Five-year clinical follow-up after intracoronary radiation: results of a randomized clinical trial

Refining Treatment Planning in STereotactic Arrhythmia Radioablation: Benchmark Results and Consensus Statement From the STOPSTORM.eu Consortium

PURPOSE

STereotactic Arrhythmia Radioablation (STAR) showed promising results in patients with refractory ventricular tachycardia. However, clinical data are scarce and heterogeneous. The STOPSTORM.eu consortium was established to investigate and harmonize STAR in Europe. The primary goal of this benchmark study was to investigate current treatment planning practice within the STOPSTORM project as a baseline for future harmonization.

METHODS AND MATERIALS

Planning target volumes (PTVs) overlapping extracardiac organs-at-risk and/or cardiac substructures were generated for 3 STAR cases. Participating centers were asked to create single-fraction treatment plans with 25 Gy dose prescriptions based on in-house clinical practice. All treatment plans were reviewed by an expert panel and quantitative crowd knowledge-based analysis was performed with independent software using descriptive statistics for International Commission on Radiation Units and Measurements report 91 relevant parameters and crowd dose-volume histograms. Thereafter, treatment planning consensus statements were established using a dual-stage voting process.

RESULTS

Twenty centers submitted 67 treatment plans for this study. In most plans (75%) intensity modulated arc therapy with 6 MV flattening filter free beams was used. Dose prescription was mainly based on PTV D95% (49%) or D96%-100% (19%). Many participants preferred to spare close extracardiac organs-at-risk (75%) and cardiac substructures (50%) by PTV coverage reduction. PTV D0.035cm3 ranged from 25.5 to 34.6 Gy, demonstrating a large variety of dose inhomogeneity. Estimated treatment times without motion compensation or setup ranged from 2 to 80 minutes. For the consensus statements, a strong agreement was reached for beam technique planning, dose calculation, prescription methods, and trade-offs between target and extracardiac critical structures. No agreement was reached on cardiac substructure dose limitations and on desired dose inhomogeneity in the target.

CONCLUSIONS

This STOPSTORM multicenter treatment planning benchmark study not only showed strong agreement on several aspects of STAR treatment planning, but also revealed disagreement on others. To standardize and harmonize STAR in the future, consensus statements were established; however, clinical data are urgently needed for actionable guidelines for treatment planning.

Intracoronary Brachytherapy for Restenosis: 20 Years of Follow-Up

BACKGROUND/PURPOSE

Intracoronary brachytherapy (ICB) has mainly been used to treat in-stent restenosis following percutaneous coronary intervention and was virtually abandoned about 20 years ago. However, patients treated with this strategy are still alive and some teams continue to perform this therapy. We aimed to investigate the very long-term clinical outcome of patients treated with ICB.

METHODS/MATERIALS

A total of 173 consecutive patients who had been treated with ICB at a large tertiary referral centre between 1998 and 2003 were included. The primary endpoint of the study was all-cause mortality. The secondary endpoints were as follows: occurrence of major adverse cardiac events (MACE, defined as all-cause death, non-fatal myocardial infarction, or target vessel revascularization), cardiac death, and presence of angina at the end of follow-up.

RESULTS

Patients' mean age at the time of ICB was 64 ± 10 years and 77 % were male. Restenosis (bare metal stent vs. balloon angioplasty) was the only indication for ICB. Unstable angina was present in 34 % of the patients. Follow-up was available for 166 patients. After a mean follow-up of 20 ± 1.3 years, 66 % of the patients had died (including 74 patients (67 %) with cardiac death). Cumulative MACE rate at 20 years was 96 %.

CONCLUSIONS

Very long-term follow-up of patients with in-stent restenosis treated with ICB confirmed a high all-cause mortality rate mainly due to cardiac causes and MACEs.

Coronary intravascular brachytherapy for in-stent restenosis: A review of the contemporary literature

Intracoronary stent restenosis (ISR) is a clinically relevant challenge in the modern era. Heterogeneity in patient- and lesion-specific factors can further compound this clinical challenge. Coronary intravascular brachytherapy (IVBT) was the standard therapeutic approach for ISR prior to the advent of drug-eluting stents (DES). Despite prospective data describing the superiority of DES over IVBT for treating de novo ISR, IVBT remains a treatment option for patients with complex disease. The purpose of this review is to evaluate the historical and contemporary literature surrounding IVBT in order to elucidate its role in modern cardiac care and to describe opportunities for future investigations to improve patient selection. Herein, we provide a review of the contemporary literature describing IVBT as a safe and effective treatment option for patients with recurrent, refractory ISR after multilayer DES and no good surgical or mechanical option. Combination therapy with emerging technologies such as DCBs may further increase efficacy.

Combined Vascular Brachytherapy and Stenting for the Treatment of In-Stent Restenosis

In-stent restenosis (ISR) remains a therapeutic challenge in the current drug-eluting stent (DES) era. Vascular brachytherapy (VBT) is a therapeutic option for ISR, but data about the outcomes of combination therapy with VBT and stenting for ISR lesions are sparse. We retrospectively analyzed patients who presented with ISR at our institution from 2003 through 2017. Three treatment arms were compared: VBT alone, VBT plus bare-metal stent (BMS), and VBT plus DES. Clinical, procedural, and 1-year outcome data were collected. Follow-up was obtained by phone calls and clinic visits. The patient cohort included 461 patients (764 ISR lesions). Of these, 333 patients (533 lesions) were treated with VBT alone, 89 patients (158 lesions) with VBT plus BMS, and 39 patients (73 lesions) with VBT plus DES. There were no significant differences in baseline characteristics among the 3 groups except for more patients with a remote smoking history in the VBT plus BMS (43.8%) and VBT plus DES groups (56.4%), and more patients with history of peripheral vascular disease (39.5%) and congestive heart failure (27%) in the VBT plus DES group. The most common clinical presentation was unstable angina (64.6%). In the VBT plus DES group, 10.3% of patients presented with MI, versus 5.5% in the VBT alone group and 2.2% in the VBT plus BMS group. At 1-year follow-up, the VBT plus DES group had higher rates of target vessel revascularization-major adverse cardiovascular events (38.5%) than the VBT plus BMS (21.3%) and VBT alone (15.6%) groups (p = 0.002). In conclusion, in patients with ISR, combination therapy with VBT and stenting at the same setup is associated with worse outcomes at 12 months and, if possible, should be avoided.

The-374T/A Variant of the Rage Gene Promoter is Associated with Clinical Restenosis after Coronary Stent Placement

Upregulation of the receptor for advanced glycation end products (RAGE) may play a crucial role in neointimal formation upon vessel injury. The −374T/A variant of the RAGE gene promoter, which has been associated with an altered expression of the cell-surface receptor, could exert a protective effect toward the development of vascular disease. The aim of this study is to determine the impact of this common genetic variant in the occurrence of clinical in-stent restenosis after coronary stent implantation. The −374T/A polymorphism of the RAGE gene promoter was evaluated by PCR-RFLPs in 267 patients with coronary artery disease who underwent coronary stent implantation and a subsequent coronary angiography 6–9 months later for suspected restenosis. In-stent restenosis was assessed by means of quantitative angiography. Carriers of the-374AA genotype showed a significantly reduced risk of developing restenosis after percutaneous transluminal intervention than non-carriers. To determine whether the protective effect of the homozygous AA genotype toward clinical restenosis was independent of potential confounders, we performed multivariable logistic regression analysis. After allowance for clinical and biochemical risk factors and stent length, the AA genotype remained significantly associated with a reduced prevalence of in-stent restenosis. No relation was evident between the RAGE genotype and established cardiovascular risk factors. In conclusion, the −374AA genotype of the RAGE gene promoter could be associated with a reduced risk of in-stent restenosis after coronary stent implantation.

