Late acute thrombotic occlusion after endovascular brachytherapy and stenting of femoropopliteal arteries

High dose-rate brachytherapy for the treatment of lower extremity in-stent restenosis

OBJECTIVE

Historically, edge stenosis and late thrombosis limited the effectiveness of adjunctive endovascular brachytherapy (EVBT) for in-stent restenosis (ISR) after percutaneous transluminal angioplasty (PTA) and stenting. We evaluated an updated protocol of PTA and EVBT for ISR among patients with lower extremity occlusive disease.

METHODS

This is a retrospective, single-center review of patients treated with PTA and EVBT for ISR in the iliac and femoropopliteal segments between 2004 and 2012. A dose of 20 Gy was given at a depth of 0.5 mm beyond the radius of the largest PTA balloon using iridium 192, with at least 2-cm-long margins of radiation coverage proximal and distal to the injured area. Stents were assessed for patency by duplex ultrasound imaging at 1, 3, 6, 9, 12, and 18 months and then yearly. The primary end point was freedom from ≥50% restenosis in the treated segment at 6 months, 1 year, and 2 years. Patency data were estimated using the Kaplan-Meier method. Secondary end points were early and late thrombotic occlusion.

RESULTS

Among 42 consecutive cases in 35 patients of EVBT for ISR in common or external iliac (9 [20.8%]) and superficial femoral or popliteal (33 [76.7%]) arteries, or both, 21 patients (50%) had claudication, asymptomatic hemodynamically significant stenoses were identified on duplex ultrasound imaging in 16 (38.1%), and 4 (9.8%) had critical limb ischemia. Mean treated length was 23.5 ± 12.3 cm over a mean duration of 16.1 ± 9.6 minutes. There was one technical failure (2.3%). Median post-EVBT follow-up time was 682 days (range, 1-2262 days). There were two (4.9%) and five (11.9%) cases of early and late thrombotic occlusions, respectively. There was one death, believed to be secondary to acute coronary syndrome. Primary, assisted primary, and secondary patency in the entire cohort was 75.2%, 89.1%, and 89.1%, respectively, at 1 year and 63.7%, 80.6%, and 85.6%, respectively, at 2 years.

CONCLUSIONS

This contemporary protocol of PTA and adjunctive EVBT for lower extremity ISR, which is updated from those used in prior trials and includes a surveillance strategy that identifies at-risk stents for reintervention before occlusion, may be a promising treatment for lower extremity ISR at institutions where a close collaboration between vascular surgeons and radiation oncologists is feasible.

Advances in Vascular Brachytherapy over the Last 10 Years: Focus on Femoropopliteal Applications

Restenosis and the need for repeated interventions after percutaneous transluminal angioplasty (PTA) remain major drawbacks limiting a widespread application of this minimally invasive technique in the femoropopliteal segment. During the last decade, vascular brachytherapy (BT) emerged as a promising, novel technology with the potential to reduce the rates of restenosis. Meanwhile, several randomized controlled trials have suggested beneficial short and midterm effects of BT in the femoropopliteal arteries. However, despite substantial advances, many questions remain regarding the utility of vascular BT and its dissemination as a practical tool to prevent restenosis. The risk of complications, such as late stent thrombosis, edge effect, catch-up late restenosis, and potential aneurysm formation, as well as the logistical issues associated with the use of this technology in the catheterization laboratory, are delaying the acceptance of BT for routine use. This article reviews the developments of BT for restenosis prevention during the past decade, focusing on implications for peripheral endovascular treatment.

Current state of endovascular treatment of femoro-popliteal artery disease

Considerable advances have been made over the last decade in percutaneous technology for the treatment of atherosclerotic diseases in the femoro-popliteal arteries. While treatment strategies are well defined in the iliac segment, where angioplasty and stenting perform well in appropriately selected lesions, the search for a durable transcatheter therapy for femoro-popliteal lesions continues. Whereas balloon angioplasty (PTA) is the accepted therapy for short lesions, long diffuse lesions are still recommended for surgical treatment. However, attractive new technologies ranging from transcatheter plaque excision to laser ablation, rotational atherectomy, cryoplasty, brachytherapy, and placement of drug-eluting stents to simple angioplasty with drug-coated balloons may have the potential to replace femoro-popliteal bypass surgery as a treatment of choice for complex lesions. This article reviews the status of percutaneous endovascular techniques for the treatment of femoro-popliteal artery occlusive disease.

