Intravascular stenting for stenosis of aortocoronary venous bypass grafts

Whole-genome sequencing of Burkholderia pseudomallei from an urban melioidosis hot spot reveals a fine-scale population structure and localised spatial clustering in the environment

Melioidosis is a severe disease caused by the environmental bacterium Burkholderia pseudomallei that affects both humans and animals throughout northern Australia, Southeast Asia and increasingly globally. While there is a considerable degree of genetic diversity amongst isolates, B. pseudomallei has a robust global biogeographic structure and genetic populations are spatially clustered in the environment. We examined the distribution and local spread of B. pseudomallei in Darwin, Northern Territory, Australia, which has the highest recorded urban incidence of melioidosis globally. We sampled soil and land runoff throughout the city centre and performed whole-genome sequencing (WGS) on B. pseudomallei isolates. By combining phylogenetic analyses, Bayesian clustering and spatial hot spot analysis our results demonstrate that some sequence types (STs) are widespread in the urban Darwin environment, while others are highly spatially clustered over a small geographic scale. This clustering matches the spatial distribution of clinical cases for one ST. Results also demonstrate a greater overall isolate diversity recovered from drains compared to park soils, further supporting the role drains may play in dispersal of B. pseudomallei STs in the environment. Collectively, knowledge gained from this study will allow for better understanding of B. pseudomallei phylogeography and melioidosis source attribution, particularly on a local level.

The History of Coronary Stenting

The history of coronary angioplasty began with the groundbreaking work of Andreas Grüntzig, who was the first to use balloon-expandable catheters for the treatment of flow-limiting atherosclerotic coronary artery lesions. Thereafter, early investigators tested self-expanding springs as a solution to abrupt closure and restenosis seen with balloon angioplasty but these devices suffered from difficult delivery and a high complication rate. Julio Palmaz and Richard Schatz introduced the first balloon-expandable stent as a mechanical support to improve vessel patency. Their pioneering work launched a new era in the treatment of coronary artery disease.

Effect of Percutaneous Interventions within the Coronary Sinus on the Success Rate of the Implantations of Resynchronization Pacemakers

BACKGROUND

Cardiac resynchronization therapy (CRT) becomes a "gold standard" in therapy of selected patients with advanced heart failure. We set out to evaluate the feasibility and safety of percutaneous interventions within coronary sinus (CS) and their effect on the success rate of left ventricular (LV) lead implantation during CRT.

METHODS

The study analyzed eight consecutive patients with the indications for CRT, who needed additional procedures within CS to overcome technical problems during left ventricular (LV) electrode implantation. The analyzed group consisted of three subgroups: patients in whom percutaneous balloon angioplasty within CS was needed (n = 4); patients with acute instability of the lead, requiring stenting of the vein to fix the electrode (n = 2); and patients with the stenting of CS due to late dislocation of the lead (n = 2). Success rate, procedure duration, fluoroscopy, complications, and electrical parameters of leads were analyzed.

RESULTS

Success rate of the procedures was 87.5%; additional interventions increased overall efficacy of CRT implantation at our center from 88% to 98% (P < 0.05). Procedure duration (155.0 minute) and fluoroscopy time (42.5 minute) remained acceptable for the patient and operator; however, both were higher than in the procedures performed routinely in our hospital. Electrical properties of the LV leads were stable and within normal ranges during the observation period. We noted two local dissections of CS during the procedure, which remained clinically silent.

CONCLUSION

Percutaneous interventions within CS seem to be feasible and safe treatment options, which can improve the short- and long-term success rates of CRT.

Short-term outcome of stent implantation in saphenous vein grafts: predictors of distal embolization and restenosis

The present study, which aimed to determine the predictors of distal embolization and restenosis after stenting for vein graft disease, retrospectively analyzed 51 consecutive patients who underwent stent implantation for diseased saphenous vein grafts. Follow-up angiography was performed 6 months after the procedure and the clinical and angiographic variables were analyzed by multivariate logistic regression to determine the predictors of distal embolization and restenosis. Initial clinical success was achieved in 49 patients, 44 of whom underwent follow-up angiography and were enrolled in the retrospective analysis. Distal embolization occurred in 6 grafts (13.6%). Multivariate analysis showed that the lesion length and the total cholesterol level were independent predictors of distal embolization. Angiographic restenosis occurred in 13 (26.5%) of 49 lesions. The minimum luminal diameter and the percent diameter stenosis after stenting were associated with the occurrence of restenosis. Multivariate analysis of lesions located in the graft body identified graft age as an independent predictor of restenosis. Distal embolization can occur after vein graft stenting, especially in patients with hypercholesterolemia and diffuse stenosis. The post-stenting minimum luminal diameter and the percent diameter stenosis are predictors of restenosis. In particular, graft age is associated with the restenosis of graft body lesions.

Angiographic and clinical one-year follow-up of the Cordis tantalum coil stent in a multicenter international study demonstrating improved restenosis rates when compared to pooled PTCA and BENESTENT-I data: the European Antiplatelet Stent Investigation (EASI)

The Cordis tantalum coil stent was assessed in a nonrandomized multicenter trial: 275 patients with stable or unstable angina were entered. Clinical follow-up was for 1 year, with repeat angiography at 6 months. The major adverse cardiac event rates (MACE) were 3%, 14%, and 17% at 1, 7, and 13 months, respectively. The procedural success rate was 96% and the subacute occlusion rate 1.5%, in a group of patients over 60% of whom had ACC/AHA type B2 or C lesions. The binary restenosis rate at 6 months was 17.3%. Minimum lumen diameter increased from 1.07 +/- 0.28 mm preprocedure to 2.93 +/- 0.34 mm poststenting and at 6 months was 1.99 +/- 0.69 mm. These results demonstrate that the Cordis tantalum stent can be used to treat complex lesions with good procedural success and low rates of subacute thrombosis and restenosis at 6 months.

Long-term clinical results after stent implantation in old obstructed saphenous vein grafts

STUDY OBJECTIVE

To assess the long-term clinical outcome of treating patients with coronary artery disease and obstructed saphenous vein grafts (SVGs) with stents deployed by oversized balloon catheters.

