Late total occlusion after intracoronary brachytherapy for patients with in-stent restenosis

The contemporary use of intracoronary brachytherapy for instent restenosis: A review

In-stent restenosis (ISR) has been a major limitation in interventional cardiology and constitutes nearly 10 % of all percutaneous coronary interventions in the United States. Drug-eluting stent (DES) restenosis proves particularly difficult to manage and poses a high risk of recurrence and repeat intervention. Intra-coronary brachytherapy (IBT) has been traditionally viewed as a potential treatment modality for ISR. However, its use was hindered by procedural complexity, cost, and the advent of newer-generation DES. Recent data suggests promising results regarding IBT for the treatment of resistant DES-ISR. This review addresses the mechanism of action of IBT, procedural details, and associated risks and complications of its use. It will also highlight the available clinical evidence supporting the use of IBT and the future directions of its utilization in the treatment of ISR.

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.

Is Coronary Brachytherapy Staging a Comeback for the Treatment of In-Stent Restenosis?

PURPOSE OF REVIEW

The catheter-based coronary intervention has become a well-established therapeutic modality for obstructive coronary artery disease. However, in-stent restenosis remains a significant limitation of coronary intervention despite the use of newer devices. Intravascular brachytherapy was introduced to treat recurrent in-stent restenosis but only modestly adopted. This review will discuss the mechanism of intracoronary brachytherapy, available clinical evidence of brachytherapy in recurrent in-stent restenosis treatment, and the future of coronary brachytherapy in coronary intervention.

RECENT FINDINGS

Drug-eluting stents have an inherent limitation as they leave a permanent metal layer inside an artery when deployed. Recently, drug-coated balloon technology has emerged to treat coronary artery disease as a combination of balloon angioplasty and local drug delivery without leaving a metal layer behind. Recent European guidelines recommended using drug-coated balloons when treating in-stent restenosis treatment, while the US guidelines have not yet addressed the use of drug-coated balloons in such cases. Coronary brachytherapy is a valuable addition to treat these challenging diseases despite several logistic issues. If there are newer technologies with easier setup, such as drug-coated balloons, coronary brachytherapy resurgence is improbable in the contemporary era, although it may not become obsolete.

Outcomes of intravascular brachytherapy for recurrent drug-eluting in-stent restenosis

OBJECTIVES

To examine the outcomes of vascular brachytherapy (VBT) for recurrent drug-eluting stents (DES) in-stent restenosis (ISR).

BACKGROUND

Recurrent DES-ISR can be challenging to treat. VBT has been used with encouraging results.

METHODS

We report the long-term outcomes of patients with recurrent DES-ISR treated with VBT between January 2014 and September 2018 at a tertiary care institution. The main outcome was target lesion failure (TLF), defined as the composite of clinically driven target lesion revascularization (TLR), target lesion myocardial infarction (MI), and target lesion-related cardiac death. Cox proportional hazards analysis was performed to identify variables associated with recurrent TLF.

RESULTS

During the study period, 116 patients (143 lesions) underwent VBT. Median follow-up was 24.7 (14.5-35.4) months. The incidence of TLR, target-lesion MI, and TLF was 18.9%, 5.6%,and 20.1% at 1 year, and 29.4%, 10.5%, and 32.9% at 2 years.Initial presentation with acute coronary syndrome (ACS) was independently associated with TLF (hazard ratio = 1.975, 95% CI [1.120, 3.485], p = .019). Lesions treated with intravascular ultrasound (IVUS) guidance had a lower incidence of TLR (14.3% vs. 39.6%, log-rank p = .038), and a trend toward lower incidence of TLF (19% vs. 42.6%, log-rank p = .086).

CONCLUSIONS

VBT can improve the treatment of recurrent DES-ISR, but TLF occurs in approximately one in three patients at 2 years. Initial presentation with ACS was associated with higher TLF and the use of IVUS with a trend for lower incidence of TLF.

Intravascular Brachytherapy for the Management of Repeated Multimetal-Layered Drug-Eluting Coronary Stent Restenosis

BACKGROUND

Because of the widespread acceptance of percutaneous coronary intervention with drug-eluting stents as an effective treatment strategy for in-stent restenosis, it is common to encounter multimetal layer stent restenosis in the recent years. This study aimed to evaluate the clinical outcomes of such patients treated with intravascular brachytherapy (IVBT) in comparison with other percutaneous options.

METHODS AND RESULTS

We enrolled patients who underwent percutaneous coronary intervention during the period between 2011 and 2015 for recurrent drug-eluting stents in-stent restenosis with at least 2 layers of stents at the lesion site. This analysis compared patients who underwent treatment with IVBT and those who did not (non-IVBT group). The primary end point measured was major adverse cardiac events defined as a composite of target lesion revascularization, myocardial infarction, and all-cause mortality at 12 months. Adjusted associations were measured using propensity score matching. A total of 328 percutaneous coronary intervention patients met the eligibility criteria, of which 197 patients received IVBT, and 131 patients underwent routine percutaneous intervention. The primary end point was significantly lower in patients undergoing IVBT (13.2% and 28.2%; P=0.01). A propensity score matching for risk factors of in-stent restenosis identified 182 patients. The advantages of IVBT with regard to 1-year major adverse cardiac events were confirmed in this matched cohort (13.2% and 30.8%; adjusted hazard ratio [95% CI]: 0.37 [0.18-0.73]; P<0.01).

CONCLUSIONS

In this analysis, IVBT led to significantly lower major adverse cardiac events in patients with multilayered drug-eluting stents restenosis when compared with other percutaneous options at 1-year follow-up.