Long term follow-up after endovascular brachytherapy of femoro-popliteal arteries

To perform a long term follow-up after endovascular brachytherapy (EVBT) and balloon angioplasty (PTA) regarding vessel patency and diameter. EVBT had been successfully used to decrease restenosis in short term, but long term data are lacking. Participants of a randomized study comparing EVBT and balloon angioplasty alone were invited for follow-up examination ten years after intervention. Using a standardized protocol measurement of the patency and vessel diameter was performed of femoral and popliteal arteries. 44 patients were included, 21 had been treated with EVBT and 23 had received PTA alone. Target lesion patency was similar between the two groups (90.5% vs. 87.0%). Vessel diameter of the target lesion was significantly greater in the EVBT group (6.4 mm, range 3.9-9.9) compared to the controls (5.0 mm, range 3.1-7.4; p = 0.002). Ten years after EVBT of femoro-popliteal arteries vessel diameter is significantly increased whereas patency rate is not different compared to angioplasty alone.

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.

Systematic review and meta-analysis of additional technologies to enhance angioplasty for infrainguinal peripheral arterial occlusive disease

Background

There are several additional techniques designed to enhance conventional percutaneous transluminal balloon angioplasty (PTA). This systematic review assessed current evidence on the clinical effectiveness of additional techniques for infrainguinal peripheral arterial occlusive disease (PAD).

Methods

Relevant electronic databases, including MEDLINE, were searched in May 2011. The population comprised participants with symptomatic PAD undergoing endovascular treatment for disease distal to the inguinal ligament. Interventions were additional techniques compared with conventional PTA. Main outcome measures were restenosis and need for reintervention. Randomized clinical trials (RCTs) of clinical effectiveness were assessed for quality and data were extracted. Where appropriate, meta-analysis was undertaken to produce risk ratios (RRs).

Results

Forty RCTs were selected. Meta-analysis showed a significant benefit in reducing restenosis rates at 6 months for self-expanding stents (RR 0·49) and drug-coated balloons (RR 0·40), and at 12 months for endovascular brachytherapy (RR 0·63). There was also evidence that use of a stent-graft significantly reduced restenosis compared with PTA, as did drug-eluting stents compared with bare-metal stents. Meta-analysis showed that use of drug-coated balloons was associated with significantly lower reintervention rates than PTA alone at 6 months (RR 0·24) and 24 months (RR 0·27) of follow-up. There was also evidence of significantly lower reintervention rates for self-expanding stents at 6 months. Other techniques did not show significant treatment effects for restenosis or reintervention.

Conclusion

The conclusions of this review should be tempered by small sample sizes, lack of clinical outcome measures and differing outcome definitions, making direct comparison across trials difficult. However, self-expanding stents, drug-eluting stents and drug-coated balloons appeared to be the most promising technologies worthy of future study.

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.

Endovascular brachytherapy and restenosis following lower limb angioplasty: Systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Restenosis is a fundamental weakness of percutaneous femoropopliteal angioplasty (PTA). The potential of endovascular brachytherapy (EVBT) to reduce restenosis has been evaluated in randomized clinical trials, but no pooled analysis has been undertaken.

METHODS

A systematic review was undertaken to identify randomized controlled trials in which PTA alone was compared to PTA plus EVBT. The Pubmed and Medline databases, American Heart Association OASIS database and conference proceedings from the Peripheral Vascular Surgery Society and Vascular Society of Great Britain and Ireland were searched. Eligible studies were randomised controlled trials comparing PTA to PTA plus EVBT in human subjects with at least one clinical outcome reported (restenosis, complications, patency). Study quality was assessed by the Jadad score. Random-effects modeling was used to generate pooled effect size estimates.