DESIGN

The study included 89 of 92 consecutive patients who had 121 SVG stent implants (average, 1.4 stents per patient). We aimed at achieving a negative stenosis using oversized balloons to achieve a catheter to artery ratio of 1.1:1, and a 100% follow-up at 24+/-14 months (range, 0 to 54 months) was achieved.

PATIENTS

As 3 of 92 patients died during hospital admission, the study follow-up population consisted of 89 of 92 patients (mean age, 67+/-10 years). The age of the SVGs was 10+/-4 years.

RESULTS

We implanted 118 Palmaz-Schatz and 3 Gianturco-Roubin stents. Procedural success was achieved in 87 of 92 patients (94.5%; < 50% stenosis, and no death, Q-wave acute myocardial infarction, or coronary artery bypass graft [CABG]). Mean SVG stenosis diameter was reduced from 80+/-13% to -11+/-12% (p<0.001) and mean luminal diameter increased from 0.6+/-0.5 mm to 3.3+/-0.8 mm (p<0.001). At follow-up, angina pectoris had developed in 42 of 89 patients (47%), acute myocardial infarction in 12 of 89 patients (14%), reperformed CABG in 12 of 89 patients (14%), cardiac death in 10 of 89 patients (11%), and unrelated death in 6 of 89 patients (7%). Coronary angiography was performed in 37 of 89 patients (42%), with restenosis in 16 of 37 patients (43%) and disease progression at other sites in 11 of 37 patients (30%). Only 25 of 89 patients (28%) experienced event-free survival at follow-up.

CONCLUSIONS

Despite high procedural success and excellent angiographic results with oversized balloon catheters, the long-term clinical outcome of SVG stent implantation is suboptimal.

Long-term clinical outcome after endoluminal reconstruction of diffusely degenerated saphenous vein grafts with less-shortening wallstents

OBJECTIVES

This study was designed to evaluate the immediate and long-term clinical results of patients undergoing endoluminal reconstruction in diffusely degenerated saphenous vein grafts (SVGs) with elective implantation of one or more less-shortening Wallstents.

BACKGROUND

The optimal treatment strategy for patients with diffusely degenerated SVGs is controversial. Endoluminal reconstruction by stent implantation is one proposed strategy; however, there are few data regarding long-term clinical outcome.

METHODS

Between May 1995 and September 1998, 6,534 consecutive patients underwent angioplasty in our institution, including 440 who were treated for SVG lesions. Of these, 126 (115 men, 11 women, median age 69.5 years, range: 33-86 years) with old SVGs (mean age: 13+/-5 years) diffusely degenerated stenosed or occluded (mean lesion length: 27+/-12 mm) were treated electively with implantation of one or multiple (total 197) less-shortening Wallstents.

RESULTS

Before discharge, 13 patients (10.3%) sustained at least one major cardiovascular event, including 4 deaths (3.2%), 11 myocardial infarctions (MI) (8.7%), and 3 repeat revascularizations (target vessel = 1, nontarget vessel = 2, 2.4%). Surviving patients were followed for 22+/-11 months: 13 patients (11.1%) died, 11 (9.4%) sustained an MI, 37 underwent angioplasty (31.6%), and 4 (3.4%) underwent bypass surgery. The estimated three-year event-free survival rates (freedom from death, and freedom from death/MI/target vessel revascularization) were (mean +/- SE) 81.1+/-7.8% and 43.2+/-18.5%, respectively.

CONCLUSIONS

The long-term clinical outcome of patients undergoing endoluminal reconstruction in diffusely degenerated SVG is relatively poor, mainly because of a high incidence of death or MI and the frequent need for repeat angioplasty. It is unlikely that percutaneous intervention alone will provide a satisfactory or definitive solution for these patients.

Comparison of debulking followed by stenting versus stenting alone for saphenous vein graft aortoostial lesions: immediate and one-year clinical outcomes

OBJECTIVES

We compared in-hospital and one-year clinical outcomes in patients undergoing debulking followed by stent implantation versus stenting alone for saphenous vein graft (SVG) aortoostial lesions.

BACKGROUND

Stent implantation in SVG aortoostial lesions may improve procedural and late clinical outcomes. However, the impact of debulking before stenting in this complex lesion subset is unknown.

METHODS

We studied 320 consecutive patients (340 SVG aortoostial lesions) treated with Palmaz-Schatz stents. Debulking with excimer laser or atherectomy was performed in 133 patients (139 lesions) before stenting (group I), while 187 patients (201 lesions) underwent stent implantation without debulking (group II). Procedural success and late clinical outcomes were compared between the groups.

RESULTS

Overall procedural success (97.6%) was similar between the groups. Procedural complications were also similar (2.2% for group I and 2.6% for group II). At one-year follow-up, target lesion revascularization (TLR) was 19.4% for group I and 18.2% for group II (p = 0.47). There was no difference in cumulative death or Q wave myocardial infarction between the groups. Overall cardiac event-free survival was similar (69% for group I and 68% for group II). By Cox regression analysis, the independent predictors of late cardiac events were final lumen cross-sectional area (CSA) by intravascular ultrasound (IVUS) (p = 0.001) and restenotic lesions (p = 0.01). Similarly, final IVUS lumen CSA (p = 0.0001) and restenotic lesions (p = 0.006) were found to predict TLR at one year.

CONCLUSIONS

These results suggest that, in most patients with SVG aortoostial lesions, debulking before stent implantation may not be necessary.

Procedural results and intermediate clinical outcomes after multiple saphenous vein graft stenting

OBJECTIVES

We evaluated the early and mid-term (18-month) clinical events in a consecutive series of patients undergoing a nonstaged multiple saphenous vein grafting (SVG) intervention with stents as compared with a single SVG stent procedure.

BACKGROUND

Saphenous vein graft angioplasty has been limited by high rates of distal embolization, myocardial infarction, restenosis and late mortality. It is unknown whether stenting of multiple, different SVGs at the same setting is associated with higher risk.

METHODS

We evaluated in-hospital and mid-term clinical outcomes (death, Q wave myocardial infarction [MI] and repeat revascularization rates up to 18 months) in 70 consecutive patients treated with coronary stents in 2 (93% of patients) or 3 SVGs, as compared with 649 patients undergoing stenting of a single SVG between January 1, 1994 and December 31, 1997.