Intracoronary Brachytherapy for Recurrent Drug-Eluting Stent Failure

OBJECTIVES

The study sought to report safety and long-term clinical efficacy of intravascular brachytherapy (VBT) for recurrent drug-eluting stent in-stent restenosis (DES-ISR).

BACKGROUND

Recurrent DES-ISR remains a therapeutic challenge, and VBT has been used selectively in recurrent DES failure.

METHODS

Patients undergoing VBT for recurrent DES-ISR were enrolled from a percutaneous coronary intervention registry. Clinical, procedural, VBT, and outcome data were collected for DES-ISR treated with radiation. Follow-up was obtained by phone call and clinic visits.

RESULTS

A total of 186 patients (283 lesions) were included. Mean age was 65 ± 11 years, and 115 (61.8%) were men. Mean time to failure from last failed DES implantation was 450.65 ± 50 days. Majority (95%) had >2 episodes of target lesion revascularization (TLR). Commonest presentation of DES-ISR was unstable angina (68, 30%). All lesions were treated with balloon angioplasty followed by VBT using Beta-Cath system (Best Vascular Inc., Springfield, Virginia) with a dose of 23 to 25 Gy at 2 mm from source center. Radiation was delivered to site of ISR, without procedural adverse events, in 99% cases. Incidence of TLR was 3.3% at 6 months, 12.1% at 1 year, 19.1% at 2 years, and 20.7% at 3 years. No subacute thrombosis event was noted. One patient had late thrombosis during a 3-year follow-up.

CONCLUSIONS

VBT for recurrent DES-ISR is safe, with low recurrence rates at 12 months post-procedure, and can be safely used as an effective short-term strategy. Overtime, there is a gradual attrition in patency requiring repeat intervention.

Layer-by-layer self-assembled laminin/fucoidan films: towards better hemocompatibility and endothelialization

The laminin/fucoidan multilayer film is prepared on glass via layer-by-layer self-assembly technique and monitored the assembled process by QCM-D. This film can inhibit platelets adhesion and improve ECs and EPCs adhesion.

Late results (>10 years) of intracoronary beta brachytherapy for diffuse in-stent restenosis

INTRODUCTION

Until the development of drug-eluting stents (DES), diffuse in-stent restenosis (ISR) was the main limitation of bare-metal stents in percutaneous coronary intervention (PCI). Among the different treatments available, intracoronary brachytherapy (BT) emerged as one of the most promising, although it was almost abandoned with the increasing use of DES.

OBJECTIVE

To assess the Portuguese experience with 90Sr/90Y beta brachytherapy for the treatment of diffuse ISR regarding long-term (>10 years) major adverse cardiac events (MACE) and angiographic restenosis.

METHODS

This single-center, retrospective, observational study included 12 consecutive patients treated between January and June 2001, mean age 58.6±9.9 years (range 43-77 years), 11 male. All had chronic stable angina, 75% had dyslipidemia, 58% had hypertension, 50% had peripheral arterial disease, 42% had diabetes and 50% had multivessel disease. Recurrent ISR was present in half of the patients and 11 had normal left ventricular function. After balloon dilatation, BT was performed using an Sr90/Y90 (Novoste Beta-CathTM) beta radiation source. All patients remained under dual antiplatelet therapy until scheduled nine-month follow-up angiography. Patients were followed for the occurrence of death (all-cause and cardiovascular), non-fatal myocardial infarction (MI), revascularization, stent thrombosis and angiographic restenosis. MACE were defined as the combined incidence of cardiac death, MI and urgent target vessel revascularization.

RESULTS

In all cases there was both clinical and angiographic success. In a mean follow-up of 10.9±2.5 years, 19 events occurred in seven patients: death in three (25%), only one cardiac (8.3%); ST-elevation MI in one (related to a non-target vessel) (8.3%); and 15 revascularizations in five (42%), of which nine were of the target vessel (mainly in the first two years). There was only one case of probable stent thrombosis. Angiographic restenosis at nine months was 27% (three out of 11 patients), of which two were total occlusions. Ten-year MACE-free survival was 42% (5 patients).

CONCLUSIONS

Intracoronary beta brachytherapy for the treatment of diffuse ISR in this small cohort of patients proved to be safe and efficacious, with no late adverse events related to intracoronary radiation.

Long-term safety of drug-eluting stents

Stent implantation in coronary stenosis has revolutionized the treatment of coronary artery disease. The introduction of antirestenotic drug coatings further improved their efficacy in reducing target vessel revascularizations. With increasing use of drug-eluting stents (DES), stent thrombosis (ST) rose as potentially fatal major complication. Initially, the incidence of ST late after stent implantation seemed to be similar for DES and bare metal stents until several studies proved otherwise in first-generation DES. Since then, the design and components of DES have been changed and new polymers, drugs and different combinations of platelet inhibitors have been introduced to further improve the safety of DES. In this review, the authors focus on the relationship between DES, lesion anatomy, implantation technique and pharmacology to avoid the occurrence of ST. Furthermore, the relationship between dual antiplatelet therapy, bleeding rate and its significant impact on patient outcome is discussed. Finally, some promising future concepts are highlighted.

Endovascular brachytherapy using liquid Beta-emitting rhenium-188 for the treatment of long-segment femoropopliteal in-stent stenosis

PURPOSE

To evaluate the efficacy and safety of endovascular brachytherapy with liquid beta-emitting rhenium-188 (Re-188) in patients with long-segment in-stent stenosis in the femoropopliteal segment.

