A prospective single-center registry for the use of intracoronary gamma radiation in patients with diffuse in-stent restenosis.

Based on single-center prospective registry data, the study evaluates short- and long-term results of intracoronary gamma radiation in patients with diffuse in-stent restenosis in the reality of routine clinical practice. Percutaneous coronary intervention and subsequent catheter-based irradiation with iridium-192 was performed in 84 vessels (81 patients) with diffuse in-stent restenosis. Repeat coronary angiography was performed in 35 patients with clinical restenosis. With a mean follow-up of 12.0 +/- 0.5 months, major adverse cardiac events were observed in 29 (34.5%) patients, including 2 cases of cardiac death, 3 myocardial infarctions, 21 target lesion revascularizations, and 4 target vessel revascularizations. Five of six patients with total occlusion of the target vessel at baseline developed target lesion restenosis. Late total occlusion of the target vessel was observed in four patients. The 1-year event-free survival rate was 69.8%. Total occlusion of the target vessel at baseline was the single independent predictor of cardiac events at 1-year follow-up (P < 0.001). In patients with a target lesion in the left anterior descending artery, predictors of cardiac events also included female sex (P = 0.014), current smoking (P = 0.014), stenting during brachytherapy session (P = 0.02), and smaller reference vessel diameter at baseline (P = 0.01). The results of our registry are similar to those of randomized trials. As applied in routine clinical practice, intracoronary gamma radiation is a feasible, safe, and effective tool in the treatment of diffuse in-stent restenosis. Late events in the entire group were predicted by total occlusion at baseline.     

Disappearance of intima over the stent and ulcer formation after intracoronary radiation for in-stent restenosis.

Little is known about the alterations of the vascular surface after radiation therapy for in-stent restenosis in humans, even though animal experiments suggest that delayed healing of the neointima is a cause of late thrombosis. Coronary angioscopy, together with coronary angiography, was performed at 3 months follow-up of 7 patients with in-stent restenosis who underwent beta-radiation therapy. Minimal lesion diameter (MLD) of the lesion increased from 1.00+/-0.30 mm (immediately before) to 2.44+/-0.39 mm (immediately after) and the MLD was well maintained 3 months later (2.34+/-0.62 mm) without any cases of restenosis. In 5 patients, the intima was so thin that some stent struts could be seen through it on angioscopy and in 2 of those, the intima over the stent had disappeared and 1 patient showed ulceration of the vascular wall beneath the stent. After intracoronary radiation therapy, the intima can become so thin that some stent struts are exposed to the lumen, which may be related to the occurrence of late thrombosis. Accordingly, patients who are treated with intracoronary radiation therapy may need long-term antiplatelet therapy.     

Clinical trials of intracoronary gamma radiation therapy for in-stent restenosis

The only gamma emitter used in clinical trials for in-stent restenosis is 192Iridium (192Ir). The efficacy of intracoronary gamma radiation therapy in reducing clinical and angiographic restenosis in patients with in-stent restenosis has been established. This review is intended to give an overview of the clinical trials utilizing gamma vascular brachytherapy in patients with in-stent restenosis and give insight into the future of intracoronary radiation therapy.     

Intracoronary radiotherapy with a 188Rhenium liquid-filled angioplasty balloon system in in-stent restenosis: a single-center, prospective, randomized, placebo-controlled, double-blind evaluation