Vascular brachytherapy versus drug-eluting stents in the treatment of in-stent restenosis: A meta-analysis of long-term outcomes

INTRODUCTION

Clinical trials have shown a short-term benefit of drug-eluting stents (DES) compared to vascular brachytherapy (VBT) for treatment of in-stent restenosis (ISR). The long-term benefits of DES vs. VBT are conflicting in the literature. This study aimed to do a meta-analysis of long-term outcomes of DES compared to VBT for treatment of ISR.

METHODS

PubMed, EMBASE, Cochrane Central and unpublished data were searched for cohort studies and randomized controlled trials (RCTs) that directly compared VBT to DES for the treatment of ISR. We evaluated the following outcomes at 2-5 years of follow-up: target lesion revascularization (TLR), target vessel revascularization (TVR), myocardial infarction (MI), stent thrombosis, cardiovascular (CV) mortality, and overall mortality. Heterogeneity was defined as I(2) values > 25%. Review Manager 5.1 was used for statistical analysis.

RESULTS

We included 1,375 patients from five studies, of which three were RCTs. VBT was used to treat ISR in 685 (49.8%) patients. After a 2-5 year follow-up, no significant differences were found between treatment groups regarding MI (P = 0.49), stent thrombosis (P = 0.86), CV mortality (P = 0.35), and overall mortality (P = 0.71). TLR (OR 2.37; CI 1.55-3.63; P < 0.001) and TVR (OR 2.23; CI 1.01-4.94; P = 0.05) were significantly increased in patients who received VBT.

CONCLUSION

This study suggests that DES are associated with decreased long-term revascularization procedures when compared to VBT for the treatment of ISR. This benefit does not appear to be associated with a significant reduction in mortality or myocardial infarction.

Eight-year clinical outcome after radioactive stent implantation: a treatment failure without irreversible long-term clinical sequelae

AIMS

To assess the long-term outcome of patients who underwent radioactive stent (RS) implantation.

METHODS AND RESULTS

The RS study population consisted of 133 consecutive patients who underwent RS implantation between November 1997 and July 2000. They were matched using the propensity score method with 266 patients who underwent bare metal stenting (BMS) in the same span. Long-term survival status and information on MACE (death, non-fatal myocardial infarction or any re-intervention) was retrospectively obtained. Eight-year cumulative survival (90.2% vs. 87.4%, p = 0.57) was similar between the RS and BMS group respectively, while 8-year cumulative MACE-free survival was significantly lower in RS patients (42.1% vs. 64.3%, p < 0.001) due to the difference in events (mainly target lesion revascularisations [TLRs]) during the first year of follow-up (cumulative 1-year MACE-free survival: 59.4% vs. 86.7%, p < 0.001); there was no difference in the MACE rate after the first year (p = 0.71). The TLR rate at six months in the RS group was 29.3%, mainly due to edge restenosis and at one year 36.2% (control group: 9.5%, p < 0.001).

CONCLUSIONS

A high incidence of MACE and re-intervention was observed during the first year following RS implantation, mainly related to TLR for edge restenosis. After the first year, the clinical outcome of RS patients was similar to the control group indicating that there are no late adverse effects related to low dose-rate intracoronary radiation therapy.

Regulation of cell cycle entry by PTEN in smooth muscle cell proliferation of human coronary artery bypass conduits

Proliferation of smooth muscle cells (SMCs) is the key event in the pathogenesis of intimal hyperplasia (IH) leading to coronary artery bypass graft (CABG) occlusion. The saphenous vein (SV) conduits are often affected by IH, while the internal mammary artery (IMA) conduits remain remarkably patent. SMC proliferation is mediated by the cell cycle, under the control of cyclin-dependent kinases (cdks), cdk-inhibitors and the retinoblastoma protein (Rb). Early passage of the SMCs through the cell cycle involves crossing the non-reversible G(1) checkpoint, the restriction (R) point. In this study, we investigated the effect of mitogenic insulin-like growth factor (IGF)-1 stimulation on the R-point and its relationship with the phosphorylation of Rb protein and the cdk inhibitors p21 and p27 in SV and IMA SMCs. We observed no change in the R-point following IGF-1 activation in either SV or IMA SMCs. However, Rb-phosphorylation occurred much earlier and was quantitatively greater in SV SMCs than IMA. Overexpression of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in SV SMCs followed by IGF-1 activation significantly decreased the expression of cyclin E and pRb and induced p27 expression in SV SMCs, while, pRb levels were markedly decreased and p27 levels were significantly increased in IMA SMCs. Silencing the PTEN gene by siRNA transfection of IMA SMCs significantly induced the expression of pRb and inhibited p27 expression, while, the expression levels of cyclin E, pRb, p21 and p27 were unaffected by the silencing of PTEN in SV SMCs. These results demonstrate that the PTEN plays a critical role in regulating cell cycle entry. Therefore, overexpression of PTEN possibly by means of gene therapy could be a viable option in regulating the cell cycle in SV SMCs in the treatment of vein graft disease.

Chronic total occlusion due to diffuse in‐stent restenosis: is brachytherapy the solution?

Percutaneous coronary intervention of chronic total occlusions (CTO) is associated with a significantly higher incidence of reocclusion and restenosis compared with non-total occlusions. Randomized and observational trials have demonstrated the effectiveness of intracoronary brachytherapy (ICBT) for the prevention of recurrent in-stent restenosis. However, limited data are available on the effectiveness of ICBT in patients with totally occluded in-stent restenosis. The authors assessed the long-term outcome of patients treated with intracoronary gamma radiation for totally occluded in-stent restenotic lesions. Percutaneous coronary intervention and subsequent catheter-based irradiation with iridium-192 was performed in 100 patients (103 vessels) with diffuse in-stent restenosis. At baseline, CTO of the target vessel at the site of the stent was present in 15 vessels (14.5%). Follow-up data were collected during follow-up visits and from telephone interviews. Repeat coronary angiography was performed in symptomatic patients with clinical restenosis. Clinical and angiographic characteristics were similar between the two groups, although there was a trend towards more unstable angina at the index procedure in CTO patients (66.7% versus 41.4%; p = 0.12) compared with patients without non-total occlusions. A higher percentage of patients (53.3%) with CTO required longer radiation sources (14 seeds, covering a length of 55 mm), compared with 23.9% of patients with non-total occlusion (p = 0.04). With a mean follow-up period of 47.5 +/- 24.0 months, major adverse cardiac events (MACE) were observed in 10 of 15 patients (66.7%) with CTO compared with 25 out of 88 patients (28.4%) without CTO (p = 0.009). According to multivariate analysis, total occlusion of the target vessel at baseline was the single independent predictor of MACE at one-year follow-up (relative risk 16.2, 95% confidence interval 4.2-62.9; p < 0.0001). This study shows that the use of gamma radiation for the prevention of recurrence of in-stent restenosis in patients with CTO does not seem to be as effective as in patients with non-total occlusions. Furthermore, CTO was an independent predictor of worse outcome at long-term follow-up in this study.

