest and during bicycle exercise in 27 patients with coronary artery disease. Fourteen patients underwent coronary stenting and were studied 10+/-3 months after intervention (control group). Thirteen patients were treated with brachytherapy (Guidant Galileo System) for in-stent restenosis with a mean dosis of 20 Gy at 1 mm into the vessel wall and were studied 9+/-1 months after radiation (brachytherapy group). Minimal luminal area, stent area, and proximal, distal, and a reference vessel area were determined. The reference vessel showed exercise-induced vasodilation (26+/-4%, P<0.001) in both groups. Vasomotion within the stented vessel segments was abolished. In control subjects, the proximal and distal segments showed exercise-induced vasodilation (17+/-2% and 22+/-7%, respectively; P<0.005). In contrast, there was exercise-induced vasoconstriction in the proximal and distal vessel segments of the brachytherapy group (-14+/-3% and -16+/-4%, respectively; P<0.01). Sublingual nitroglycerin was associated with maximal vasodilation of the proximal and distal vessel segments in both groups.

CONCLUSIONS

Normal vessel segments elicit flow-mediated vasodilation during exercise. Stent implantation does not affect physiological response to exercise proximal and distal to the stent. Brachytherapy eliminates exercise-induced vasodilation, although dilatory response to nitroglycerin is maintained, suggesting endothelial dysfunction as the underlying mechanism.

Biological aspects of radiation and drug-eluting stents for the prevention of restenosis

Based on recent advances, this article aims to review the biological basis for the use of either radiation or drug-eluting stents for the prevention of restenosis, and to elucidate the complementary role that they may play in the future. Vascular restenosis is a multifactorial process primarily driven by the remodeling of the arterial wall, as well as by the hyperproliferation of smooth muscle cells (SMC). These pathophysiological features are the target of therapeutic strategies aimed at inhibiting constrictive remodeling as well as inhibiting SMC proliferation. The success of radiation as well as anti-proliferative drugs such as paclitaxel and sirolimus lies in the primary and/or multifactorial inhibition of cell proliferation. Radiation has the additional feature of preventing constrictive remodeling while sirolimus has the potential property of being anti-inflammatory, which may be a desirable feature. The effects of radiation are not reliant on any uptake and "metabolism" by the target cells, as in the case with drugs, and thus radiation potentially may be more effective as a result of its more-direct action. However, radiation does have some significant drawbacks compared to drug-eluting stents, including a much delayed re-endothelialization resulting in the need for prolonged anti-platelet therapy. Based on recent clinical data, drug-eluting stents have been shown to markedly reduce the likelihood of restenosis, which actually favors this approach for the prevention of restenosis. From a biological perspective, drug-eluting stents and radiation have certain differences, which are reviewed in this article.

Effect of ionizing radiation on the stability and performance of the TAXUS Express2 paclitaxel-eluting stent

BACKGROUND

The advent of drug-eluting stents has provided the interventional cardiologist an effective new tool in treating coronary restenosis. There remains, however, a small group of patients that still require intervention following drug-eluting stent therapy. Currently, intravascular brachytherapy (IVBT) is approved for use in the treatment of in-stent restenosis (ISR). This study investigated the effect of gamma and beta radiation doses typically used in IVBT on the performance of the TAXUS Express(2) paclitaxel-eluting stent.

METHODS AND RESULTS

It was determined that there were no statistically significant changes to in vitro paclitaxel release from stent exposed to radiation compared to controls subjected to the same conditions except for the radiation exposure. The molecular weight of the Translute polymer carrier matrix and the level of paclitaxel degradants were not changed following exposure to radiation doses up to twice what is typically used in IVBT. Beta and gamma radiation doses typically used in IVBT had no significant effect on the Translute polymer carrier, paclitaxel degradation, or paclitaxel release in this in vitro model.

CONCLUSION

The data are encouraging and support further evaluation of the use of IVBT in the treatment of ISR in the presence of drug-eluting stents.

Results of intracoronary beta-brachytherapy administered by 60 mm transfer device/radiation source train: a subgroup analysis from the RENO registry

To investigate the safety and efficacy of a 60 mm transfer device, delivering 60 mm radiation source train, in the treatment of coronary lesions by b-brachytherapy employing the BetaCath system (Novoste, Norcross, Georgia).