BACKGROUND: In cases of in-stent restenosis, intracoronary radiotherapy with beta-emitters and gamma-emitters has been shown to reduce the risk of repeat restenosis. The present randomised, placebo-controlled study addresses the question of whether intracoronary radiotherapy applied by the easy-to-handle Rhenium liquid-filled angioplasty balloon system is also able to reduce the angiographic re-restenosis rate in stents. METHODS AND RESULTS: At our center, from May 2000 to December 2003, 165 patients (mean age 64+/-10, median 65 years; 127 men, 38 women) with symptomatic in-stent restenosis underwent either intracoronary brachytherapy or sham procedure. Index clinical and angiographic parameters were largely comparable in both groups. Radiation therapy was performed with a standard percutaneous transluminal coronary angioplasty (PTCA) balloon catheter inflated with liquid Rhenium in the redilated in-stent restenosis for 240-890, mean 384+/-125 s with low pressure (3 atm) in order to reach 30 Gy at 0.5 mm depth of the vessel wall. In 82 patients, intracoronary radiotherapy was carried out without complications, but one of the 83 patients who underwent sham procedure suffered small myocardial infarction. During follow-up, stent thrombosis with subsequent non-Q-wave myocardial infarction occurred in one patient in each group (6 days and 8 months after the procedure, respectively). At 6 months after the index procedure, repeat angiography was performed in 156 of the 164 patients with successful procedure (rate 95%): restenosis (stenosis >50% in diameter) or reocclusion was observed in only 19 of 78 (=24%) patients of the radiation but in 31 of 78 (=40%) patients of the sham procedure group (P=0.04). Event-free survival (free of death, myocardial infarction, target vessel revascularization) at 1 year was 87% for patients being radiated and 74% for patients having undergone sham procedure (P=0.05). CONCLUSIONS: Intracoronary radiation therapy with the liquid-filled beta-emitting Rhenium balloon is not only easy to perform, safe, and comparably inexpensive but also an effective option to prevent repeat restenosis and the need for target vessel revascularization in cases of in-stent 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.     

Angiographic and clinical outcome for the treatment of in-stent restenosis with sirolimus-eluting stent compared to vascular brachytherapy

Summary Background With the use of coronary stents for the treatment of coronary artery disease, in-stent restenosis became a major clinical problem. In this non-randomized study, we examined the use of stent-based delivery of sirolimus (rapamycin) for the treatment of in-stent restenosis in comparison to intracoronary -brachytherapy, regarding the clinical effectiveness and the angiographic results for the treatment of in-stent restenosis after 6–9 months. Methods and results Between July 2001 and May 2002, 28 patients (65±11 years) with instent restenosis were treated with intracoronary brachytherapy. Consecutively, between May 2002 and April 2003, 28 patients (65±10 years) with in-stent restenosis were treated with the implantation of a sirolimus-eluting stent (SES). Patients with in-stent restenosis treated by implantation of a SES had significantly lower incidence of in-stent restenosis (1/28 (3.6%) vs 10/28 (36%); p=0.007) and insegment restenosis (4/28 (14%) vs 14/28 (50%); p=0.013) compared to patients treated with brachytherapy. Target lesion and target vessel revascularization rate tended to be lower in the SES group (14 vs 25%) but did not yet reach statistical significance. One patient died in the group treated by implantation of a SES eight months after stenting, one patient suffered from myocardial infarction due to a subtotal in-stent restenosis after brachytherapy. Two patients after brachytherapy underwent surgical revascularization due to recurrent in-stent restenosis similar to the patient with in-stent restenosis after SES implantation. Conclusion In this study we show the feasibility and safety of the treatment of in-stent restenosis by implantation of sirolimus-eluting stents and demonstrate a lower incidence of recurrent in-stent restenosis as well as lower late luminal loss compared to treatment by intravascular brachytherapy.

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Intracoronary radiotherapy with a (188)rhenium liquid-filled PTCA balloon system in in-stent restenosis: acute and long-term angiographic results, as well as 1-year clinical follow-up