Intracoronary β‐irradiation enhances balloon‐injury‐induced tissue factor expression in the porcine injury model

Intracoronary brachytherapy (ICBT) effectively reduces restenosis but is associated with late thrombosis. Since tissue factor (TF) is an important mediator of arterial thrombosis, we tested the hypothesis that ICBT results in persistently augmented TF expression. Coronary arteries from 12 pigs were randomized to: control (C; no injury), oversized balloon injury (BI), or BI followed by ICBT. Animals were sacrificed at 1, 7, 14, or 60 days postprocedure, and coronary arteries collected for expression analyses and immunostaining. ICBT-treated arteries had higher TF antigen and activity at all time-points compared to BI arteries (Western blot: 16 571 +/- 2090 vs 10 135 +/- 2939 densitometric units, p = 0.001; ELISA: 0.42 +/- 0.13 nM vs 0.25 +/- 0.14 nM, p = 0.001; TF activity assay: 0.303 +/- 0.11 nM vs 0.18 +/- 0.07 nM, p = 0.01; immunohistochemical staining: 30.6 +/- 6.6% vs 11.5% +/- 3.2%, p = 0.01). TF expression increased following BI, increased further following ICBT, and persisted for the duration of the study. We conclude that TF expression increases after BI, but is further increased and persists for a longer duration following ICBT, suggesting that a TF-mediated mechanism may play a role in late thrombosis following ICBT.

3-year follow-up of the SISR (Sirolimus-Eluting Stents Versus Vascular Brachytherapy for In-Stent Restenosis) trial

OBJECTIVES

The aim of this study was to evaluate long-term outcome of patients treated for in-stent restenosis of bare-metal stents (BMS).

BACKGROUND

Treatment of restenosis of BMS is characterized by high recurrence rates. Vascular brachytherapy (VBT) improved outcome although late catch-up events were documented. Drug-eluting stents tested against VBT in this setting were found superior for at least the first year; superiority at longer follow-up is uncertain.

METHODS

We evaluated 3-year outcome of the multicenter SISR (Sirolimus-Eluting Stents Versus Vascular Brachytherapy for In-Stent Restenosis) trial, which randomized patients with restenosis of BMS to either a sirolimus-eluting stents (SES) or VBT.

RESULTS

Target vessel failure (cardiac death, infarction, or target vessel revascularization [TVR]) at 9 months as previously reported was significantly improved with SES. Kaplan-Meier analysis at 3 years documented that survival free from target lesion revascularization (TLR) and TVR continues to be significantly improved with SES: freedom from TLR 81.0% versus 71.6% (log-rank p = 0.018), and TVR 78.2% versus 68.8% (log-rank p = 0.022), SES versus VBT. At 3 years, target vessel failure and major adverse cardiac events (death, infarction, emergency coronary artery bypass grafting, or repeat TLR) remained improved with SES, but did not reach statistical significance. There was no statistically significant difference in definite or probable stent thrombosis (3.5% for SES, 2.4% for VBT; p = 0.758).

CONCLUSIONS

At 3 years of follow-up, after treatment of in-stent restenosis of BMS, patients treated with SES have improved survival free of TLR and TVR compared with patients treated with VBT. Stent thrombosis rates are not different between the 2 groups but are higher than reported in trials of treatment of de novo lesions.

Neointimal hyperplasia associated with synthetic hemodialysis grafts

Stenosis is a major cause of failure of hemodialysis vascular grafts and is primarily caused by neointimal hyperplasia (NH) at the anastomoses. The objective of this article is to provide a scientific review of the biology underlying this disorder and a critical review of the state-of-the-art investigational preventive strategies in order to stimulate further research in this exciting area. The histology of the NH shows myofibroblasts (that are probably derived from adventitial fibroblasts), extracellular matrices, pro-inflammatory cells including foreign-body giant cells, a variety of growth factors and cytokines, and neovasculature. The contributing factors of the pathogenesis of NH include surgical trauma, bioincompatibility of the synthetic graft, and the various mechanical stresses that result from luminal hypertension and compliance mismatch between the vessel wall and graft. These mechanical stimuli are focal in nature and may have a significant influence on the preferential localization of the NH. Novel mechanical graft designs and local drug delivery strategies show promise in animal models in preventing graft NH development. Successful prevention of graft stenosis would provide a superior alternative to the native fistula as hemodialysis vascular access.

Mitofusin 2 Triggers Vascular Smooth Muscle Cell Apoptosis via Mitochondrial Death Pathway

Previous studies have shown that mitofusin 2 (Mfn-2) (or hyperplasia suppressor gene [HSG]) inhibits vascular smooth muscle cell (VSMC) proliferation. Here, we demonstrate that Mfn-2 is a primary determinant of VSMC apoptosis. First, oxidative stress with H2O2, inhibition of protein kinase C with staurosporine, activation of protein kinase A with forskolin, and serum deprivation concurrently elevate Mfn-2 expression and induce VSMC apoptosis. Second, overexpression of Mfn-2 also triggers apoptosis of VSMCs in culture and in balloon-injured rat carotid arteries, thus contributing to Mfn-2-mediated prevention of neointima formation after angioplasty. Third, Mfn-2 silencing protects VSMCs against H2O2 or Mfn-2 overexpression-induced apoptosis, indicating that upregulation of Mfn-2 is necessary and sufficient for oxidative stress-mediated VSMC apoptosis. The Mfn-2 proapoptotic effect is independent of its role in mitochondrial fusion but mainly mediated by inhibition of Akt signaling and the resultant activation of the mitochondrial apoptotic pathway, as manifested by decreased Akt phosphorylation, increased mitochondrial Bax/Bcl-2 ratio, cytochrome c release, and activation of caspases-9 and caspase-3. Furthermore, Mfn-2-induced apoptosis was blocked by overexpression of an active phosphoinositide 3-kinase mutant or Bcl-xL or inhibition of caspase-9 but not caspases-8. Thus, in addition to its antiproliferative effects, Mfn-2 constitutes a primary determinant of VSMC apoptosis.