METHODS

From July 2009 to April 2011, 90 consecutive patients (59 men; mean age 68.3±10.3 years, range 43-86) with symptomatic in-stent stenosis/occlusion (24.6-cm mean lesion length) of the femoropopliteal segment underwent angioplasty and subsequent endovascular brachytherapy. The liquid beta-emitting Re-188 was applied to the target lesion within an angioplasty balloon using a dose of 13 Gy at a depth of 2 mm into the vessel wall. Clinical and angiographic follow-up data were collected up to 2 years. The main study endpoints were the 6- and 12-month primary patency rates defined as <50% in-stent stenosis as detected by duplex ultrasound. Clinical endpoints were the cumulative rates of death, amputation, and bypass surgery, as well as improvement in the Rutherford category and the ankle-brachial index. Results were correlated with patient and lesion characteristics.

RESULTS

Primary technical success was achieved in all patients, with 1 early stent thrombosis, but no other complications related to the irradiation. Eighty-eight patients reached the 6-month and 82 the 12-month examinations; the primary patency was 95.2% and 79.8%, respectively. In-stent stenosis occurred in 9 patients, while 10 patients had reocclusion of the treated segment. During follow-up, there were 2 late acute thrombotic occlusions, both after discontinuation of clopidogrel. The clinical status improved in 67.0% and 62.2% of the patients after 6 and 12 months, respectively. No patient, lesion, or procedure variables were predictive of restenosis after EVBT.

CONCLUSION

EVBT with liquid beta-emitting Re-188 was safe and effective in preventing restenosis in long-segment femoropopliteal ISS.

Radiation therapy for dialysis access stenosis: unfulfilled promise or false expectations

Hemodialysis vascular access dysfunction is a major cause of morbidity and hospitalization in the hemodialysis population at a cost of well over $1 billion per annum. Venous stenosis (due to venous neointimal hyperplasia [VNH]) is the most common cause of polytetrafluroethylene PTFE) dialysis access graft and arteriovenous fistula (AVF) failure. Despite the magnitude of the clinical problem, however, there are currently no effective therapies for this condition. We and others have previously demonstrated that VNH in PTFE dialysis grafts and AVF is composed of smooth muscle cells/myofibroblasts, endothelial cells within neointimal microvessels, and peri-graft macrophages. Radiation therapy blocks the proliferation and activation of all these cell types. The current review will dissect out the available in vitro, experimental, and clinical data on the use of radiation therapy for vascular stenosis in general, and for dialysis access dysfunction in particular. It is important to try and identify whether there is still a role for radiation therapy in this specific clinical setting. We believe that this is a critically important question to answer in view of the huge unmet clinical need that is currently associated with hemodialysis vascular access dysfunction.

Cardiovascular disease associated with radiotherapy: activation of nuclear factor kappa-B

There have been several recent reports of an increased risk of cardiovascular disease after radiotherapy. Hence, with an increasing number of cancer survivors, the incidence of cardiovascular disease caused by radiotherapy will increase. The existence of a type of vascular disease, or vasculopathy, induced by radiotherapy has been known for decades. It is important to identify and understand the molecular causes of this vasculopathy to determine preventive strategies. Recently, a chronic inflammation with similarities to atherosclerosis has been observed, with activation of the transcription factor nuclear factor kappa-B (NF-κB) as a possible cause. However, the trigger for NF-κB activation is unclear although it may be that reactive oxygen species or direct DNA damage is involved. To minimize the risk of cardiovascular disease in vulnerable patients, careful selection of patients, radiation dose and fractionation are important, together with the development of new techniques that reduce radiation dose to the blood vessels. In the light of the finding of an interaction between risk factors for cardiovascular disease and radiotherapy, it is reasonable to modify these factors including diabetes mellitus, hyperlipidaemia, hypertension and smoking. We believe that preventive strategies focusing on NF-κB can reduce the risk of future adverse cardiovascular events.

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.

Interplay between heme oxygenase-1 and the multifunctional transcription factor yin yang 1 in the inhibition of intimal hyperplasia

RATIONALE

induction of heme oxygenase (HO)-1 protects against experimental atherosclerotic diseases, and certain pharmacological HO-1 inducers, like probucol, inhibit the proliferation of vascular smooth muscle cells and, at the same time, promote the growth of endothelial cells in vivo and in vitro.

OBJECTIVE

because such cell-specific effects are reminiscent of the action of the transcription factor Yin Yang (YY)1, we tested the hypothesis that there is a functional relationship between HO-1 and YY1.

METHODS AND RESULTS

we report that probucol increases the number of YY1(+) cells in rat carotid artery following balloon injury at a time coinciding with increased HO-1 expression. The drug also induces the expression of YY1 mRNA and protein in rat aortic smooth muscle cells (RASMCs) in vitro, as do other known HO-1 inducers (tert-butylhydroquinone and hemin) and overexpression of HO-1 using a human HMOX1 cDNA plasmid. Conversely, overexpression of YY1 induces expression of HO-1 in RASMCs. Induction of YY1 expression is dependent on HO-1 enzyme activity and its reaction product CO, because pharmacological inhibition of heme oxygenase activity or CO scavenging block, whereas exposure of RASMCs to a CO-releasing molecule increases, YY1 expression. Furthermore, RNA interference knockdown of YY1 prevents probucol or adeno-HO-1 from inhibiting RASMC proliferation in vitro and neointimal formation in vivo.

CONCLUSIONS

our findings show, for the first time, that HO-1 functionally interplays with the multifunctional transcription factor YY1 and that this interplay explains some of the protective activities of HO-1.

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.

Non thermal irreversible electroporation: novel technology for vascular smooth muscle cells ablation

Background

Non thermal Irreversible electroporation (NTIRE) is a new tissue ablation method that induces selective damage only to the cell membrane while sparing all other tissue components. Our group has recently showed that NTIRE attenuated neointimal formation in rodent model. The goal of this study was to determine optimal values of NTIRE for vascular smooth muscle cell (VSMC) ablation.

