Endoluminal beta-radiation therapy for the prevention of coronary restenosis after balloon angioplasty. The Dose-Finding Study Group

Extreme coronary radiation doses from intravascular brachytherapy

PURPOSE

To evaluate coronary artery integrity after very high radiation doses from intravascular brachytherapy (IVBT) in the setting of source asymmetry.

METHODS

Ten patients treated for right coronary artery (RCA) in-stent restenosis (ISR) between 2017 and 2021 and for whom follow-up angiograms were available were identified from departmental records. Procedural angiograms, taken to document source position, were used to estimate vascular wall doses. The 2.5 mm proximal source marker was used to estimate the distance from source center to the media and adventitia. Distances were converted to dose (Gy) using the manufacturers' dose fall-off table, measured in water. Follow-up films were scrutinized for any sign of late vascular damage.

RESULTS

The average minimal distance from catheter center to the adjacent media and the adventitia was 0.9 mm (±0.2) mm and 1.4 mm (±0.2), respectively. The average maximum media and adventitial doses adjacent to the source were 75 Gy (±26) and 39 Gy (±14), respectively. Follow-up angiograms were available from 0.6 years to 3.9 years following IVBT (median: 1.6 years). No IVBT-treated vascular segment showed signs of degeneration, dissection or aneurysm.

CONCLUSION

IVBT vascular wall doses are frequently far higher than prescribed. The lack of complications in this unselected group of patients gives a modicum of reassurance that raising the prescription dose is unlikely to lead to a sudden appearance of complications.

Improved safety and quality in intravascular brachytherapy: A multi-institutional study using failure modes and effects analysis

PURPOSE

Highlight safety considerations in intravascular brachytherapy (IVBT) programs, provide relevant quality assurance (QA) and safety measures, and establish their effectiveness.

METHODS AND MATERIALS

Radiation oncologists, medical physicists, and cardiologists from three institutions performed a failure modes and effects analysis (FMEA) on the radiation delivery portion of IVBT. We identified 40 failure modes and rated the severity, occurrence, and detectability before and after consideration of safety practices. Risk priority numbers (RPN) and relative risk rankings were determined, and a sample QA safety checklist was developed.

RESULTS

We developed a process map based on multi-institutional consensus. Highest-RPN failure modes were due to incorrect source train length, incorrect vessel diameter, and missing prior radiation history. Based on these, we proposed QA and safety measures: ten of which were not previously recommended. These measures improved occurrence and detectability: reducing the average RPN from 116 to 58 and median from 84 to 40. Importantly, the average RPN of the top 10% of failure modes reduced from 311 to 172. With QA considered, the highest risk failure modes were from contamination and incorrect source train length.

CONCLUSIONS

We identified several high-risk failure modes in IVBT procedures and practical safety and QA measures to address them.

Increased prescription dose for large vessel intravascular brachytherapy

BACKGROUND

Most randomized studies testing the effectiveness of IVBT were limited to vessels less than 4 mm diameter. In fact, it is now common to treat vessels larger than 4 mm. Accordingly, the authors instituted a prescription dose increase to 34 Gy at 2 mm from source center for vessels greater than 4.0 mm. The increase in prescription dose to 34 Gy at 2 mm from center is substantial, being 50% higher than the conventional maximum of 23 Gy.

AIM

To take a close look at group of patients treated to 34 Gy, and for whom follow-up angiograms are available.

METHODS

Ten patients treated for ISR with a prescription dose of 34 Gy and for whom follow-up angiograms were available were studied. Beta-radiation brachytherapy was performed with a Novoste Beta-Cath System using a strontium-90 (beta) source (Best Vascular, Springfield, VA). Source lengths of 40 or 60 mm were used. A dose of 34 Gy was prescribed at 2 mm from the source center.

RESULTS

Patients were re-catheterized from 2 to 21 months (median: 16 months) following IVBT, all for symptoms suggested of restenosis. All patients had some degree of ISR of the target vessel, but no IVBT-treated vascular segment showed angiographic signs of degeneration, dissection or aneurysm.

CONCLUSION

The authors' clinical impression, along with detailed review of the 10 cases, suggest that using a 34 Gy prescription dose at 2 mm from source center does not result in increased toxicity.

Image-guided intravascular brachytherapy dose escalation

PURPOSE

Coronary stents reduce IVBT radiation dose with a single layer by 10-30%. However, the impact of multiple stent layers and stent expansion remains unexplored. Individualized dose adjustments considering variations in stent layers and expansion could improve radiation delivery effectiveness.

METHODS

EGSnrc was used to compute the delivered vessel wall dose in various IVBT scenarios. Stent effects were modeled for the stent density of 25%, 50%, and 75% with 1, 2, and 3 layers respectively. Doses were calculated at 1.75 to 5.00 mm away from the source center, normalized to 100% at 2 mm.

