A call for provisional stenting: the balloon is back!

Gallic Acid Inhibits Proliferation and Migration of Smooth Muscle Cells in a Pig In-Stent Restenosis Model

In-stent restenosis (ISR) develops primarily due to neointimal hyperplasia. Gallic acid (GA) has anti-inflammatory, antioxidant, and cardioprotective effects. This study sought to investigate the effects of GA on neointimal hyperplasia and proliferation and migration of vascular smooth muscle cells (VSMCs) in a pig ISR model. In vitro proliferation and migration experiments were confirmed, after VSMCs were treated with platelet-derived growth factor (PDGF-BB) and GA (100 µM) using a 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay and a scratch wound assay for 24 hours and 48 hours. A bare metal stent (BMS) was implanted in the pig coronary artery to induce ISR with overdilation (1.1-1.2:1), and GA (10 mg/kg/day) was administered for 4 weeks. At the 4-week follow-up, optical coherence tomography (OCT) and histopathological analyses were performed. GA decreased the proliferation of VSMCs by PDGF-BB for 24 hours (89.24±24.56% vs. 170.04±19.98%, p<0.001) and 48 hours (124.87±7.35% vs. 187.64±4.83%, p<0.001). GA inhibited the migration of VSMCs induced by PDGF-BB for 24 hours (26.73±2.38% vs. 65.38±9.73%, p<0.001) and 48 hours (32.96±3.04% vs. 77.04±10.07%, p<0.001). Using OCT, % neointimal hyperplasia was shown to have significantly decreased in the GA group compared with control vehicle group (28.25±10.07% vs. 37.60±10.84%, p<0.001). GA effectively reduced neointimal hyperplasia by inhibiting the proliferation and migration of VSMCs in a pig ISR model. GA could be a potential treatment strategy for reducing ISR after stent implantation.

Development of a New Biodegradable Intravascular Polymer Stent with Simultaneous Incorporation of Bioactive Substances

Objective

Due to the thrombogenicity and permanent implant nature of metallic stents, bioresorable synthetic polymers have been proposed for stents and local drug delivery systems. Bioresorbable polyesters like poly(D,L-lactide) demonstrated excellent biocompatibility in various tissues. This paper describes a novel method for the molding of these polymers. The specific CESP-process (Controlled Expansion of Saturated Polymers) is characterised by the use of the plasticizer carbon dioxide and allows the incorporation of bioactive substances at physiologic temperatures into the polymer bulk and the production of complex designed implants.

Methods

The CESP-process is characterised by the exposure of an amorphous polymer to an inert gas at high pressure with a significant lower glass transition point. The plasticizing effect makes it possible to process polylactides at a temperature close to room temperature. The low process temperature constitutes a key advantage for thermally sensitive polymers and allows the incorporation of thermally sensitive pharmaceutical additives. To obtain some preliminary information on the biocompatibility, in vitro cell toxicity testing as well as drug release assessment was performed.

Results

Different polymer sheets were produced using the CESP-process. Cytotoxicity was not observed in any molded polymer material. According to the mechanical and biocompatibility results Poly(D,L-lactide) (P-DL-LA) was investigated in the CESP-process. Finite element analysis was used to test the possible geometry of an adequate stent. A helical design was chosen and a stent-prototype was produced using the CESP-process. Peroxidase activity as an incorporated marker enzyme could be measured over 6 weeks. DIfferent drug release profiles were obtained due to various pore sizes of the polymer.

Conclusions

The new CESP-process can be used to process biodegradable polymers and to mold different stent geometries without inducing cytotoxic effects to the material. Furthermore, this procedure permits the simultaneous incorporation of bioactive substances during the molding process. Drug release kinetics can be regulated by different pore sizes of the material.

Drug Eluting Stent Technology

The authors discuss the mechanism of action, clinical trial data, and economic impact of both the paclitaxel and sirolimus drug eluting stents (DESs). Both DESs have been approved by the Food and Drug Administration for the treatment of native coronary arteries to prevent in-stent restenosis (ISR), which patients have experienced since the advent of balloon angioplasty and the bare metal stent. In-stent restenosis, which manifests itself as ischemic symptoms in patients, occurs as a result of the healing process after stent implantation. Until now, there has not been an effective method to prevent ISR. The sirolimus and paclitaxel DESs elute agents that act locally by different mechanisms to reduce neointimal hyperplasia, which is primarily responsible for ISR. Both DESs are capable of reducing the rate of ISR. There are certain physical and mechanistic differences between the 2 stents; the stents have not been compared head to head. Currently, they are indicated for uncomplicated native coronary lesions. Further investigation is needed to define their roles in the treatment of more complex lesions.

Coronary artery stents: Part I. Evolution of percutaneous coronary intervention

The subspecialty of interventional cardiology has made significant progress in the management of coronary artery disease over the past three decades with the development of percutaneous coronary transluminal angioplasty, atherectomy, and bare-metal and drug-eluting stents (DES). Bare-metal stents (BMS) maintain vessel lumen diameter by acting as a scaffold and prevent collapse incurred by angioplasty. However, these devices cause neointimal hyperplasia leading to in-stent restenosis and requiring reintervention in more than 20% of patients by 6 mo. DES (sirolimus and paclitaxel) prevent restenosis by inhibiting neointimal hyperplasia. However, DESs also delay endothelialization, causing the stents to remain thrombogenic for an extended, yet unknown, period of time. Late stent thrombosis is associated with a 45% mortality rate. Premature discontinuation of antiplatelet therapy, particularly clopidogrel, is the strongest predictor of stent thrombosis. Sixty percent of patients receive stents for off-label (unapproved) indications, which also increases the frequency of stent thrombosis. Clopidogrel and aspirin are the cornerstone of therapy in the prevention of stent thrombosis in both BMS and DES. Recommendations pertaining to the optimal duration of dual-antiplatelet therapy have been debated. Both the Food and Drug Administration and the American Heart Association/American College of Cardiologists, in association with other major societies, have made recommendations to extend the duration of dual-antiplatelet therapy in patients with DES to 1 yr. The 6-wk duration of dual-antiplatelet therapy in patients with BMS remains unchanged. All patients with coronary stents must remain on life-long aspirin monotherapy. Since the introduction of percutaneous transluminal coronary angioplasty for the treatment of coronary atherosclerosis, the practice of percutaneous coronary intervention has undergone a dramatic transformation from simple balloon dilation catheters to sophisticated mechanical endoprostheses. These advancements have impacted the practice of perioperative medicine. In this series of two articles, in Part I we will review the evolution of percutaneous coronary intervention and discuss the issues associated with percutaneous transluminal coronary angioplasty and coronary stenting; in Part II we will discuss perioperative issues and management strategies of coronary stents during noncardiac surgery.

A new approach to the assessment of lumen visibility of coronary artery stent at various heart rates using 64-slice MDCT

Coronary artery stent lumen visibility was assessed as a function of cardiac movement and temporal resolution with an automated objective method using an anthropomorphic moving heart phantom. Nine different coronary stents filled with contrast fluid and surrounded by fat were scanned using 64-slice multi-detector computed tomography (MDCT) at 50–100 beats/min with the moving heart phantom. Image quality was assessed by measuring in-stent CT attenuation and by a dedicated tool in the longitudinal and axial plane. Images were scored by CT attenuation and lumen visibility and compared with theoretical scoring to analyse the effect of multi-segment reconstruction (MSR). An average increase in CT attenuation of 144 ± 59 HU and average diminished lumen visibility of 29 ± 12% was observed at higher heart rates in both planes. A negative correlation between image quality and heart rate was non-significant for the majority of measurements (P > 0.06). No improvement of image quality was observed in using MSR. In conclusion, in-stent CT attenuation increases and lumen visibility decreases at increasing heart rate. Results obtained with the automated tool show similar behaviour compared with attenuation measurements. Cardiac movement during data acquisition causes approximately twice as much blurring compared with the influence of temporal resolution on image quality.

Initial Results on Visualization of Coronary Artery Stents at Multiple Heart Rates on a Moving Heart Phantom Using 64-MDCT

OBJECTIVE

Evaluation of the image quality of coronary artery stents at various heart rates using Multi Detector Computed Tomography (MDCT).