RESULTS

Six trials (687 patients) were identified. EVBT reduced 12-month restenosis rates (pooled odds ratio 0.50; 95% CI 0.301-0.836; p=0.008). The benefit disappeared by 24 months. The short-term risk of new lesions elsewhere in the treated artery was significantly increased by EVBT (pooled odds ratio 8.65; 95% CI 2.176-34.391; p=0.002).

CONCLUSIONS

While limited by the small sample sizes in the included trials, this analysis suggests that the early benefit of EVBT is counter-balanced by the increased risk of new lesions and the lack of medium- to long-term reductions in restenosis risk. Based upon the best available evidence, EVBT cannot be recommended for routine clinical use.

Current approach to the diagnosis and treatment of femoral-popliteal arterial disease. A systematic review

Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis affecting 5 million adults in the United States, with an age-adjusted prevalence of 4% to 15% and increasing up to 30% with age and the presence of cardiovascular risk factors. In this article we focus on lower extremity PAD and specifically on the superficial femoral and proximal popliteal artery (SFPA), which are the most common anatomic locations of lower extremity atherosclerosis. We summarize current evidence and perform a systematic review on the diagnostic evaluation as well as the medical, endovascular and surgical management of SFPA disease.

[Evolution of stents for the treatment of femoral artery lesions]

Endovascular treatment and stent implantation in the superficial femoral artery have been proposed for over 20 years. However, the first experiments with stainless stents were relatively disappointing. The first improvement consisted in the introduction of nitinol self-expanding stents. This technology allowed an initial improvement of clinical performances, but the first generation of nitinol stents demonstrated a relatively high rate of fractures. Better knowledge of the femoral artery biomechanics and advances in technology allowed to propose a second generation of nitinol stents with improved flexibility, which decreased the rates of fracture. In-stent restenosis related to neointimal hyperplasia has also led to the development of new concepts to improve patency rates after stenting of the femoral artery: drug-eluting stents (coated-stents), biodegradable stents, and covered stents. These technologies will help to treat more complex lesions of the femoral artery in the future, with comparable results to those obtained with femoropopliteal bypasses, but we are still waiting for results of ongoing studies.

Effects of percutaneous transluminal angioplasty and endovascular brachytherapy on vascular remodeling of human femoropopliteal artery: 2 years follow-up by noninvasive magnetic resonance imaging

OBJECTIVES

We aimed to assess in vivo the long-term effects of percutaneous transluminal angioplasty (PTA) and endovascular brachytherapy (EVBT) on vessel wall by serial MRI.

METHODS

Twenty patients with symptomatic stenosis of the femoropopliteal artery were randomly assigned to PTA (n=10) or PTA+EVBT (n=10, 14Gy by gamma-source). High-resolution MRI was performed prior, at 24-hours, 3-months, and 24-months after intervention. MRI data were analyzed by an independent, blinded observer.

RESULTS

The effects of both procedures on vessel wall at 24-hours and 3-months have been reported. Despite similar percent decrease in lumen area between 3- and 24-months in both groups (-8% for PTA and -11% for PTA+EVBT), at 24-months lumen area gain compared to baseline was +30% in PTA versus +82% in PTA+EVBT (p<0.05). Total vessel area, which was increased at 24-hours and 3-months, returned to pre-treatment value in both groups.

CONCLUSIONS

We demonstrated non-invasively that restenosis and inward remodeling after PTA are delayed by EVBT. At 24-months, patients treated with brachytherapy have larger lumen than those treated with PTA alone. The decrease in luminal and total vessel area between 3- and 24-months after EVBT indicates that the restenotic and remodeling process is not abolished but delayed with this therapy.

Peripheral arterial disease: diagnosis, treatment, and systemic implications

Peripheral arterial disease is common in adults and is found in many patients with lower extremity ulcers. It is important to diagnose peripheral arterial disease not only because of its impact on the involved lower extremity but also because it often occurs with atherosclerotic disease in other vascular beds. Although patient symptoms may be helpful in the diagnosis, most afflicted patients either are asymptomatic or have atypical symptoms. Physical examination, an ankle-brachial index, referral to a noninvasive vascular laboratory, contrast angiography, and magnetic resonance angiography can be helpful diagnostically. Beneficial therapies include smoking cessation, exercise therapy, cholesterol reduction, antiplatelet therapy, and treatment of hypertension and diabetes. For patients with symptomatic claudication, cilostazol can be considered. Patients with nonhealing ulcers, rest pain, or severe claudication should be referred for interventions.