RESULTS

Overall procedural success was obtained in 97% of patients with 2 or 3 SVGs and 97% of patients with a single SVG (p = 0.94). Procedural complications were also similar (2.8% for multiple SVGs vs. 2.7% for a single SVG, p = 0.94). There was a higher prevalence of periprocedural non-Q wave MI (28% vs. 16%, p = 0.009) in the multiple SVG group. During follow-up (18 months), target lesion revascularization was 11% in multiple SVG and 15% in single SVG interventions (p = 0.19), and repeat revascularization (calculated per treated patient) was also similar for both groups (19% vs. 18%, p = 0.94). There was no difference in death (5.6% vs. 5.3%, p = 0.92) and Q wave MI rate (4.3% vs. 2.9%, p = 0.55) after the multiple SVG intervention. Overall cardiac event-free survival was similar for both groups (62% vs. 60%, p = 0.75). The study was powered to detect a clinically meaningful difference of 10% in mortality; smaller differences could not be evaluated on the basis of this sample size.

CONCLUSIONS

Simultaneous stenting of multiple SVGs in carefully selected patients has similar in-hospital procedural success and major complications rates, as well as mid-term (18-month) clinical outcomes, as compared with single SVG stenting. Thus, multiple SVG interventions using stents may be a viable revascularization strategy for carefully selected patients and suitable lesions in multiple SVG disease.

Utilisation of transluminal extraction atherectomy in the treatment of saphenous vein graft disease: two case reports

Saphenous vein graft disease is an increasing problem as more patients undergo bypass grafting and to date the most effective management strategy remains undefined. The major limitations of angioplasty for saphenous vein graft lesions are the risk of distal embolization and restenosis. Primary stenting in this situation results in superior lumen enlargement and higher procedural success but is still associated with significant restenosis. We describe two cases in which transluminal extraction (TEC) atherectomy is utilised for the treatment of vein graft disease with good immediate and long term angiographic results. The first case reports the use of TEC atherectomy for the primary treatment of a discrete eccentric filling defect, and the second case describes the use of this technique in the management of in-stent restenosis.

In-laboratory removal of femoral sheath following protamine administration in patients having intracoronary stent implantation

Two hundred twenty-eight patients with successful coronary stent implantation were randomized either to protamine administration and femoral sheath removal (group I, n = 117) or no heparin neutralization and delayed sheath removal (group II, n = 111). The hospital stay after treatment was shorter in patients receiving protamine; therefore, protamine use for neutralizing circulating heparin may be safely administered immediately after stent implantation.

Obliteration of femoral pseudoaneurysm complicating coronary intervention by direct puncture and permanent or removable coil insertion

We report on percutaneous obliteration of femoral pseudoaneurysm complicating percutaneous coronary interventions in 6 patients. Our findings suggest that permanent or transient direct coil insertion may be an useful alternative in the treatment of pseudoaneurysm in patients who do not respond to mechanical compression.

Rupture of coronary artery and cardiac tamponade complicating Wallstent implantation

A so-far undescribed complication of Wallstent deployment occurred in a 68-yr-old patient with symptomatic coronary artery disease. The patient had coronary angioplasty to the right coronary artery, complicated by a dissection which necessitated stent implantation. After insertion of one Wallstent, further significant distal disease was observed. An attempt to insert a second Wallstent failed due to inability to retract the constraining membrane and deploy the stent. The stent was withdrawn and another Wallstent was inserted through and distally to the first deployed stent. This time it was not only impossible to retract the membrane but also to withdraw the unimplanted stent. Further attempts to withdraw the stent ended in breakage of the stent delivery system, coronary artery rupture, and cardiac tamponade. The patient was successfully resuscitated and an emergency bypass operation was performed. The mechanism of failure of the Wallstent delivery system is discussed, and recommendations for operators are made.

Coronary artery and saphenous vein graft remodeling: a review of histologic findings after various interventional procedures--Part V

Catheter balloon angioplasty is a well accepted form of nonsurgical treatment of acutely and chronically obstructed coronary artery vessels. It is also the centerpiece for various new intervention techniques. Their morphologic effect on the site of obstruction has been termed "remodeling." Part V of this six-part series focuses on remodeling effects of balloon angioplasty on obstructed young (< or = 1 year) and old (> 1 year) saphenous vein bypass grafts.

Coronary artery stenting: indications and cost implications

The practice of coronary stenting is evolving rapidly, with new stent designs, deployment techniques, and adjunctive therapy. In many respects, clinical practice is changing in advance of the availability of supporting data. The consistent excellent angiographic result with stent deployment exceeds that achieved by any other previous interventional device, and the extent to which this accounts for the exponential increase in stent utilization cannot be accurately determined but is undoubtedly considerable. Controlled randomized trials have confirmed that stent deployment is superior to balloon angioplasty in certain lesion subsets or clinical scenarios. These include focal de novo native vessel lesions, lesions with late recoil after balloon angioplasty, acute closure after balloon angioplasty, and proximal left anterior descending coronary artery lesions. In addition, observational data is persuasive in focal coronary saphenous vein graft lesions and aorto-ostial lesions. On the other hand, the evidence supporting the use of stents strictly to improve on a suboptimal result, possibly the most frequent indication, is indirect and circumstantial. Stents are expensive, but it was anticipated that with the reduction in restenosis not only would they be cost-effective but also ultimately would reduce costs. This hope has not as yet been realized. However, there is little question that the introduction of intracoronary stents has been the most significant and exciting development since the introduction of percutaneous revascularization almost 20 years ago. It has revitalized the field.

Balloon catheter injury and vein graft morphology and function

Endovascular interventions to salvage failing vein bypass grafts are often associated with suboptimal outcomes. This study examines the effect of experimental vein graft catheter injury on vein graft morphology and vasomotor function. Thirty New Zealand white rabbits underwent a right common carotid interposition vein bypass graft. Ten grafts were harvested at 14 days, 10 were harvested at 28 days, and 10 had a balloon catheter injury induced at 14 days (4 F Fogarty catheter, 0.6 to 0.75 ml water inflation, 3 passes) and these 10 grafts were harvested after an additional 14 days. Morphologic and morphometric determinations (n = 5) or in vitro contractile studies (n = 5) were performed on segments of the vein grafts. Intimal thickness, without any intervention, increased by 84% from 14 to 28 days (p < 0.01), whereas catheter injury at 14 days induced a twofold increase (p < 0.001) in the formation of intimal hyperplasia by 28 days. Scanning electron microscopy demonstrated near-complete endothelial denudation after balloon catheter injury. In the 14- and 28-day control vein grafts, and in the balloon-injured vein grafts, the vascular surfaces had confluent endothelial linings. However, the ultrastructural features of the endothelial cells were group specific. Transmission electron microscopy of the same specimens confirmed this. There were no significant differences in contractility between the 28-day control and the catheter-injured vein grafts. This study demonstrates that balloon catheter injury doubles the rate at which intimal hyperplasia develops in vein grafts without significantly altering the physiologic phenotype of the smooth muscle cells as defined by their vasomotor function.