METHODS

Nine different coronary stents were attached to a moving heart phantom and scanned using a 64-MDCT with a rotation time of 330 milliseconds (ms). The heart rate of the phantom was varied between 0 and 115 beats per minute (bpm). Two independent methods were used to investigate image quality. After reconstruction the average Houndsfield Unit (HU) value in the stent lumen was measured in the longitudinal and the cross-sectional plane. The stent images were then presented to two radiologists. The radiologists were asked to rank the images from good to bad based on lumen visibility and overall image quality. A second ranking was obtained using the CT density values. Finally two rankings were compared.

RESULTS

Compared to the value for air, the HU-values measured in the lumen increased by 50 to 700 HU. Average slope value in the longitudinal plane was 1.7 +/- 0.6 HU/bpm, and the average slope value in the cross-sectional plane was 1.7 +/- 0.8 HU/bpm. This shows increased attenuation with increasing heart rate and thus a negative correlation between image quality and heart rate in both planes for all stents. The ranking acquired from the radiologists resembled the measured results as they also showed a negative correlation between the two variables. Using the results of the CT density measurements an analysis was done on multi-segment reconstruction (MSR).

CONCLUSION

A negative correlation between the heart rate and image quality of coronary stents was found by two independent methods. MSR showed no benefit for image quality in this study.

Tissue Inhibitor of Metalloproteinase 1 Adenoviral Gene Therapy Alone Is Equally Effective in Reducing Restenosis as Combination Gene Therapy in a Rabbit Restenosis Model

Neointimal formation is a common feature after angioplasty, bypass grafting and stenting. Angioplasty damages endothelium, causing pathological changes in arteries which lead to smooth muscle cell proliferation, synthesis of extracellular matrix components and eventually restenosis formation. Adenoviruses offer an efficient transgene expression in the vascular system. In this study, we compared the effects of different gene combinations. We wanted to find out whether adenoviral catheter-mediated delivery of an additive combination of the vascular endothelial growth factor (VEGF)-A with VEGF-C is more effective than the combination of tissue inhibitor of metalloproteinase 1 (TIMP-1) alone or with VEGF-C in a rabbit balloon denudation model. Additionally, we wanted to clarify whether the combination therapy prolongs the treatment effect. It was found that TIMP-1 alone prevents restenosis and that the combination of VEGF-A and VEGF-C has a similar effect at the 2-week time point. However, the combination of VEGF-A and VEGF-C lost the treatment effect at the 4-week time point due to the catch-up growth of neointima. On the other hand, TIMP-1 and the combination of TIMP-1 with VEGF-C still had an extended treatment effect at the 4-week time point. When considering the gene combination used in this study, it is concluded that gene therapy with adenoviral TIMP-1 alone is sufficient in reducing restenosis and that combination gene therapy does not bring any significant advantages.

Gene transfer using the mature form of VEGF-D reduces neointimal thickening through nitric oxide-dependent mechanism

Gene transfer to the vessel wall using vascular endothelial growth factors (VEGFs) has shown therapeutic potential for the treatment of restenosis. In this study, we evaluated the effect of catheter-mediated adenoviral (Ad) gene transfer of the mature form of VEGF-D (VEGF-D(DeltaNDeltaC)) in balloon-denuded cholesterol-fed rabbit aorta. AdLacZ was used as a control. Transduced VEGF-D(DeltaNDeltaC) mRNA was detectable in the arterial wall with RT-PCR at 6, 14 and 28 days. Gene transfer efficiency as detected with X-gal staining 6 days after the AdLacZ transduction was 1.91 +/- 1.32% in intima. AdVEGF-D(DeltaNDeltaC) gene transfer led to 52% reduction in intima/media ratio (I/M) as compared to the AdLacZ controls at 14 days time point. At 6 days there were no differences in I/M, but the number of macrophages in the vessel wall was 85% lower in the AdVEGF-D(DeltaNDeltaC) group as compared to the controls. The therapeutic effect was no longer detectable 28 days after the gene transfer. The therapeutic effect of VEGF-D(DeltaNDeltaC) was nitric oxide (NO)-dependent as the feeding of NO synthase inhibitor, L-NAME, blocked the reduction in intimal thickening. It is concluded that AdVEGF-D(DeltaNDeltaC) gene transfer reduces intimal thickening and macrophage influx into the vessel wall in balloon-denuded rabbit aortas.

Catheter-mediated delivery of adenoviral vectors expressing beta-adrenergic receptor kinase C-terminus inhibits intimal hyperplasia and luminal stenosis in rabbit iliac arteries

BACKGROUND

Previous studies have shown that incubation of balloon-injured rat carotid arteries with adenoviral vectors encoding the carboxyl terminus of the beta-adrenergic receptor kinase (Ad2/betaARKct) for 30 min reduces neointima formation. However, it is unclear whether this beneficial effect of betaARKct could be achieved using a catheter-based vector delivery system and whether the observed inhibition of neointima formation translated into a reduction of vessel stenosis.

METHODS

In this study, Ad2/betaARKct was infused into the balloon-injured site of rabbit iliac arteries using a porous infusion catheter over 2 min. Twenty-eight days after gene transfer, angiographic and histological assessments were performed.

RESULTS

Angiographic and histological assessments indicate significant (p < 0.05) inhibition of iliac artery neointima formation and lumen stenosis by Ad2/betaARKct. Our studies demonstrate that an inhibitory effect of Ad2/betaARKct on neointima formation is achievable using a catheter-based vector delivery system and that the inhibition of neointima formation translates into a gain in the vessel minimal luminal diameter. The extent of inhibition (35%) was comparable to that observed with adenoviral-mediated expression of thymidine kinase plus ganciclovir treatment, a cytotoxic gene therapy approach for restenosis.

CONCLUSIONS

These results suggest that adenoviral-mediated gene transfer of betaARKct is a clinically viable cytostatic gene therapy strategy for the treatment of restenosis.

Is bare-metal stenting superior to balloon angioplasty for small vessel coronary artery disease? Evidence from a meta-analysis of randomized trials

AIMS

To compare, by meta-analytical techniques, the clinical impact of bare-metal stenting vs. balloon angioplasty for the treatment of lesions in small coronary arteries.

METHODS AND RESULTS

We included trials with random allocation and prospective comparison of angioplasty vs. stenting, reference vessel diameter<3 mm, and follow-up>or=6 months. Random effect odds ratios (OR) for death, myocardial infarction (MI), repeat revascularization (RR), and major adverse cardiac events (MACEs) were computed. In a pre-specified subgroup analysis, we compared stenting with optimal (post-procedural stenosis<20%) and suboptimal (>20%) angioplasty. Thirteen studies (4383 patients) were selected. No differences were found in terms of death and MI, while MACEs, mainly driven by RR, were significantly less common after stenting (17.6%) than after angioplasty (22.7%), OR 0.71 (0.57-0.90). Heterogeneity among trials was present. When considering only optimal angioplasty, MACE rates were homogeneously similar, 17.9 vs. 21.1%, OR 0.86 (0.66-1.11). If angioplasty were suboptimal, MACEs were significantly more common after angioplasty (24%) than after stenting (17.3%), OR 0.62 (0.44-0.88).

CONCLUSION

Stenting is superior to balloon angioplasty for the treatment of small vessels, in particular after suboptimal angioplasty. However, MACE and RR rates remain high after stenting, and the advantage of stent over angioplasty is moderate. An optimal balloon angioplasty strategy (with provisional stenting) may achieve results not inferior to routine stenting.

Deteriorative Effect of Smoking on Target Lesion Revascularization After Implantation of Coronary Stents With Diameter of 3.0 mm or Less

BACKGROUND

Although smoking cessation is widely encouraged because of the associated risk of cardiovascular events, the impact of smoking on target lesion revascularization (TLR) after percutaneous coronary intervention (PCI) is controversial. Therefore, the present study retrospectively investigated the effect of smoking on TLR after plain-old balloon angioplasty (POBA; n=376) and stenting (STENT; n=434) in patients undergoing secondary coronary angiography at a single center.

