Abrupt Vessel Closure Research Articles

Late occlusive in-stent restenosis of a bare-metal stent presenting with ST-elevation anterior MI: Is restenosis better than a late stent thrombosis?

In-stent restenosis (ISR) occurs in 20% to 40% of de novo coronary lesions treated with bare-metal stents (BMS), depending on lesion and patient-related factors. Drug-eluting stents coated with antiproliferative agents, represent a valid rationale for treatment and prevention of recurrent ISR, with low MACE rates. However, case reports and observational studies reported a definite increase in the incidence of late stent thrombosis after drug-eluting stents use, particularly in off-label cases and after clopidogrel withdrawal. The case we present shows target vessel occlusion occurring at the site of a previously implanted BMS, suggesting that in-stent restenosis was the main pathological mechanism leading to abrupt thrombotic vessel closure and acute myocardial infarction.

Side-by-side false and true lumen stenting for recanalization of the chronically occluded right coronary artery

Subintimal or false lumen stent deployment is a rare complication of percutaneous coronary interventions. The most balloon-induced small non-flow limiting dissections heal spontaneously and can be treated medically with close observation if distal coronary flow is not compromised. However, the complex and severe flow-limiting postprocedural dissections may result in abrupt vessel closure and thrombosis, with ensuing myocardial ischemia and necrosis, and can be treated effectively by coronary stenting. It is essential to ensure that the guide-wire is in the true lumen before placing the stent in total occlusive lesions, otherwise the stent placement will impair distal coronary flow. We present here an interesting case of successful coronary recanalization despite false lumen stenting of the proximal right coronary artery followed by true lumen stenting.

Taking interventional cardiology forward: hindsight, foresight and insight

Interventional cardiology has made rapid advances in the last three decades and has contributed immensely to patient care1. Bare metal stents and subsequently drug-eluting coronary stents (DES) have surmounted the major obstacles, abrupt vessel closure and restenosis (to a large extent), during this evolution. However, evidence from recently reported trials2,3, and the widely publicised concerns of late thrombosis associated with DES4,5 have dampened the interventionalist’s enthusiasm for their use of implantation in patients with stable coronary disease. The data for 2005 presented by the ESC Working Group on Interventional Cardiology in this issue of the Journal6 may offer some important insights into the antecedents of the current imbroglio. With rapid advances in technology and hardware, interventional procedures have become less and less daunting. This has lead to an exponential increase in the number of procedures and their complexity. Most striking is the doubling of stent use over five years to more than 800,000 in 20056,7. Drug eluting stents have been adopted quickly (too quickly, some would say) since their introduction. The mean DES usage rate of 26% does not accurately reflect the overall picture because of the wide variability in the volumes of procedures among the surveyed countries. The Scandinavian countries for example have rapidly scaled up DES use to rates in excess of 75%. Concurrently, the rates of primary angioplasty for myocardial infarction have steadily increased from levels as low as 11% in 2000 to 19% in 20048. In this scenario, the initial optimism surrounding DES results led to the change in clinical practice outpacing the generation of evidence. Widespread use across all subsets of patients and lesions, some of which we would now consider “off-label” was therefore clearly inevitable. In hindsight, this sequence of events set the alarm bells ringing in 2006. An important trend that we would like to highlight is the favour that “ad-hoc” angioplasty has found among interventional cardiologists. “Ad-hoc” angioplasty increased from a modest 25% in 1992 to 65% in 2005, with some countries reporting rates as high as 98% (Spain, 2004)6-8. In our view, this trend represents the single most important impediment to evidence-based care. “Ad-hoc” angioplasty encourages lesion-based decision making in place of overall riskbenefit assessment and clinical decision-making as advocated by recent randomised trials2,3. It also increases the risk of bleeding complications because of indiscriminate clopidogrel loading9. While the exigencies of cost-effectiveness dictate otherwise, we advocate restricting this strategy to only the most suitable patients (such as those with known coronary anatomy on invasive or non-invasive imaging, and in the setting of ACS). Pause and dialogue with the patient are the key elements so as to prevent the “oculostenotic” and “auditory-stenotic” reflexes from coming into play. The lesson for all of us is that, while “gut-feeling” stands us in good stead at times of crisis, our practice needs to stay in tune with the available evidence, in order for our patients to reap the maximum benefit in the long run.