Long-term clinical outcome after stent implantation in saphenous vein grafts

OBJECTIVES

We sought to determine the role of stent implantation in vein grafts by evaluating the long-term clinical outcome and estimated event-free survival at 5 years in 62 patients and by comparing our data with those of other treatment modalities previously reported.

BACKGROUND

Patients with recurrent angina after coronary artery bypass graft surgery pose a problem. Stent implantation has been advocated in an effort to avoid repeat operation and to address the limitations of balloon angioplasty.

METHODS

Patients undergoing stenting of a vein graft were entered into a dedicated data base. They were screened for death, infarction, bypass surgery and repeat angioplasty. Procedure-related events were included in the follow-up analysis. Survival and event-free survival curves were constructed by the Kaplan Meier method.

RESULTS

A total of 93 stents (84 Wallstent and 9 Palmaz-Shatz) were implanted in 62 patients. During the in-hospital period seven patients (11%) sustained a major cardiac event: two deaths (3%), two myocardial infarctions (3%) and three urgent bypass surgeries (5%). The clinical success rate, therefore, was 89%. During the follow-up period (median 2.5 years, range 0 to 5.9), another five patients (8%) died, 14 (23%) sustained a myocardial infarction, 12 (20%) underwent bypass surgery, and 14 (23%) underwent angioplasty. The estimated 5-year survival and event-free survival rates (free from infarction, repeat surgery and repeat angioplasty) were (mean +/- SD) 83 +/- 5% (95% confidence interval [CI] 73% to 93%) and 30 +/- 7% (95% CI 16% to 44%), respectively.

CONCLUSIONS

The in-hospital outcome of patients who underwent stent implantation in a vein graft is acceptable, but the long-term clinical outcome is poor. It is unlikely that mechanical intervention alone will provide a satisfactory or definite answer for the patient with graft sclerosis over the long term.

Subacute stent thrombosis: evolving issues and current concepts

During percutaneous coronary revascularization, intracoronary stents are effective in the treatment of abrupt vessel closure and improvement of suboptimal angioplasty results, and compared to balloon angioplasty, they reduce stenosis recurrence. Opposing these benefits, subacute thrombosis of stents is associated with a substantial increase in periprocedural morbidity and mortality. To review factors associated with stent thrombosis and to study the impact of evolving procedural techniques on the incidence of stent thrombosis, we reviewed all English articles from MEDLINE (1988 to 1995) with key words "stent" and "thrombosis." Stent registry data and recent abstracts from scientific meetings were also reviewed. Factors related to the clinical setting, the lesion, the stent and the procedural technique that affect the risk of stent thrombosis were identified. Sixty clinical studies were reviewed and include 7,914 patients receiving intracoronary stents. Studies were separated into those reporting stents placed emergently or electively without adjunct high-pressure balloon inflations, stents placed in saphenous vein graft conduits, and stents placed with high-pressure balloon inflations but without subsequent oral anticoagulants. Overall, subacute thrombosis was substantially higher in stents placed emergently (10.1%) compared to those placed electively (4.3%). Among contemporary trials employing high-pressure balloon inflations, the rate of stent thrombosis appears markedly lower (1.3%) despite reduced postprocedural anticoagulation. Taken together, these studies suggest factors associated with a heightened risk of stent thrombosis, many of which can be avoided with proper case selection and contemporary techniques.

Immediate results and late outcomes after stent implantation in saphenous vein graft lesions: the multicenter U.S. Palmaz-Schatz stent experience. The Palmaz-Schatz Stent Study Group

OBJECTIVES

This study reports the multicenter registry experience evaluating the safety and efficacy of the Palmaz-Schatz stent in the treatment of saphenous vein graft disease.

BACKGROUND

Saphenous vein graft angioplasty is associated with frequent periprocedural complications and a high frequency of restenosis. Stent implantation has been shown to reduce restenosis, with improved long-term outcomes in the treatment of native coronary artery disease. Preliminary experience with stent placement in the treatment of saphenous vein graft lesions has been favorable.

METHODS

Twenty U.S. investigator sites enrolled a total of 589 symptomatic patients (624 lesions) for treatment of focal vein graft stenoses between January 1990 and April 1992. Follow-up angiography was performed at 6 months, and the clinical course of all study patients was prospectively collected at regular intervals for up to 12 months.

RESULTS

Stent delivery was successful in 98.8% of cases, and the procedural success rate was 97.1%. The lesion diameter stenosis decreased from 82 +/- 12% (mean +/- SD) before to 6.6 +/- 10.2% after treatment. Major in-hospital complications occurred in 17 patients (2.9%); stent thrombosis was found in 8 (1.4%); and major vascular or bleeding complications were noted in 83 (14.3%). Six-month angiographic follow-up revealed an overall restenosis rate (> or = 50% diameter stenosis) of 29.7%. Multivariate logistic regression analysis indicated that 1) restenotic lesions, 2) smaller reference vessel size, 3) history of diabetes mellitus, and 4) higher percent poststent diameter stenosis were independent predictors of restenosis. The 12-month actuarial event-free survival was 76.3%.

CONCLUSIONS

Stent implantation in patients with focal saphenous vein graft lesions can be achieved with a high rate of procedural success, acceptable major complications, reduced angiographic restenosis and favorable late clinical outcome compared with historical balloon angioplasty control series. The rigorous anticoagulation regimen after stent placement results in more frequent vascular and other bleeding complications. Future randomized studies comparing standard balloon angioplasty with stent implantation are warranted to properly assess the full impact of stent placement in the treatment of saphenous vein graft lesions.

