Outcome from balloon induced coronary artery dissection after intracoronary beta radiation

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.

Incidence, predictors, and outcomes of coronary dissections left untreated after drug-eluting stent implantation†

AIMS

Coronary dissections left untreated after percutaneous coronary intervention are associated with unfavourable outcomes. However, their role after drug-eluting stent (DES) implantation is still undescribed. We assessed incidence, predictors, and outcomes of residual dissections in DES-treated lesions.

METHODS AND RESULTS

Consecutive patients undergoing DES implantation were enrolled in four Italian centres, with baseline, procedural, and outcome data entered into a dedicated database. Residual dissections were classified according to the National Heart Lung and Blood Institute criteria. End-points of interest were in-hospital, 1-month, and 6-month major adverse cardiovascular events (MACE, i.e. death, myocardial infarction, or target vessel revascularization), and stent thrombosis (ST). Among the 2418 included patients (4630 lesions), a total of 77 (1.7%) final dissections occurred in 67 (2.8%) subjects. Dissections were more frequent in longer and complex lesions and in the left anterior descending, and were associated with increased rates of in-hospital (11.9 vs. 5.2%, P=0.017) and 1-month MACE (13.4 vs. 6.0%, P=0.013), with similar 6-month trends. Cumulative ST was also greater in patients with dissections (6.3 vs. 1.3%, P=0.011). Even non-obstructive dissections with thrombolysis in myocardial infarction 3 flow conferred a significantly worse prognosis.

CONCLUSION

This study, reporting for the first time on incidence, predictors, and outcomes of residual dissections in DES-treated coronary lesions, demonstrates their adverse clinical impact and supports the pursuit of a strategy of sealing dissection flaps with other DES.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

ISR II study: A long-term evaluation of sirolimus-eluting stent in the treatment of patients with in-stent restenotic native coronary artery lesions

The aim of this pilot study was to determine the safety and long-term efficacy of treating intrastent restenosis (ISR) with the slow-release sirolimus-eluting stent Bx Velocity (Cypher stent) without intravascular ultrasound (IVUS) guidance. Of patients who received a bare metal stent implantation and presented an ISR, 30-80% of the patients will develop a second restenosis within the stent, at the stent edges or both. To date, intravascular brachytherapy using beta- and gamma-radiation has been the only effective treatment for ISR. Twenty-three patients with ISR and evidence of ischemia were treated with Cypher stent. Clinical information was collected 1, 8, 12, and 24 months after stent implantation. During the first 8 months of the study, in-stent lumen diameter remained essentially unchanged from postprocedure in 80% of the case. The target lesion repeat revascularization (TLR) was 17%, of which 50% were oculostenotic reflexes. Only one patient presented a restenosis greater than 70%. During the 2-year study period, the TLR rate was 17%; the major adverse coronary event rate was 26%, and the non-Q-wave myocardial infarction (MI) rate was 9%. There were no reports of death, coronary artery bypass grafting, or Q-wave MI during the study. This study demonstrates the feasibility of using sirolimus-eluting stents without IVUS guidance for the treatment of ISR, providing long-term stability of immediate results.

Local drug delivery in restenosis injury: thermoresponsive co-polymers as potential drug delivery systems

The success of percutaneous transluminal coronary angioplasty in treatment of acute coronary syndromes has been compromised by the incidence of restenosis. The physical insult of balloon insertion can damage or remove the endothelial monolayer, thereby generating a prothrombotic surface. The resulting inappropriate response to injury can also lead to penetration of inflammatory cells, conversion of the underlying media to a synthetic phenotype, deposition of extracellular matrix, constrictive remodeling, and neointimal hyperplasia. While stent implantation at the time of balloon insertion has offset some of these events, inflammatory responses to the implanted biomaterial (stent) and intimal hyperplasia are still prominent features of the procedure, leading in 20-30% of cases to in-stent restenosis within a year. Systemic delivery of drugs designed to offset in-stent restenosis injury has been largely unsuccessful, which has led to the development of strategies for coating stents with drugs for local delivery. Drug-eluting stents constitute an innovative means of further reducing the incidence of restenosis injury and clinical trials have shown encouraging results. This review focuses on properties of a class of environment-sensitive hydrogels, the N-isopropylacrylamide-based thermoresponsive co-polymers, on their potential roles as stent coatings, on their demonstrated ability to incorporate and release drugs that modify vascular endothelial and smooth muscle cell functions, and on issues that still await clarification, prior to their adoption in a clinical setting.