METHODS AND RESULTS

A smoker was defined as current smoking or quitting within 2 years of the first PCI. In the POBA group, the predictors for TLR, as calculated by multiple logistic regression analysis, were a complex type of lesion (p<0.0001) and the left anterior descending artery (LAD) as affected vessel (p<0.05). In the STENT group, the predictors were the final % diameter of stenosis after stenting, measured by quantitative coronary arteriography (p<0.0005), LAD (p<0.01), and smoking (p=0.049). When the STENT group was divided into 2 groups according to the diameter of the implanted stent, smoking was a predictive factors for TLR in the group that received relatively small stents (diameter < or =3.0 mm) (p<0.02), but not in the group that received larger stents (diameter > or =3.5 mm).

CONCLUSION

Smoking has a deteriorative effect on TLR after implantation of relatively small coronary stents with a diameter of 3.0 mm or less.

In-hospital Costs of Self-Expanding Nitinol Stent Implantation versus Balloon Angioplasty in the Femoropopliteal Artery (The VascuCoil Trial)

PURPOSE

Although several prospective studies have examined the safety and efficacy of stent placement for femoropopliteal arterial disease, the current cost of these procedures is unknown. To estimate and compare hospital costs associated with conventional balloon angioplasty (percutaneous transluminal angioplasty [PTA]) and stent placement for patients with symptomatic peripheral arterial disease, the authors performed a prospective economic evaluation in conjunction with the Intracoil Femoropopliteal Stent Trial (VascuCoil).

MATERIALS AND METHODS

Between May 1997 and December 1999, 266 patients with stenotic or occluded superficial femoral or popliteal arteries were prospectively randomized to treatment with the IntraCoil stent or PTA. Detailed resource use and cost data for each patient's initial revascularization procedure and ensuing hospitalization were collected and analyzed on an intention-to-treat basis.

RESULTS

Compared with conventional balloon angioplasty, stent placement did not improve clinical outcomes but increased procedure duration, equipment costs, and physician services. As a result, initial hospital costs were approximately 3,500 dollars higher for patients randomized to the IntraCoil stent, compared with PTA (8,435 dollars vs 4,980 dollars; P < .001).

CONCLUSIONS

As performed in the VascuCoil trial, primary stent placement for femoropopliteal disease did not improve clinical outcomes but increased initial treatment costs by more than 3,000 dollars. Because there were no substantial differences in subsequent clinical outcomes between the two treatments, it is unlikely that these increased initial costs would be offset by savings in follow-up costs. These findings suggest that a strategy of routine stent implantation for patients undergoing femoropopliteal PTA is not optimal on economic grounds and that PTA with provisional stent implantation is preferred.

Prevention of restenosis after coronary angioplasty

PURPOSE OF REVIEW

Despite numerous advances in coronary interventional techniques, the frequent occurrence of restenosis continues to plague interventional cardiology. With the widespread use of drug-eluting stents, there is a need to reexamine critically the roles of the various interventional techniques currently available.

RECENT FINDINGS

Drug-eluting stents have dramatically reduced the rates of restenosis and target vessel revascularization in a wide spectrum of patients with varying lesion morphologies. However, when restenosis does occur, it still tends to be dependent on the same factors that predict restenosis with bare metal stenting. The routine use of drug-eluting stents entails high initial costs to the health care system. Debulking as a means to improve outcomes after angioplasty has not lived up to expectations. Gene therapy is rapidly evolving into a viable means to reduce neointimal proliferation after angioplasty.

SUMMARY

Careful patient selection and attention to the procedure of stent deployment optimize the results of angioplasty with drug-eluting stents. Because of cost considerations, drug-eluting stents should be used in patients who are expected to have the greatest absolute benefit. In this context, when judiciously used, conventional balloon angioplasty and bare metal stenting still have a definite role in the management of patients with obstructive coronary artery disease.

Effect of diabetes on long-term mortality following contemporary percutaneous coronary intervention: analysis of 4,284 cases

OBJECTIVE

Diabetic patients are known to have reduced long-term survival following percutaneous transluminal coronary angioplasty compared with nondiabetic patients. However, it is unknown whether this survival disadvantage has persisted in the era of contemporary percutaneous coronary intervention (PCI) techniques, which include the widespread use of stents and the availability of platelet glycoprotein (GP) IIb/IIIa inhibitors.

RESEARCH DESIGN AND METHODS

Three hospitals in New York City contributed prospectively defined data on 4,284 patients undergoing PCI. The primary end point was all-cause mortality following hospital discharge for PCI.

RESULTS

Hypertension, renal insufficiency, and renal failure requiring dialysis were all more common in diabetic patients, whereas active smoking was less frequent. Congestive heart failure on admission was more common in diabetic than nondiabetic patients (7.7 vs. 4.0%, P < 0.001). Stents were placed in 78% of nondiabetic patients and 75% of diabetic patients (P = 0.045). Platelet GP IIb/IIIa antagonists were administered to 23% of nondiabetic and 24% of diabetic patients (P = NS). At a mean follow-up of 3 years, mortality was 8% among nondiabetic patients and 13% for diabetic patients (P < 0.001). After adjustment for differences in baseline characteristics between nondiabetic and diabetic patients, diabetes remained a significant independent hazard for late mortality (hazard ratio 1.462, 95% CI 1.169-1.828; P = 0.001).

CONCLUSIONS

Following contemporary PCI, diabetic patients continue to have worse survival than nondiabetic patients.

Function and structure of pressurized and perfused porcine carotid arteries: effects of in vitro balloon angioplasty

In this report we describe the application of an in vitro pressure-perfusion system for study of functional/structural changes after in vitro balloon dilation injury. Pig carotid arteries were perfused at P = 100 mm Hg and Q = 100 ml/min, balloon angioplastied (BA), and cultured under these hemodynamic conditions for 4 or 8 days (n = 5 BA and 6 controls for each time point). To assess endothelial function, outer diameter changes in response to bradykinin (BK) were measured daily. Remodeling was determined from the shift in pressure-passive diameter relation, as obtained after papaverine addition. Arterial samples were processed for histology. Control arteries showed spontaneous tone, BK-induced relaxation, and inward remodeling that was more pronounced at day 8 (ratio end-to-start passive diameter at P = 100 mm Hg, 0.69 +/- 0.04; P < 0.001) than at day 4 (0.85 +/- 0.03, P = 0.03). Intimal hyperplasia was detectable in these control vessels at day 8 with accumulation of alpha-smooth muscle actin-positive cells around the lumen. Angioplasty caused ruptures and dissections and abolished tone that returned after 5 days of perfusion along with BK-dependent relaxation. No significant inward remodeling or intimal hyperplasia was observed at day 8 after angioplasty. Thus, BA inhibits remodeling, which occurs after in vitro perfusion of conductance arteries.

Outcomes of optimal or “stent-like”balloon angioplasty in acutemyocardial infarction: the CADILLAC trial

OBJECTIVES

We sought to compare outcomes between patients with acute myocardial infarction (AMI) undergoing percutaneous transluminal coronary angioplasty (PTCA) with an optimal or "stent-like" result versus patients who underwent routine stent placement.

BACKGROUND

Recent studies in patients with AMI undergoing stent implantation have suggested that PTCA may no longer be a relevant treatment modality for stent eligible lesions. However, whether routine stent placement is superior or necessary when an optimal PTCA or "stent-like" result is achieved is unknown.

METHODS

In the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial, 2,082 patients with AMI were randomly assigned to undergo PTCA alone, PTCA + abciximab, stenting alone, or stenting + abciximab. Outcomes were compared in patients achieving an optimal acute PTCA result (residual core laboratory diameter stenosis <30% without significant dissection) versus those assigned to routine stenting.

RESULTS

Optimal PTCA was achieved in 40.7% of patients randomized to balloon angioplasty, including 38.5% and 42.7% assigned to PTCA alone and PTCA + abciximab, respectively. Ischemic target vessel revascularization (TVR) at 30 days occurred more frequently after optimal PTCA than routine stenting (5.1% vs. 2.3%, p = 0.007). The one-year composite adverse event rate (death, reinfarction, disabling stroke, or TVR) was greater after optimal PTCA than routine stenting (21.9% vs. 13.8%, p < 0.001), driven largely by increased rates of ischemic TVR (19.1% vs. 9.1%, p < 0.001); no significant differences were present in the rates of death, reinfarction, or disabling stroke between the two groups. Angiographic restenosis also was more common with optimal PTCA than routine stenting (36.2% vs. 22.2%, p = 0.003). Even a post-PTCA diameter stenosis of <20% (realized in 12% of patients) did not result in outcomes equivalent to stenting.