METHODS AND RESULTS

As part of the REgistry NOvoste (RENO), the first large-scale registry of intracoronary beta-radiation applied in routine clinical practice, 46 centers registered 1,098 consecutive patients undergoing brachytherapy with the BetaCath system. Of these, 49 patients with 56 lesions were treated with a 60 mm transfer device/radiation source train (TD/RST) in at least 1 vessel, constituting the study population. With 75.4% in-stent restenosis (ISR), 3.6% graft lesions, long lesions (30.9 +/- 14.7 mm) and 19% diabetes, the cohort had a high-risk for recurrence. The in-hospital major adverse cardiac event (MACE) rate was 4.1%. The 6-month follow-up revealed 2.0% death, 4.1% myocardial infarction, 8.2% target vessel revascularization, 12.2% MACE, 82.6% improved angina, 16.7% binary restenosis and 4.1% late thrombosis. The results were comparable to all other patients in the registry treated with standard source lengths of 30 mm and 40 mm, although much longer lesions were treated by the 60 mm device (18.4 +/- 11.3 mm versus 30.9 +/- 14.7 mm; p < 0.0001). In the ISR subgroup (mean lesion length, 32.03 +/- 14.99 mm), the 6-month MACE rate was 12.8%, while the angiographic restenosis rate was 16.0% and the late thrombosis rate was 2.6%.

CONCLUSION

Beta-brachytherapy with 60 mm TD/RST was safe, feasible and effective in this broad population of high-risk patients presenting in day-to-day practice. Its efficacy in long-segment ISR, where conventional interventional strategies have poor outcome rates, is particularly noteworthy.

Intracoronary brachytherapy. Treatment of in-stent restenosis with the Beta-Cath system. Initial experience in Latin America

OBJECTIVE

To assess the safety and efficacy of intracoronary brachytherapy using the Beta-Cath system for preventing recurrence of in-stent restenosis (ISR), by analyzing clinical, angiographic, and intracoronary ultrasound (ICUS) results.

METHODS

This study assessed 30 patients with ISR in native coronary arteries who underwent balloon catheter angioplasty followed by intracoronary beta radiation with the Beta-Cath system (90Sr/Y).

RESULTS

The study comprised complex, extensive (18.66 +/- 4.15 mm) restenotic lesions, 77% of which were of the diffuse-proliferative type. Brachytherapy was successful in 100% of the cases. The mean radiation dose used was 20.7 +/- 2.3 Gy, released for a mean period of 3.8 +/- 2.1 minutes. On late follow-up, the in-stent minimum luminal diameter (MLD) slightly decreased (from 1.98 +/- 0.30 mm to 1.84 +/- 0.39 mm at 6 months; P=0.13), with a late loss of 0.14 +/- 0.18 mm. The intrasegmentary MLD was significantly smaller than the in-stent diameter (1.55 +/- 0.40 mm vs 1.84 +/- 0.39 mm; P=0.008), and was associated with a more significant late loss (0.40 +/- 0.29 mm vs 0.14 +/- 0.18 mm; P=0.0001). On ICUS, a mild increase of 6.8 +/- 14.3 mm3 in the neointimal tissue was observed at 6 months (P=0.19), and the percentage of volumetric obstruction increased by 4.7 +/- 7.5%. Binary restenosis and revascularization of the target vessel recurred in 17% of the cases; late occlusion associated with myocardial infarction occurred in 1 case (3%). Event-free survival was 80%.

CONCLUSION

The management of in-stent restenosis with intracoronary beta radiation proved to be a safe and effective procedure, with a high rate of immediate success, representing a therapeutic option for inhibiting neointimal hyperplasia.

Dose model for stent-based delivery of a radioactive compound for the treatment of restenosis in coronary arteries

Radiolabeled drug-eluting stents have been proposed recently as a novel method to potentially reduce restenosis in coronary arteries. A P-32 labeled oligonucleotide (ODN) loaded on a polymer coated stent is slowly released in the arterial wall to deliver a therapeutic dose to the target tissue. However, the relatively low proportion of drugs transferred to the arterial wall (<2%-5% typically) raises questions about the degree to which radiolabeled drugs eluted from the stent can contribute to the total radiation dose delivered to tissues. A three-dimensional diffusion-convection transport model is used to model the transport of a hydrophilic drug released from the surface of a stent to the arterial media. Large drug concentration gradients are observed near the stent struts giving rise to a nonuniform radiation activity distribution for the drug in the tissues as a function of time. A voxel-based kernel convolution method is used to calculate the radiation dose rate resulting from this activity build-up in the arterial wall based on the medical internal radiation dose formalism. Measured residence time for the P-32 ODN in the arterial wall and at the stent surface obtained from animal studies are used to normalize the results in terms of absolute dose to tissue. The results indicate that radiation due to drug eluted from the stent contributes only a small fraction of the total radiation delivered to the arterial wall, the main contribution coming from the activity that remains embedded in the stent coating. For hydrophilic compounds with rapid transit times in arterial tissue and minimal binding interactions, the activity build-up in the arterial wall contributes only a small fraction to the total dose delivered by the P-32 ODN stent. For these compounds, it is concluded that radiolabeled drug-eluting stent will not likely improve the performance of radioactive stents for the treatment of restenosis. Also, variability in the delivery efficacy of drug delivery devices makes accurate dosimetry difficult and the drug washout in the systemic circulatory system may yield an unnecessary activity build-up and dose to healthy organs.