Predictors and sequelae of distal embolization during saphenous vein graft intervention from the CAVEAT-II trial. Coronary Angioplasty Versus Excisional Atherectomy Trial

BACKGROUND

The purpose of this study was to identify the predictors and sequelae of distal embolization from a multicenter, randomized trial of saphenous vein graft intervention. The CAVEAT-II trial demonstrated that saphenous vein graft directional coronary atherectomy (DCA) was associated with greater angiographic success and less need for repeat intervention compared with percutaneous transluminal coronary angioplasty (PTCA) but at the cost of more acute complications--notably distal embolization.

METHODS AND RESULTS

In CAVEAT-II, 305 patients were randomly assigned to DCA (149 patients) or PTCA (156 patients) for lesions with > 60% diameter stenosis in vein grafts > or = 3 mm in diameter. Distal embolization occurred in 20 patients (13.4%) assigned to DCA and 8 patients (5.1%) assigned to PTCA (P = .011). Independent predictors of distal embolization were use of DCA (71% in distal embolization patients versus 47% in patients without distal embolization, P = .011) and presence of thrombus (39% in distal embolization patients versus 14% in patients without distal embolization, P < .00). In-hospital adverse events were more frequent after distal embolization; 71% versus 20%, odds ratio plus (95% confidence intervals) 9.87 (4.65, 20.94). At 12-month follow-up, adverse event rates were also higher in patients with distal embolization (odds ratio, 3.05 [1.95, 4.76]).

CONCLUSIONS

In this first prospective multicenter trial of saphenous vein graft intervention, distal embolization was more common after DCA than PTCA and in lesions containing thrombus. It also was associated with worse in-hospital and 12-month outcomes. The risk and sequelae of distal embolization should be considered when choosing a treatment strategy for vein graft disease.

Comparison of clinical and angiographic outcomes after saphenous vein graft angioplasty using coronary versus 'biliary' tubular slotted stents

BACKGROUND

Saphenous vein graft (SVG) angioplasty using 15-mm articulated, tubular slotted stents results in low (0% to 20%) residual diameter stenoses and infrequent (< 5%) major complications. A "biliary" stent design with greater radial compressive strength, enhanced visibility, and more variable sizing (diameter and length) has been approved for noncoronary indications. A comparison of outcomes after coronary versus biliary stent placement in SVG stenoses has not been performed. The purpose of this study was to compare the angiographic and clinical results after SVG angioplasty using these two balloon-expandable, tubular slotted stent designs.

METHODS AND RESULTS

During a 3-year period, 231 patients with 305 SVG lesions were treated using Palmaz-Schatz coronary (n = 108) or biliary (n = 123) stents. Cineangiograms were reviewed using qualitative morphological and quantitative angiographic methods. Time-dependent clinical outcome (freedom from death, Q-wave myocardial infarction, or the need for repeat coronary bypass surgery or SVG angioplasty) was assessed using Kaplan-Meier life-table methods. Unstable angina (P < .001) and recent myocardial infarction (P = .001) were present more often in patients undergoing biliary stent versus coronary stent placement. Biliary stent-treated SVG lesions were more frequently de novo (P = .001), ostial in location (P = .002), > or = 10 mm in length (P = .009), thrombus containing (P = .001), and ulcerated (P < .001) than coronary stent-treated SVG lesions. Angiographically, biliary stent-treated lesions had larger reference vessel diameter (3.43 +/- 0.59 mm versus 3.10 +/- 0.64 mm, P < .001), higher balloon-to-artery ratio (1.15 +/- 0.16 mm versus 1.07 +/- 0.19, P = .0001), and lower residual diameter stenosis (6 +/- 17% versus 14 +/- 11% in coronary stent-treated patients; P < .001). Procedural success rates were high (95%), in-hospital major complications were uncommon (< 3%), and follow-up clinical outcomes were favorable (6-month event-free survival approximately 80%) in both groups.

CONCLUSIONS

Despite frequent short-term ischemic syndromes and unfavorable lesion characteristics, both biliary and coronary cohorts have similarly favorable short-term procedural results and long-term clinical outcomes. The increased strut thickness of the biliary stent confers greater fluoroscopic visibility and radial compressive strength in exchange for decreased stent flexibility and added technical demand in stent deployment. Extreme caution is recommended with biliary stent placement in the treatment of SVG lesions as clinical results are highly operator dependent.

Long-term angiographic and clinical outcome after implantation of balloon-expandable stents in aortocoronary saphenous vein grafts

Balloon angioplasty of aortocoronary saphenous vein graft lesions is associated with high restenosis and clinical event rates. The goal of this multicenter study was to assess long-term angiographic and clinical outcome of patients electively treated with single Palmaz-Schatz stents in aortocoronary saphenous vein grafts. In 198 patients (209 lesions), elective placement of single Palmaz-Schatz stents was attempted. Angiography was performed at baseline, immediately after stent placement, and at 6-month follow-up. Stent placement was successful in 98.5% of patients. One patient (0.5%) had stent thrombosis. Restenosis occurred in 34% (45 of 133) of the restudied lesions. Restenosis was lower in de novo lesions than in restenotic lesions (22% vs 51%, p < 0.001). Ostial lesions had a higher restenosis rate than nonostial lesions (61% vs 28%, p = 0.003). Freedom from death, myocardial infarction, coronary artery bypass surgery, and repeat angioplasty was present in 70% of patients. Eighty-two percent of patients with de novo lesions remained event-free at 1 year, whereas only 55% of patients with prior angioplasty were event-free at 1 year (p < 0.001). The use of the Palmaz-Schatz stent for the treatment of focal, de novo, aortocoronary saphenous vein graft lesions is associated with a high procedural success rate, a low angiographic restenosis rate, and low clinical event rates, including the need for repeat revascularization. The results of this study need validation by a prospective randomized trial comparing stent implantation with angioplasty.