RESULTS

Dose fall-off increased with increasing stent density. With a single layer, the dose at 2 mm from source fell from 100% of prescription to 92%, 83% and 73% at 25%, 50% and 75% density, respectively. The computed dose to points with increasing radial distance from the source decreased progressively with increasing stent layers. With three layers, at 75% stent density, the dose at 2 mm from source center fell to 38%.

CONCLUSIONS

A schema for image-guided IVBT dose adjustment is described. While it would be an improvement over current standard of care, myriad factors remain to be addressed in a comprehensive effort to optimize IVBT.

The Ongoing Saga of the Evolution of Percutaneous Coronary Intervention: From Balloon Angioplasty to Recent Innovations to Future Prospects

The advances in percutaneous coronary intervention (PCI) have been, above all, dependent on the work of pioneers in surgery, radiology, and interventional cardiology. From Grüntzig's first balloon angioplasty, PCI has expanded through technology development, improved protocols, and dissemination of best-practice techniques. We can nowadays treat more complex lesions in higher-risk patients with favourable results. Guide wires, balloon types and profiles, debulking techniques such as atherectomy or lithotripsy, stents, and scaffolds all represent evolutions that have allowed us to tackle complex lesions such as an unprotected left main coronary artery, complex bifurcations, or chronic total occlusions. Best-practice PCI, including physiology assessment, imaging, and optimal lesion preparation are now the gold standard when performing PCI for sound indications, and new technologies such as intravascular lithotripsy for lesion preparation, or artificial intelligence, are innovations in the steps of 4 decades of pioneers to improve patient care in interventional cardiology. In the present review, major innovations in PCI since the first balloon angioplasty and also uncertainties and obstacles inherent to such medical advances are described.

Failure patterns after intravascular brachytherapy for in-stent coronary restenosis

INTRODUCTION

One strategy to improve the effectiveness of intravascular brachytherapy (IVBT) is to study its failures. Previous investigations described mostly discrete, focal recurrences, typically at the proximal or distal edges of the irradiated segment after plain angioplasty or bare metal stents. We reviewed failure patterns of 30 unselected drug-eluting stent (DES) patients who had follow-up angiograms for recurrence within their IVBT-treated vessel.

METHODS

Records of 53 unselected IVBT patients treated between 2016 and 2021 were reviewed. Thirty of the 53 patients had at least one subsequent percutaneous intervention (PCI) for in-stent restenosis (ISR) after IVBT. Angiographic findings of those 30 patients with ISR within their previously irradiated vessel are reported here.

RESULTS

Of the 30 patients, 21 (70%) developed recurrent ISR within the irradiated segment. Six of the 21 patients who failed within the irradiated segment also experienced ISR proximal or distal to the irradiated segment. Only 15 patients (50%) failed exclusively within the irradiated segment. In nine patients (30%), restenosis occurred proximally and/or distally to the irradiated segment, but not inside of the irradiated segment itself.

CONCLUSIONS

We have shown here that 50% of failures after coronary IVBT for DES ISR occur exclusively within the irradiated segment. An additional 20% of patients had failure within and outside of the irradiated segment. These percentages suggest that a higher radiation dose might improve the long-term patency rates, a conclusion that should be tempered by the lack of universal follow-up.

Conundrums of coronary brachytherapy

PURPOSE

In the 1998-2005 heyday of intravascular coronary brachytherapy, a variety of delivery devices were developed and marketed. As the industry shrank, only one device, the Novoste Beta-Cath 3.5F System (Best Vascular, Norcross, GA) remained in commercial production. The 2008 instruction manual, the only official source of technical guidance, lacks recommendations for various common scenarios.

METHODS AND MATERIALS

The clinical conundrums described here were encountered during regular use of the Novoste system in 81 patients treated from January to December of 2020 in the course of using the Novoste device in accordance with the 2008 manufacturer's instruction manual. Our experience and strategies are reported and critiqued.

RESULTS

Ambiguous patient selection factors include vein grafts, multiple affected vessels, large vessels, retreatment, multiple overlapping stents and prior radiation. Procedural ambiguities include vessel size determination, proper prescription dose, very long lesions and eccentric source positioning. Potential procedural mishaps include stuck sources and the risk of contamination.

CONCLUSIONS

The Novoste intravascular coronary brachytherapy system is the only commercially available brachytherapy delivery catheter, and may remain so for some time. The issues detailed here provide insight and guidance for current users and may prompt research into areas lacking adequate information.

Radiation-Induced Coronary Artery Disease and Its Treatment: A Quick Review of Current Evidence

As advances in medical technology arise and the availability of cancer treatment increases, an increased number of patients are receiving cancer treatment. Radiation therapy has evolved to become one of the cornerstones of treatment for various types of cancers. One of the long-term consequences of radiation therapy is radiation-induced coronary artery disease (RICAD). Although the pathophysiology of RICAD may be slightly different and more acute onset than the commonly seen “generic” coronary artery disease, it is common practice to treat RICAD in the same method as nonradiation-induced CAD. This paper summarizes the current research available on the topic and shows there is not enough research to obtain significant data about outcomes and restenosis rates of PCI or outcomes of CABG in RICAD. The aim of this review is to create a concise and easy-to-follow review of the relevant data regarding RICAD and hopefully spark further interest in future studies in this field.