Comparison of six-month angiographic and three-year outcomes after sirolimus-eluting stent implantation versus brachytherapy for bare metal in-stent restenosis

To evaluate long-term effectiveness of sirolimus-eluting stent (SES) implantation for diffuse bare metal in-stent restenosis (ISR), we compared 6-month angiographic and long-term (3-year) clinical outcomes of SES implantation and intracoronary brachytherapy (ICBT). SES implantation for diffuse ISR was performed in 120 consecutive patients and their results were compared with those from 240 patients treated with beta-radiation with balloons filled with rhenium-188 and mercaptoacetyltriglycine. The radiation dose was 15 or 18 Gy at a depth of 1.0 mm into the vessel wall. The primary end point was 3-year major adverse cardiac events including myocardial infarction, cardiac death, and target lesion revascularization. The 2 groups were similar in baseline clinical and angiographic characteristics. Lesion lengths were 25.1 +/- 14.2 mm in the SES group and 24.5 +/- 10.4 mm in the ICBT group (p = 0.15). In-stent acute gain was greater in the SES group than in the ICBT group (2.23 +/- 0.62 vs 1.91 +/- 0.54 mm, p <0.001). We obtained 6-month angiographic follow-up in 287 patients (79.7%). In-segment angiographic restenoses were 7.4% (7 of 94) in the SES group and 26.4% (51 of 193) in the ICBT group (p <0.05). Two myocardial infarctions (1 in each group) and 5 deaths (4 in SES group, 1 in ICBT group) occurred during 3-year follow-up. At 3 years, survival rates without target lesion revascularization (94.1 +/- 2.2% vs 84.6 +/- 2.3%, p = 0.011) and major adverse cardiac events (92.5 +/- 2.4% vs 84.2 +/- 2.4%, respectively, p = 0.03) were higher in the SES than in the ICBT group. In conclusion, compared with ICBT, SES implantation for diffuse ISR is more effective in decreasing recurrent restenosis and improving long-term outcomes.

Four-year results after brachytherapy for diffuse coronary in-stent restenosis: will coronary radiation therapy survive?

BACKGROUND

Prior to the introduction of drug-eluting stents (DES), diffuse coronary in-stent restenosis (ISR) was mainly treated by brachytherapy (BT), with good short-term and mid-term results. However, there exist limited data on the long-term effects of BT that justify its continuous use.

MATERIALS AND METHODS

Two hundred patients with diffuse ISR treated with intravascular BT were retrospectively followed over 4 years. Group A (n=134) was treated with the noncentered (90)Sr/Y BetaCath radiation system, whereas Group B (n=66) was treated with the centered 32P Galileo source wire system. Primary endpoints after 4 years were target lesion restenosis (TLS) and target lesion revascularization (TLR). Secondary endpoints were target vessel revascularization (TVR) and nontarget vessel revascularization (NTVR), as well as major adverse cardiac events (MACE).

RESULTS

Follow-up at 4 years yielded a TLS rate of 37.6% (Group A, 40.8%; Group B, 31.1%; P=.48). TLR was performed in 34.8% of patients (37.5% in Group A vs. 29.5% in Group B; P=.55). Ten percent of patients underwent coronary bypass surgery. Percutaneous coronary intervention was performed more often in Group A (27.5%) than in Group B (19.7%), while TVR was less frequent in Group A (10.0%) than in Group B (18.0%). NTVR was undertaken in 25.0% of Group A patients versus 21.3% of Group B patients, and MACE occurred in 1.7% of Group A patients versus 3.3% of Group B patients. These differences were not statistically significant (P>.05).

CONCLUSIONS

While excellent short-term and mid-term results after coronary BT are widely accepted, a high TLS rate can be observed after 4 years. The potential superiority of DES to BT will depend on the availability of long-term clinical data.

A meta-analysis of randomised controlled trials assessing drug-eluting stents and vascular brachytherapy in the treatment of coronary artery in-stent restenosis

OBJECTIVE

We undertook a meta-analysis of randomised trials assessing the outcome of vascular brachytherapy (VBT) or DES for the treatment of coronary artery ISR.

METHODS AND RESULTS

Studies utilising DES or VBT for ISR were identified by a systematic search. Data was pooled and combined overall effect measures were calculated for a random effect model in terms of deaths, myocardial infarctions, revascularisation, binary restenosis, mean late luminal loss and major adverse cardiac events (MACE). Fourteen eligible studies (3103 patients) were included. Neither therapy had any effect on mortality or myocardial infarction rate. VBT reduced the rate of revascularisation (RR 0.59, 95%CI 0.50-0.68), MACE (RR 0.58, 95%CI 0.51-0.67), binary restenosis (RR 0.51, 95%CI 0.44-0.59) and late loss (-0.73 mm, 95%CI -0.91 to -0.55 mm) compared to balloon angioplasty and selective bare metal stents (BMS) alone at intermediate follow-up and MACE (RR 0.72, 95%CI 0.61-0.85) at long-term follow-up. DES reduced the rate of revascularisation (OR 0.51, 95% CI 0.36-0.71), MACE (OR 0.55, 95% CI 0.39-0.79) and binary restenosis (OR 0.57, 95% CI 0.40-0.81) compared to VBT but follow-up was limited to 9 months.

CONCLUSIONS

VBT improves the long-term outcome of angioplasty compared with BMS alone in the treatment of ISR. DES appears to provide similar results to that of VBT during short-term follow-up.

Long-term clinical outcome of patients treated with β-brachytherapy in routine clinical practice

BACKGROUND

Only limited data exist regarding the long-term efficacy of beta-brachytherapy (beta-VBT) in routine clinical practice and the impact of the prolonged (>6 months) combined antiplatelet therapy after beta-VBT. Our aim is to examine the long-term clinical efficacy of routine beta brachytherapy (beta-VBT) followed by indefinite administration of combined antiplatelet therapy in patients at high restenotic risk.

METHODS

Sixty-one patients with 65 lesions [de novo: 41, in-stent restenotic (ISR): 24] underwent intracoronary beta-VBT and were followed prospectively. All patients received indefinite administration of aspirin and clopidogrel, underwent routine angiography 6 months later and were followed-up clinically for 43.7 months (range: 32 to 52 months).

RESULTS

Acute success was achieved in 60/61 (98.4%) patients. Lesion length was 36.1 (+/-17.6) mm for the de novo and 22.0 (+/-9.8) mm for the ISR (p=0.001). Stents were implanted in 35/41 de novo and 7/24 ISR lesions (p<0.01). Six-month binary restenosis after successful beta-VBT was 35.9% (23/64). During follow-up patients with de-novo lesions who received a new stent during index procedure had a higher incidence of major cardiac events than patients with ISR lesions without a new stent (log rank test, p=0.02). Acute and late thrombotic events were reported at 6 patients, all with de novo lesions and stent implantation.

CONCLUSIONS

Beta-VBT plus stenting in de novo lesions is related to an unacceptable high rate of thrombotic complications and clinical restenosis despite prolonged administration of combined antiplatelet therapy. Brachytherapy remains a reasonable option for patients with ISR lesions until full data from large randomized trials comparing drug eluting stents with brachytherapy are available.

Randomized comparison between intracoronary β-radiation brachytherapy and implantation of paclitaxel-eluting stents for the treatment of diffuse in-stent restenosis

BACKGROUND AND PURPOSE

Intracoronary brachytherapy was the primary therapeutic option for the treatment of in-stent restenosis (ISR) during the last years. Especially for the treatment of diffuse ISR (lesions >10mm), beta-source brachytherapy was significantly superior to singular balloon angioplasty. Despite lacking clinical database, the implantation of drug eluting stents recently became a common procedure for the treatment of ISR. This randomized trial aimed to compare the efficacy of beta-brachytherapy with beta-radioisotopes (90)Sr/(90)Y and paclitaxel-eluting stent implantation for the treatment of diffuse ISR.