Use of Stent Grafts and Coils in Vessel Rupture and Perforation

Vessel rupture and perforation are important complications of percutaneous treatment of coronary and peripheral arterial disease. These complications can result in abrupt vessel closure, distal organ injury, bleeding into the surrounding tissue, and death. Prompt management of such complications is therefore critically important. This paper reviews the management of vessel rupture and perforation, including the use of different types of covered stents (balloon-expandable and self-expanding), as well as the various types of embolization coils. Particular focus will be placed on percutaneous coronary artery and peripheral arterial interventions.

Late Coronary Stent Thrombosis

Introduced >20 years ago,1 coronary artery stents have improved the safety and particularly the efficacy of percutaneous coronary interventions (PCIs).2 Abrupt vessel closure, complicating 6% to 8% of balloon angioplasty procedures, was associated with a 5% mortality, 40% rate of myocardial infarction (MI), and 40% rate of emergency coronary artery bypass grafting.3 Stents significantly reduced these adverse events (Figure 1).4,5 The reduction of restenosis afforded by bare metal stents (BMS) was modest (30% to 40%). Repeat revascularization still occurred in 15% to 20% of cases.6 Drug-eluting stents (DES) with antiproliferative drugs attached via polymers on the stent surface to minimize smooth muscle proliferation have reduced restenosis and rates of target lesion revascularization by 50% to 70% compared with BMS across nearly all lesion and patient subsets.7 Initially8 and again more recently,9–16 safety concerns were raised about DES, particularly about late stent thrombosis (ST). Figure 1. Outcome of 112 patients with abrupt vessel closure in the prestent balloon angioplasty experience of a registry (1985 to 1986; total, 1801 patients)3 and 339 patients with abrupt vessel closure during balloon angioplasty treated with BMS (Palmaz-Schatz) (total, 4596 patients).5 CABG indicates coronary artery bypass grafting. ST was a bane of stent implantation from the beginning. The initial experience with Wallstents in the late 1980s was overshadowed by ST rates approaching 24%.17 Subsequent series with Palmaz-Schatz and Gianturco-Roubin stents (still predominantly bailout stenting) observed ST in 6% to 12% of cases.4,18 The postprocedural antithrombotic regimen at the time consisted of aspirin, often in conjunction with oral anticoagulation. Dual antiplatelet therapy of aspirin and the thienopyridine ticlopidine in conjunction with a shift from bailout to elective stenting resulted in a significant reduction of ST to <2%.5,19 Earlier oral antiplatelet drug loading and …

Myocardial infarction: contemporary management strategies

Myocardial infarction (MI) is a common clinical diagnosis, associated with significant morbidity and mortality, not only in the short term, but also years following the index event. A more complete understanding of the pathophysiology of MI has ushered the era of multipronged treatment approach, with a combination of goal-directed revascularization, a broad adjunctive pharmacological therapy and aggressive secondary prevention measures. The goals of this article are to review the basic pathophysiological processes, which lead up to a clinical diagnosis of MI, to highlight the essential elements of clinical presentation and to summarize the evidence for comprehensive therapy. Emphasis has been placed on the choice of primary reperfusion therapy for ST-elevation MI, on risk-stratification of patients with non-ST elevation MI, and on rationale behind the selection of anti-ischaemic and antithrombotic therapy. Finally, evidence-based approach to secondary prevention is outlined.

Efficacy and safety of enoxaparin compared with unfractionated heparin in high-risk patients with non–ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention in the Superior Yield of the New Strategy of Enoxaparin, Revascularization and Glycoprotein IIb/IIIa Inhibitors (SYNERGY) trial