Radiation suppresses neointimal hyperplasia through affecting proliferation and apoptosis of vascular smooth muscle cells

PURPOSE

To study the effect of x-ray radiotherapy on vascular smooth muscle cells (VSMCs) and elucidate the mechanisms in preventing neointimal hyperplasia of prosthetic vascular grafts.

MATERIALS AND METHODS

In model I, twelve mongrel dogs underwent revascularization with prosthetic grafts and half the dogs underwent irradiation of the grafts at 28 Gy. In model II, human VSMCs (hVSMCs) were maintained and divided into six groups to which external radiation was applied at six different doses: 0 Gy, 2 Gy, 8 Gy, 16 Gy, 24 Gy and 30 Gy. In both models, specimens were harvested and examined by using morphological, immunological, cellular and molecular methods.

RESULTS

After irradiation, the neointima thickness was significantly lower in irradiated groups (p≤0.01). The radiotherapy could up-regulate p27^kip1, and down-regulate proliferating cell nuclear antigen (PCNA) and S phase kinase associated protein 2 (Skp2). X-ray irradiation inhibits the proliferation of hVSMCs via acting on G1/S phase of cell cycle. The apoptosis of hVSMCs increased significantly with dose and time. The expression of PCNA and Skp2 were decreased after a first increasing trend with dose, but had a significant negative correlation with time. The expression of p27^kip1 had a significant positive correlation with dose and time.

CONCLUSIONS

Postoperative external fractionated irradiation after prosthetic vessel replacement of the abdominal aorta suppressed the development of hyperplasia in the graft neointima in the short term. There was a prominent time- and dose-dependent inhibition of VSMC proliferation by radiation when it was administered.

Ten Years of Advancements in Interventional Cardiology

The past decade has seen the evolution of an exciting technology that has changed forever the treatment of aortic aneurysmal disease. From rather crude homemade stent-grafts constructed in the surgical suite to elegant commercially manufactured devices in a variety of configurations and sizes, the aortic endograft has experienced a meteoric rise in popularity to become a beneficial, minimally invasive therapy that can obviate the risk of rupture and death. There are now 3 approved endovascular devices on the market for infrarenal abdominal aortic aneurysm repair, and it is likely that additional and improved devices will become available in the future. This review revisits the developmental history of the aortic endograft, noting the ongoing refinements that have arisen from our experiences with the growing population of stent-graft patients. Although research continues to search for solutions to the problems of endoleak and migration, long-term results even with the earlier second and third-generation devices are better than has been achieved with open surgical repair.

Intravascular brachytherapy for peripheral vascular disease

BACKGROUND

Interventional treatment of arteries that are narrowed and obstructed by atherosclerosis involves either bypassing the blockage using a graft; widening the artery from the inside with a balloon, a procedure known as percutaneous transluminal angioplasty (PTA); or providing a strut to hold the vessel open, known as a stent. All of these treatments are, however, limited by the high numbers that fail within a year. Intravascular brachytherapy is the application of radiation directly to the site of vessel narrowing. It is known to inhibit the processes that lead to restenosis (narrowing) of vessels and grafts after treatment. This is an update of a review first published in 2002.

OBJECTIVES

To assess the efficacy of, and complications associated with, intravascular brachytherapy (IVBT) for maintaining patency after angioplasty or stent insertion in native vessels or bypass grafts of the iliac or infrainguinal arteries.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched their Specialised Register (last searched August 2013) and CENTRAL (2013, Issue 7).

SELECTION CRITERIA

Randomised controlled trials of the use of brachytherapy as an adjunct to the endovascular treatment of people with peripheral arterial disease (PAD) or stenosed bypass grafts of the iliac or infrainguinal arteries versus the procedure without brachytherapy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and two other review authors independently extracted the data. Adverse event information was collected from the trials.