BACKGROUND: Intracoronary radiotherapy with beta- and gamma-emitters has been shown to reduce the risk of restenosis after balloon angioplasty and after coronary stenting. The present study addresses the question whether intracoronary radiotherapy using the (188)rhenium liquid-filled PTCA balloon system is feasible, safe and effective in cases of in-stent restenosis. Acute and long-term angiographic results as well as clinical events within 1 year after the procedure were evaluated. METHODS AND RESULTS: From September 1999 to April 2000, 41 patients (mean age 60+/-10 years, 33 male, 8 female) with symptomatic in-stent restenosis underwent repeat PTCA and immediate intracoronary brachytherapy. After successful repeat PTCA (residual stenosis less than 30% in diameter), a second standard PTCA catheter was inflated with liquid (188)rhenium in the redilated in-stent restenosis for 315-880, mean 540+/-155 s with low pressure (3 atm) in order to reach 30 Gy at 0.5 mm depth of the vessel wall. In all patients with successful reintervention, intracoronary radiotherapy was unproblematically performed; in 16 patients, 21 new stents were implanted during the procedure-either immediately before or after radiation therapy. During follow-up, four episodes of stent thrombosis with subsequent myocardial infarction occurred in three patients (8 days, 37 days, 5 months and 6 months after the procedure, respectively). This complication was seen exclusively in patients with newly implanted stents. One patient of the stent group died suddenly 46 days after the procedure. All 40 surviving patients underwent repeat angiography in cases of repeat angina or routinely 6 months after brachytherapy, respectively. In the redilated target vessels without new stenting, restenosis (stenosis >50% in diameter) or reocclusion was observed in only 5 of 25 (=20%) cases, but in the restented target lesions, in 10 of 15 (=67%). Event-free survival (death, myocardial infarction, TVR) at 1 year after repeat dilatation and subsequent brachytherapy was 80% for patients not newly stented, but only 44% for patients with new stents. CONCLUSIONS: Intracoronary radiation therapy with the liquid-filled beta-emitting (188)rhenium balloon is a safe and effective therapy in cases of in-stent restenosis. The positive effect of irradiation, however, is abolished if a new stent is needed. In the not newly stented patients, 1-year follow-up is encouraging.     

Debulking for in-stent restenosis in the brachytherapy era: does it still have a role?

Despite the advent of intracoronary brachytherapy, treatment of in-stent restenosis, particularly diffuse in-stent restenosis, remains problematic. Adjunctive debulking prior to brachytherapy may improve long-term outcomes. We review the literature and report our results of a series of patients treated with excimer laser coronary atherectomy along with balloon angioplasty and brachytherapy for in-stent restenosis. We conclude that adjunctive debulking may improve the long-term clinical outcomes of patients with diffuse in-stent restenosis treated with angioplasty and intracoronary radiation. A randomized controlled trial is warranted.     

Restenosis: Intracoronary brachytherapy

Opinion statement Though interventional strategies have revolutionized the management of patients with symptomatic coronary artery disease, in-stent restenosis has emerged as the single most important limitation of long-term success following percutaneous coronary intervention. Once present, in-stent restenosis is extraordinarily difficult to treat, with conventional revascularization techniques failing in 50% to 80% of patients. Intracoronary radiation, or brachytherapy, targets cellular proliferation within the culprit neointima. Clinical trials have demonstrated that brachytherapy is a highly effective treatment for in-stent restenosis, reducing angiographic restenosis by 50% to 60% and the need for target vessel revascularization by 40% to 50%. The benefits of intracoronary brachytherapy may be particularly pronounced in certain patient subgroups (eg, those with diabetes, long lesions, or lesions in saphenous vein bypass grafts), but comes at the cost of an increased rate of late stent thrombosis and the need for extended antiplatelet therapy. The role of brachytherapy in the arsenal of the interventional cardiologist will continue to evolve, particularly in light of the unprecedented recent advances with the use of drug-eluting stents for restenosis prevention.     

The impact of lesion length and reference vessel diameter on angiographic restenosis and target vessel revascularization in treating in-stent restenosis with radiation