Methods and Results

33 Sprague-Dawley rats were used to compare NTIRE protocols. Each animal had NTIRE applied to its left common carotid artery using a custom-made electrodes. The right carotid artery was used as control. Electric pulses of 100 microseconds were used. Eight IRE protocols were compared: 1–4) 10 pulses at a frequency of 10 Hz with electric fields of 3500, 1750, 875 and 437.5 V/cm and 5–8) 45 and 90 pulses at a frequency of 1 Hz with electric fields of 1750 and 875 V/cm. Animals were euthanized after one week. Histological analysis included VSMC counting and morphometry of 152 sections. Selective slides were stained with elastic Van Gieson and Masson trichrome to evaluate extra-cellular structures. The most efficient protocols were 10 pulses of 3500 V/cm at a frequency of 10 Hz and 90 pulses of 1750 V/cm at a frequency of 1 Hz, with ablation efficiency of 89±16% and 94±9% respectively. Extra-cellular structures were not damaged and the endothelial layer recovered completely.

Conclusions

NTIRE is a promising, efficient and simple novel technology for VMSC ablation. It enables ablation within seconds without causing damage to extra-cellular structures, thus preserving the arterial scaffold and enabling endothelial regeneration. This study provides scientific information for future anti-restenosis experiments utilizing NTIRE.

[Late stent thrombosis]

INTRODUCTION

Late stent thrombosis is a serious complication after stent implantation and it can lead to the development of acute myocardial infarction or death.

A CASE REPORT

A 43-year-old patient was admitted to our clinic to coronary care unit. He was diagnosed with acute ST elevation myocardial reinfarction of inferoposterior localization and with right ventricular myocardial infarction. Eighteen months ago, he had acute myocardial infarction of the same localization, and at the same time, PCI (Percutaneous Coronary Intervention) was performed in acute phase, and two bare metal stents were implanted. Now, the patient had chest discomfort two hours before admittance, and PCI was performed once again in acute phase. The diagnostic coronarography resulted in occlusion of the right coronary artery, on the spot of the previously implanted stents. After the passage of guidewire, the artery was recanalized, and defects of artery opacification, which might have been thrombs, were noticed. The thrombs were seen on the spots of earlier implanted stents and in the posterior inteventricular and posterolateral branches of the right coronary artery. PTCA was performed and the patient received the GP IIb/IIIa antagonist therapy after which the control coronarography showed minimal defects of artery opacification, with good anterograde flow. After complete treatment the patient was in good condition.

CONCLUSION

Late stent thrombosis, although not very often, is a very serious complication and can lead to death or acute myocardial infarction. To prevent it, it is necessary that the patient receives dual antiplatelet therapy, and that PCI procedure is performed technically correctly (suitable stent dimensions and proper stent expansion).

Local vascular dysfunction after coronary paclitaxel-eluting stent implantation

BACKGROUND

Paclitaxel-eluting stents (PES) have been shown to reduce the rate of restenosis and the need for repeated revascularization procedures compared with bare metal stents. However, long-term effects of paclitaxel on vascular function are unknown. The purpose of the present study was to assess coronary vasomotor response to exercise after paclitaxel-eluting stent implantation.

METHODS

Coronary vasomotion was evaluated by biplane quantitative coronary angiography at rest and during supine bicycle exercise in 27 patients with coronary artery disease. Twelve patients were treated with a bare metal stent (controls), and fifteen patients with a paclitaxel-eluting stent. All patients were restudied 6+/-2 (range 2-12) months after stent implantation. Minimal luminal diameter, stent diameter, proximal, distal and a reference vessel diameter were determined.

RESULTS

Reference vessels showed exercise-induced vasodilation in both groups (+20+/-5% controls; +26+/-3% PES group). Vasomotion within the stented vessel segments was abolished. In the controls, the adjacent segments proximal and distal to the stent showed exercise-induced vasodilation (+17+/-3% and +24+/-4%). In contrast, there was exercise-induced vasoconstriction of the proximal and distal vessel segments adjacent to the paclitaxel-eluting stent (-13+/-6% and -18+/-4%; p<0.005). After sublingual nitroglycerin, the proximal and distal vessel segments dilated in both groups. Exercise-induced vasoconstriction adjacent to paclitaxel-eluting stent correlated inversely with the time interval after stent implantation.

CONCLUSIONS

Paclitaxel-eluting stent implantation is associated with exercise-induced vasoconstriction in the persistent region suggesting endothelial dysfunction as the underlying mechanism. Improvement of vascular function occurs over time, indicating delayed vascular healing.

Clinical end points in coronary stent trials: a case for standardized definitions

BACKGROUND

Although most clinical trials of coronary stents have measured nominally identical safety and effectiveness end points, differences in definitions and timing of assessment have created confusion in interpretation.

METHODS AND RESULTS

The Academic Research Consortium is an informal collaboration between academic research organizations in the United States and Europe. Two meetings, in Washington, DC, in January 2006 and in Dublin, Ireland, in June 2006, sponsored by the Academic Research Consortium and including representatives of the US Food and Drug Administration and all device manufacturers who were working with the Food and Drug Administration on drug-eluting stent clinical trial programs, were focused on consensus end point definitions for drug-eluting stent evaluations. The effort was pursued with the objective to establish consistency among end point definitions and provide consensus recommendations. On the basis of considerations from historical legacy to key pathophysiological mechanisms and relevance to clinical interpretability, criteria for assessment of death, myocardial infarction, repeat revascularization, and stent thrombosis were developed. The broadly based consensus end point definitions in this document may be usefully applied or recognized for regulatory and clinical trial purposes.