Geographical miss during centered intracoronary beta-radiation with 90Yttrium: incidence and implications for recurrence rates after vascular brachytherapy for de novo lesions

OBJECTIVES

The authors sought to determine the incidence and causes of geographical miss (GM) and evaluate its impact on edge restenosis after 'primary', centered, intracoronary beta-radiation therapy.

BACKGROUND

Edge restenosis is a limitation of intracoronary beta-radiation therapy. GM occurs when the radiation source does not fully cover the injured segment and may account for this phenomenon.

METHODS

One hundred and eighty-one patients enrolled in the Dose-Finding study were retrospectively analyzed. The patients were randomized to receive 9, 12, 15 or 18 Gy at 1 mm tissue depth. Using quantitative coronary angiography the effective irradiated segment (EIRS) and both edges were studied prior to and after intervention, and at six-month follow-up. GM was defined as a situation where the effective radiation source length (24 mm) did not fully cover the injured segment. The edges of the EIRS that were injured during the procedure constituted the GM edges. A greater than 50% diameter stenosis at follow-up was considered significant. GM was determined by the simultaneous, electrocardiographically matched, side-by-side projection of the source and balloons in place, in identical projections surrounded by contrast.

RESULTS

In 16% of patients GM was noninterpretable owing to inadequate filming. GM constituted 21.1% of the interpretable edges and 40.1% of the interpretable vessels analyzed. The occurrence of restenosis in the EIRS and the analyzed vessel segment (VS) was similar between procedures with and without GM. In vessels with GM, restenosis was significantly increased from the EIRS to the VS (from 8.77% to 21%, p = 0.05) as opposed to non-GM vessels (from 11.9% to 19%, p = 0.6). GM tended to be associated with a greater incidence of significant stenosis at the edges of the EIRS (8.3% versus 4.0%, p = 0.15) compared with individuals with >50 % stenosis but no GM. This effect was more prominent at the distal edge. The relation of GM and edge restenosis was independent of dosage.

CONCLUSIONS

Since GM does not affect the incidence of restenosis in the EIRS, restenosis in this segment should be considered a treatment failure, probably due to inadequate dosage. GM is related to significant increase in restenosis from the EIRS to the VS. GM tends to be associated with restenosis at the edges of the EIRS. This is a local phenomenon, which is independent of dosage and which has a specific pathophysiology (combination of injury and low-dose radiation). If GM can be eliminated, the results of vascular brachytherapy will be improved.

Coronary artery pseudoaneurysm after balloon angioplasty and intracoronary ?-radiation for in-stent restenosis

Intracoronary brachytherapy is an effective method for treating in-stent restenosis. We report a case of coronary artery pseudoaneurysm after balloon angioplasty and intracoronary beta-radiation. The pseudoaneurysm was treated successfully with implantation of two coronary stent grafts.

The black hole: echolucent tissue observed following intracoronary radiation

AIMS

Recent trials in humans have given us insight into some of the consequences of intracoronary radiation. The authors describe a new observation noted on intravascular ultrasound: that of intraluminal echolucent tissue, dubbed the 'black hole', noted at six-month follow-up.

METHODS AND RESULTS

One hundred and twenty-eight consecutive patients enrolled in brachytherapy protocols were analyzed. The control group (C) consisted of individuals who underwent percutaneous transluminal coronary angioplasty with (n = 48) and without (n = 22) stent implantation. Radiation groups included those who underwent low activity (LA) (n = 18), high activity (HA) (n = 26) and cold-end (CE) (n = 18) radioactive stenting. The Novoste Betacath (n = 39) and Guidant (n = 27) catheter-based radiation systems were also employed. At six-month follow-up echolucent tissue was identified in a total of 28 cases (22%). Angiographic restenosis occurred in 17 cases (61%). No echolucent tissue was seen in the control group or in the LA group. HA and CE radioactive stents were most commonly associated with echolucent tissue. Echolucent tissue was seen in all groups treated with catheter-based radiation with and without stenting. Pathology after atherectomy demonstrated smooth muscle cells scattered in extracellular matrix containing abundant proteoglycans and an absence of elastin and mature collagen.

CONCLUSIONS

Echolucent tissue is common after radioactive stenting. It is composed of tissue rich in proteoglycans while poor in mature collagen and elastin.