Role of Stents, Drug-Eluting Stents, and Stent-Grafts in Treatment of Infrainguinal Arterial Disease

Infrainguinal peripheral arterial disease is increasingly treatable by endovascular techniques. Bare-metal, drug-eluting, and covered stents (stent-grafts) are increasingly important adjuncts to percutaneous transluminal angioplasty in the treatment of occlusive and aneurysmal disease. Preliminary data suggest bioabsorbable stents may also have a significant clinical impact as well. In this article, we describe the available evidence supporting use of stents in the femoropopliteal and tibial arteries, as well as some of their limitations and complications.

External Beam Irradiation and Restenosis Following Femoral Stenting: Long-Term Results of a Prospective Randomized Study

PURPOSE

To assess the long-term outcome of external beam irradiation (EBI) for the prevention of restenosis due to neointimal hyperplasia, following percutaneous transluminal angioplasty (PTA) and stenting of the superficial femoral artery.

METHODS

Sixty consecutive patients with peripheral arterial disease, who were treated with "bail-out" stent implantation in the superficial femoral artery due to suboptimal PTA, were included in this study. Patients were randomly allocated into two groups, receiving either external beam irradiation (6 MV photons, total dose 24 Gy in a hypofractionated schedule) plus antiplatelet therapy (EBI group) or antiplatelet therapy alone (control group).

RESULTS

No procedure-related complications occurred, and all patients of the EBI group received the full dose of 24 Gy. During the long-term follow-up, an overall statistically significant difference was demonstrated in favor of the EBI group patients, regarding both the in-stent (log-rank test, p = 0.0072) and the in-segment binary restenosis (log-rank test, p = 0.0103). The primary patency rates were also significantly better in the EBI group at specific time-points, such as in the first (74.2% vs 46.5%, p = 0.019), second (62.5% vs 33.8%, p = 0.020), and third (54.6% vs 29.0%, p = 0.039) year, respectively. Moreover, the overall clinically driven reintervention rate was significantly lower among patients of the irradiated group (log-rank test, p = 0.038).

CONCLUSION

Our long-term follow-up analysis revealed that EBI following femoral artery PTA and stenting significantly reduces restenosis and reintervention rates, while improving primary patency.

Noninvasive imaging of atherosclerotic vessels by MRI for clinical assessment of the effectiveness of therapy

Atherosclerosis and its thrombotic complications are the major cause of morbidity and mortality in the industrialized countries. Despite advances in our understanding of the mechanisms of pathogenesis and new treatment modalities, the absence of an adequate noninvasive method for early detection limits prevention or treatment of patients with various degrees and localizations of atherothrombotic disease. The ideal clinical imaging modality for atherosclerosis should be safe, inexpensive, noninvasive or minimally invasive, accurate, and reproducible, thus allowing longitudinal studies in the same patients. Additionally, the results should correlate with the extent of atherosclerotic disease and have high predictive values for clinical events. In vivo, high-resolution magnetic resonance imaging (MRI) has recently emerged as one of the most promising techniques for the noninvasive study of atherothrombotic disease in several vascular beds such as the aorta, the carotid arteries, and the coronary arteries. Most importantly MRI can be used to characterize plaque composition as it allows the discrimination of lipid core, fibrosis, calcification, and intra-plaque hemorrhage deposits. MRI findings have been extensively validated against pathology in ex vivo studies of carotid, aortic, and coronary artery specimens obtained at autopsy and using experimental models of atherosclerosis. In vivo MRI of carotid arteries of patients referred for endarterectomy has shown a high correlation with pathology and with previous ex vivo results. A recent study in patients with plaques in the thoracic aorta showed that compared with transesophageal echocardiography plaque composition and size are more accurately characterized and measured using in vivo MRI. The composition of the plaque rather than the degree of stenosis determines the patient outcome. Therefore, a reliable noninvasive imaging tool able to detect early atherosclerotic disease in the various regions and identify the plaque composition is clinically desirable. MRI has potential in the detection arterial thrombi and in the definition of thrombus age. MRI has been used to monitor plaque progression and regression in several animal model of atherosclerosis and more recently in human. Advances in diagnosis prosper when they march hand-in-hand with advances in treatment. We stand at the threshold of accurate noninvasive assessment of atherosclerosis. Thus, MRI opens new strategies ranging from screening of high-risk patients for early detection and treatment as well as monitoring the target areas for pharmacological intervention.