Endoluminal stenting of narrowed saphenous vein grafts: long-term clinical and angiographic follow-up

From April 1986 through April 1993, 58 intracoronary stents (41 Wall and 17 Wiktor stents) were implanted for the treatment of saphenous vein graft stenosis in 40 symptomatic patients. The indication was a primary stenosis in 44 and restenosis in 14 procedures. In-hospital complications were subacute stent thrombosis (2%), myocardial infarction (2%), and emergency coronary artery bypass grafting (CABG) (2%). Complications during a mean follow-up period of 42+/-27 months were restenosis (35% by patient, 33% by lesion), myocardial infarction (12%), late bypass grafting (12%), and death (7%). On quantitative coronary angiographic analysis, the mean minimal luminal diameter (and its confidence interval) increased from 1.3 mm (1.1-1.5 mm, preprocedure) to 2.9 mm (2.7-3.1 mm, postprocedure) and 2.2 mm (2.0-2.5 mm, 6 months follow-up, 95% angiographic follow-up). Progression of the underlying coronary artery disease and restenosis were the main reasons for a continual decline of the proportion without cardiac event on a Kaplan-Meier estimate. Restenosis occurred in one-third of cases beyond the first 6 months of follow-up. A relative risk ratio analysis for restenosis, performed on 14 variables, disclosed an increased risk for the following variables: (1) stenting of the proximal, distal or anastomosis part of the vein graft (relative risk 2.41, confidence interval: 1.28-3.59), (2) the implantation of stents < 4.5 mm (2.59, 1.18-4.00), and (3) stenting of a redo-CABG vein graft (2.37, 1.17-3.58). Saphenous vein graft stenting seems to be characterized by excellent immediate clinical and angiographic results; in particular, stent thrombosis is rare.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting: ten years' experience

We evaluated the acute and long-term results of percutaneous transluminal coronary angioplasty in 140 patients with prior coronary artery bypass grafting treated over a 10-year period (1981-1991). Angioplasty was technically successful in 85% of 122 nonoccluded native vessels and in 86% of 50 saphenous vein grafts. Two patients (1.4%) had a myocardial infarction and there were three procedure-related deaths (2.1%). The cumulative probability of survival was 91.5% and 74.5% at 1 and 5 years, respectively. Survival free from myocardial infarction and repeat bypass grafting at 1 and 5 years was 77.3% and 53.9%, respectively. At census, 31% of the 117 survivors were asymptomatic, and 47% were improved by at least two angina grades. Coronary angioplasty provides an apparently safe and effective alternative method of revascularization in selected patients with prior coronary artery bypass grafting. This treatment strategy potentially avoids reoperation with its attendant risks.

Palmaz-Schatz stenting for treatment of focal vein graft stenosis: immediate results and long-term outcome

OBJECTIVES

This study aimed to evaluate the effectiveness of Palmaz-Schatz stenting for the treatment of saphenous vein graft stenoses.

BACKGROUND

Failure of saphenous vein grafts is a common cause of recurrent ischemia after coronary bypass surgery. A second bypass surgery carries more risk than the initial procedure, and balloon angioplasty of vein grafts has yielded disappointing results. It has been hoped that stenting might offer a better treatment option.

METHODS

We examined the results of stent placement in 200 saphenous bypass graft lesions consecutively treated with either coronary (n = 146) or biliary (n = 54) Palmaz-Schatz stents. Immediate outcome and clinical follow-up (median 15.5 months) were examined in all patients. To document angiographic outcome, a second angiography was performed at 3 to 6 months for the first 120 consecutively stented lesions and was successfully obtained for 94 (78%).

RESULTS

The mean graft age (+/- SD) was 8.7 +/- 4 years. Stent placement was successful in 197 (98.5%) of 200 lesions, reducing the mean diameter stenosis from 74 +/- 14% to 1 +/- 15%. In 164 procedures, there was one in-hospital death (0.6%), no emergency bypass operations and no Q wave myocardial infarctions. There was one acute stent thrombosis (0.6%) but no subacute thromboses. Vascular repair was required after 14 procedures (8.5%), with transfusion in 23 additional cases (14%). Angiographic restenosis (diameter stenosis > or = 50%) at 3- to 6-month follow-up was 17% (95% confidence interval 9% to 25%). By Kaplan-Meier estimates, however, the 2-year second revascularization rate was 49%, reflecting the predominant revascularization performed to treat progressive disease at other sites because failure at the stented site occurred in only 22% of lesions.

CONCLUSIONS

Stenting resulted in excellent immediate and long-term angiographic results in this group of focally diseased, older saphenous vein grafts. Despite the high immediate success and very low (17%) angiographic restenosis rate at 6 months, approximately one half of these patients required further revascularization in the following 2 years, mainly because of disease progression at other sites.

Stenting or balloon angioplasty of stenosed autologous saphenous vein grafts in pigs

In a model of early and aggressive vein graft stenosis in pigs, an intervention was performed with a single stent (n = 12 grafts), multiple stents (n = 6), or balloon angioplasty (n = 6), while grafts with mild stenoses were left untreated (n = 8). Four weeks after intervention, angiography showed that grafts with single stents, balloon angioplasty, or untreated grafts had patency rates of 92%, 83%, and 83%, respectively. Grafts receiving multiple stents, however, showed only a 17% patency rate (p < 0.05). Balloon dilatation or placement of a single stent improved the angiographic minimal diameter by 0.6 +/- 0.2 and 0.8 +/- 0.3 mm, respectively, over the short term, but this gain was lost during the follow-up period. Multiple stents showed a similar gain (0.5 +/- 0.2 mm) but more loss occurred during the follow-up period (2.4 +/- 0.2 mm). Histology revealed no significant differences between the treatment groups except for the prolonged presence of thrombus remnants in association with the stent wires. In conclusion, single stents and balloon angioplasty show good patency in early saphenous vein graft narrowing but multiple stents show a high occlusion rate.

Clinical and angiographic results of transluminal extraction coronary atherectomy in saphenous vein bypass grafts

BACKGROUND

Transluminal extraction coronary (TEC) atherectomy is a relatively new device that has recently been approved by the Food and Drug Administration. Because of its ability to aspirate clot and atheromatous material, TEC atherectomy may be useful in patients with stenoses in saphenous vein bypass grafts.