TAXUS III Trial: in-stent restenosis treated with stent-based delivery of paclitaxel incorporated in a slow-release polymer formulation

BACKGROUND

The first clinical study of paclitaxel-eluting stent for de novo lesions showed promising results. We performed the TAXUS III trial to evaluate the feasibility and safety of paclitaxel-eluting stent for the treatment of in-stent restenosis (ISR).

METHODS AND RESULTS

The TAXUS III trial was a single-arm, 2-center study that enrolled 28 patients with ISR meeting the criteria of lesion length < or =30 mm, 50% to 99% diameter stenosis, and vessel diameter 3.0 to 3.5 mm. They were treated with one or more TAXUS NIRx paclitaxel-eluting stents. Twenty-five patients completed the angiographic follow-up at 6 months, and 17 of these underwent intravascular ultrasound (IVUS) examination. No subacute stent thrombosis occurred up to 12 months, but there was one late chronic total occlusion, and additional 3 patients showed angiographic restenosis. The mean late loss was 0.54 mm, with neointimal hyperplasia volume of 20.3 mm3. The major adverse cardiac event rate was 29% (8 patients; 1 non-Q-wave myocardial infarction, 1 coronary artery bypass grafting, and 6 target lesion revascularization [TLR]). Of the patients with TLR, 1 had restenosis in a bare stent implanted for edge dissection and 2 had restenosis in a gap between 2 paclitaxel-eluting stents. Two patients without angiographic restenosis underwent TLR as a result of the IVUS assessment at follow-up (1 incomplete apposition and 1 insufficient expansion of the stent).

CONCLUSIONS

Paclitaxel-eluting stent implantation is considered safe and potentially efficacious in the treatment of ISR. IVUS guidance to ensure good stent deployment with complete coverage of target lesion may reduce reintervention.

Intravascular ultrasound findings in the multicenter, randomized, double-blind RAVEL (RAndomized study with the sirolimus-eluting VElocity balloon-expandable stent in the treatment of patients with de novo native coronary artery Lesions) trial

BACKGROUND

The goal of this intravascular ultrasound investigation was to provide a more detailed morphological analysis of the local biological effects of the implantation of a sirolimus-eluting stent compared with an uncoated stent.

METHODS AND RESULTS

In the RAVEL trial, 238 patients with single de novo lesions were randomized to receive either an 18-mm sirolimus-eluting stent (Bx VELOCITY stent, Cordis) or an uncoated stent (Bx VELOCITY stent). In a subset of 95 patients (sirolimus-eluting stent=48, uncoated stent=47), motorized intravascular ultrasound pullback (0.5 mm/s) was performed at a 6-month follow-up. Stent volumes, total vessel volumes, and plaque-behind-stent volumes were comparable. However, the difference in neointimal hyperplasia (2+/-5 versus 37+/-28 mm3) and percent of volume obstruction (1+/-3% versus 29+/-20%) at 6 months between the 2 groups was highly significant (P<0.001), emphasizing the nearly complete abolition of the proliferative process inside the drug-eluting stent. Analysis of the proximal and distal edge volumes showed no significant difference between the 2 groups in external elastic membrane or lumen and plaque volume at the proximal and distal edges. There was also no evidence of intrastent thrombosis or persisting dissection at the stent edges. Although there was a higher incidence of incomplete stent apposition in the sirolimus group compared with the uncoated stent group (P<0.05), it was not associated with any adverse clinical events at 1 year.

CONCLUSIONS

Sirolimus-eluting stents are effective in preventing neointimal hyperplasia without creating edge effect and without affecting the plaque burden behind the struts.

Geographical miss and restenosis during catheter-based intracoronary beta-radiation for de novo lesions

OBJECTIVES

We sought to determine the impact of geographical miss (GM) on restenosis rates after intracoronary beta-radiation therapy for de novo lesions.

BACKGROUND

GM is the situation in which injured vessel segments (VSs) are receiving low-dose radiation and is accounted for edge restenosis. Its impact on the overall restenosis rates remains to be determined.

METHODS

We analyzed 330 patients (356 vessels) treated according to the Beta Radiation in Europe (BRIE) and the Dose Finding study protocols. Using quantitative coronary angiography (QCA), the effective irradiated segment (EIRS), its edges and the total VS were analysed. The edges of the EIRS that were injured constituted the GM edges. Restenosis was defined as diameter stenosis > 50% at follow-up. GM was determined by the simultaneous electrocardiographic-matched, side-by-side projection of the source and balloons deflated and surrounded by contrast, at the site of injury, in identical angiographic projections.