Beta radiation in the treatment of in-stent restenosis of an in situ saphenous vein bypass graft A case report

We describe a case of instent restenosis in a femoral-distal saphenous vein bypass graft successfully treated with brachytherapy. A 45-year-old insulin-requiring diabetic woman underwent an in-situ femoral-anterior tibial bypass graft for a non-healing ischemic ulcer. Despite a technically successful percutaneous transluminal angioplasty and endovascular stenting of a retained valve within the threatened graft, the wound failed to heal. At the 1-month follow-up, instent restenosis was documented and successful cutting balloon angioplasty, complemented by adjunctive beta-irradiation was successfully performed. Clinical and hemodynamic success was achieved, with prompt ulcer healing and intermediate-term graft patency maintained on surveillance duplex ultrasound follow-up. We review the literature on radiation therapy in the management of peripheral arterial disease and discuss therapeutic options in the management of restenosis.

Vascular Brachytherapy with192Ir after Femoropopliteal Stent Implantation in High-Risk Patients: Twelve-month Follow-up Results from the Vienna-5 Trial

PURPOSE

To prospectively evaluate the effectiveness of endovascular brachytherapy in the prevention of restenosis after femoropopliteal stent implantation in high-risk patients.

MATERIALS AND METHODS

Patients provided written informed consent to participate in this study, which was approved by the ethics committee. A total of 88 patients (mean age, 67.7 years +/- 10.1; 57 men [65%], 31 women [35%]) with femoropopliteal lesions (mean treatment length, 16.8 cm +/- 7.3) were included. Patients underwent percutaneous transluminal angioplasty (PTA) and stent implantation and were randomized in a double-blind fashion to undergo either gamma brachytherapy with an iridium 192 source or treatment with nonradioactive seeds. A 14-Gy dose of iridium 192 was prescribed at 2 mm into the arterial wall (target depth equals vessel radius plus 2 mm). The primary end point of the study was angiographic binary restenosis of more than 50% at 6-month follow-up. Secondary end point was either percutaneous or surgical target lesion revascularization after 6 months. Continuous data are presented as mean +/- standard deviation. Categorical data are expressed as percentages. Student t test was used to compare continuous data; chi(2) test was used to compare categorical values. Survival function was calculated with the Kaplan-Meier method. Multivariate Cox proportional hazard regression analysis was performed to enable evaluation of multivariate predictors of recurrence at 6- and 12-month follow-up. Variables included brachytherapy, clinical stage, lesion length, de novo and recurrent lesion, vessel run off, prior stenosis or occlusion, diabetes mellitus, and stent model.

RESULTS

Revascularization and brachytherapy were accomplished successfully in all patients. The overall 6-month recurrence rate was 35% in patients who underwent only stent implantation and 33% in patients who underwent both stent implantation and brachytherapy (P = .89). Nine (10%) patients developed early reocclusion in the segment treated with a stent (two patients [4%] in the stent group and seven [17%] in the stent and brachytherapy group); of these patients, three in the stent and brachytherapy group experienced reocclusion within 24 hours of the intervention. Late (>30 days after intervention) thrombotic occlusion was observed in three patients (7%) in the stent and brachytherapy group.

CONCLUSION

Brachytherapy does not improve 6-month patency after femoropopliteal stent implantation in high-risk patients because of a high incidence of early and late thrombotic occlusion.

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.