MAIN RESULTS

Eight trials with a combined total of 1090 participants were included in this review. All included studies used the femoropopliteal artery. We did not identify any studies that used the iliac arteries. All studies compared PTA with or without stenting plus IVBT versus PTA with or without stenting alone. No trials were found comparing IVBT to technologies such as drug eluting stents or balloons, or cryoplasty. Follow-up ranged from six months to five years. The quality of the included trials was moderate with our concerns relating to the difficulty of blinding due to the nature of the procedures and the small sample sizes for some studies. Primary outcomes (patency or restenosis and need for re-intervention) were reported in the majority of the trials, but reporting at various time points and the use of multiple definitions of the outcomes by the included studies meant that not all data were available for pooling. The secondary outcomes were not reported in many of the included studies.For brachytherapy, cumulative patency was higher at 24 months (odds ratio (OR) 2.36, 95% confidence interval (CI) 1.36 to 4.10, n = 222, P = 0.002). A statistically significant difference was found for restenosis at six months (OR 0.27, 95% CI 0.11 to 0.66, n = 562, P = 0.004), 12 months (OR 0.44, 95% CI 0.28 to 0.68, n = 375, P = 0.0002) and 24 months (OR 0.41, 95% CI 0.21 to 0.78, n = 164, P = 0.007) in favour of IVBT. No difference was found after five years as measured in one study. The need for re-interventions was reported in six studies. Target lesion revascularisation was significantly reduced in trial participants treated with IVBT compared with angioplasty alone (OR 0.51, 95% CI 0.27 to 0.97, P = 0.04) at six months after the interventions. No statistically significant difference was found between the procedures on the need for re-intervention at 12 and 24 months after the procedures.A statistically significant lower number of occlusions was found in the control group at more than three months (OR 11.46, 95% CI 1.44 to 90.96, n = 363, P = 0.02) but no differences were found at less than one month nor at 12 months after the procedures making the clinical significance uncertain. Ankle brachial index was statistically significantly better for IVBT at the 12 month follow-up (mean difference 0.08, 95% CI 0.02 to 0.14, n = 100, P = 0.02) but no statistically significant differences were found at 24 hours and at six months.Quality of life, complications, limb loss, cardiovascular deaths, death from all causes, pain free walking distance and maximum walking distance on a treadmill were similar for the two arms of the trials with no statistically significant difference found between the treatment groups.

AUTHORS' CONCLUSIONS

The evidence for using peripheral artery brachytherapy as an adjunct to percutaneous transluminal angioplasty to maintain patency and for the prevention of restenosis in people with peripheral vascular disease is limited, mainly due to the inconsistency of assessment and reporting of clinically relevant outcomes. More data are needed on clinically relevant outcomes such as health related quality of life (HRQOL) or limb salvage and longer-term outcomes, together with comparisons with other techniques such as drug eluting balloons and stents. Adequately powered randomised controlled trials, health economics and cost-effectiveness data are required before the procedure could be recommended for widespread use.

Radiation coronary arteritis refractory to surgical and percutaneous revascularization culminating in orthotopic heart transplantation

BACKGROUND

Hodgkin's lymphoma (HL) comprises of 4% of malignancies diagnosed in children from birth to 14 years of age. While overall survival rates have increased, HL survivors can be at risk of late cardiovascular complications from radiotherapy. HL survivors with a history of mediastinal RT have been found to have an increased incidence of myocardial infarction, angina, congestive heart failure, and valvular disorders compared to the general population.

METHODS

A 33 year old female with a history of HL status post chemotherapy and mediastinal radiation 11 years ago became symptomatic with multivessel coronary artery disease with aggressive progression of her disease despite coronary bypass graft surgery, patch angioplasty of the left main coronary artery (LMCA) with an extracellular bioscaffold, and repeated percutaneous coronary intervention of the LMCA. She eventually underwent orthotopic heart transplant and did well postoperatively.

RESULTS

Histopathological analysis of the explanted heart revealed a variety of sequelae of radiation arteritis, including thrombosis of both native vessels and arterial grafts, intimal hyperplasia and involvement of the bioscaffold in the left main coronary vasculature. The bioscaffold did not contribute significantly to the stenosis within the LMCA.

CONCLUSION

Our case demonstrates an unusual indication for OHT due to severe refractory radiation induced CAD, as well the wide spectrum of the histopathologic manifestations of radiation induced arteritis.

Highly cited German research contributions to the fields of radiation oncology, biology, and physics: focus on collaboration and diversity

BACKGROUND AND PURPOSE

Tight budgets and increasing competition for research funding pose challenges for highly specialized medical disciplines such as radiation oncology. Therefore, a systematic review was performed of successfully completed research that had a high impact on clinical practice. These data might be helpful when preparing new projects.

METHODS

Different measures of impact, visibility, and quality of published research are available, each with its own pros and cons. For this study, the article citation rate was chosen (minimum 15 citations per year on average). Highly cited German contributions to the fields of radiation oncology, biology, and physics (published between 1990 and 2010) were identified from the Scopus database.

RESULTS

Between 1990 and 2010, 106 articles published in 44 scientific journals met the citation requirement. The median average of yearly citations was 21 (maximum 167, minimum 15). All articles with ≥ 40 citations per year were published between 2003 and 2009, consistent with the assumption that the citation rate gradually increases for up to 2 years after publication. Most citations per year were recorded for meta-analyses and randomized phase III trials, which typically were performed by collaborative groups.

CONCLUSION

A large variety of clinical radiotherapy, biology, and physics topics achieved high numbers of citations. However, areas such as quality of life and side effects, palliative radiotherapy, and radiotherapy for nonmalignant disorders were underrepresented. Efforts to increase their visibility might be warranted.