MATERIAL AND METHODS

Thirty-seven patients with diffuse ISR were randomly assigned to beta-brachytherapy after balloon angioplasty (Beta-Cath in 17 patients) or paclitaxel-eluting stent implantation (Taxus-Express2 in 20 patients). Six-month clinical follow-up was obtained for all patients, while angiographic follow-up was available for 30 patients.

RESULTS

Binary ISR (restenosis >50%) within target segment was observed in three patients treated with Beta-Cath, of which one needed target segment revascularisation for recurrent ISR, whereas no significant restenosis occurred in the patients treated with Taxus-Express2 (P=0.037). No further major adverse cardiac (target segment revascularisation, myocardial infarction, death) was found in either group (P=NS). Stent implantation was the more time-saving (31+/-11 min versus 60+/-23 min, P<0.001) procedure.

CONCLUSIONS

Although this trial revealed a significant reduction of binary restenosis in the Taxus-Express2 arm, we found no difference in clinical outcome after implantation of paclitaxel-eluting stents for the treatment of diffuse ISR when compared to beta-brachytherapy.

Implementing a best-treatment strategy with intracoronary brachytherapy for in-stent restenosis in patients at high risk for recurrence

BACKGROUND

The deployment of drug-eluting stents (DES) to treat bare-metal stent restenosis [in-stent restenosis (ISR)] has become routine practice, with a consequential decline in the use of intracoronary brachytherapy (ICBT). However, there are concerns as to the long-term safety profile of DES, particularly in terms of late stent thrombosis. In addition, an appropriate treatment strategy for stenosis within DES has not been developed. The aim of this study was to examine the efficacy of best treatment with ICBT for ISR in patients at high risk for future recurrence.

METHODS

Forty-seven consecutive patients with symptomatic ISR with at least one or more increased risk criteria for recurrence were treated with beta-radiation. The patients received best treatment based on avoidance of previously reported procedural risk factors for recurrence (incomplete stent apposition, dissection, geographical miss, and damage to the noninjured vessel segment), deferring ICBT when provisional stenting was performed. A beta-radiation dose of 20 Gy was used, and clopidogrel was prescribed for at least 6 months.

RESULTS

Treatment was successful for all patients without in-hospital complications. ICBT increased the total intervention procedure time by 15+/-10 min. ISR length was 25.4+/-11.5 mm. The angiographic minimal luminal diameter (MLD) was 2.24+/-0.43 mm after ICBT versus 0.75+/-0.58 mm at baseline (P<.05). On 9-month follow-up, the MLD was 1.93+/-0.48 mm (P<.05 vs. baseline). Binary restenosis was detected in six (13%) patients. At 29.7+/-9.3 months of follow-up, target lesion revascularization or target vessel (nonlesion) revascularization was performed in 17 (36%) patients. Only one patient suffered a myocardial infarction, and no deaths were observed.

CONCLUSION

The adoption of a best-practice protocol for the use of ICBT to treat ISR can result in a safe and effective clinical and angiographic outcome. Under these circumstances and with appropriate patient selection, ICBT may continue to be of value despite the popular use of DES.

Comparison between drug-eluting stents and beta-radiation for the treatment of diffuse in-stent restenosis: clinical and angiographic outcomes

BACKGROUND

Initial reports on drug-eluting stents (DES) for the treatment for in-stent restenosis (ISR) show very good outcomes. Nevertheless, few data are available on direct comparison with intracoronary brachytherapy (IBT). The aim of this study was to compare brachytherapy and DES in treatment of diffuse ISR.

METHODS

One hundred forty-one consecutive patients with diffuse ISR were treated with IBT (68 patients; beta (90Sr/90Y) emitters) or with DES (73 patients; 32 with sirolimus-eluting and 41 with paclitaxel-eluting stents). Angiographic and clinical follow-up was scheduled within 9 months.

RESULTS

The first 74 lesions were treated with IBT (group 1) and the latter 74 with DES (group 2). The two groups were well matched for clinical/angiographic characteristics. At follow-up, restenosis rates were 37.8% (28/74) in IBT group and 14.9% (11/74) in DES group (P = .0028). A diffuse pattern of recurrence was more frequent after IBT (20/74 vs 6/74, P = .005). A worse outcome after IBT was associated with the "edge effect," accounting for most failures. Recurrence within the original restenotic stent was similar in both groups (12.9% vs 14.9% in groups 1 and 2 respectively, P = .8).

CONCLUSIONS

Drug-eluting stents are more effective than IBT with beta-irradiation in reducing recurrence rates after treatment of diffuse ISR. In case of failure, the pattern of restenosis is more benign after treatment with DES.

Repeat intracoronary beta-brachytherapy using a rhenium-188-filled balloon catheter for recurrent restenosis in patients who failed intracoronary radiation therapy

BACKGROUND

Conventional percutaneous coronary intervention (PCI) in restenotic lesions after brachytherapy failure is associated with a high recurrence rate of restenoses and revascularizations. Intracoronary brachytherapy using a liquid rhenium-188-filled balloon in de novo or restenotic lesions safely and effectively reduced restenosis rates. We report clinical and angiographic data regarding the safety and efficacy of rhenium-188 brachytherapy in restenoses after brachytherapy failure.

METHODS

Fourteen patients with restenosis after brachytherapy failure received rhenium-188 beta-brachytherapy. Follow-up was performed angiographically after 6 months and clinically after 12 months. Primary clinical endpoint was the incidence of major adverse cardiac events (MACE) defined as any death, myocardial infarction or repeat revascularization in the target vessel within 12 months. Secondary angiographic endpoints were the binary restenosis rate and late loss in the total segment including edge effects at 6 months.

RESULTS

The prescribed dose of 22.5 Gy (n=12) or 30 Gy (n=2) was successfully delivered in all patients. In two lesions, a bare-metal stent was implanted. The mean length of the irradiated segment was 40.0+/-15.7 mm. The mean diameter of the irradiation balloon was 2.96+/-0.37 mm. Angiographic follow-up was done in 13 of 14 patients. There was no edge stenosis or coronary aneurysm. Within the total segment, late loss was 0.39+/-0.64 mm and late loss index was 0.18+/-0.40 with a binary restenosis rate of 23%. Twelve months' clinical follow-up was available in all patients, which showed a MACE rate of 7% due to one target lesion revascularization (TLR).

CONCLUSIONS

Intracoronary beta-brachytherapy with a liquid rhenium-188-filled balloon in restenoses after intracoronary radiation therapy failure including 12 months combined antiplatelet therapy is safe with respect to vessel thrombosis, late coronary occlusion or aneurysm formation. With limited use of stenting, angiographic and clinical follow-up for repeat brachytherapy were favorable and it is associated with low restenosis and target vessel revascularization rate.