METHODS AND RESULTS

TEC atherectomy was performed on 158 saphenous vein graft lesions in 146 consecutive patients with a mean age of 65 +/- 8 years (78% men). Clinical indications for atherectomy included stable angina (37%), unstable angina (54%), and postinfarction angina after recent (< 1 month) myocardial infarction (8%). Patients with acute myocardial infarction and target vessels < 2 mm in diameter were excluded. The mean age of the bypass graft was 8.3 +/- 3.0 years, and 17% were diffusely diseased and degenerated. Complex lesion morphology included total occlusion (6%), eccentricity (64%), ulceration (18%), and thrombus (28%). The TEC atherectomy cutter was successfully advanced through 144 lesions (91%), but technical failures occurred in 14 lesions (9%), and these were subsequently managed by successful balloon angioplasty. Quantitative angiography revealed an increase in lumen diameter from 0.9 +/- 0.5 mm, to 1.5 +/- 0.7 mm after TEC atherectomy, to 2.3 +/- 0.8 mm after percutaneous transluminal coronary angioplasty (PTCA) (P < .001), which corresponded to decreases in diameter stenosis from 75 +/- 14%, to 58 +/- 20% after TEC atherectomy, to 36 +/- 22% after PTCA (P < .001). Device success was achieved in 39.2% (post-TEC atherectomy decrease in diameter stenosis > or = 20%), and procedural success was achieved in 84% (final diameter stenosis < 50% in the absence of a major complication). Angiographic complications were evident in 33 lesions (20.7%) immediately after TEC atherectomy and in 8 lesions (5%) after PTCA, including distal embolization (11.9%), no-reflow (8.8%), and abrupt closure (5.0%), but no perforations. Adjunctive PTCA (and other medical therapy) successfully managed 61% of angiographic complications. Serious clinical complications included in-hospital death in 3 patients (2.0%), emergency bypass surgery in 1 patient who died (0.7%), Q wave myocardial infarction in 3 patients (2.0%), non-Q wave myocardial infarction in 4 patients (2.7%), vascular injury requiring surgical repair and/or blood transfusion in 9 patients (6.1%), and hemorrhagic cerebral infarction in 4 patients (2.7%). Using a composite clinical end point defined as in-hospital death, emergency bypass surgery, or myocardial infarction, the strongest independent correlate (P < .001) of a severe clinical complication was the development of one or more serious angiographic complications (no-reflow, distal embolization, or abrupt closure) immediately after TEC atherectomy. Complete clinical follow-up was available in 118 (92%) of 128 eligible patients at an interval of 6.0 +/- 2.5 months after discharge. Late cardiac outcome included recurrent angina treated with medical therapy (18%), repeat percutaneous intervention on the original target lesion (26%), repeat coronary artery bypass surgery (5%), Q wave myocardial infarction (4%), and late cardiac death (7%). Angiographic follow-up in 105 (80%) of 132 eligible lesions revealed a restenosis rate of 69% (defined as a diameter stenosis > 50%), including 30 lesions (29%) with total occlusion of the original lesion.

CONCLUSIONS

In patients with stenoses in saphenous vein bypass grafts, TEC atherectomy is limited by the frequent need for adjunctive balloon angioplasty to achieve adequate lumen enlargement and to manage TEC atherectomy-induced complications. Although the incidence of serious clinical complications is similar to that of other percutaneous interventions in vein grafts, there is a high incidence of restenosis and late vessel occlusion. Prospective randomized studies are needed to determine the best revascularization strategy for high-risk patients with old degenerated vein

Implantation and recovery of temporary metallic stents in canine coronary arteries

OBJECTIVES

The purpose of this study was to test the feasibility of implanting and retrieving a heat-activated recoverable temporary stent and to determine its effect on the angiographic, gross and histologic appearance of a normal coronary artery wall.

BACKGROUND

Permanent coronary stenting is associated with a significant incidence of thrombosis, bleeding and vascular complications. These may be avoided by temporarily stenting for a period of hours to several days.

METHODS

Seventy-eight stents constructed from the shape-memory nickel-titanium alloy nitinol were deployed by balloon expansion in the coronary arteries of 28 dogs and left in place for up to 6 months. Thirty minutes to 1 week after implantation, 70 stents were recovered by flushing the coronary arteries with 3 to 5 ml of 75 degrees C lactated Ringer solution, with collapse of the stent over a recovery catheter and subsequent withdrawal.

RESULTS

All stents were successfully recovered and removed percutaneously. Mean vessel diameter after stenting was 12 +/- 6% (p < 0.05) greater than baseline diameter. Mean vessel diameter after stent removal remained enlarged (6 +/- 3%, p < 0.05). No angiographic or gross evidence of thrombosis, dissection, embolization, migration or spasm was associated with implantation or recovery. Microscopic examination revealed minor intimal injury in 40 segments (51%). Microscopic focal medial necrosis was associated with mural platelet-fibrin thrombus in 23 stented segments (29%) and media was interrupted in 7 (9%).

CONCLUSIONS

This study demonstrates the feasibility of a new method of temporary stenting that uses the thermoelastic properties of nitinol to permit reliable recovery of the stent in normal canine coronary arteries.

Ultrafast computed tomographic scanning to assess patency of coronary artery stents in bypass grafts

Anginal chest pain after implantation of coronary stents in bypass grafts is a concern because it suggests the possibility of occlusion. Coronary angiography is the definitive method for determining patency of a stent; however, this procedure is relatively contraindicated in a patient receiving warfarin sodium, who has a therapeutic international normalized ratio. An alternative method for determining patency of a stent is by ultrafast computed tomography. This new, minimally invasive technique shows promise for determining blood flow within the large vessels of the thorax. Herein we describe a case in which a metallic stent placed in a vein graft was noninvasively established to be patent, despite chest pain in the patient. This method may be clinically applicable for determining patency of stents in vein grafts in the setting of patients with chest pain who have undergone complete anticoagulation.

Balloon angioplasty for the treatment of lesions in saphenous vein bypass grafts

OBJECTIVES

The purpose of this review is to assess the value and limitations of balloon angioplasty for the treatment of saphenous vein bypass graft obstructions. The potential efficacy of new interventional techniques is discussed.

BACKGROUND

Treatment of ischemia due to saphenous vein bypass graft obstructions poses a difficult problem that will be encountered more often as the pool of surgically treated patients continues to accumulate. Reoperation is technically demanding and is associated with high mortality and morbidity rates. Balloon angioplasty may provide a suitable alternative.

METHODS

The review proposes a classification of patients with attempted saphenous vein graft angioplasty according to expected early and late outcome based on the data obtained from the relevant published data and personal experience.