Treatment of small coronary arteries with a paclitaxel-coated balloon catheter

BACKGROUND

Treatment of lesions in small coronary arteries by percutaneous transluminal coronary intervention is limited by a high recurrence rate. We assessed the use of a paclitaxel-coated balloon in this indication.

METHODS

One-hundred eighteen patients with stenoses in small coronary vessels were treated by a paclitaxel-coated balloon (3 microg/mm(2)). The main inclusion criteria encompassed diameter stenosis of > or =70% and < or =22 mm in length with a vessel diameter of 2.25-2.8 mm. Follow-up angiography was performed at scheduled 6-month post-intervention or whenever driven by clinical or electrocardiographic signs of ischemia. The primary endpoint was angiographic in-segment late lumen loss.

RESULTS

Eighty-two of 118 patients (70%) with a vessel diameter of 2.35 +/- 0.19 mm were treated with the drug-coated balloon only, while 32 patients required additional stent deployment. The mean in-segment late lumen loss was 0.28 +/- 0.53 mm. In patients treated with the drug-coated balloon only, the in-segment late lumen loss was 0.16 +/- 0.38 mm. At 12 months, the rate of major adverse cardiac events was 15% which was primarily due to the need for target lesion revascularization in 14 patients (12%). In those with additional bare metal stent implantation geographical mismatch between coated-balloon dilatation and stent implantation was significantly associated with the occurrence of restenosis.

CONCLUSION

Treatment of coronary stenosis in small coronary vessels with the paclitaxel-coated balloon was well tolerated. It may offer an alternative to the implantation of a drug-eluting stent (ClinicalTrials.gov Identifier: NCT00404144).

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.

Outcome differences with the use of drug-eluting stents for the treatment of in-stent restenosis of bare-metal stents versus drug-eluting stents

Drug-eluting stent (DES) implantation is the standard treatment for patients with bare-metal stent (BMS) in-stent restenosis (ISR) and is associated with low rates of target-vessel revascularization. Outcomes in patients with DES ISR treated using repeated DES placement are less certain. A total of 119 patients who presented with BMS ISR and 119 patients with DES ISR matched for baseline characteristics were evaluated. Both groups of patients were treated using DESs and compared with regard to major adverse cardiac events, including death, myocardial infarction, and target-vessel revascularization, at 1 year. Baseline characteristics were similar between groups. Compared with patients with BMS ISR, those with DES ISR had similar 1-year rates of death (5.1% BMS ISR vs 3.5% DES ISR; p = 0.75) and myocardial infarction (2.6% BMS ISR vs 3.5% DES ISR; p = 0.72) when treated using DESs. However, at 1 year, patients with DES ISR experienced significantly higher rates of target-vessel revascularization (10.3% BMS ISR vs 22.2% DES ISR; p = 0.01), with a trend toward increased overall major adverse cardiac events, including death, myocardial infarction, and target-vessel revascularization (16.0% BMS ISR vs 25.2% DES ISR; p = 0.08). Stent thrombosis occurred with similar frequency in both groups (2.5% BMS ISR vs 0.8% DES ISR; p = 0.62). In conclusion, DES ISR continues to be a therapeutic challenge because patients with DES ISR treated using DESs experience higher rates of recurrence compared with patients with BMS ISR treated using DESs. The optimal treatment of patients with DES restenosis remains to be defined.

Differential citation rates of major cardiovascular clinical trials according to source of funding: a survey from 2000 to 2005

BACKGROUND

Prior work indicates that therapeutic trials funded by for-profit organizations are more likely to report positive findings than trials funded by not-for-profit organizations. What impact, if any, funding source has on subsequent dissemination of trial data is uncertain. To address this issue, we used the number of citations per publication per year to assess differences in trial dissemination according to funding source.

METHODS AND RESULTS

We assessed 303 consecutive superiority trials of cardiovascular medicine published between January 1, 2000, and July 30, 2005, in the Journal of the American Medical Association, The Lancet, and the New England Journal of Medicine. The primary outcome measure was the number of citations per publication per year up to December 31, 2006. Overall, the median number of citations per publication per year was 46 for trials funded exclusively by for-profit organizations, 37 for trials jointly funded, and 29 for trials funded by not-for-profit organizations (P=0.0007). Higher citation rates for trials funded by for-profit organizations were consistently observed in analyses stratified by journal and various trial design features and were most striking when the new intervention was favored over the standard of care; in this subgroup, the median number of citations per publication per year was 52 for trials funded by for-profit organizations compared with 25 for trials funded by not-for-profit organizations (P=0.0006). In marked contrast, in analyses limited to trials in which the new intervention was significantly worse than the standard of care, an inverse pattern was observed with fewer citations per publication per year for trials funded by for-profit organizations compared with not-for-profit organizations (33 versus 41; P=0.048). Higher citation rates were observed for industry-funded trials than for federally funded trials even when the trials dealt with similar issues and were published back-to-back in the same journal.