Cellular, molecular and immunological mechanisms in the pathophysiology of vein graft intimal hyperplasia

Coronary artery disease, leading to myocardial infarction and ischaemia, affects millions of persons and is one of the leading causes of morbidity and mortality worldwide. Invasive techniques such as coronary artery bypass grafting are used to alleviate the sequelae of arterial occlusion. Unfortunately, restenosis or occlusion of the grafted conduit occurs over a time frame of months to years with a gradual reduction in patency, especially in vein grafts. The events leading to intimal hyperplasia (IH) formation involve numerous cellular and molecular components. Various cellular elements of the vessel wall are involved as are leucocyte-endothelial interactions that trigger the coagulation cascade leading to localized thrombus formation. Subsequent phenotypic modification of the medial smooth muscle cells and their intimal migration is the basis of the lesion formation that is thought to be propagated by an immune-mediated reaction. Despite intense scrutiny, the pathophysiology of IH remains an enigma. Although several growth factors, cytokines and numerous other biomolecules have been implicated and their relationship to prohyperplasia pathways such as the phosphatidyl-inositol 3-kinase (PI3K)-Akt pathway has been established, many pieces of the puzzle are still missing. An in-depth understanding of early vein graft adaptation and progression is necessary to improve the long-term prognosis and develop more effective therapeutic measures. In this review, we have critically evaluated and summarized the literature to elucidate and interlink the numerous established and emerging factors that play a key role in the development of IH leading to vein graft restenosis.

Intracoronary β-brachytherapy using a rhenium-188 filled balloon catheter in restenotic lesions of native coronary arteries and venous bypass grafts

PURPOSE

We have previously demonstrated the efficacy of intracoronary beta-brachytherapy using a liquid (188)Re-filled balloon in a randomised trial including de novo lesions. Percutaneous coronary interventions in restenotic lesions and in stenoses of venous bypass grafts are characterised by a high recurrence rate for restenosis and re-interventions. Against this background, we wanted to assess the impact of intracoronary beta-brachytherapy using a liquid (188)Re-filled balloon in restenotic lesions in native coronary arteries and venous bypass grafts.

METHODS

In 243 patients, beta-brachytherapy with 22.5 Gy was applied at a tissue depth of 0.5 mm. Patients were followed up angiographically after 6 months and clinically for 12 months. The primary clinical endpoint was the incidence of MACE (death, myocardial infarction, target vessel revascularisation). Secondary angiographic endpoints were late loss and binary restenosis rate in the total segment.

RESULTS

All irradiation procedures were successfully performed. A total of 222 lesions were in native coronary arteries; 21 were bypass lesions. Mean irradiation length was 41.6+/-17.3 mm (range 20-150 mm) in native coronary arteries and 48.1+/-33.9 mm (range 30-180 mm) in bypass lesions; the reference diameter was 2.57+/-0.52 mm and 2.83+/-0.76 mm, respectively. There was no vessel thrombosis during antiplatelet therapy. Angiographic/clinical follow-up rate was 84%/100%. MACE rate was 17.6% in the native coronary artery group and 38.1% in the CABG group (p<0.03). Binary restenosis rate was 22.5% and 55.6% (p<0.01), and late loss was 0.38+/-0.72 mm and 1.33+/-1.11 mm (p<0.001), respectively.

CONCLUSIONS

We conclude that intracoronary beta-brachytherapy with a liquid (188)Re-filled balloon using 22.5 Gy at a tissue depth of 0.5 mm in restenotic lesions is safe. It is associated with a low binary restenosis rate, resulting in a low occurrence rate of MACE within 12 months in restenotic lesions in native coronary arteries but not in vein grafts.

Restenosis following implantation of bare metal coronary stents: pathophysiology and pathways involved in the vascular response to injury

This review summarizes the restenotic process that occurs after the implantation of bare metal coronary stents. The pathology of in-stent restenosis is distinct from that seen after balloon angioplasty and is characterized by neointimal proliferation and extracellular matrix deposition. The degree of neointimal proliferation is proportional to the amount of injury, the intensity of the inflammatory infiltrate and the association of stent struts with lipid-filled plaque. In-stent restenosis also appears to be associated with systemic markers of inflammation. Shear stress has an important influence on restenosis as does the presence and adhesiveness of vascular progenitor cells. Clinical predictors (e.g., artery size, stent length, diabetes, and gender) may affect the incidence of restenosis seen after stent placement. A number of catheter-based interventions have been used to treat in-stent restenosis. Although preliminary data suggest that the use of drug-eluting stents may be effective, only intracoronary radiation has shown consistent efficacy in randomized trials.

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.

Incomplete Neointimal Coverage of Sirolimus-Eluting Stents

OBJECTIVES

The goal of this study was to use angioscopy to investigate the amount of neointimal coverage after sirolimus-eluting stent (SES) implantation.

BACKGROUND

Sirolimus-eluting stents reduce intimal hyperplasia.

METHODS

We used angioscopy to evaluate 37 consecutive stented coronary artery lesions (15 SES and 22 bare-metal stents [BMS]) in 25 patients (18 men, 7 women) at 3 to 6 months after stent implantation. Angioscopic evaluation focused on: 1) neointimal coverage of stent struts, and 2) the existence of thrombi. The degree of neointimal coverage was classified as grade 0 when there was no neointimal coverage (similar to immediately after the implantation); grade 1 when stent struts bulged into the lumen, but were covered and still translucently visible; grade 2 when stent struts were visible but not clearly seen (not translucent); and grade 3 when stent struts were not visible because they were embedded in the neointima.

RESULTS

Thrombi were identified in eight stented segments, tended to be more common with SES (p = 0.14), but were not seen on angiography. Three of the 15 SES (20%) had grade 0 neointimal coverage, and only 2 SES (13.3%) had complete coverage (grades 2/3). In contrast, all 22 BMS showed complete intimal coverage (grades 2/3). Thrombi were more common in stents with incomplete neointimal coverage (p = 0.09).

CONCLUSIONS

The SES had incomplete neointimal coverage three to six months after implantation, and this was associated with subclinical thrombus formation.

Percutaneous coronary intervention: recommendations for good practice and training

Cardiologists undertaking percutaneous coronary intervention (PCI) are excited by the combination of patient and physician satisfaction and technological advance occurring on the background of the necessary manual dexterity. Progress and applicability of percutaneous techniques since their inception in 1977 have been remarkable; a sound evidence base coupled with the enthusiasm and ingenuity of the medical device industry has resulted in a sea change in the treatment of coronary heart disease (CHD), which continues to evolve at breakneck speed. This is the third set of guidelines produced by the British Cardiovascular Intervention Society and the British Cardiac Society. Following the last set of guidelines published in 2000, we have seen PCI activity in the UK increase from 33,652 to 62,780 (87% in four years) such that the PCI to coronary artery bypass grafting ratio has increased to 2.5:1. The impact of drug eluting stents has been profound, and the Department of Health is investigating the feasibility of primary PCI for acute myocardial infarction. Nevertheless, the changes in the structure of National Health Service funding are likely to focus our attention on cost effective treatments and will require physician engagement and sensitive handling if we are to continue the rapid and appropriate growth in our chosen field. It is important with this burgeoning development now occurring on a broad front (in both regional centres and district general hospitals) that we maintain our vigilance on audit and outcome measures so that standards are maintained for both operators and institutions alike. This set of guidelines includes new sections on training, informed consent, and a core evidence base, which we hope you will find useful and informative.