CONCLUSION

Although consensus criteria will inevitably include certain arbitrary features, consensus criteria for clinical end points provide consistency across studies that can facilitate the evaluation of safety and effectiveness of these devices.

Stent thrombosis in randomized clinical trials of drug-eluting stents

BACKGROUND

Definitions of stent thrombosis that have been used in clinical trials of drug-eluting stents have been restrictive and have not been used in a uniform manner.

METHODS

We applied a hierarchical classification of stent thrombosis set by the Academic Research Consortium (ARC) across randomized trials involving 878 patients treated with sirolimus-eluting stents, 1400 treated with paclitaxel-eluting stents, and 2267 treated with bare-metal stents. We then pooled 4 years of follow-up data. All events were adjudicated by an independent clinical-events committee.

RESULTS

The cumulative incidence of stent thrombosis according to the original protocol definitions was 1.2% in the sirolimus-stent group versus 0.6% in the bare-metal-stent group (P=0.20; 95% confidence interval [CI], -0.4 to 1.5) and 1.3% in the paclitaxel-stent group versus 0.8% in the bare-metal-stent group (P=0.24; 95% CI, -0.3 to 1.4). The incidence of definite or probable stent thrombosis as defined by the ARC was 1.5% in the sirolimus-stent group versus 1.7% in the bare-metal-stent group (P=0.70; 95% CI, -1.5 to 1.0) and 1.8% in the paclitaxel-stent group versus 1.4% in the bare-metal-stent group (P=0.52; 95% CI, -0.7 to 1.4). The incidence of definite or probable events occurring 1 to 4 years after implantation was 0.9% in the sirolimus-stent group versus 0.4% in the bare-metal-stent group and 0.9% in the paclitaxel-stent group versus 0.6% in the bare-metal-stent group.

CONCLUSIONS

The incidence of stent thrombosis did not differ significantly between patients with drug-eluting stents and those with bare-metal stents in randomized clinical trials, although the power to detect small differences in rates was limited.

Characterizing the spectrum of in-stent restenosis: implications for contemporary treatment

BACKGROUND

Reports addressing treatment of in-stent restenosis (ISR) are principally derived from clinical trials.

OBJECTIVES

To characterize the spectrum of ISR in an unselected population, and to explore clinical and angiographic factors determining management.

METHODS

During a prespecified six-month period before the introduction of drug-eluting stents, consecutive cases of ISR that were identified during clinically driven cardiac catheterization at five hospitals offering all approved treatment modalities for ISR were prospectively registered.

RESULTS

ISR was identified in 363 patients; 301 (84%) had one ISR lesion and 62 (16%) had multiple lesions. Unstable clinical presentations accounted for 51%, including 15% with ST-elevation myocardial infarction. The median interval (25th, 75th percentiles) from stent insertion to angiographic diagnosis of ISR was eight months (Q1,Q3: 4,15), with a median stented length of 18 mm (Q1,Q3: 15,28). The majority of lesions (60%) displayed a diffuse ISR pattern (Mehran types 2 and 3). ISR type was independent of time to re-presentation, diabetes, arterial territory and total stent length. Treatment included percutaneous coronary intervention (PCI) alone (n=139 [38%]), PCI with brachytherapy (n=105 [29%]), medical therapy (n=60 [17%]) and coronary artery bypass graft surgery (n=59 [16%]). Medical therapy was associated with small vessel size and recurrent ISR, and coronary artery bypass graft surgery was associated with multiple lesions, as well as diffuse, occlusive and recurrent ISR. For patients treated percutaneously, PCI treatment alone was more common for focal restenosis and after ST-elevation myocardial infarction, and brachytherapy was the more common treatment for diffuse and recurrent ISR, and stable angina.

CONCLUSIONS

These data provide a benchmark description of the spectrum of ISR with which the impact of drug-eluting stents may be compared and better understood.

Gene therapy for restenosis: biological solution to a biological problem

Coronary artery disease remains a significant health threat afflicting millions of individuals worldwide. Despite the development of a variety of technologies and catheter based interventions, post-procedure restenosis is still a significant concern. Gene therapy has emerged as a promising approach aimed at modification of cellular processes that give rise to restenosis. When juxtaposed alongside the failure of traditional pharmacotherapeutics to eliminate restenosis, gene therapy has engendered great expectations for cubing coronary restenosis. In this review we have discussed an overview of gene therapy approaches that hve been utilized to reduce restenosis in preclinical and clinical studies, current status of anti-restenosis gene therapy and perspectives on its future application. For brevity, we have limited our discussion on anti-restenosis gene therapy to the introduction of a nucleic acid to the cell, tissue, organ or organism in order to give rise to the expression of a protein, the function of which will confer therapeutic effect. For the purpose of this review, we have focused ou discussion on two relevant anti-restenosis strategies, anti-proliferative and pro-endothelialization.

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.

Probucol inhibits in-stent thrombosis and neointimal hyperplasia by promoting re-endothelialization

BACKGROUND

Evidence suggests that delayed re-endothelialization is responsible for in-stent thrombosis. Probucol inhibits neointimal thickening in animals via enhanced re-endothelialization and is the only oral drug that consistently inhibits restenosis after coronary angioplasty in humans. Here, we examined the effects of probucol on re-endothelialization and neointimal formation in a stent model.