CONCLUSIONS

Dissemination of clinical trial results is important for clinical practice but appears to be biased in favor of for-profit entities. Consideration should be given to more extensive promotion of clinical trial results that are funded by not-for-profit organizations.

Paclitaxel-eluting stents for the treatment of complex coronary lesions: immediate and 12-month results

OBJECTIVE

One of the drug-eluting stents that have been introduced into clinical practice is the paclitaxel-eluting stent (PES). Several randomised, controlled clinical trials have already been conducted to evaluate the safety and efficacy of this stent, but data regarding clinical practice are still lacking. The aim of this study was to evaluate the safety and efficacy of PESs in a 'real-world' population.

METHODS

Two hundred and seventy-three patients with a high cardiovascular risk profile and complex coronary lesions were treated with PESs. Each patient was categorised using the following parameters: cardiovascular risk factors, clinical history, clinical presentation, angiographic pattern, and procedural characteristics. Primary endpoints were major adverse cardiac events (cardiovascular death, coronary artery bypass grafting, myocardial infarction, stroke, target vessel revascularisation, target lesion revascularisation, and remote revascularisation).

RESULTS

A low rate of intraprocedural and periprocedural complications was observed. During the clinical follow-up period (mean 10.5 +/- 4.2 months), 78% of patients were event-free. Twenty-six patients (9.8%) underwent target vessel revascularisation, but only 11 of them (4.2%) had target lesion revascularisation. Seven patients (2.7%) had myocardial infarction, and cardiac death occurred in two patients (0.76%). Only one case (0.37%) of subacute stent thrombosis and one case of late stent thrombosis were observed.

CONCLUSIONS

The present study demonstrates that the use of PESs is safe and effective also in patients with a high cardiovascular risk profile and complex coronary lesions.

Intracoronary beta-irradiation for the treatment of de novo lesions: 5-year clinical follow-up of the BetAce randomized trial

BACKGROUND

Vascular brachytherapy (VBT) has been used for the prevention of restenosis. Despite initial positive results, long-term follow-up has shown a progressive loss of benefit in clinical outcome after beta-irradiation. We report the 5-year follow-up of the BetAce trial.

METHODS

This prospective, randomized, single-blind trial included 61 patients treated for 64 de novo coronary lesions: 31 patients (33 stenoses) were treated with bare metal stents (control group), and 30 patients (31 stenoses) were treated with intracoronary beta-irradiation at the time of stented angioplasty (VBT group).

RESULTS

Baseline and procedural data were similar between treatment arms. At 6 months, VBT reduced the need for target vessel revascularization (13% vs 35.5%, P = .04), but there was no significant difference in the 6- and 12-month event-free survival when clinical events were ranked. Between 1 and 5 years, an increasing number of target vessel failures was observed in both groups, leading to a similar long-term clinical outcome at 5 years (event-free survival 43% and 45% in the VBT and control groups, respectively, log-rank 0.001, P = .9).

CONCLUSIONS

Beta-irradiation in de novo coronary lesions significantly reduced in-stent recurrences at 6 months compared with standard procedures. However, this initial benefit was not sustained in the long term. The results of this randomized study confirm the delayed and progressive restenotic process after beta-irradiation and stent implantation in de novo lesions.

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.

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.

BRAVO I: A pilot study of vascular brachytherapy in polytetrafluoroethylene dialysis access grafts

Hemodialysis vascular access dysfunction owing to stenosis and thrombosis in polytetrafluoroethylene dialysis access grafts is a huge clinical problem for which there are currently no long lasting durable therapies. Vascular brachytherapy has been used successfully for the prevention of coronary restenosis following angioplasty and stent placement. The Beta Radiation for Treatment of Arterial-Venous Graft Outflow I study was a pilot study of vascular brachytherapy in hemodialysis patients with patent but dysfunctional grafts. Twenty-five patients were randomized to receive either radiation therapy (a single dose of 18.4 Gy) or sham radiation, following angioplasty. The primary efficacy end point of the study was target lesion primary patency at 6 months. The primary safety end point was a composite of death, emergency surgery on the graft, venous rupture, or aneurysm formation. Forty-two percent of the radiated grafts achieved the target lesion primary patency end point at 6 months as compared to 0% of the control group (P = 0.015), but this did not translate into an improvement in secondary patency at either 6 or 12 months. Radiation therapy was found to be safe in the setting of hemodialysis vascular access dysfunction. Our results suggest that vascular brachytherapy is an intervention that is worthy of further examination in the setting of non-thrombosed dialysis access grafts.

Predictors of recurrent in-stent restenosis after beta-radiation: An analysis from the START 40/20 trial

OBJECTIVE

The purpose of this study was to identify potential predictors, including clinical, procedural, angiographic, and intravascular ultrasound (IVUS) parameters, for recurrent in-stent restenosis (ISR) following beta-radiation 90Strontium/Yttrium (90Sr/Y) in a large multicenter trial.