OBJECTIVES: The study assessed the influence of lesion length and reference vessel diameter (RVD) on recurrent restenosis after gamma intracoronary radiation therapy (ICRT) for in-stent restenosis (IRS). BACKGROUND: Intracoronary radiation therapy reduces angiographic and clinical restenosis in patients with ISR. The impact of ICRT on challenging subgroups, such as long lesions and small vessels, has not been established. METHODS: Six-month quantitative coronary angiography and clinical follow-up were conducted to evaluate the influence of lesion length and RVD in patients with ISR treated with ICRT who were enrolled in gamma radiation trials. Angiographic binary restenosis (>50% diameter stenosis) and clinical events were assessed in 311 patients treated with gamma ICRT and 105 patients who received placebo. RESULTS: Baseline demographic, angiographic and procedural details were similar in the two treatment groups. The ICRT group had reduced binary restenosis in vessels of all sizes (30% vs. 66%, p < 0.001), with the most benefit seen in small vessels. A trend toward reduced restenosis with ICRT was found across all lesion lengths. At six months, major adverse cardiac events (MACE) were reduced in the ICRT group compared to placebo (34% vs. 71%, p < 0.0001), driven by reduced target vessel revascularization (27% vs. 71%, p < 0.0001). The independent predictors of angiographic restenosis include ICRT (OR [odds ratio] 0.16; CI [confidence interval] 0.10 to 0.28, p < 0.001), lesion length (OR 1.03; CI 1.01 to 1.05, p = 0.004) and RVD (OR 0.40; CI 0.23 to 0.67, p < 0.001). CONCLUSIONS: Intracoronary radiation therapy, compared to placebo, results in a significant reduction of angiographic restenosis across all vessel sizes, with a trend toward reduction of angiographic restenosis across all lesion lengths; this effect is seen predominantly in small vessels and diffuse lesions.     

Beta radiation in lesions > 15 mm: a START subgroup

BACKGROUND: Following conventional treatment of in-stent restenosis, clinical restenosis may be as high as 60% in long lesions. Results of the START (Stents and Radiation Therapy) trial indicate that intracoronary beta radiation yields significant reductions in the incidence of recurrent in-stent restenosis as compared with placebo. METHODS AND RESULTS: In a subgroup of the START trial, results in patients with coronary lesions > 15 mm in length (n = 239) were analyzed to assess treatment with a 30 mm, beta radiation source train. Patients received an intracoronary catheter with (90)Strontium/(90)Yttrium (n = 128) or placebo (n = 111). Clinical and angiographic parameters were evaluated at 8 months. Patient demographics and angiographic lesion characteristics were similar between the 2 groups. The mean lesion lengths were comparable in the radiation and placebo groups (21.5 5.2 mm versus 22.1 5.5 mm, respectively; p = 0.3873). A total of 14.1% and 22.5% of patients in the radiation and placebo groups, respectively, received new stents (p = 0.09). At 8 months, radiation therapy yielded significant reductions in major adverse cardiac events (16.4% versus 29.7%; p = 0.014), target vessel revascularization (14.8% versus 28.8%; p = 0.0085) and target lesion revascularization (11.7% versus 27.9%; p = 0.0015). There was no stent thrombosis, and binary restenosis rates were significantly lower in the radiation group compared to placebo. CONCLUSION: Intracoronary beta radiation may prevent early recurrent restenosis in long lesions. Additional study is required to determine if the reduction persists throughout mid- to long-term follow-up.     

Brachytherapy after coronary interventions: current state and future perspectives

Intracoronary brachytherapy is a novel, meanwhile established therapy. It is currently the only interventional procedure which has proven to effectively reduce the restenosis rates after intervention of long and diffuse in-stent restenosis. For this indication, brachytherapy can be regarded as the current treatment of choice. Randomized studies yield promising results for bypass interventions or interventions in small vessels or diabetic patients. These findings may encourage the decision to perform a percutaneous, transluminal intervention in such high-risk patients. In clinical practice, implantation of new stents in combination with brachytherapy procedures should be avoided as far as possible. In any case, the combined antiaggregatory therapy should be conducted sufficiently long to minimize the danger of late stent thrombosis. Under this treatment, the expected thrombosis rates ar within the range of placebo-treated patients. The length of the radiation source should be sufficient to cover the entire interventional injury length to avoid recurrent edge stenosis. De novo lesions are currently not a routine indication for intracoronary brachytherapy. Although intracoronary brachytherapy may effectively reduce restenosis rates in sufficiently irradiated de novo lesion segments, de novo lesions should be treated only within the set-up of controlled studies. The current available data with a follow-up period of up to 5 years show that intracoronary brachytherapy is also in the mid-term a safe and effective therapy for the reduction of restenosis after coronary interventions.     