CONCLUSIONS

Even if an optimal result is achieved after primary PTCA in AMI, early and late outcomes can be further improved with routine stent implantation.

Multislice spiral computed tomography for the detection of coronary stent restenosis and patency

BACKGROUND

Multislice spiral computed tomography (MSCT) has evolved as a new promising method for non-invasive visualization of the coronary arteries and detection of native coronary artery stenosis. We determined the value of MSCT to non-invasively detect significant in-stent restenosis after coronary artery stenting.

METHODS

Twenty patients (age 56.3+/-8.6 years) were investigated by MSCT (4x1 mm cross-sections, 500 ms tube rotation, table feed 1.5 mm/rotation, intravenous contrast agent, retrospectively ECG-gated image reconstruction) at a mean interval of 9.6+/-4.2 months after coronary stent implantation. Results were compared with conventional quantitative coronary angiography (QCA). A total number of 32 stents were studied, four different stent types were evaluated.

RESULTS

QCA showed in-stent restenosis >50% diameter stenosis in five (16%) stents. Using MSCT it was impossible in all stents, irrespective of stent type or diameter, to directly visualize the stent lumen due to partial volume effects and beam hardening. MSCT allowed the visualization of the coronary vessel proximal and distal to the stent. This allowed confirmation of stent patency in 18/18 cases and correct identification of total stent occlusion in two patients.

CONCLUSIONS

MSCT allows no direct visualization of coronary in-stent restenosis, but it correctly differentiates between stent patency and stent occlusion. The reasons are mainly partial volume effects and beam hardening, which are induced by the stent material.

Heparin-coated balloon-expandable stent reduces intimal hyperplasia in the iliac artery in baboons

PURPOSE

To examine the effect of heparin-coated balloon-expandable iliac stent placement on intimal hyperplasia in a baboon model.

MATERIALS AND METHODS

Balloon-expandable (Palmaz-Schatz) stents were placed in bilateral common iliac arteries in 20 male baboons (mean weight: 8.8 kg). In each animal, a heparin-coated iliac stent was placed on one side and the contralateral iliac artery received an uncoated stent that served as a control. The iliac artery stents were harvested at 30 days (n = 10) and 90 days (n = 10). Arteriography was performed to assess iliac patency and intravascular ultrasonography was used to determine neointimal and luminal areas. Histologic and morphometric analysis and scanning electron microscopy were performed in the stent-implanted iliac arteries.

RESULTS

One animal was excluded in the 30-day group because of premature death. In the remaining nine surviving animals, seven control stents (78%) and nine heparin-coated stents (100%) remained patent. Morphometric analysis showed that the iliac arteries with heparin-coated stents had larger luminal areas (17%, P <.05), less neointimal area (26%, P <.05), lower neointima-to-media ratios (32%, P <.05), and equivalent medial areas (P =.92) compared to the control group at 30 days. In contrast, all control and heparin-coated stents were patent (100%) in the 90-day group. In that group, the heparin-coated stent group had less neointimal area (28%, P <.05), lower neointima-to-media ratios (42%, P <.05), and equivalent medial area (P =.92) and luminal area (P =.07) compared to the control group.

CONCLUSIONS

The data demonstrate that heparin-coated balloon-expandable stents reduce intimal hyperplasia after iliac artery stent placement. This approach may represent a useful strategy for prolonging luminal patency after iliac stent placement.

Gene therapy for restenosis: current status

Atherosclerosis is a major cause of morbidity and mortality in Western world. Vascular occlusion caused by atherosclerosis usually requires invasive treatment, such as surgical bypass or angioplasty. However, bypass graft failure and restenosis limit the usefulness of these procedures, with 20% of patients needing a new revascularisation procedure within 6 months of angioplasty. Numerous pharmacological agents have been investigated for the prevention of restenosis but none has shown undisputed efficacy in clinical medicine. Gene transfer offers a novel approach to the treatment of restenosis because of easy accessibility of vessels and already existing gene delivery methods. It can be used to overexpress therapeutically important proteins locally without high systemic toxicity, and the therapeutic effect can be targeted to a particular pathophysiological event. Promising results have been obtained from many pre-clinical experiments using therapeutic genes or oligonucleotides to prevent restenosis. Early clinical trials have shown that plasmid- and adenovirus-mediated vascular gene transfers can be conducted safely and are well tolerated. Ex vivo gene therapy with E2F-decoy succeeded in reducing graft occlusion rate after surgical bypass in a randomised, double-blind clinical trial. In the future, further development of gene delivery methods and vectors is needed to improve the efficacy and safety of gene therapy. Also, better knowledge of vascular biology at the molecular level is needed to find optimal strategies and gene combinations to treat restenosis. Provided that these difficulties can be solved, gene therapy offers an enormous potential for clinical medicine in the future.

Stent design-related coronary artery remodeling and patterns of neointima formation following self-expanding and balloon-expandable stent implantation

The self-expanding Wallstent (WS) and balloon-expandable Palmaz-Schatz stents (PS) display different mechanical and dynamical stent properties. We analyzed the impact of the respective stent design on coronary wall geometry using quantitative coronary angiography (QCA) and intracoronary ultrasound (ICUS) measurements. Serial measurements were performed within the stent and within reference segments of 50 patients (25 WS, 25 PS). Relative changes for each parameter in both stent designs were calculated (Mann-Whitney U-test; 95% CI). The luminal net gain in WS was not significantly higher in WS compared with PS (1.63 +/- 1.11 vs. 1.44 +/- 0.63 mm; P = 0.2554). The respective loss indexes were also similar (0.38 +/- 0.42 vs. 0.36 +/- 0.23; P = 0.8578). The WS segments showed significant postinterventional stent expansion with positive vessel remodeling. The neointima formation was significantly higher in WS segments (4.23 +/- 2.07 vs. 2.22 +/- 2.22 mm(2)). The coronary wall morphology and stent geometry after 6.5 +/- 1.2 months are related to the stent design. In WS segments, the neointima formation was balanced by postinterventional stent expansion, resulting in a comparable relative lumen loss in both stent types. The respective stent design had no impact on the vessel reference segments.

Resource utilization, cost, and health status impacts of coronary stent versus "optimal" percutaneous coronary angioplasty: results from the OPUS-I trial

In the OPUS-I trial, primary coronary stent implantation reduced 6-month composite incidence of death, myocardial infarction, cardiac surgery, or target vessel revascularization relative to a strategy of initial PTCA with provisional stenting in patients undergoing single vessel coronary angioplasty. The purpose of this research was to compare the economic and health status impacts of each treatment strategy. Resource utilization data were collected for the 479 patients randomized in OPUS-I. Itemized cost estimates were derived from primary hospital charge data gathered in previous multicenter trials evaluating coronary stents, and adjusted to approximate 1997 Medicare-based costs for a cardiac population. Health status at 6 months was assessed using the Seattle Angina Questionnaire (SAQ). Initial procedure related costs for patients treated with a primary stent strategy were higher than those treated with optimal PTCA/provisional stent ($5,389 vs $4,339, P < 0.001). Costs of initial hospitalization were also higher for patients in the primary stent group ($9,234 vs $8,434, P < 0.01) chiefly because of the cost differences in the index revascularization. Mean 6-month costs were similar in the two groups; however, there was a slight cost advantage associated with primary stenting. Bootstrap replication of 6-month cost data sustained the economic attractiveness of the primary stent strategy. There were no differences in SAQ scores between treatment groups. In patients undergoing single vessel coronary angioplasty, routine stent implantation improves important clinical outcomes at comparable, or even reduced cost, compared to a strategy of initial balloon angioplasty with provisional stenting.