BACKGROUND

Although adjunct brachytherapy reduces recurrent ISR after primary catheter-based intervention, recurrence of stenosis after brachytherapy still occurs.

METHODS

We analyzed 185 IVUS cohort patients in the STent And Restenosis Therapy (START) 40/20 trial where a 40-mm, 90Sr/Y, radioactive source train was exclusively used for treatment of ISR to be treatable with a 20-mm balloon.

RESULTS

Thirty-nine patients underwent target lesion revascularization. Preliminary univariate analysis showed that age, smoking, balloon/artery ratio, geographic miss, minimum lumen diameter, and diameter stenosis at baseline were associated with target lesion revascularization, while none of IVUS variables were (minimum lumen area, minimum stent area, or residual plaque burden). The multivariate logistic regression analysis showed that younger age, lower balloon/artery ratio, and presence of geographic miss were independent predictors of target lesion revascularization.

CONCLUSIONS

Even with adjunct beta-radiation therapy, initial mechanical optimization, such as appropriate balloon sizing and positioning, may be critical for the prevention of recurrent ISR.

Optimization of dose prescription protocol and its impact on delivered dose and vascular response after beta-radiation for in-stent restenosis. A randomized trial with serial volumetric intravascular ultrasound and dose volume histograms

AIM

The incidence of restenosis within stented segment after intravascular brachytherapy with recommended dose prescription protocols is up to 25%. Therefore, we designed a randomized trial comparing recommended dose prescription protocol with dosing adjusted for the source-to-target distance.

METHODS

Fifty-one in-stent restenosis (ISR) lesions in 48 patients underwent centered source beta-irradiation with serial intravascular ultrasound. Patients randomly received 20 Gy at 1 mm either beyond lumen surface [n=25, standard group (S)] or external elastic membrane [n=26, dosing-adjusted (DA) group]. Minimum dose absorbed by 90% of adventitia (DV(90%Adv)) was calculated.

RESULTS

DV(90%Adv) was higher for the DA group than for the S group (21.63+/-5.67 vs. 12.05+/-4.88 Gy, P<.001). After 8.9+/-4.5 months there was complete lumen preservation in DA vs. lumen decrease subsequent to neointimal hyperplasia (NIH) in S group (0.10+/-1.20 vs. -0.61+/-1.29 mm3/mm, P<.05). Vessel volume increased significantly in the DA group and was unchanged in S group (+1.73, P=.002 vs. 0.14 mm3/mm, P=NS). DV(90%Adv) correlated inversely with NIH volume and positively with vessel volume change (r=-.405, P=.007 and r=.363, P=.017, respectively).

CONCLUSION

For beta-irradiation of ISR, dosing adjusted for the source-to-target distance leads to significant increase in target delivered doses, which is associated with complete NIH inhibition and induction of positive vessel remodeling.

Percutaneous coronary revascularization in diabetics: from balloon angioplasty to drug-eluting stents

Diabetic patients may have aggressive coronary disease with an excessive rate of restenosis and accelerated atherosclerotic progression. This article reviews the different modalities of percutaneous treatment and their results in the diabetic population, from the early days of balloon angioplasty to the current implementation of drug-eluting stents. As restenosis may be virtually eradicated in the near future, plaque progression remains the cornerstone for interventional cardiologists and the medical community. In this regard, attempts to modify life habits, and a more accurate control of the components of the metabolic syndrome should be the main therapeutic objective.

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.

In stent restenosis: bane of the stent era

The long term outcome of stent implantation is affected by a process called in stent restenosis (ISR). Multiple contributory factors have been identified, but clear understanding of the overall underlying mechanism remains an enigma. ISR progresses through several different phases and involves numerous cellular and molecular constituents. Platelets and macrophages play a central role via vascular smooth muscle cell migration and proliferation in the intima to produce neointimal hyperplasia, which is pathognomic of ISR. Increased extracellular matrix formation appears to form the bulk of the neointimal hyperplasia tissue. Emerging evidence of the role of inflammatory cytokines and suppressors of cytokine signalling make this an exciting and novel field of antirestenosis research. Activation of Akt pathway triggered by mechanical stretch may also be a contributory factor to ISR formation. Prevention of ISR appears to be a multipronged attack as no therapeutic "magic bullet" exists to block all the processes in one go.

Ionizing radiation to prevent arterial intimal hyperplasia at the edges of the stent: induces necrosis and fibrosis

BACKGROUND

Although ionizing radiation has been proposed for the prevention of intimal hyperplasia in coronary and peripheral arteries in multicenter clinical trials, information is lacking on how irradiation affects arterial histology after stenting and especially how it affects the edges of the stent. We investigated intimal hyperplasia recasting with histological changes in arterial wall at the edges of the stent after arterial stenting followed by adequate external radiation for the prevention of intimal hyperplasia in pigs.

MATERIALS AND METHODS

The aorta was experimentally stented in 30 pigs who were then assigned to two groups: irradiation with 20 Gy and a control group with no irradiation. The aorta was resected for morphometric and histological studies 6 weeks after procedure.