Three-year follow-up after intracoronary beta-radiation therapy for in-stent restenosis

BACKGROUND

Most studies that proved intracoronary radiation therapy (IRT) to be highly effective to reduce recurrent restenosis after treatment of in-stent restenosis (ISR) have looked at time periods up to 12 months. Whether the beneficial effect from radiation is sustained during long-term follow-up remains a concern. This study sought to evaluate the effectiveness of IRT using a beta-emitter during a 3-year follow-up period.

METHODS

One hundred twenty-eight consecutive symptomatic patients (mean age, 63 +/- 11 years) with 134 in-stent restenotic lesions were treated for ISR with IRT (noncentred beta-emitter, Novoste; radiation dosis 21.1 +/- 3.1 Gy). Six-month angiographic follow-up was obtained in 104 patients (81%) with 105 lesions (78%). All patients underwent 36-month clinical follow-up.

RESULTS

Six-month angiographic restenosis rate was 22% in stent (29% in lesion) with an in-stent late loss of 0.49 +/- 0.62 mm. Target lesion resvascularization (TLR) at 6-month follow-up was performed in 23 cases (18%). MACE (death, myocardial infarction, and target vessel revascularisation) was observed in 24 patients (19%). At 36-month follow-up, TLR increased to 36 cases (28%) and MACE was observed in 47 patients (37%). In a multivariate analysis, minimal lumen diameter before treatment of ISR using IRT was the only predictor of recurrent TLR at 36 months (OR = 0.131; 95% CI, 0.068-0.254; p = 0.002). In a subgroup of patients (N = 15) without restenosis at 6-month angiography but with clinically driven recurrent late angiography (mean, 18 +/- 7 months); in-lesion late loss increased from 0.47 +/- 0.54 mm at 6 months to 1.27 +/- 0.76 mm at repeated angiography (p = 0.005).

CONCLUSION

There is a considerable number of delayed recurrent restenosis post IRT for ISR. This is due to ongoing late loss more than 6-month post IRT. The minimal lumen diameter before IRT predicts the need for recurrent TLR at 36 months.

Incidence and predictors of late recurrence after beta-radiation therapy with a 188Re-MAG3-filled balloon for diffuse in-stent restenosis

BACKGROUND

The long-term fate of patent irradiated segments at 6 months after beta-radiation therapy has not been sufficiently evaluated.

METHODS

Two-year follow-up angiography was performed in 52 patients with patent irradiated segments at 6 months after beta-radiation with a rhenium 188-mercaptoacetyltriglycine-filled balloon for diffuse in-stent restenosis. We evaluated late recurrence (LR) and its predictors after beta-radiation.

RESULTS

Late recurrence at 2 years after radiation was observed in 10 (19.2%) of 52 patients. The minimal lumen diameter (MLD) progressively decreased, from 2.67 +/- 0.44 mm at postprocedure to 2.42 +/- 0.53 mm at 6 months to 2.09 +/- 0.75 mm at 2 years (P = .001). In the 42 patients without LR, the MLD decreased from postprocedure (2.74 +/- 0.43 mm) to 6 months (2.44 +/- 0.54 mm; P = .006), but did not change between 6 months and 2 years (2.35 +/- 0.49 mm, P = .13). In the LR group, the MLD was unchanged from postprocedure (2.33 +/- 0.29 mm) to 6 months (2.30 +/- 0.43 mm; P = .81), but decreased significantly between 6 months and 2 years (1.02 +/- 0.75 mm, P = .001). Multivariate analysis identified postprocedural MLD as an independent predictor of LR (odds ratio 0.025, 95% CI 0.007-0.94, P = .04). Late target lesion revascularization was performed in 6 patients (11.5%) between 6 months and 2 years after radiation.

CONCLUSION

Although LR after radiation was observed in some patients, irradiated segments remained stable for up to 2 years in most patients. Smaller postprocedural MLD, followed by delayed late loss between 6 months and 2 years, was associated with LR.

Intracoronary radiation therapy for multi-drug resistant in-stent restenosis: Initial clinical experience

While randomized clinical trials have demonstrated the excellent efficacy of sirolimus-eluting stents (SES) for de novo lesions, the optimal treatment for SES-restenosis is not known. Management may include stand-alone balloon angioplasty, repeat SES implantation, or placement of a drug-eluting stent (DES) with an alternative antiproliferative agent (i.e., a paclitaxel-eluting stent, PES). The appropriate management strategy for recurrent restenosis after PES implantation for SES restenosis is even less clear. We report the initial clinical experience with intracoronary radiation therapy (ICRT) for multi-DES resistant restenosis. We performed ICRT in five patients with recurrent restenosis after treatment with both SES and PES. Over a median follow-up of 256 days (range 75-489 days), one patient had a target lesion revascularization at 182 days and subsequently died at 483 days following the procedure. Our findings support the further study of this management approach.

Use of Taxus polymer-coated paclitaxel-eluting stents for treatment of in-stent restenosis in real world patients: Results of clinical and angiographic follow-up at six months in a single-center registry

OBJECTIVE

To evaluate the safety and efficacy of Taxus paclitaxel-eluting stents in a real world group of unselected patients with coronary in-stent restenosis (ISR) lesions.

METHODS

This is a prospective single-center registry of a consecutive series of 94 patients with 104 ISR lesions, without previous brachytherapy, over a period of 1 year. Quantitative coronary angiographic analyses were performed at baseline and at 6-month angiographic follow-up. Clinical follow-up were obtained at 6 months.

RESULTS

Pre-intervention mean reference vessel diameter was 2.62 +/- 0.50 mm and mean lesion length was 13.95 +/- 6.78 mm. Baseline ISR patterns were mostly either Type I focal (32.7%) or Type II diffuse intrastent (48.1%). At 6-month angiographic follow-up, the in-stent and in-segment binary restenosis was 3.8% (4/105) and 7.6% (8/105) respectively, and the in-stent and in-segment late loss was 0.30 +/- 0.50 mm and 0.57 +/- 0.54 mm, respectively. Seven of these eight restenosed lesions had a diffuse or proliferative ISR pattern prior to intervention. Lesions that restenosed had longer mean stent length per lesion (37.3 mm vs. 22.5 mm in nonrestenosed group; P = 0.001) and more likely to have had a pattern of total occlusion pre-intervention (25.0% vs. 3.1% in nonrestenosed group; P = 0.046). At 6-month clinical follow-up, the MACE rate was 8.5% and target lesion revascularization rate was 7.4%. There was no death but subacute stent thrombosis occurred in 1 patient (1.1%) at 3 days after intervention.

CONCLUSIONS

Paclitaxel-eluting Taxus stent for the treatment of ISR effectively suppresses recurrent neointimal proliferation, and was safe and efficacious at 6-month follow-up.