Enoxaparin reduces ischemic events more effectively than unfractionated heparin (UFH) in patients treated conservatively for non-ST-segment elevation acute coronary syndrome. The SYNERGY trial compared these agents in high-risk patients undergoing early invasive treatment. Enoxaparin was noninferior to UFH for the 30-day primary end point of death/myocardial infarction (MI), but modestly increased bleeding. This article compares the outcomes of the 4687 SYNERGY patients (47%) undergoing percutaneous coronary intervention, who were randomized to receive enoxaparin or UFH. Antithrombotic therapy was administered prerandomization in 78%. Crossover (usually in the catheterization laboratory) to the alternative antithrombotic occurred in 14.6% of enoxaparin patients and 2.9% of UFH-treated patients (P < .0001). Stenting was performed in 86.3%. Abrupt vessel closure occurred in 1.3% of enoxaparin patients and 1.7% of UFH-treated patients (P = .318). The rates of death/MI were similar at 30 days (13.1% with enoxaparin vs 14.2% with UFH, P = .289). GUSTO severe bleeding occurred with similar frequency in both groups (1.5% vs 1.6%, P = .688). TIMI major bleeding was more common with enoxaparin (3.7% vs 2.5% with UFH, P = .028). Transfusions were more frequent with enoxaparin than with UFH (6.8% vs 5.4%, P = .047). TIMI major bleeding increased with crossover from enoxaparin to UFH (from 3.7% to 7.8%) and from UFH to enoxaparin (from 2.5% to 8.6%). Statistical adjustment to model reasons for crossover did not affect the overall safety and efficacy outcomes. In high-risk patients undergoing early percutaneous coronary intervention for acute coronary syndrome, enoxaparin avoids the need for monitoring and achieves similar effectiveness to UFH but is associated with more bleeding.

New Developments in Coronary Stent Technology

Coronary stent technology has rapidly evolved from a mechanical solution to abrupt vessel closure and elastic recoil following plain balloon angioplasty, to become a vector for local drug delivery and modification of coronary plaque pathophysiology. The advent of drug-eluting stents (DES) has significantly reduced restenosis, although there is increasing concern over the risk of late stent thrombosis, particularly following cessation of antiplatelet therapy. Here we consider the limitations of the current generation of DES, and review recent advances in platform, carrier, and pharmacological technology, and their place in future clinical practice.

Comparison of Direct Stenting Versus Conventional Stent Implantation on Blood Flow in Patients With ST-Segment Elevation Myocardial Infarction

As compared with balloon angioplasty, stent implantation in treatment of acute myocardial infarction (AMI) reduces abrupt vessel closure, restenosis, and reocclusion rate. However, a few studies have demonstrated the safety and feasibility of direct stenting compared to conventional stent implantation technique. This study was designed to compare possible advantages of direct stenting with conventional stent implantation on immediate coronary blood flow and short-term clinical benefits in patients with AMI. Fifty patients with AMI who underwent mechanical revascularization were eligible for the study. The patients were randomly assigned to undergo either direct stenting (n = 25) or conventional stent implantation (n = 25). Before and after the procedure thrombolysis in myocardial infarction (TIMI) flow and postprocedural corrected TIMI frame count (cTFC) of the infarct-related artery were measured. There was no difference in TIMI flow distribution at baseline between the 2 groups. TIMI 3 flow rate significantly increased after procedure in both groups compared to baseline (p < 0.05). Postprocedural cTFC was found significantly lower in the direct stent arm compared to conventional stenting (p < 0.001). Both during and after the procedure the complication rate and procedural time were lower in the direct stenting arm. Direct stenting provides better immediate coronary blood flow and is a safe and feasible method compared with conventional stenting in patients with AMI. Improvement in coronary blood flow measured by the corrected TIMI frame count method may suggests a significant reduction of microvascular injury.

Treatment of Coronary Artery Perforations Complicating Percutaneous Coronary Intervention With a Polytetrafluoroethylene-Covered Stent Graft

Coronary artery perforation is a rare, but dreaded, complication of percutaneous coronary intervention. Conventional treatment, including reversal of anticoagulation and prolonged balloon inflation, is associated with a high incidence of death, Q-wave myocardial infarction, and emergency coronary bypass surgery. Although a number of case reports have demonstrated the feasibility of sealing coronary perforations with synthetic material-covered stent grafts, the efficacy of this treatment has not been reported in a large, multicenter series. We used a retrospective international registry to examine the outcomes of the polytetrafluoroethylene-coated JOSTENT coronary stent graft (CSG) in 41 cases of coronary perforations. Perforations were relatively severe: 16.7% Ellis grade 1, 54.2% grade 2, and 29.1% grade 3. Of the 41 patients, > 1/3 (n = 14) experienced life-threatening complications before stent graft implantation, including pericardial tamponade (12.2%), cardiogenic shock (9.8%), and cardiac arrest (2.4%). A total of 52 CSGs were used to treat the 41 perforations (mean 1.3 per lesion). All CSGs were placed successfully, with 92.9% of the perforations sealed completely and 7.1% partially. One patient developed abrupt vessel closure after CSG deployment, resulting in an overall procedure success rate of 96.4%. No in-hospital Q-wave myocardial infarctions, emergency coronary bypass surgeries, or deaths resulted. The CSG may be a reliable and highly effective treatment option for sealing coronary perforations complicating percutaneous coronary interventions.