High shear stress after successful balloon angioplasty is associated with restenosis and target lesion revascularization

BACKGROUND

Vascular wall shear stress (WSS) has been implied in the pathogenesis of atherosclerosis and vascular remodeling. Our aim was to calculate WSS after balloon angioplasty and evaluate its predictive value for long-term outcome.

METHODS

WSS was calculated proximal to, in, and distal to the lesion after angiographically successful balloon dilatation and at follow-up with the Hagen-Poiseuille formula (WSS = 4 microQ/piR3) in 202 patients. Volumetric blood flow (Q) and lumen radius (R) were derived from Doppler scanning velocities and videodensitometric cross-sectional areas.

RESULTS

Postprocedural proximal and in-lesion values were higher in vessels that developed restenosis (n = 72; 1.22 +/- 0.61 N/m2 and 3.61 +/- 2.38 N/m2, respectively) than in those without restenosis (n = 130, 1.05 +/- 0.51 N/m2 and 2.46 +/- 1.39 N/m2, respectively; P <.05). In-lesion WSS was revealed to be predictive of restenosis by means of logistic regression analysis (odds ratio [OR] = 1.42, P <.05), whereas WSS of the proximal segment was associated with an increased rate of target lesion revascularization (OR = 2.33, P <.005). In the multivariate regression model, WSS of the proximal segment was the only independent predictor when entered with known predictors such as diameter stenosis and coronary flow reserve (OR = 2.15, P <.05).

CONCLUSIONS

WSS in the lesion after balloon angioplasty is predictive of angiographic restenosis. Moreover, the proximal value is an independent predictor of target lesion revascularization. This study opens perspectives for the on-line use of WSS as a combined parameter of anatomy and physiology to assess the necessity of adjunctive therapy after successful balloon dilatation.

Impact of pre-interventional arterial remodeling on subsequent vessel behavior after balloon angioplasty: a serial intravascular ultrasound study

OBJECTIVES

The purpose of this study was to assess the impact of pre-intervention arterial remodeling on subsequent vessel behavior following balloon angioplasty.

BACKGROUND

Positive arterial remodeling before intervention has been shown to have a negative impact on the clinical outcome after nonstented coronary interventional procedures. However, the mechanism of interventions in coronary vessel geometry over time is less well characterized.

METHODS

Serial (pre-, post- and follow-up) intravascular ultrasound analysis was performed in 46 native coronary lesions. Positive remodeling (PR) was defined as vessel area (VA) at the target lesion greater than that of average reference segments. Intermediate or negative remodeling (IR/NR) was defined as VA at the target lesion less than or equal to that of average reference segment. Remodeling index was defined as VA at the target lesion site divided by that of average references.

RESULTS

Pre-interventional PR and IR/NR were present in 21 (46%) and 25 (54%) of 46 patients, respectively. At follow-up, the change in plaque area was similar between the two groups (1.3 +/- 2.1 vs. 1.2 +/- 2.1 mm(2), p = 0.840). Lesions with PR showed a significantly smaller change in VA than those with IR/NR (-0.2 +/- 2.5 vs. 1.4 +/- 2.3 mm(2), p = 0.03). As a result, late lumen loss was significantly larger in lesions whose pre-intervention configuration exhibited PR (-1.5 +/- 1.8 vs. 0.2 +/- 1.6 mm(2), p = 0.002).

CONCLUSIONS

Lesions with PR appear to have less capacity to compensate for further plaque growth after balloon angioplasty and thus show a proportional increase in late lumen loss. This may in part explain the less favorable clinical outcomes of positively remodeled lesions.

Three-year follow-up after rotational atherectomy for the treatment of diffuse in-stent restenosis: predictors of major adverse cardiac events

Restenosis remains the major limitation of coronary stent implantation, especially in diffuse forms of in-stent restenosis. In this study, rotablation (RA) with adjunct angioplasty of in-stent restenosis was performed in 84 patients. Clinical follow-up and control angiography were obtained 6-month postprocedure. The rate of recurrent restenosis after rotablation for in-stent restenosis at 6-month angiographic follow-up was 45%, resulting in a rate of major adverse cardiac events of 35%. At 3-year follow-up, the cumulative event-free survival rate was 57% for the entire population. The only predictor of MACE at 3-year clinical follow-up by multivariate logistic regression analysis was in-stent lesion length. RA for the treatment of diffuse in-stent restenosis is thereby characterized by high procedural success rates and recurrent angiographic restenosis in 45% of patients with diffuse lesions. Major adverse cardiac events occur most likely within the first 6 months postprocedure. Three years after rotablation of in-stent restenosis, 43% of patients had experienced at least one major adverse cardiac event. Cathet Cardiovasc Intervent 2001;53:334-340.

Angiographic classification of coronary dissections after plain old balloon angioplasty for prediction of regression at follow-up

Coronary dissection after plain old balloon angioplasty often shows regression during follow-up. This study sought to determine whether we can predict such phenomenon angiographically. We analyzed 64 patients with 71 type B-D coronary dissections determined by the National, Heart, Lung, and Blood Institute (NHLBI) criteria. Regression was considered present when minimal lumen diameter increased by more than 0.3 mm during follow-up. Dissections were divided into subgroups using the NHLBI criteria and our classification in which type a and b dissections were characterized by the width of a dissection lumen exceeding one quarter of the reference diameter with the outer edge of the dissection lumen within the boundary of reference in type a and beyond it in type b. In type c and type d dissections, the width of the dissection lumen was within one quarter of the reference with its outer edge within the boundary of reference in type c and beyond it in type d. Type e dissection had a protruding flap or spiral appearance. Regression was recognized in 23.9%. The distribution of dissection types was similar in the groups with and without regression by the NHLBI criteria, but type c dissection had regression more frequently than the other types of coronary dissections (p<0.001) using our classification.

Long-term prognostic value of 201Tl single-photon emission computed tomographic myocardial perfusion imaging after coronary stenting

BACKGROUND

The prognostic value of (201)Tl myocardial imaging has been demonstrated in several studies concerning patients with a known significant coronary artery disease. However, the evolution of a coronary stenosis after stenting is difficult to predict. This study was designed to assess the prognostic value of (201)Tl single-photon emission computed tomography (thallium SPECT) perfusion imaging in patients after intracoronary stenting.

METHODS

One hundred fifty-two patients were studied. They were followed up during 40 +/- 13 (mean +/- SD) months after thallium SPECT. Stent-related events were studied after thallium stress testing and included cardiovascular death, myocardial infarction, and revascularization. Stress thallium imaging was performed 5 +/- 2 months after stenting, and ischemia was considered to be present if at least 2 contiguous segments were showing reversible defects.

RESULTS

Only 3 (3%) among the 105 nonischemic patients had major cardiac events during the follow-up versus 13 (28%) of the 47 ischemic patients (P < .001) after thallium SPECT. The relative risk of major cardiac events for patients with significant ischemia was 10.5 compared with nonischemic patients (P < .001). Fourteen (30%) of the ischemic patients and 8 (8%) among the nonischemic patients underwent iterative revascularization (P < .001). Therefore, only 11 (10%) of the nonischemic patients had major cardiac events or revascularization compared with 24 (51%) of the ischemic patients (P < .001).

CONCLUSIONS

Absence of ischemia on thallium SPECT imaging at 5 months after coronary stenting indicates a low risk for cardiovascular events or interventional procedure. These results may have important clinical implications in patient treatment.

Achieving optimal results with standard balloon angioplasty: can baseline and angiographic variables predict stent-like outcomes?

OBJECTIVES

To predict which patients might not require stent implantation, we identified clinical and angiographic characteristics associated with repeat revascularization after standard balloon angioplasty.

BACKGROUND

Stents reduce the risk of repeat revascularization but are costly and may lead to in-stent restenosis, which remains difficult to treat. Identification of patients at low risk for repeat revascularization may allow clinicians to reserve stents for patients most likely to benefit.

METHODS

Data from five interventional trials (5,146 patients) were pooled for analysis. We identified patients with optimal angiographic results (final diameter stenosis < or =30% and no dissection) after balloon angioplasty and determined the multivariable predictors of repeat revascularization.