Intrakoronare Strahlentherapie in kontrollierten und offenen Studien mit Afterloading-Systemen und “heißen” Ballonkathetern Eine Analyse von 6 692 Patienten

The prevention and treatment of a restenosis, which occurs in ca. 30% of the cases following balloon dilatation of coronary stenoses, using intravascular radiation relies on the inhibition of proliferation that is inherent in every radiation therapy. The analysis is based on 6,692 patients assigned to either a control group (1,717 patients) or to radiation therapy (4,975 patients) in 41 studies. A total of 14 placebo-controlled, randomized and 27 open trials have been completed: 22 regarding in-stent restenosis, ten regarding de-novo stenosis (or restenosis without a stent) as strict inclusion criteria, and nine with all types of stenoses. For in-stent restenoses, vessel size as defined for inclusion was between 2.0 mm and 5.5 mm, stenosis length between 10 mm and 80 mm. In all trials with in-stent restenosis, the primary endpoints were reached; the restenosis rate in the longest coronary segment analyzed was between 45% and 100% in the control groups and between 7.7% and 53.5% in the brachytherapy groups. The respective values for the TVR were between 24.1% and 80% in the control groups and between 2.0% and 41.7% in the brachytherapy groups. In the control groups, MACE was between 25.9% and 80%; it was between 2.0% and 41.7% in the brachytherapy groups. Attaining results for de-novo stenoses was problematic due to "geographic miss" apparently playing a larger role in these cases; but when taking this into consideration, good results were also attained. The known limitations due to late stent thromboses (4-15% in older trials) were to the most part eliminated by administration of clopidogrel for 1 year and the limitations due to the "edge effect" by the application of longer radiation sources. With antiproliferative coated stents as treatment for de-novo stenoses, we can count on intracoronary brachytherapy losing significance in this area. But for in-stent restenoses, intracoronary brachytherapy is the only evidence-based interventional form of therapy.     

Quantitative angiographic methods for appropriate end-point analysis, edge-effect evaluation, and prediction of recurrent restenosis after coronary brachytherapy with gamma irradiation.

OBJECTIVES: The study was done to investigate the relationship between clinical restenosis and the relative angiographic location of the recurrent restenotic lesion, after treatment of in-stent restenosis with vascular brachytherapy in the Washington Radiation for In-Stent Restenosis Trial (WRIST). BACKGROUND: Intracoronary radiation therapy reduces recurrence of in-stent restenosis. We investigated the above objective in patients enrolled in WRIST. METHODS: The WRIST study randomized 130 patients to double-blinded therapy with gamma irradiation (iridium-192 [(192)Ir]) versus placebo after interventional treatment of diffuse in-stent restenosis. After the intervention and at follow-up, three vessel segments were individually analyzed with quantitative coronary angiography: 1) the "stent," 2) the "radiation ribbon," and 3) the "ribbon+margin" segment (including 5 mm on either end of the injured or radiation-ribbon segment). Receiver operator curves (ROC) were used to assess the value of the follow-up percent diameter stenosis (DS) for each of the three analyzed segments in predicting target vessel revascularization (TVR). RESULTS: (192)Ir reduced recurrent restenosis (23.7% vs. 60.7%, p < 0.001) and the length of recurrent restenosis (8.99 +/- 4.34 mm vs. 17.54 +/- 10.48 mm, p < 0.001) at follow-up compared to placebo. Isolated stent edge (3.4%) and ribbon edge (1.7%) restenoses were infrequent in both groups. The best angiographic surrogate of TVR was the 50% follow-up DS obtained from the ribbon+margin analysis (ROC area 0.806). CONCLUSIONS: In WRIST, not only was (192)Ir therapy effective in reducing restenosis, but it also reduced the lesion length of treatment failures by 50%, and it was not associated with edge proliferation. The restenosis rate obtained from the vessel segment inclusive of the dose fall-off zones was the best correlate of TVR and should become a standard analysis site in all vascular brachytherapy trials.     