METHODS AND RESULTS

New Zealand White rabbits were fed a hypercholesterolemic diet with probucol (1%) or without (control) (n=11 each) for 6 weeks. At 2 weeks, endothelial denudation and stenting of the iliac artery was performed. Iliac arteries were harvested at week 6, and stented segments sectioned and analyzed. Compared with control, probucol increased in-stent re-endothelialization (74+/-6% in controls versus 93+/-3% in probucol-treated; P=0.008), and decreased average luminal stenosis (58+/-27 versus 31+/-16%; P=0.01) and stent depth (619+/-310 versus 314+/-158 microm; P=0.009). Compared with control, probucol also decreased accumulation of macrophages in the neointima. Furthermore, none of the probucol-treated rabbits had in-stent thrombosis, whereas four of eleven control rabbits showed thrombosis (P=0.04).

CONCLUSIONS

Probucol demonstrates anti-restenotic and appears to have anti-thrombotic properties that are likely related to its ability to promote in-stent re-endothelialization.

Granulation encapsulated stent: a new therapeutic approach for vascular implantation

OBJECTIVES

To determine if stents could be encapsulated with immunocompatible granulation tissue for the treatment of vascular diseases.

METHODS

Bare metal stents were implanted in New Zealand white rabbits so they would be encapsulated with immunocompatible granulation tissue. The granulation encapsulated stents (GES) were then treated with either mitomycin C or saline, and implanted into rabbit iliac arteries for 4 weeks. To test whether the effect of mitomycin C was retained, we co-cultured smooth muscle cells for 3 h with subcutaneous tissue (as control) or with granulation tissue from GES treated with mitomycin C and saline.

RESULTS

Vessels with GES treated with mitomycin C (MS) and washed with saline had significantly less neointimal area (NA) after 4 weeks (0.27 (SD 0.03) mm(2) than vessels containing bare metal stents (B) (1.15 (SD 0.10) mm(2), n = 5, p<0.05) or GES treated with saline (S) (4.78 (SD 0.72) mm(2), n = 5, p<0.05). The average vessel injury score was not significantly different among these three groups (S: 1.98 (SD 0.51), MS: 1.46 (SD 0.18) and B: 1.51 (SD 0.32)). GES treated with saline had significantly less NA than the other two groups and also blocked blood flow in the contralateral iliac artery in the abdominal aortic bifurcation immediately after implantation and 4 weeks later. Histology also showed neointimal overgrowth in the vessel wall over the contralateral iliac artery.

CONCLUSIONS

GES treated with mitomycin C can significantly inhibit neointimal formation in rabbit arteries due to the formation of granulation tissue. GES treated with saline demonstrated significantly increased NA and resisted normal rabbit artery pressures.

Effectiveness and safety of sirolimus stent implantation for coronary in-stent restenosis: the TRUE (Tuscany Registry of Sirolimus for Unselected In-Stent Restenosis) Registry

OBJECTIVES

This study sought to evaluate the effectiveness and safety of the sirolimus-eluting stent in the treatment of in-stent restenosis (ISR) in consecutive unselected patients undergoing coronary intervention in a real-world scenario.

BACKGROUND

Restenosis after bare metal stenting is characterized by a high rate of re-restenosis once treated with repeated percutaneous coronary intervention.

METHODS

The study was designed as a prospective two-center registry. We enrolled 244 patients with ISR in a native coronary artery or saphenous vein graft who had clinical indication for repeat intervention.

RESULTS

Sirolimus stent implantation was successful in all lesions. At 9-month follow-up, death occurred in 4 (1.6%) patients, myocardial infarction in 4 (1.6%), and ischemia-driven target lesion revascularization (TLR) in 12 (4.9%), for a cumulative event-free survival of 227 (93%). Although 9-month follow-up angiography was planned in all patients, only 150 (62%) patients completed it, and restenosis was present in 13 (8.7%) patients. Diabetes and non-ST-segment elevation acute coronary syndrome at presentation were the only independent predictors of freedom from ischemia-driven TLR and major adverse cardiac events.

CONCLUSIONS

Sirolimus stent implantation for the treatment of ISR is effective and safe. In diabetic patients and in those with acute coronary syndrome, the higher rate of recurrence requires further evaluation.

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.

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.

Serial angioscopic findings after successful intracoronary brachytherapy for in-stent restenosis

The intracoronary changes that occur after brachytherapy for in-stent restenosis (ISR) have yet to be fully established. The purpose of this study in patients who had ISR was to examine the serial angioscopic changes in intracoronary lesions that occurred after brachytherapy. Forty-four patients who had ISR (49 lesions) underwent balloon angioplasty (n = 34) or directional atherectomy (n = 15), followed by intracoronary brachytherapy using a beta-emitting phosphorus-32 source wire. Angioscopic investigations were performed 3 and 9 months after brachytherapy. Uncovered stents were detected in 63.3% of lesions at 3 months. A significant decrease (p = 0.028) in this prevalence occurred over the next 6 months, with 36% of lesions having uncovered stents at 9 months. At 3 months, 33% of the lesions had visible erosion or ulceration and superficial thrombus. The prevalence of these characteristics was decreased at 9 months, although 17% of the lesions were still ulcerated or eroded at that time. Protruding thrombus was not observed in any lesion at 3 and 9 months. In conclusion, uncovered stents and intimal erosions or ulcerations were still present 9 months after brachytherapy in 36% and 17% of lesions, respectively. These results suggest that the healing process was not completed 9 months after brachytherapy in approximately 33% of lesions.

Long-term clinical outcomes of dissections after intracoronary beta-radiation with rhenium-188-diethylene triamine penta-acetic acid-filled balloon system

BACKGROUND

Intracoronary radiation with a rhenium-188 ((188)Re)-filled balloon is safe and efficiently reduces restenosis, but there is a potential risk of a (188)Re-filled balloon induced dissection. Little is known about the effect of radiation on dissection resolution and the late clinical outcome of dissection after brachytherapy.