RESULTS

In 20.5% of the vessels, GM was non-interpretable due to inadequate filming. GM occurred at 30.4% of the interpretable edges and 53% of the interpretable vessels that were analysed. Edge restenosis was significantly increased in the GM compared to non-GM edges (13.16% vs. 4.17%, respectively, P = .001), both in the proximal (P = .03) and the distal (P = .001) edges. GM associated with stent injury significantly increased edge restenosis (P = .006). GM related to balloon injury tended to be associated with increment in edge restenosis (P = .07). The restenosis in the EIRS was similar between vessels with and without GM (17.78% and 14.85%, respectively, P = .6). GM was associated with significant increment in the restenosis at the analyzed VS (31.85% vs. 21.48%, P = .05).

CONCLUSIONS

GM is strongly associated with edges and restenosis in the analysed VS. GM does not increase restenosis in the EIRS.

[Current status of intracoronary brachytherapy]

Intracoronary radiation therapy or intracoronary brachytherapy has been developed as an attempt to decrease restenosis after percutaneous coronary interventions. Two parallel technologies, one employing radioactive stents, the other catheter-based radiation (using either beta- or gamma- emitters), have been the subject of numerous animal and human studies. In vivo intravascular ultrasound imaging studies have played a major role in determining the possible mechanism of action of intracoronary radiation therapy and the pathogeny of many of the complications related to the use of this technique. This manuscript is aimed at revising the potential and limitations of intracoronary brachytherapy, as well as at summarizing the results of the currently reported clinical trials.

Mechanisms of angioplasty and stent restenosis: implications for design of rational therapy

Restenosis after angioplasty or stenting remains the major limitation of both procedures. A vast array of drug therapies has been used to prevent restenosis, but they have proven to be predominantly unsuccessful. Recent trends in drug therapy have attempted to refine the molecular and biological targets of therapy, based on the assumption that a single biological process or molecule is critical to restenosis. In contrast, both stenting and brachytherapy, which are highly nonspecific, can successfully reduce restenosis after angioplasty or stenting, respectively. This review examines the biology of both angioplasty and stent stenosis, focussing on human studies. We also review the landmark human trials that have definitively proven successful therapies, such as stenting and brachytherapy. We suggest that the successful trials of stenting and brachytherapy and the failure of other treatments have highlighted the shortcomings of conventional animal models of arterial intervention, and gaps in our knowledge of human disease. In contrast to arguments advocating gene therapy, these studies suggest that the most likely successful drug therapy will have a wide therapeutic range, targeting as many of the components or biological processes contributing to restenosis as possible.

Intracoronary radiotherapy for prevention of restenosis after percutaneous coronary interventions

More than 50 different pharmacological and mechanical interventions have been tested to date for prevention of vascular restenosis without success. Intracoronary radiotherapy is the first one showing promise of significantly attenuating neointimal proliferation, causing positive vascular remodelling and thus inhibiting restenosis. This promising modality has moved from animal experiments via safety and feasibility testing into the phase of clinical trials of efficacy in large numbers of patients. While ongoing research continues to search for new sources and delivery techniques, currently available technology is being optimized. The randomized clinical trials conducted to date have shown consistently a reduction of target site restenosis rates by 55-79%. Lower incidence of major adverse cardiac events after radiotherapy has also been demonstrated, primarily as a result of reduction in target site and target vessel revascularization rates. However, experimental and clinical research has identified two major complications of this approach: stenosis at the ends of the radiation zone ('edge effect' or 'candywrapper') as well as late thrombosis (beyond 30 days after intervention) of the angioplasty or stent site. If these two adverse effects can be minimized, intracoronary radiotherapy may prove to be a major breakthrough in percutaneous coronary interventions.

Intracoronary irradiation and stent placement in a chronic total coronary occlusion: long-term clinical, angiographic, and intracoronary ultrasound follow-up

Intracoronary irradiation emerges as a promising method in a variety of restenosis prone coronary lesions. We report the acute and long-term clinical, angiographic, and ICUS follow-up of a patient who underwent a successful angioplasty with stent placement in a chronic coronary occlusion with adjuvant gamma-intracoronary radiation.