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.

[Long-term effects and complications of intravascular brachytherapy]

Since the introduction of percutaneous transluminal coronary angioplasty, restenosis has remained the most challenging problem facing interventional cardiologist. Intravascular radiation is a feasible and promising adjunctive therapy in restenosis treatment by suppressing both neointimal proliferation and constrictive remodeling, while there are growing concerns about its long-term effects and complications in clinical perspectives as well as dosing and paradoxical stimulation. Current comments on them may well favor the choice of comprehensive treatment protocol for clinicians.

Treatment of in-stent restenosis using a paclitaxel-eluting stent: acute results and long-term follow-up of a matched-pair comparison with intracoronary $beta;-radiation therapy

AIMS

Intracoronary radiation therapy (ICR) has significantly improved the long-term outcome after treatment of diffuse in-stent restenosis (ISR). The efficacy of drug eluting stents in this setting remains less well defined. This matched-pair analysis compared the procedural and long-term clinical and angiographic outcome after treatment of diffuse ISR using a paclitaxel-eluting stent (PES) with intracoronary beta-radiation therapy.

METHODS AND RESULTS

Twenty-two patients receiving 25 PES (ACHIEVE, Cook, 3.1 microg paclitaxel per square millimeter, non-polymer based coating) for ISR underwent 6-month angiographic and 12-month clinical follow-up. From a database including 141 patients (174 lesions) undergoing intracoronary beta-radiation for ISR, 25 lesions (25 patients) were pair-matched with the former group for lesion length and vessel size. PES implantation and ICR were successful in all patients with a significantly lower postprocedural in-stent diameter stenosis in the PES group (8+/-12% vs. 18+/-8%, p < 0.01). Angiographic binary in-lesion restenosis at 6 month was 20% (5/25 lesions) in the PES group and 16% (4/25) in the ICR group (p = 1.0). PES implantation resulted in significantly higher in-stent MLD at FU (2.10+/-0.71 vs. 1.75+/-0.36, p = 0.03) and a higher in-stent net gain (PES: 1.19+/-0.69, ICR: 0.84+/-0.49, p = 0.04). Two patients in the PES group and 6 patients in the ICR group experienced a target lesion revascularisation at 12-month follow-up (p = 0.25).

CONCLUSION

Implantation of a non-polymer based paclitaxel-elution stent and conventional ICR therapy for complex ISR lead to comparable acute and long-term clinical and angiographic follow-up results.

Human coronary morphology after beta radiation brachytherapy of in-stent restenosis

This case report discusses the human coronary morphological findings 18 hours after brachytherapy (beta radiation) of an in-stent restenosis. Brachytherapy produced aseptic inflammation of the periadventitial connective tissue integrating the vasa vasorum in the acute phase. The stent neointima eight months after stenting and acutely 18 hours after radiation consisted of the same cellular components as human stent neointima of specimen not additionally treated with radiation. No evidence of necrosis or excessive fibrotic alterations of the arterial vessel wall have been found.

[In 2003, what are the indications of brachytherapy in coronary arteries?]

Significant results obtained with coated stents in "de novo" coronary lesion treatment, particularly in complex lesions, have substituted brachytherapy indications. However, curitherapy results in diffuse or proliferative in-stent restenosis treatment show a significant reduction (30-50%) of restenosis and major adverse cardiac events. So, without sufficient scientific proofs with active stents in this indication, curitherapy is the only validated and authorized treatment of second diffuse or proliferative in-stent restenosis.