METHODS

After successful catheter-based treatments of de novo or restenotic lesion, 256 patients were randomly assigned to the radiation or control group. The (188)Re-filled balloon system was designed to deliver 17.6 Gy in 1.0-mm tissue depth.

RESULTS

Dissections were identified in 15 patients among the 138 patients of the radiation group (10.9%). Additional stents were deployed in 10 patients to cover the flow-limiting dissection. Binary restenosis rate (53.3% vs. 16.3%, p=0.001) and target vessel revascularization (TVR) rate (53.3% vs. 11.1%, p<0.001) were significantly higher in patients with the dissection at 9 months. Geographic miss (GM) was identified in 4 of the 10 patients who underwent additional stenting. Binary restenosis rate in the GM group (100%; 4 of 4 patients) was significantly higher than the non-GM group (33.3%; 2 of 6 patients, p=0.02). Long-term follow-up of the patients with dissections who had not undergone TVR (n=7, mean follow-up duration: 640.7+/-387.3 days) has demonstrated persistent unhealed dissections.

CONCLUSIONS

Intracoronary radiation impairs the healing process after vessel injury and residual dissection after brachytherapy leads to adverse clinical outcomes, which was mainly due to GM in case of stent implantation.

Endovascular gamma irradiation for the prevention restenosis after angioplasty of femoropopliteal de novo stenoses

The purpose of this study was to investigate the effectiveness and detect side effects of centered, overlapped endovascular gamma irradiation after angioplasty of de novo femoropopliteal stenoses. Thirty patients (age 65.3+/-9.2 years) with arterial occlusive disease were prospectively enrolled to receive endovascular gamma irradiation (192-iridium, 14 Gy centered at 2 mm vessel wall) immediately after percutaneous transluminal angioplasty (PTA) of femoropopliteal stenoses. Irradiation overlapped dilatation by 1-2 cm at each end. Follow-up involved angiography after 12 months; duplex sonography; and interviews before and after PTA and at 1, 6, and 12 months follow-up. PTA and centered endovascular irradiation were performed successfully in all patients. Three thromboembolic complications occurred during irradiation. Angiographic and clinical follow-up was possible in 28 patients. The angiographic degree of stenosis was 73.8%+/-16.3% before and 3.6%+/-23.5% after PTA and was 3.5%+/-43.7% at the 1-year follow-up. Restenosis (>50%) of the target lesion developed in three patients (10.7%) and edge stenoses (>30%) in nine patients (32.1%). An aneurysm of the irradiated segment in one patient was treated by stenting. The rate of retreatment was 17.9%. The vessel diameter after endovascular gamma irradiation and PTA of femoropopliteal stenoses remained stable. Restenosis, induction of edge stenoses, and aneurysm were reasons for reinterventions.

Long term outcome after intracoronary beta radiation therapy

OBJECTIVES

To determine the long term outcome after intracoronary beta radiation therapy (IRT).

SETTING

Tertiary referral centre.

METHODS

The rate of major adverse cardiac events (MACE) was retrospectively determined in 301 consecutive patients who were treated with IRT. MACE was defined as death, myocardial infarction, or any reintervention. Long term clinical outcome was obtained from an electronic database of hospital records and from questionnaires to the patients and referring physicians. Long term survival status was assessed by written inquiries to the municipal civil registries.

RESULTS

The mean (SD) follow up was 3.6 (1.2) years. The cumulative incidence of MACE at six months was 19.1%, at one year 36.4%, and at four years 58.3%. The target lesion revascularisation (TLR) rate at six months was 12.9%, at one year 28.3%, and at four years 50.4%. From multivariate analysis, dose < 18 Gy was the most significant predictor of TLR. At four years the cumulative incidence of death was 3.8%, of myocardial infarction 13.4%, and of coronary artery bypass surgery 11.3%. Total vessel occlusion was documented in 12.3% of the patients.

CONCLUSIONS

In the long term follow up of patients after IRT, there are increased adverse cardiac events beyond the first six months.

Comparison of angiographic and clinical outcomes between rotational atherectomy versus balloon angioplasty followed by radiation therapy with a rhenium-188-mercaptoacetyltriglycine-filled balloon in the treatment of diffuse in-stent restenosis

BACKGROUND

The purpose of this study was to compare the efficacy of rotational atherectomy (RA) with simple balloon angioplasty, prior to beta-radiation therapy with a rhenium-188-mercaptoacetyltriglycine (188Re-MAG3)-filled balloon for diffuse in-stent restenosis (ISR).

METHODS

After completing 50 cases with RA prior to beta-radiation (Group I), we performed optimal balloon angioplasty followed by beta-radiation in the next 53 consecutive patients (Group II) for the treatment of diffuse ISR. The radiation dose was 15 Gy at a depth of 1.0 mm into the vessel wall.

RESULTS

The baseline clinical and angiographic characteristics were similar between the two groups. The mean length of the lesion was 25.6+/-12.7 mm in Group I and 22.9+/-8.6 mm in Group II (p=0.26). Radiation was successfully delivered to all patients, with a mean irradiation time of 179+/-55 s. The 6-month angiographic restenosis rate was 10% (5/50) in Group I versus 33% (17/51) in Group II (p=0.007). No adverse event including myocardial infarction, death, or stent thrombosis occurred during the 1-year follow-up period. The risk of a target lesion revascularization or a major adverse cardiac event was significantly lower in Group I than in Group II (two patients in Group I vs. nine patients in Group II; OR, 0.20; 95% CI, 0.04-0.96; p=0.04).

CONCLUSION

Concomitant treatment with rotational atherectomy and beta-irradiation using a 188Re-MAG3-filled balloon for diffuse ISR has a synergistic effect, in terms of 6-month angiographic restenosis and 1-year cardiac event-free survival.