Advances in vascular brachytherapy over the last 10 years: focus on femoropopliteal applications

Restenosis and the need for repeated interventions after percutaneous transluminal angioplasty (PTA) remain major drawbacks limiting a widespread application of this minimally invasive technique in the femoropopliteal segment. During the last decade, vascular brachytherapy (BT) emerged as a promising, novel technology with the potential to reduce the rates of restenosis. Meanwhile, several randomized controlled trials have suggested beneficial short and midterm effects of BT in the femoropopliteal arteries. However, despite substantial advances, many questions remain regarding the utility of vascular BT and its dissemination as a practical tool to prevent restenosis. The risk of complications, such as late stent thrombosis, edge effect, catch-up late restenosis, and potential aneurysm formation, as well as the logistical issues associated with the use of this technology in the catheterization laboratory, are delaying the acceptance of BT for routine use. This article reviews the developments of BT for restenosis prevention during the past decade, focusing on implications for peripheral endovascular treatment.

Lower extremity arterial occlusive disease: Role of percutaneous revascularization

Percutaneous endovascular interventions for peripheral arterial disease are indicated in carefully selected patients with favorable anatomy and associated clinical symptoms. Although endovascular therapy appears to be hemodynamically equivalent to other modalities in isolated iliac disease, this does not appear to be the case for infrainguinal disease, particularly when the disease is diffuse and extensive. Such disease in these beds can often be treated surgically, although there is an increasing role for percutaneous therapies, particularly in patients at higher surgical risk. Catheter-based therapy should be considered an integral part of comprehensive medical therapy in patients with lower extremity peripheral arterial disease. Embarking on an endovascular approach to therapy should involve a frank physician-patient discussion of the risks, benefits, and durability of the proposed procedure tailored to anatomic locale and patient-specific factors.

External beam radiation therapy reduces the rate of re-stenosis in patients treated with femoral stenting: results of a randomised study

BACKGROUND AND PURPOSE

To evaluate the feasibility and efficacy of external beam irradiation (EBI) for the prevention of re-stenosis due to neointimal hyperplasia, after percutaneous transluminal angioplasty (PTA) and stent placement of the superficial femoral artery.

PATIENTS AND METHODS

A total of 60 patients with the diagnosis of superficial femoral artery stenoses or occlusions due to peripheral arterial obstructive disease underwent PTA and implantation of a self-expandable stent at their superficial femoral artery. After the procedure, patients were randomised and 30 of them received EBI (6 MV photons, total dose 24 Gy in six fractions in 2 weeks), while the rest 30 received no radiation therapy.

RESULTS

EBI was technically feasible in all patients, without serious radiation related side effects. Overall, a statistically significant difference was observed in stenosis categories between the two groups at 6 months follow-up (P=0.04). More specifically, significantly more patients in the control group presented with stenosis greater or equal than 70% [EBI group 30% (9/30); control group 66.7% (20/30); P=0.009]. This difference in the percentage of re-stenosis had as a consequence significantly lower re-intervention rates among the patients of the irradiated group [17% (5/30) versus 47% (14/30); P=0.025] during the 6 months follow-up period. We also observed that the irradiated patients had re-stenosis at the stent ends, while the non-irradiated had re-stenosis at the stent ends and the lumen. Three of the irradiated patients, who discontinued the anti-platelet treatment, have shown thrombosis of the irradiated artery during the first month from the completion of the treatment.

CONCLUSIONS

It is our belief that EBI is a feasible, safe and effective method for the prevention of neointimal hyperplasia at the superficial femoral artery. Further studies are deemed necessary to optimise the radiotherapy schedule.

Endovascular Interventions in Iliac and Infrainguinal Occlusive Artery Disease

Percutaneous endovascular procedures are increasingly applied to treat symptomatic peripheral occlusive artery disease. While the primary technical success and recanalization rates in iliac and infrainguinal interventions are high, differences in the long-term patency rates exist with respect to the anatomic localization, separating the iliac, femoropopliteal, and infrapopliteal arterial regions. In iliac arteries, even complex lesions can be recanalized with good long-term patency rates, especially when using self-expanding nitinol stents. In the infrainguinal arteries the method of choice is still under debate (e.g., balloon angioplasty vs stent implantation). A high restenosis rate represents one of the major limitations in femoropopliteal and infrapopliteal interventions. Therefore, additional methods and treatment strategies for peripheral interventions with the potential for future applications are under investigation and will be discussed such as drug-eluting stents, brachytherapy, subintimal angioplasty, laser angioplasty, atherectomy/thrombectomy, cutting balloon, polytetrafluoroethylene (PTFE)-covered stent grafts, biodegradable stents, and cryoplasty. The increasing amount of data on successful peripheral interventions supports the necessity to adapt and reevaluate the current consensus guidelines that were put together in 2000.