RESULTS

Optimal angiographic results were achieved in 18% of patients after angioplasty. The repeat revascularization rate at six months was lower for patients with optimal results (20% vs. 26%, p < 0.001) but still higher than observed in stent trials. Independent predictors of repeat revascularization were female gender (odds ratio [OR] 1.67, p = 0.01), lesion length > or =10 mm (OR 1.62, p = 0.03) and proximal left anterior descending coronary artery lesions (OR 1.62, p = 0.03). For the 8% of patients with optimal angiographic results and none of these risk factors, the repeat revascularization and target vessel revascularization rates were 14% and 8% respectively, similar to rates after stent implantation. Cost analysis estimated that $78 million per year might be saved in the U.S. with a provisional stenting strategy using these criteria compared with elective stenting.

CONCLUSIONS

A combination of baseline characteristics and angiographic results can be used to identify a small group of patients at very low risk for repeat revascularization after balloon angioplasty. Provisional stenting for these low risk patients could substantially reduce costs without compromising clinical outcomes.

Lipid peroxidation may predict restenosis after coronary balloon angioplasty

The present study assessed whether lipid peroxidation in plasma might predict restenosis after coronary balloon angioplasty. A total of 87 patients, who had undergone successful coronary balloon angioplasty using standard techniques, were enrolled. Fasting blood samples before the intervention were measured for plasma levels of thiobarbituric acid reactive substances (TBARS, an indicator of lipid peroxidation). Angiography was carried out before and 15 min after angioplasty, and at follow-up (4 months after angioplasty), and evaluated using a quantitative approach. There were 23 patients with restenosis (group R) and 64 patients without restenosis (group N) after coronary balloon angioplasty. The plasma TBARS level (mean+/-SEM) of 4.3+/-0.1 micromol/L in group R was significantly higher than that of 3.2+/-0.1 micromol/L in group N (p<0.01). There were no significant differences in other parameters, including plasma lipid levels, between the 2 groups. The plasma level of TBARS positively correlated with lumen loss of the coronary artery at the time of follow-up angiography (r=0.57, p<0.01). Our results suggest that oxidative stress contributes to restenosis and indicate that an elevated plasma level of TBARS may be a reliable predictor of restenosis.

New developments in percutaneous coronary intervention

The field of percutaneous coronary intervention continues to progress at a tremendous rate. Advances in techniques, in device technology, and in adjunctive therapy have increased significantly the number of patients who may benefit from angioplasty and have increased the early and long-term success rates of these procedures. Future progress in radiation therapy, IIb/IIIa inhibitors, stent design, and other novel approaches undoubtedly will offer further improvements in the capability of coronary interventions to help patients live longer and feel better.

Provisional stenting for symptomatic intracranial stenosis using a multidisciplinary approach: acute results, unexpected benefit, and one-year outcome

Percutaneous techniques have dramatically changed our approach to coronary and peripheral revascularization. Intracranial atherosclerosis is a highly morbid disease; however, techniques for revascularization are still in evolution. The authors comprise a multidisciplinary team of neurologists, neuroradiologists, and interventional cardiologists who have collaborated in treating fifteen patients with symptomatic intracranial stenosis who have failed medical therapy. The acute success rate (100%) and one-year freedom from death and stroke (93.4%) using balloon angioplasty and provisional stenting are encouraging. A surprising observation in this patient cohort was that 53% of patients had improvement or resolution of a deficit that was chronic and presumed to be permanent and irreversible. This type of chronic but reversible deficit is termed "brain angina". The background, rationale for a multidisciplinary team, techniques, and preliminary results of intracranial angioplasty with provisional stenting are presented.

Complete inhibition of intimal hyperplasia by perivascular delivery of paclitaxel in balloon-injured rat carotid arteries

PURPOSE

To determine whether perivascular delivery of paclitaxel prevents luminal narrowing after balloon injury by inhibiting intimal hyperplasia.

MATERIALS AND METHODS

Immediately after balloon injury of the entire left common carotid artery, three slow-release formulations of paclitaxel or control formulations without drug were applied around a distal segment of the artery. The noninjured right carotid arteries were evaluated as a control. The animals were maintained for 14 and 28 days (n = 5 in each group at each time interval). Histology, immunohistochemistry, and morphometric analysis were performed.

RESULTS

Injured nontreated arteries exhibited a pronounced intimal hyperplasia (0.185 +/- 0.01 mm2 at 14 days and 0.189 +/- 0.01 mm2 at 28 days) and a marked reduction in luminal area (44% at 14 days and 43% at 28 days). Medial area and the number of medial cells increased by 44% and 45%, respectively, at 14 days, and by 22% and 37%, respectively, at 28 days. Injured arteries treated with perivascular paclitaxel did not show any intimal hyperplasia, and luminal area was increased in five of six groups and was unchanged in one group. These arteries had an increased medial area but they had fewer medial cells than noninjured arteries. Injured arteries treated with control implants without paclitaxel exhibited intimal hyperplasia and luminal narrowing.

CONCLUSION

Perivascular slow release of paclitaxel totally inhibits intimal hyperplasia and prevents luminal narrowing after balloon injury. Because of its efficacy, perivascular paclitaxel represents a possible approach for prevention of restenosis in humans.

Abciximab inhibits the migration and invasion potential of human coronary artery smooth muscle cells

In the EPIC trial, high-risk patients received the integrin receptor antagonist abciximab v placebo during and for 12 h following percutaneous coronary intervention with a significant 23% decrease of repeat revascularisation at 6 months. However, EPILOG and CAPTURE trials could not confirm these promising long-term results. Recently presented data from the EPISTENT trial suggested a beneficial effect of abciximab on restenosis in patients with diabetes. Based on these divergent results the aim of this study was to test whether alpha v beta 3 receptor blockade by abciximab could cause inhibition of human coronary smooth muscle cell (hcSMC) proliferation, migration, and invasion which represent crucial steps during restenosis development. In contrast to quiescent hcSMCs, proliferating cells were capable to migrate towards chemoattractive stimuli and even capable to invade through a basement membrane equivalent. Abciximab and LM609, an alpha v beta 3 specific inhibiting antibody, caused only a modest dose-dependent inhibition of hcSMC proliferation. On the contrary, the chemotactic and invasive potential of hcSMCs was significantly inhibited by abciximab administration 24 h prior to and during migration. (IC(50)=33.0 microg/ml for chemotaxis and IC(50)=0.5 microg/ml for invasion). For LM609 similar results were obtained. Administration of the drugs just during migration without pretreatment inhibited migration equally but invasion to a lower extent (abciximab: IC(50)=32.6 microg/ml for chemotaxis and IC(50)=44.9 microg/ml for invasion; LM609 IC(50)=3.1 microg/ml for chemotaxis and IC(50)=2.0 microg/ml for invasion). The attachment to the extracellular matrix proteins collagen I, collagen IV, laminin and vitronectin was not influenced. Pretreatment for 24 h with abciximab or LM609 did not cause a downregulation of the alpha v beta 3-integrin receptor. The results of this study indicate that the alpha v beta 3 antagonist abciximab is a potent inhibitor of hcSMC migration and invasion which could explain the observed lower reintervention rate after PTCA and stent implantation.

Revascularization interventions for ischemic heart disease

Coronary artery bypass grafting and percutaneous transluminal coronary angioplasty are now well established methods of myocardial revascularization. The choice of a method of revascularization depends on several clinical and angiographic parameters. Patients who derive the greatest benefit from coronary artery bypass grafting are those with left main coronary artery disease or those with three-vessel disease with left ventricular impairment. Patients with single-vessel disease achieve more symptomatic relief with coronary angioplasty than with medical therapy alone, but with no improvement in long-term mortality. In nondiabetic patients with multiple-vessel disease, angioplasty and bypass grafting likely yield similar results, and the choice of revascularization technique rests on weighing the more invasive nature of bypass grafting against the need for additional future revascularizations with angioplasty. Diabetic patients with multiple-vessel disease seem to achieve better outcomes with bypass grafting. Minimally invasive bypass surgery is an evolving technique. It is less invasive in nature but its applications are limited, and its advantages over traditional bypass grafting have not yet been shown. Stenting now plays a major role in percutaneous revascularization and is performed in more than two thirds of all interventional procedures. It improves both the short-term and the long-term outcomes of coronary angioplasty. Other novel percutaneous techniques such as directional or rotational atherectomy, laser angioplasty, or thrombectomy devices have not shown convincing superiority over coronary angioplasty alone. Transmyocardial laser revascularization can be performed surgically or percutaneously and may be beneficial in patients with angina refractory to traditional revascularization procedures.