Pravastatin limits endothelial activation after irradiation and decreases the resulting inflammatory and thrombotic responses

Endothelial dysfunction has been implicated in the pathogenesis of atherosclerosis, fibrosis and vascular occlusion after radiation therapy. Statins have been reported to improve endothelial function; however, this beneficial effect on endothelial cells has never been investigated after irradiation. Therefore, using human microvascular endothelial cells from lung that had been irradiated with 5 or 10 Gy, we assessed the effect of pravastatin on endothelial activation by ELISA, cell-ELISA and electrophoretic mobility shift assay and increased blood-endothelial cell interactions by a flow adhesion assay. Pravastatin inhibited the overproduction of monocyte chemoattractant protein 1, IL6 and IL8 and the enhanced expression of intercellular adhesion molecule 1 but had no effect on platelet-endothelial cell adhesion molecule 1 expression. Moreover, pravastatin down-regulated the radiation-induced activation of the transcription factor activator protein 1 but not of nuclear factor-kappaB. Finally, an inhibition by pravastatin of increased adhesion of leukocytes and platelets to irradiated endothelial cells was observed. The effect of pravastatin was maintained up to 14 days after irradiation and was reversed by mevalonate. Pravastatin exerts persistent anti-inflammatory and anti-thrombotic effects on irradiated endothelial cells. Statins may be considered in therapeutic strategies for the management of patients treated with radiation therapy.

Brachytherapy for restenosis after stenting for coronary artery disease: its role in the drug-eluting stent era

PURPOSE OF REVIEW

Recent years have brought remarkable changes to the field of interventional cardiology. The need for repeat intervention due to restenosis, the most vexing long-term failure of percutaneous coronary intervention, has been significantly reduced owing to the introduction of two major advances, the vascular brachytherapy (VBT) and the drug-eluting stents (DES).

RECENT FINDINGS

Vascular brachytherapy has demonstrated its efficacy in limiting recurrence of existing in-stent restenosis. The past 2 years have sealed its reputation, with a variety of studies demonstrating its superiority over conventional therapy in challenging patient subsets with high risk for restenosis recurrence. Moreover, the long-term follow-up confirmed durability of this therapy, and the failures of VBT were characterized as easy to treat. Conversely, DES have shown spectacular efficacy at primarily preventing the first restenosis episode following the initial stent placement. Consequently, the role of VBT may be minimized, as the overall need for repeat revascularization is diminished as a result of the wide acceptance of DES. Furthermore, if the capacity of DES to treat in-stent restenosis is confirmed in randomized trials, they may eventually supersede VBT as the therapy of choice for in-stent restenosis.

SUMMARY

At present, VBT is the proven and durable therapeutic choice for patients with complex, diffuse in-stent restenosis who would otherwise have a very poor prognosis for long-term event-free survival. DES have emerged as remarkably effective in minimizing the first restenosis occurrence; they also represent a promising and competitive alternative to VBT for the treatment of in-stent restenosis.

Effects of probucol versus aspirin and versus brachytherapy on restenosis after femoropopliteal angioplasty: the PAB randomized multicenter trial

PURPOSE

To evaluate the effect of probucol and/or of endovascular brachytherapy (EVBT) on restenosis after percutaneous transluminal angioplasty (PTA) of femoropopliteal arteries.

METHODS

A total of 335 patients (206 men; mean age 72+/-9 years) with intermittent claudication were randomized according to a 2x2 factorial design to 1 of the 4 groups: probucol, placebo, EVBT, and EVBT+probucol. Probucol (1 g/d) or placebo were given in double-blinded fashion 1 month before and for 6 months after PTA. Gamma irradiation (192Iridium, 14 Gy, 5-mm reference depth) was randomly applied in an unblinded manner from a noncentered endoluminal catheter. All patients received aspirin (100 mg/d). Primary endpoint was restenosis (>50% diameter reduction) detected by duplex ultrasound 6 months after PTA. Secondary endpoints included clinical and hemodynamic assessment.

RESULTS

Restenosis in patients undergoing EVBT was 17% (23/133) versus 35% (50/142) in patients without EVBT (p<0.001); in patients treated with probucol versus placebo, the rates were 23% (31/135) and 30% (43/140, p<0.001). Three quarters (77%, 102/133) of patients were free of claudication after EVBT therapy versus 61% (87/142) without EVBT (p<0.05). Need for target vessel revascularization was 6% (8/133) with EVBT versus 14% (20/142) without EVBT (p<0.01). Late thrombotic occlusions occurred in 4% (6/133), exclusively in patients treated with EVBT after stent implantation.

CONCLUSIONS

Endovascular brachytherapy significantly reduces restenosis, improves symptoms, and reduces reinterventions after PTA of femoropopliteal arteries. Probucol reduces restenosis but has no additive effect when combined with brachytherapy.

[Late stent-thrombosis-related myocardial infarction]

The objective of the study was to assess the frequency of late stent-thrombosis-related acute myocardial infarction in patients with LAD stents. A series of 930 PCI procedures involving LAD stenting were performed in 920 patients (mean age: 63 years, 667 men) from January 1999 to December 2001. Among those 14 patients had late (> 30 days), thrombosis-related acute myocardial infarction after a mean delay of 135 +/- 131 days. Three-year thrombosis-free survival was 97.6%. By univariate analysis, risk of late thrombosis was associated with LAD-diagonal bifurcation stenting, placement of a stent on the ostium of a diagonal branch and number of stents implanted on the LAD. Patients with these risk factors might be appropriate candidates for long-term combined antiplatelet therapy.

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

OBJECTIVE

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

METHODS AND RESULTS

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

CONCLUSION

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