Intracoronary brachytherapy for the prevention of restenosis after percutaneous coronary revascularization

Purpose

The purpose of this article is to review the current literature pertaining to intracoronary brachytherapy for the prevention of restenosis after percutaneous coronary revascularization (PCR).

Methods

English-language articles were identified through a MEDLINE search (January 1984 to January 2003) using the keywords brachytherapy, radioactive stents, and coronary arteries. In addition, pertinent reference citations from relevant articles were reviewed.

Results

Restenosis after PCR is a complex process, thought to be due to a combination of vessel wall remodeling and neointimal proliferation. To date, catheter-based delivery of intracoronary brachytherapy has been found to prevent vessel wall remodeling and causes a reduction in the proliferation of the neointima. Neointimal proliferation, as measured by mean neointimal area, was reduced in all animal studies (range 26%-91%). In contrast, animal studies examining radioactive stents demonstrated an increase in neointimal proliferation, suggesting that they may not be helpful at preventing post-PCR restenosis. All human studies using catheter-based intracoronary brachytherapy for in-stent restenosis have employed either β (beta) or γ (gamma) radiation sources with variable doses of radiation (range 7-56 Grays [Gy]). Restenosis occurred in 12% to 40% of patients in nonrandomized studies, and clinical events occurred in 13% to 50% of patients. To date, there have been 7 published randomized trials in humans comparing catheter-based intracoronary brachytherapy to placebo, with a total of 1047 patients. The dose of radiation in the trials ranged from 14 Gy to 30 Gy. During follow-up, 8% to 33% of patients who received brachytherapy had restenosis versus 39% to 64% of patients receiving placebo. Clinical events occurred in 19% to 50% among patients who received brachytherapy versus 29% to 79% among patients receiving placebo. The majority of human studies examining radioactive stents do not demonstrate a reduction in restenosis in patients post-PCR. There are no randomized trials examining radioactive stents in humans.

Conclusion

Nonrandomized studies of radioactive stents suggest they are not effective at preventing in-stent restenosis. In contrast, data from animal and human studies suggest that catheter-based intracoronary brachytherapy can prevent in-stent restenosis and reduce clinical events post-PCR.     

Serial intravascular ultrasound assessment of the efficacy of intracoronary gamma radiation for preventing recurrent in-stent restenosis

Intracoronary stents reduce restenosis compared with balloon angioplasty. However, a major limitation of stenting is in-stent restenosis, which occurs in 10% to 40% of the patients depending upon risk factors. Serial intravascular ultrasound studies have shown that in-stent restenosis is primarily due to neointimal hyperplasia. Treatment of in-stent restenosis is challenging and recurrence rates are high regardless of interventional technique used. Several randomized clinical trials with intracoronary ionizing radiation using both beta (b) and gamma (g) emitters following primary catheter-based intervention have demonstrated a significant reduction in recurrence. The majority of these studies have used both serial angiographic and serial intravascular ultrasound endpoints to assess the efficacy of intracoronary radiation to prevent recurrence after the treatment of in-stent restenosis. As different mechanism of postradiation restenosis may operate in the original lesion segment, the ballooned segment and the actual irradiated segment, these imaging techniques have also helped to document any long-term affects of radiation including aneurysm formation, edge effects, geographical miss, and the presence or absence of remodeling. The angiographic results have correlated well with intravascular ultrasound results after radiation therapy and at follow-up. Thus, a combination of both serial intravascular ultrasound and careful angiography, which documents balloon, stent, and radiation source positioning, can fully assess the effectiveness of this modality of treatment.     