Is provisional stenting the effective option? The WIDEST study (Wiktor stent in de novo stenosis). Widest Trial Investigators' Group

AIM

To compare the immediate and late outcomes of patients treated by a policy of routine stent implantation with routine balloon angioplasty and the use of stents only when an ideal result has not been obtained.

METHODS

A nine centre, multinational, randomised study of 300 patients with coronary artery disease thought suitable for treatment of a single lesion by balloon angioplasty or stent implantation. Only new lesions in patients who had not undergone previous bypass surgery were included, and totally occluded vessels were excluded.

RESULTS

The initial procedure was considered successful in 96% of patients. There was more complete angiographic restoration of luminal diameter in patients treated by elective stent (minimum lumen diameter (MLD) 2.68 mm for stent v 2.27 mm for balloon; p < 0.007), but analysis of the subgroup of balloon angioplasty patients who crossed over to stenting showed that they achieved similar results to the elective stent group. Late luminal loss was greater in stented patients than in those undergoing balloon angioplasty only, and by six months the angiographic benefit of stenting had disappeared (MLD 1.90 mm for stent group v 2.00 mm for balloon angioplasty). Angiographic and clinical results in the balloon angioplasty group were assisted by the high crossover rate (30.1%). Both groups had similar symptom relief, with 58.9% of patients improving by two or more angina grades. The need for further revascularisation was also similar in the two groups at one year (18.2% in the stented group v 17.1% in the balloon angioplasty group). Haemorrhagic complications at the local arterial entry site were more common than expected and were distributed equally between the patients receiving full anticoagulation and those receiving antiplatelet treatment only. The results of both Wiktor stent placement and balloon angioplasty were similar to the findings in the stent group in previous randomised studies (Benestent II, STRESS).

CONCLUSIONS

Provisional stenting appears to offer the same longer term outcome as elective stenting in this selected group of patients. Improvement in the results of conventional balloon angioplasty in the past 10 years means that a policy of obtaining an ideal result without the use of stents appears to be practicable in many of these patients, with consequent cost savings.

Provisional stenting strategies: systematic overview and implications for clinical decision-making

Coronary stents reduce the rates of abrupt closure, emergency coronary artery bypass graft surgery and restenosis, but do not prevent myocardial infarction or death at six months. The financial burden of increased stent use and the difficulty in managing in-stent restenosis have provided the impetus to develop provisional stenting strategies. Patients at low risk for restenosis after balloon angioplasty may not derive additional benefit from stent implantation and may be successfully managed with percutaneous transluminal coronary angioplasty (PTCA) alone. Numerous patient, lesion and procedural predictors of restenosis have been identified. Postprocedural assessment using quantitative coronary angiography, intravascular ultrasound (IVUS), coronary flow velocity reserve (CVR) or fractional flow reserve (FFR) may further enhance the ability to predict adverse outcomes after PTCA. Several studies have been performed to investigate the feasibility of provisional stenting strategies using various modalities to identify low risk patients who could be managed with PTCA alone. An optimal or "stent-like" angiographic result after PTCA is associated with favorable clinical outcomes. Preliminary results of studies using IVUS or CVR to guide provisional stenting appear promising. Angiography alone may be inadequate to identify truly low risk patients and may need to be combined with clinical factors, assessment of recoil, IVUS or physiologic indexes. Strategies that avoid unnecessary stenting in even a small proportion of patients may have large impacts on health care costs. Provisional stenting may potentially reduce costs and rates of in-stent restenosis without compromising the quality of health care delivery.

Coronary stenting versus balloon angioplasty in small coronary artery with complex lesions

The impact of stenting on small vessels (< 3.0 mm) with complex lesions (B2-C) is still controversial. Restenosis rate in this population is high (> 40%). We compared early and late outcome of patients with complex coronary lesions in small vessel treated with traditional coronary angioplasty (angioplasty group) and with elective stent implantation (stent group). Angioplasty group (n = 97) and stent group (n = 112) were comparable for all clinical and angiographic characteristics. All patients in the two groups had clinical and angiographic follow-up. Major adverse cardiac events (MACE) and restenosis rate were evaluated. No patients in the two groups experienced in-hospital death or bypass surgery. Myocardial infarction occurred in four patients in the angioplasty group and in seven patients in the stent group (P = 0.36). No patients in either the angioplasty or the stent group had acute stent thrombosis, whereas subacute stent thrombosis occurred in only one patients of the stent group (0.9%). Long-term MACEs (20 +/- 4 month) were not different in the two groups (angioplasty group 39% vs. stent group 44%, P = 0.35). Target lesion revascularization rate was 33% in the angioplasty group and 34% in the stent group (P = 0.50). Restenosis rate was not statistically different in the two groups (stent group 41% vs. angioplasty group 38%, P = 0.41). In conclusion, compared to balloon angioplasty, elective stent implantation in small vessels with complex lesions does not improve early and late outcome. Cathet. Cardiovasc. Intervent. 50:390-397, 2000.

Optimum percutaneous transluminal coronary angioplasty compared with routine stent strategy trial (OPUS-1): a randomised trial

BACKGROUND

Whether routine implantation of coronary stents is the best strategy to treat flow-limiting coronary stenoses is unclear. An alternative approach is to do balloon angioplasty and provisionally use stents only to treat suboptimum results. We did a multicentre trial to compare the outcomes of patients treated with these strategies.

METHODS

We randomly assigned 479 patients undergoing single-vessel coronary angioplasty routine stent implantation or initial balloon angioplasty and provisional stenting. We followed up patients for 6 months to determine the composite rate of death, myocardial infarction, cardiac surgery, and target-vessel revascularisation.

RESULTS

Stents were implanted in 227 (98.7%) of the patients assigned routine stenting. 93 (37%) patients assigned balloon angioplasty had at least one stent placed because of suboptimum angioplasty results. At 6 months the composite endpoint was significantly lower in the routine stent strategy (14 events, 6.1%) than with the strategy of balloon angioplasty with provisional stenting (37 events, 14.9%, p=0.003). The cost of the initial revascularisation procedure was higher than when a routine stent strategy was used (US$389 vs $339, p<0.001) but at 6 months, average per-patient hospital costs did not differ ($10,206 vs $10,490). Bootstrap replication of 6-month cost data showed continued economic benefit of the routine stent strategy.

INTERPRETATION

Routine stent implantation leads to better acute and long-term clinical outcomes at a cost similar to that of initial balloon angioplasty with provisional stenting.

Insights into the molecular pathogenesis of atherosclerosis and therapeutic strategies using gene transfer

Gene therapy for the treatment of atherosclerosis and related diseases has shown its potential in animal models and in the first human trials. Gene transfer to the vascular system can be performed both via intravascular and extravascular periadventitial routes. Intravascular gene transfer can be done with several types of catheters under fluoroscopic control. Extravascular gene transfer, on the other hand, provides a well-targeted gene delivery route available during vascular surgery. It can be done with direct injection or by using perivascular cuffs or surgical collagen sheets. Ex vivo gene delivery via transfected smooth muscle cells or endothelial cells might be useful for the production of secreted therapeutic compounds. Gene transfer to the liver has been used for the treatment of hyperlipidemia. The first clinical trials for the induction of therapeutic angiogenesis in ischemic myocardium or peripheral muscles with VEGF or FGF gene transfer are under way and preliminary results are promising. VEGF has also been used for the prevention of postangioplasty restenosis because of its capability to induce endothelial repair and production of NO and prostacyclin. However, further basic research is needed to fully understand the pathophysiological mechanisms involved in conditions related to atherosclerosis. Also, further development of gene transfer vectors and gene delivery techniques will improve the efficacy and safety of human gene therapy.