RESULTS

Angioplasty of a nonocclusive obstruction in a saphenous vein bypass graft has an initial success rate of approximately 90% and is a safe procedure (procedural death rate < 1%, myocardial infarction rate < 4%). The overall average restenosis rate is 42%. Surgical standby is limited and technically difficult. Angioplasty of chronic total occlusions in old grafts is associated with poor initial and long-term results. The long-term clinical results are unfavorable because of the continuing progression of disease in nontreated vein graft segments and native coronary arteries, in addition to the high restenosis rate. New techniques, although promising, have shown neither better initial results nor reduction of restenosis. Stent placement may be useful in longer graft lesions containing friable material.

CONCLUSIONS

Patients may be classified into three groups according to expected early and late outcome on the basis of 1) unfavorable graft anatomy, 2) risk of cardiogenic shock in event of acute graft closure, and 3) age of grafts. The three groups are 1) those with an initial high success, low procedural risk and low restenosis rate; 2) those with an initial high success but high procedural risk and moderate to high restenosis rate; and 3) those with a low success, high risk and high restenosis rate. Balloon angioplasty to treat lesions in venous bypass grafts should be considered a palliative procedure, not a long-term solution, for ongoing progression of coronary artery and vein graft disease. The induced high restenosis rate remains a significant problem.

Endovascular stents: preliminary clinical results and future developments

At present, there is an exponential use of new interventional techniques whose proper role and value have not yet been defined. The intracoronary stent is just one example. There is no doubt that stents can be implanted with a high technical success rate associated with highly predictable immediate angiographic results and that they appear to be superior to all other interventional techniques. However, the intrinsic thrombogenicity of all devices currently available for clinical use warrants a vigorous anticoagulation, exposing the patient either to the risk of (sub)acute stent thrombosis or to the risk of hemorrhage and vascular complications. It remains to be determined whether stent implantation will reduce the incidence of restenosis and whether this results in an improved long-term event and symptom-free survival. Experimental studies indicate that the thrombogenic nature of stents may be controlled by coating the struts with endothelial cells or polymers. With respect to restenosis, it is evident that as long as mechanical injury is applied to the vessel wall, the vessel wall will respond with neointimal thickening. The intracoronary stent has the potential to control this tissue response by serving as a carrier for local antiproliferative drug delivery or eventually for genetic manipulation. The intensive research which is now going on in combination with experimental animal data, human postmortem pathologic observations, and angiographic studies is yielding clear insights and future directions to address these issues.

Histology after stenting of human saphenous vein bypass grafts: observations from surgically excised grafts 3 to 320 days after stent implantation

OBJECTIVES

To gain insight into the mechanism of stenting in humans and its short- and long-term implications, we studied the vascular wall of saphenous vein aortocoronary bypass grafts after implantation of the Wallstent.

BACKGROUND

The implantation of a stent in aortocoronary bypass grafts may provide an alternative solution for revascularization in patients who are poor candidates for reoperation. Because human histopathologic findings after stenting with the Wallstent have not previously been described in detail, we examined graft segments that were surgically retrieved from 10 patients (21 stents) at 3 days to 10 months after implantation of the stent.

METHODS

The grafts were examined by a combination of the following techniques: light microscopy, immunocytochemistry and both scanning and transmission electron microscopy.

RESULTS

Early observations revealed that large amounts of platelets and leukocytes adhered to the stent wires during the first few days. At 3 months, the wires were embedded in a layered new intimal thickening, consisting of smooth muscle cells in a collagenous matrix. In addition, foam cells were abundant near the wires. Extracellular lipids and cholesterol crystals were found after 6 months. Smooth muscle cells and extracellular matrix formed the predominant component of restenosis. This new intimal thickening was lined with endothelium, in some cases showing defect intercellular junctions and abnormal adherence of leukocytes and platelets as late as 10 months after implantation.

CONCLUSIONS

This type of stent is potentially thrombogenic and seems to be associated with extracellular lipid accumulation in venous aortocoronary bypass grafts.

Angiographic restenosis after successful Wallstent stent implantation: an analysis of risk predictors

Follow-up angiographic study was performed in 86 patients after initially successful Wallstent stent (Medinvent, Lausanne, Switzerland) implantation between April 1986 and October 1990. The stent angiographic restenosis rate was 16% at a mean of 8 months after stenting despite the inclusion of a substantial number of patients at high risk of restenosis after percutaneous transluminal coronary angioplasty (PTCA). Of a total 15 variables analyzed, only suboptimal stent placement was found to be a significant predictor of stent restenosis. Age; gender; baseline New York Heart Association functional class; previous PTCA; indication for stenting; left ventricular ejection fraction; preangioplasty and immediate postangioplasty diameter stenosis severity; stented vessel site, lesional morphology; number, diameter, and length of stents implanted; and the interval between stenting and follow-up angiographic restudy were not significant risk factors of stent restenosis. Our study suggests that intracoronary stent implantation with the Wallstent may be a useful and promising adjunctive option after PTCA, particularly in patients at high risk of restenosis after PTCA. However, because of the significantly enhanced risk of restenosis after suboptimal stent implantation, we strongly recommend the selection and placement of Wallstent stents that adequately cover the entire length of the dilated coronary segment.

Palmaz-Schatz stent implantation in stenosed saphenous vein grafts: clinical and angiographic follow-up

Balloon-expandable stents may reduce the restenosis rate following coronary angioplasty. To evaluate this potential in saphenous vein grafts, 26 patients with 30 discrete stenoses underwent conventional balloon dilation and successful Palmaz-Schatz stent implantation as part of a multicenter trial. All patients had resolution of their angina following the procedure. In a mean 5-month follow-up period, 14 patients (54%, 16 lesions) had repeat arteriography; two patients (14%) developed recurrent ischemia ascribed to their venous grafts from in-stent restenosis (2 of 16 lesions, 13%). Two asymptomatic patients (8%) died: one from cardiac arrest (stent patent) and one from stroke (no autopsy). The clinical recurrence rate (cardiac death, myocardial infarction, bypass surgery, repeat angioplasty, or symptom recurrence) was 15%. These preliminary results show trends toward an improved primary success rate with combined vein graft angioplasty/stenting and a lower restenosis rate in stented saphenous vein grafts, but continuing follow-up will be needed to verify these observations.