RESULTS

Intimal thickness was reduced and the intima/media ratio was significantly lower in irradiated groups than in control pigs. In the irradiated group histological examination at the edges of the stent showed thin neointimal proliferation with an intact endothelium. In all sections analyzed in the 20-Gy irradiated group the vascular media at 45 days contained necrotic areas and fibrosis with calcifications.

CONCLUSIONS

After arterial injury, adequate ionizing radiation effectively reduces neointimal thickening. Irradiation-induced histological changes include previously undetected recasting with necrosis and fibrosis at the arterial edges of the stent. The parietal recasting we observed in animal arteries irradiated at high doses is unclear and a cause of concern especially after clinical spontaneous dissection was recently reported. The use of ionizing radiation for the prevention of arterial restenosis awaits confirmation with a long-term follow-up including specific experimental histological analyses.

Comparison between sirolimus-eluting stents and intracoronary catheter-based beta radiation for the treatment of in-stent restenosis

We report the outcomes of patients who had in-stent restenosis (IRS) that was treated with intravascular brachytherapy (IVBT) or sirolimus-eluting stent (SES) implantation. The benefit of IVBT for treating ISR is well documented. SES implantation decreases first-time ISR and, in preliminary reports, has been used to treat ISR. Fifty consecutive patients who had ISR were treated; the first 25 patients underwent SES implantation and the next 25 patients were treated with IVBT using a beta-Cath System (a 40-mm strontium-90/yttrium-90 source). Quantitative angiographic and intravascular ultrasound follow-up were performed at 5.2 +/- 1.1 and 12.1 +/- 1.2 months; clinical follow-up was performed at 15 months. SES deployment and IVBT were successful in all patients. At 12-month follow-up, 8 patients who underwent IVBT had angiographic recurrence (4 in the stent and 4 at the stent edge); only 1 patient who underwent SES implantation developed recurrent ISR. At 12 months, in-stent late luminal loss was similar between the SES and IVBT groups (0.35 +/- 0.45 vs 0.34 +/- 0.46 mm, p = 0.9); however, in-stent net luminal gain was higher in the SES group than in the IVBT group (1.32 +/- 0.13 vs 0.57 +/- 0.19 mm, p <0.0001), and in-lesion late luminal loss was higher in the IVBT group (0.48 +/- 0.32 vs 0.16 +/- 0.42 mm, p = 0.004). At 12 months, intravascular ultrasound stent volume obstruction was higher after IVBT versus than after SES implantation (38.7% vs 6.7%, p <0.0001). At 15-month clinical follow-up, 64% and 96% (p <0.01) of patients who underwent IVBT and SES implantation, respectively, were free of major adverse cardiac events. In conclusion SES implantation for the treatment of ISR was effective and superior to catheter-based IVBT in preventing recurrent neointimal proliferation and angiographic restenosis at 1-year follow-up.

Chronological Changes in Morphometry and Histology in the Rabbit Vascular Wall after External Radiation for the Prevention of Intimal Hyperplasia

BACKGROUND

Although ionizing radiation has been proposed for the prevention of intimal hyperplasia in coronary and peripheral arteries, information is lacking on how irradiation affects arterial histology and neointimal smooth-muscle cell proliferation-the hallmark of restenosis. We chronologically investigated early histological changes and quantitative changes in arterial wall cell proliferation after arterial injury followed by external radiation for the prevention of intimal hyperplasia in rabbits.

MATERIALS AND METHODS

The aorta was experimentally injured in 26 rabbits who were then assigned to two groups: irradiation with 20 Gy and a control group with no irradiation. The aorta was resected for morphometric and histological studies at 3, 7, 15, 30, and 45 days after experimental injury.

RESULTS

Intimal thickness was reduced and the intima/media ratio was significantly lower in irradiated groups than in control rabbits. In the irradiated group histological examination showed delayed neointimal proliferation with an intact endothelium. In the 20-Gy irradiated group the vascular media at 7 days contained necrotic areas and delayed fibrosis with calcifications. There was no statistical difference between the number of proliferating cells in the irradiated groups and the control group. Proliferating cells reached maximum numbers later in irradiated groups than in control rabbits (45 days versus 3 days).

CONCLUSION

After arterial injury, external irradiation at 20 Gy effectively reduced aortic neointimal thickening. Irradiation-induced histological changes include recasting with rapid necrosis and delayed fibrosis. Radiation-induced parietal recasting with necrosis, fibrosis, and calcifications might worsen in time. Although irradiation after arterial injury leaves proliferative smooth-muscle cells within the arterial wall quantitatively unchanged in the early days after the procedure, it then induces a delayed reaction (observed over 45 days in our study). Whether neointimal hyperplasia is merely delayed or will ultimately develop causing restenosis awaits confirmation from experimental and clinical studies with a long-term follow-up.

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.