Preclinical restenosis models and drug-eluting stents: still important, still much to learn

Percutaneous coronary intervention continues to revolutionize the treatment of coronary atherosclerosis. Restenosis remains a significant problem but may at last be yielding to technologic advances. The examination of neointimal hyperplasia in injured animal artery models has helped in our understanding of angioplasty and stenting mechanisms, and as drug-eluting stent (DES) technologies have arrived, they too have been advanced through the study of animal models. These models are useful for predicting adverse clinical outcomes in patients with DESs because suboptimal animal model studies typically lead to problematic human trials. Similarly, stent thrombosis in animal models suggests stent thrombogenicity in human patients. Equivocal animal model results at six or nine months occasionally have been mirrored by excellent clinical outcomes in patients. The causes of such disparities are unclear but may result from differing methods, including less injury severity than originally described in the models. Ongoing research into animal models will reconcile apparent differences with clinical trials and advance our understanding of how to apply animal models to clinical stenting in the era of DESs.

Evaluation and medical treatment of peripheral arterial disease

PURPOSE OF REVIEW

This review reports various advances in the evaluation and medical management of patients with peripheral arterial disease (PAD) in the last 1 to 2 years.

RECENT FINDINGS

Several community surveys have clearly highlighted the fact that despite being a very highly prevalent disease, physicians underdiagnose and undertreat PAD. This led to the Executive Committee of the Prevention of Atherothrombotic Disease Network to issue a "call to action," citing critical issues in PAD detection and management.

SUMMARY

PAD affects more than 27 million people in North America and Europe, and the prevalence of this disease continues to increase as the population ages. This disease has significant adverse effects on the quality of life and survival, with mortality as high as 30% in 5 years and 50% in 10 years. Although surgical, endovascular, and medical therapies for atherosclerosis in general, and PAD specifically, continue to be developed, there appears to be considerable room for improvement in physician adoption of proven effective therapies, such as cholesterol-lowering therapies and blood pressure management. Additionally, new therapies, such as gene transfer and cell therapy, are under development for this population.

Endovascular brachytherapy after percutaneous transluminal angioplasty of recurrent femoropopliteal obstructions

PURPOSE

To test the preventive effect of endovascular brachytherapy (EVBT) on restenosis following secondary angioplasty in patients with presumed neointimal restenosis in the femoropopliteal segment.

METHODS

From March 1997 through May 2000, 100 patients (58 men; mean age 70 years, range 45-87) with postangioplasty femoropopliteal segment restenoses were enrolled and randomized to treatment with repeat angioplasty and EVBT (n=51) or to angioplasty alone (n=49) as control. The groups were similar with regard to demographics and lesion characteristics. High-dose-rate EVBT was performed with (192)Ir irradiation without a centering device (12 Gy for a reference vessel radius of 3 mm and a 2-mm reference depth). Primary endpoint in the 1-year follow-up was recurrent obstruction >50% documented by duplex ultrasound; the secondary endpoint was clinical improvement.

RESULTS

Only 44 (86%) of 51 patients received adequate EVBT due to technical failure, so the 7 failures were included with the controls in the per-protocol adherence analysis. At 1 year, the patients receiving EVBT had a restenosis rate of 23% (10/44), which differed significantly (p<0.028) from the 42% (23/56) rate in controls. Clinical results tended to be better with EVBT, but differences did not achieve statistical significance.

CONCLUSIONS

EVBT without a centering device reduced restenosis significantly in patients with recurrent stenosis after angioplasty, which confirms previous results in primary long-segment femoropopliteal obstructions.