Randomized blinded clinical trial of intracoronary brachytherapy with 90Sr/Y beta-radiation for the prevention of restenosis after stent implantation in native coronary arteries in diabetic patients

BACKGROUND

We report a double-blind, randomized clinical trial of intracoronary beta-radiation for prevention of restenosis after stent implantation in native coronary de novo lesions in diabetic patients.

METHODS

After successful stent implantation in native coronary de novo lesions, 106 lesions in 89 diabetic patients were randomly allocated to treatment with beta-radiation with 18 Gy at 1 mm vessel depth (n = 53) or placebo treatment (n = 53).

RESULTS

Angiographic analysis at 9 month follow-up revealed a late lumen loss of 0.7+/-0.9 mm in the radiotherapy group versus 1.2+/-0.8 mm in the control group at the injured segment (P = 0.006), 0.9+/-1.0 versus 1.3+/-0.7 mm at the radiated segment (P = 0.02), and 0.9+/-1.0 versus 1.3+/-0.7 mm at the target segment (P = 0.04) (defined as active source length plus 5mm on proximal and distal sites). Binary restenosis rates were significantly lower in the radiation group in all subsegments (injured segment: 10.9 versus 37.3%, P = 0.003; radiated segment: 21.7 versus 49.0%, P = 0.005; target segment: 23.9 versus 49.0%, P = 0.01). Target lesion revascularization for restenosis was required in nine lesions (17.6%) in the radiotherapy group versus 18 (34.0%) in the placebo group (P = 0.05). Late thrombosis occurred in four radiated patients (after premature discontinuation of antiplatelet therapy in all), resulting in a major adverse clinical event rate of 37.2% in the brachytherapy group versus 38.6% in the placebo group (P = ns).

CONCLUSIONS

In diabetic patients with de novo coronary lesions, intracoronary radiation after stent implantation significantly reduced restenosis. However, this clinical benefit was reduced by the frequent occurrence of late thrombosis.

Gadolinium neutron capture brachytherapy (GdNCB), a new treatment method for intravascular brachytherapy

Restenosis is a major problem after balloon angioplasty and stent implantation. The aim of this study is to introduce gadolinium neutron capture brachytherapy (GdNCB) as a suitable modality for treatment of stenosis. The utility of GdNCB in intravascular brachytherapy (IVBT) of stent stenosis is investigated by using the GEANT4 and MCNP4B Monte Carlo radiation transport codes. To study capture rate, Kerma, absorbed dose and absorbed dose rate around a Gd-containing stent activated with neutrons, a 30 mm long, 5 mm diameter gadolinium foil is chosen. The input data is a neutron spectrum used for clinical neutron capture therapy in Studsvik, Sweden. Thermal neutron capture in gadolinium yields a spectrum of high-energy gamma photons, which due to the build-up effect gives an almost flat dose delivery pattern to the first 4 mm around the stent. The absorbed dose rate is 1.33 Gy/min, 0.25 mm from the stent surface while the dose to normal tissue is in order of 0.22 Gy/min, i.e., a factor of 6 lower. To spare normal tissue further fractionation of the dose is also possible. The capture rate is relatively high at both ends of the foil. The dose distribution from gamma and charge particle radiation at the edges and inside the stent contributes to a nonuniform dose distribution. This will lead to higher doses to the surrounding tissue and may prevent stent edge and in-stent restenosis. The position of the stent can be verified and corrected by the treatment plan prior to activation. Activation of the stent by an external neutron field can be performed days after catherization when the target cells start to proliferate and can be expected to be more radiation sensitive. Another advantage of the nonradioactive gadolinium stent is the possibility to avoid radiation hazard to personnel.

Peristent remodeling and neointimal suppression 2 years after polymer-based, paclitaxel-eluting stent implantation: insights from serial intravascular ultrasound analysis in the TAXUS II study

BACKGROUND

The purpose of this study was to evaluate long-term vascular responses as long as 2 years after implantation of polymer-based, paclitaxel-eluting stents in contrast to uncoated stents.

METHODS AND RESULTS

TAXUS II is a randomized, double-blind trial comparing slow-release (SR) and moderate-release (MR) TAXUS stents with bare-metal control stents (BMSs). One hundred sixty-one event-free patients (SR, 43; MR, 41; and BMS, 77) underwent serial intravascular ultrasound (IVUS) analysis after the procedure and at 6 months and 2 years. At 2 years, neointimal responses continued to be significantly suppressed in the SR and MR groups when compared with the BMS group (BMS, 1.49+/-1.12 mm2; SR, 0.94+/-0.76 mm2 [P=0.004]; and MR, 1.06+/-0.90 mm2 [P=0.02]). Between 6 months and 2 years, the BMS group showed compaction of the neointima (Delta, -0.22+/-1.05 mm2 [P=0.08]). In contrast, both the SR and MR groups exhibited an increase (Delta SR, 0.30+/-0.76 mm2 (P=0.01); MR, 0.41+/-0.94 mm2 [P=0.009]). Between 6 months and 2 years, the initial increase in plaque outside the stent regressed in the BMS and SR groups to levels comparable to those after the procedure, whereas expansive remodeling partially regressed in the MR group (Delta between after the procedure and 2 years BMS, -0.34+/-1.28 mm2 [P=0.05]; SR, -0.02+/-1.40 mm2 [P=0.93]; MR, 0.32+/-1.56 mm2 [P=0.27]).

CONCLUSIONS

The 2-year follow-up demonstrates that neointimal suppression was dose independent and that this effect was still sustained at 2 years. However, the increase in area outside the stent seen at 6 months regressed to different extents in a dose-dependent manner at 2 years.

Three-year clinical follow-up after strontium-90/yttrium-90 beta-irradiation for the treatment of in-stent coronary restenosis

Because late vessel failure has been speculated as a possible limitation of vascular brachytherapy, we conducted a prospective clinical evaluation at 6, 12, 24, and 36 months of follow-up after irradiation with strontium-90/yttrium-90 for in-stent restenosis, regardless of the patient's symptomatic status. We report complete 3-year follow-up data for 106 consecutive patients. The cumulative rate of death at 6, 12, 24, and 36 months was 0.9%, 0.9%, 0.9%, and 1.9% respectively. The corresponding rates for acute ST-elevation myocardial infarction were 2.8%, 4.7%, 4.7%, and 4.7%, respectively. The cumulative rate of late thrombotic occlusion at 6, 12, 24, and 36 months was 3.8%, 4.7%, 4.7%, and 4.7%, respectively. The corresponding rates of target lesion revascularization and target vessel revascularization were 8.5% and 12.3% (p = 0.046), 14.2% (p = 0.157) and 18.0% (p = 0.046), 12.3% and 18.9% (p = 0.008), and 21.7% (p = 0.083) and 29.2% (p = 0.005), respectively. The cumulative rate of all major adverse cardiovascular events at 6, 12, 24, and 36 months was 16.1%, 24.5% (p = 0.003), 27.4% (p = 0.083), and 35.8% (p = 0.003), respectively. In conclusion, these results indicate a delayed and, even in the third year after the index procedure, continued restenotic process after beta irradiation of in-stent restenotic lesions.

Comparison of a centered 32P source wire system with a noncentered 90Sr/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.