Comparison of a centered P source wire system with a noncentered Sr/Y brachytherapy system for intracoronary β-radiation following PCI of diffuse in-stent restenosis

BACKGROUND: We investigated the potential impact of differences in effective radiation dose between the centered Guidant 32P source wire system and the noncentered Novoste 90Sr/Y BetaCath system on clinical and angiographic outcomes of intracoronary brachytherapy for the prevention of in-stent restenosis. METHODS: From 10/00 to 05/04, a total of 400 patients underwent percutaneous coronary intervention (PCI) with brachytherapy for diffuse in-stent restenosis at our institution. Following balloon dilatation, patient Group A (n=200) was treated with the centered 32P Galileo source wire system, patient Group B (n=200) was treated with the noncentered 90Sr/Y BetaCath radiation system. In Group A, the prescribed dose of 20 Gy was applied in 1-mm depth of the vessel wall. In Group B, the prescribed dose of 18.4 Gy was applied for visual reference vessel sizes >2.7 and <3.35 mm, 23 Gy for >3.36 and <4.00 mm, and 25.3 Gy for >4.00 mm, each calculated at a distance of 2 mm from the center line of the radiation source. Patients received aspirin and clopidogrel over 12 months. Primary endpoint was target lesion revascularization (TLR) at 6 months. Secondary endpoints were the binary restenosis rate and major adverse cardiac event (MACE) at 30 days and 6 months. RESULTS: At 30 days, one patient of each group underwent PCI at a nontarget lesion (0.5%). At 6 months, MACEs were equally distributed in both groups. Target lesion revascularization at 6 months was 5.9% in Group A and 9.2% in Group B (P=.08). Binary angiographic restenosis rate at 6 months was 5.5% in Group A and 11.2% in Group B (P=.014). CONCLUSION: Intracoronary beta-radiation using the centered 32P source wire system yielded a significant reduction of recurrence rate compared to the noncentered 90S/Y BetaCath system after PCI of diffuse in-stent restenosis. There was a nonsignificant trend toward reduction of TLR among patients treated with the centered 32P source wire system.     

Intracoronary Beta-Radiation Therapy for In-stent Restenosis: Long-Term Success Rate and Prediction of Failure

Objective: The following retrospective observational study assesses the long-term results of intracoronary beta-radiation therapy for patients with in-stent restenosis.
Background: Beta-radiation has been used to treat patients with coronary in-stent restenosis. However, long-term clinical success using this technique has not at this time been established.
Methods: Two-hundred and thirteen consecutive patients received intracoronary brachytherapy (noncentered beta-emitter, Novoste BetaCath™) for in-stent restenosis and were followed up over a period of 39.1 ± 18.4 months. The combined end-point was defined as a major adverse clinical event (MACE) and comprised mortality, acute myocardial infarction, or target vessel revascularization (TVR).
Results: MACE occurred in 110 patients (51.6%): death in 27 patients (12.7%), acute myocardial infarction in 8 patients (3.8%), TVR in 90 patients (42.3%). TVR comprised percutaneous coronary reinterventions in 76 patients (35.7%) and coronary bypass surgery in 24 patients (11.3%). Secondary end-point was determined as target vessel failure and occurred in 93 patients (43.7%). Of note, the frequency of at least two previous target lesion interventions as well as impairment of left ventricular function was associated with reduced success rate, whereas other clinical parameters did not indicate outcome after treatment with intracoronary radiation therapy.
Conclusion: During the mean, a period of 3 years, more than half of the patients receiving intracoronary radiation therapy reached primary end-point, representing, in the main, TVR. During this period a mortality rate of nearly 13% was documented. These results signify a delayed, though continued, restenotic process after index procedure. (J Interven Cardiol 2010;23:60–65)     

Late thrombosis following intracoronary brachytherapy.

Vascular brachytherapy has been the subject of an extensive ongoing investigation into the safety and efficacy of this technique for preventing restenosis. Preclinical studies have demonstrated reduction of the neointimal proliferation and the late vascular constriction with radiation therapy. However, radiation is also known to delay the healing process and may contribute to a new phenomenon of late thrombosis. We report on two cases of patients with in-stent restenosis who underwent intervention followed by intracoronary vascular radiation therapy (utilizing beta and gamma radiation) and presented with acute onset of unstable angina. Angiographic study demonstrated late thrombosis, which were treated successfully with the Angiojet thrombectomy device.