Coronary stent symmetry and vascular injury determine experimental restenosis

OBJECTIVE

To assess the impact of stent symmetry on restenosis using the coronary overstretch sheep model.

METHODS

Neointimal thickness, injury index, and percentage diameter and area stenosis were calculated by digital morphometry. The standard deviation of the angular burden was used to assess stent symmetry for each section.

MATERIALS

15 healthy Merino sheep (63-75 kg) underwent implantation of 30 slotted tube stents (7 mm). Restenosis was induced by calculated overstretch of the coronary artery. Twenty eight days after implantation, stents were excised and underwent histological examination using quantitative digital morphometry.

RESULTS

The severity of vessel injury was positively correlated with neointimal thickness and with percentage diameter and area stenosis (p < 0.001). Mean neointimal thickness and mean vascular injury per cross section were strongly related to the standard deviation of angular burden, with correlation coefficients of 0.6 and 0.8, respectively (p < 0.001).

CONCLUSIONS

The well known relation between vascular injury and restenosis was confirmed, and a new relation was discovered between stent asymmetry and restenosis. If these results apply to human coronary arteries, restenosis may also be dependent on the degree of asymmetric stent expansion. These results should influence the development of new stent designs to reduce asymmetric stent expansion, leading to a more homogeneous strain distribution in stented coronary segments.

Cost analysis between stent and conventional balloon angioplasty

The present study evaluated the cost of coronary stenting compared with conventional balloon angioplasty in Japan. Procedural cost was estimated as the sum of the procedural fee and the cost of devices such as angioplasty balloon and stent. The data such as the number of balloon catheters and stents used, and the rate of crossovers that was shown by the Stent Restenosis Study (STRESS) were applied to calculate the costs of stenting and conventional balloon angioplasty. For the estimation of hospital room and nursing costs, the length of the in-hospital stay was estimated at 7 days. The costs of procedures such as laboratory and radiological tests were determined based on routine coronary intervention at Chiba University Hospital. The rates of target lesion revascularization in the STRESS trial (conventional balloon angioplasty: 21%, stenting: 15%) were used to calculate the cost during follow up. The in-hospital costs of conventional balloon angioplasty and stenting were estimated to be Yens 982,300 and Yens 1,416,893, respectively. The overall costs, including follow-up cost, of conventional balloon angioplasty and stenting were estimated to be Yens 1,188,583 and Yens 1,564,238, respectively. The in-hospital cost of stenting is higher compared with conventional balloon angioplasty because of greater balloon use and direct stent cost. Lower target lesion revascularization reduces the cost difference between conventional balloon angioplasty and stenting, but the higher initial cost of stenting is not fully offset.

[The practical clinical guidelines of the Sociedad Española de Cardiología on interventional cardiology: coronary angioplasty and other technics]

Interventional cardiology has had an extraordinary expansion in last years. This clinical guideline is a review of the scientific evidence of the techniques in relation to clinical and anatomic findings. The review includes: 1. Coronary arteriography. 2. Coronary balloon angioplasty. 3. Coronary stents. 4. Other techniques: directional atherectomy, rotational atherectomy, transluminal extraction atherectomy, cutting balloon, laser angioplasty and transmyocardial laser and endovascular radiotherapy. 5. Platelet glycoprotein IIb/IIIa inhibitors. 6. New diagnostic techniques: intravascular ultrasound, coronary angioscopy, Doppler and pressure wire. For the recommendations we have used the classification system: class I, IIa, IIb, III like in the guidelines of the American College of Cardiology and the American Heart Association.

Cardiovascular gene therapy

Vascular gene transfer potentially offers new treatments for cardiovascular diseases. It can be used to overexpress therapeutically important proteins and correct genetic defects, and to test experimentally the effects of various genes in a local vascular compartment. Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) gene transfers have improved blood flow and collateral development in ischaemic limb and myocardium. Promising therapeutic effects have been obtained in animal models of restenosis or vein-graft thickening with the transfer of genes coding for VEGF, nitric-oxide synthase, thymidine kinase, retinoblastoma, growth arrest homoeobox, tissue inhibitor of metalloproteinases, cyclin or cyclin-dependent kinase inhibitors, fas ligand and hirudin, and antisense oligonucleotides against transcription factors or cell-cycle regulatory proteins. First experiences of VEGF gene transfer and decoy oligonucleotides in human beings have been reported. However, further developments in gene-transfer vectors, gene-delivery techniques and identification of effective treatment genes will be required before the full therapeutic potential of gene therapy in cardiovascular disease can be assessed.

Acute and long-term results of an intravascular ultrasound-guided percutaneous transluminal coronary angioplasty/provisional stent implantation strategy

Two hundred eighty-four consecutive patients with 438 native coronary artery stenoses were enrolled prospectively in a study of intravascular ultrasound (IVUS)-guided provisional percutaneous transluminal coronary angioplasty (PTCA): (1) IVUS-guided, aggressive lesion-site media-to-media balloon sizing, (2) IVUS assessment of residual lumen dimensions to identify optimal PTCA results (minimum lumen area > or =65% of the average of the proximal and distal reference lumen areas or > or =6.0 mm2 and no major dissection), and (3) liberal stent crossover. Overall, 206 stenoses in 134 patients were treated with PTCA alone. Reasons for crossover were flow-limiting or lumen compromising dissections in 28% of patients or a suboptimal IVUS minimum lumen area in 72% of patients. Sixty-three stenoses (27%) were treated with Gianturco-Roubin stents and 169 (73%) with Palmaz-Schatz stents. The clinical success rate and major in-hospital complication rates were similar in the optimal PTCA and stent crossover groups. At 1 year, 42 patients (15%) with 53 stenoses (12%) underwent revascularization: 8% of stenoses in the PTCA group and 16% in the stent crossover group. In approximately half of the patients treated using an IVUS guided aggressive PTCA strategy, stent implantation could be avoided without sacrificing an increase in acute complications or late clinical outcome. This provides an alternative strategy for interventionalists less inclined to use routine elective stenting.

The Organization to Assess Strategies for Ischemic Syndromes (OASIS) registry in patients with unstable angina

Clinical approaches to the prevention of the potentially catastrophic consequences of coronary ischemic phenomena such as unstable angina and suspected non-Q-wave myocardial infarction (MI) differ across the world. In addition to prevailing physician beliefs in different societies, the level of access to catheterization laboratories largely determines whether an interventionist or conservative strategy is adopted. The Organization to Assess Strategies for Ischemic Syndromes (OASIS)--a prospective registry of approximately 8,000 patients with acute myocardial ischemia with no ST elevation, treated in 95 hospitals across 6 countries--furnished a unique window into regional differences in clinical management and the frequency and timing of invasive procedures (i.e., angiography, percutaneous transluminal coronary angioplasty [PTCA], and coronary artery bypass graft [CABG] surgery), as well as the outcomes of these trends. At 6 months after symptom onset, patients in the United States and Brazil, where the catheterization laboratory facilities are more accessible, underwent significantly (p <0.001) more angiography (69.4%), PTCA (23.6%), and CABG (25.2%) than in Canada and Australia, where the corresponding rates were 48.4%, 17.0%, and 16.8% (p <0.001), respectively; and in Hungary and Poland, where the respective rates were 23.5%, 5.8%, and 10.9% (p <0.001). This relatively aggressive approach led at 6 months to a more substantial decrease in refractory angina in the United States and Brazil than in Canada and Australia (20.4% vs 13.9%; p <0.001), but no improvement in rates of cardiovascular mortality and MI (10.5% versus 10.5%; p = 0.36). There was a significant (p < or = 0.012) increase in stroke, (1.9% vs 1.3%; p = 0.010) and major bleeding (1.9% vs 1.1%; p = 0.009) events. Furthermore, an inverse correlation emerged between baseline cardiovascular risk status and frequency of angiography and PTCA interventions preferentially for low-risk compared with high-risk patients. In concert with findings from other recent randomized trials, the OASIS Registry data suggest that although there are fewer hospital readmissions for unstable angina, there is a trend toward increased rates of death, MI, and stroke. These data urge a cautious approach to the use of invasive procedures in patients with unstable angina unless future trials demonstrate a clear benefit with an aggressive approach.