[Treatment of intrastent restenosis]

In-stent restenosis (ISR) remains an important limitation after stent implantation occurring in 20-30% of patients. Different techniques and treatments have been evaluated in this setting. Repeat balloon angioplasty alone has been rapidly followed by ablative techniques such as laser, rotational atherectomy or implantation of a second stent within the stent. Cutting balloon represents another alternative technique. None of these techniques has proven its superiority over plain balloon angioplasty alone. Brachytherapy is the only effective treatment for ISR by significantly decreasing recurrent restenosis rate at follow-up. However, its use is limited by cost and infrastructure associated with the risk of late thrombosis requiring prolonged antiplatelet therapy. Surgical treatment can be proposed in recurrent ISR as well as medical therapy alone in pauci-symptomatic patients. New drug-eluting stents are under evaluation in this indication.

Predictors of 32P beta brachytherapy failure in patients with high-risk in-stent restenosis

BACKGROUND

The effectiveness of coronary radiation therapy for the treatment of in-stent restenosis (ISR) has been established in several randomized clinical trials. The efficacy of this treatment in the general population is less well established.

METHODS AND MATERIALS

We report our experience in 118 consecutive patients with nonselected high-risk ISR who had undergone successful percutaneous coronary intervention and brachytherapy with (32)P beta-irradiation and who were prospectively enrolled in a quantitative angiographic and clinical follow-up protocol at 7 months after the index procedure. The aim of this study was to investigate the independent predictor of angiographic restenosis after (32)P brachytherapy treatment.

RESULTS

Of the patients, 28.8% were diabetics. The mean lesion and mean radiated lengths were, respectively, 30.1 +/- 17.2 and 43.8 +/- 16.9 mm. The ISR pattern was diffuse in 96% of the treated lesions; in particular, 22.1% presented an occlusive pattern and 37.1% a proliferative pattern. At follow-up angiographic, restenosis and major adverse cardiac events (MACE) rates were, respectively, 20.8% and 29.6%. The univariate predictors of angiographic restenosis were procedural geographic miss, pattern IV ISR, manual pullback maneuver of the radiation source, preprocedural lesion percentage stenosis and preprocedural lesion MLD. At logistic regression analysis, only geographic miss and pattern IV ISR were independent predictors of post intracoronary radiation therapy (IRT) angiographic restenosis.

CONCLUSION

These data indicate that 7-month angiographic restenosis after (32)P IRT in complex patients with ISR is not a frequent event and is predicted mainly by an occlusive lesion at baseline and by procedural geographical miss.

Successful reduction of in-stent restenosis in long lesions using beta-radiation--subanalysis from the RENO registry

PURPOSE

Long lesions remain a challenging task in interventional cardiology, with a high propensity of restenosis, especially within the stented segment. Although intracoronary gamma-radiation has been proved to reduce diffuse in-stent restenosis in long lesions, such an effect remains to be determined using beta-radiation.

METHODS AND MATERIALS

Of 1098 consecutive patients at 46 European centers treated with localized beta-radiation ((90)Sr, Novoste Beta-Cath System), 139 patients (mean age 61.5 +/- 10.7 years, 84% male, 22% with diabetes mellitus) with lesions treated using a >40-mm source length underwent radiation using a single 60-mm source train (34%) or a stepping/pullback procedure with a 30-mm (12%) or 40-mm (87%) source length after conventional interventional procedures. The mean lesion length was 35.3 +/- 17.9 mm.

RESULTS

Technical success was achieved in 96% of cases. Geographic miss was noted in 9 patients (6.5%). The reference (placebo) group was obtained from the Washington Hospital Center for In-Stent Restenosis Trial (WRIST) and the WRIST Trial for long lesions (LONG WRIST) studies by selecting the cases (94 patients) that required a dummy source length >/=13 seeds (or >51 mm in length). Statistically significant improvement was noted in late angiographic restenosis (34.7% vs. 76.5%, p <0.0001), target vessel revascularization (14.9% vs. 60.6), and major adverse cardiac events (i.e., death, myocardial infarction, or total vessel revascularization) (17.9% vs. 64.9%, p <0.0001) at 6 months in reference to the nonradiation group.

CONCLUSION

This subanalysis from the Radiation in Europe with Novoste study confirms the safety and efficacy of beta-radiation combined with conventional interventional procedures in patients with diffuse, long, in-stent restenosis

Coronary in-stent restenosis following beta brachytherapy A histopathological examination

Two cases of in-stent restenosis of a coronary artery bypass vein graft following beta (beta) brachytheraphy are presented. Previously unreported histopathology of directed atherectomy specimens of such restenotic lesions and a discussion of their proposed significance form the basis of this report.