Emergency Coronary Artery Bypass Surgery for Percutaneous Coronary Interventions: Changes in the Incidence, Clinical Characteristics, and Indications From 1979 to 2003

The purpose of the current study was to evaluate the changes in incidence, clinical characteristics, and indications for emergency coronary artery bypass grafting (CABG) in patients undergoing percutaneous coronary intervention (PCI) from 1979 to 2003. Emergency CABG after PCI is associated with significant morbidity and mortality. Data from 23,087 patients who underwent PCI at Mayo Clinic from 1979 to 2003 were analyzed. Patients were divided into three groups: the "pre-stent" era, 1979 to 1994 (n = 8,905); the "initial stent era," 1995 to 1999 (n = 7,605); and the "current stent era," 2000 to 2003 (n = 6,577). Although patients undergoing PCI in the recent time periods had more high-risk features, there was a significant decrease in the incidence of emergency CABG from 2.9% to 0.7% to 0.3% across the groups (p < 0.001). Patients requiring emergency surgery in the recent time periods had a higher prevalence of hypertension, prior revascularization, and left ventricular dysfunction (ejection fraction <40%), as well as more complex coronary lesions. Fewer patients in the current stent era had coronary artery dissections and abrupt vessel closure requiring emergency CABG. The in-hospital mortality rate for emergency CABG patients remains unchanged and ranges from 10% to 14%. The current study demonstrates that despite the increase in high-risk patients undergoing PCI, there has been a marked decrease in the incidence of patients requiring emergency CABG. However, the in-hospital mortality rate for those requiring emergency CABG remains high and unchanged.

Modulating thrombotic potential in catheter-based percutaneous coronary and peripheral vascular interventions.

Thrombosis is an obligatory consequence of all percutaneous vascular interventions. Balloon angioplasty, intravascular stents and other devices routinely used to facilitate dilatation of critical vascular stenoses result in fracture of the intima and exposure of the thrombogenic subendothelium with initiation and perpetuation of platelet activation and aggregation. This not uncommonly results in thrombus formation that may lead to abrupt vessel closure, distal ischemia and tissue infarction, and target organ dysfunction. Fortunately, advances in our understanding of the mechanisms that underlie vascular thrombosis have led to advances in the use of adjunctive pharmacological agents that modulate this pathophysiological response and have led to important reductions in the incidence and severity of thrombotic complications of percutaneous transluminal interventions.

Sirolimus eluting stent: a new era in interventional cardiology?

Coronary artery stents have emerged as the preferred tool for percutaneous coronary interventions during the past decade by eliminating abrupt vessel closure and reducing restenosis compared with balloon angioplasty. While coronary artery stents prevent constrictive arterial remodeling and elastic recoil, the implantation is associated with more severe arterial vascular injury than balloon angioplasty alone. The arterial injury initiates a vasculoproliferative response with smooth muscle cell proliferation and migration as well as extracellular matrix formation, which may lead to severe neointimal hyperplasia with in-stent restenosis in 10-30% of cases. Sirolimus, a naturally occurring macrocyclic lactone, has been identified as a pharmacological cell cycle inhibitor with potent antiproliferative and antimigratory effects on vascular smooth muscle cells in vitro. The systemic administration of sirolimus has been shown to effectively reduce neointimal hyperplasia in experimental restenosis models. Subsequently, sirolimus has been incorporated at therapeutically important doses into biocompatible polymers, which made it suitable for stent-based drug elution. Investigation of sirolimus eluting stents in both experimental and clinical restenosis studies have demonstrated dramatic reductions in neointimal hyperplasia. Accordingly, sirolimus eluting stents offer an attractive mode of local drug delivery by minimizing systemic toxicity and maximizing local dose requirements. In addition, sirolimus eluting stents hold great promise to effectively prevent restenosis.

Mechanisms of abrupt vessel closure after coronary i ultrasound study

Mechanisms of abrupt vessel closure after coronary i ultrasound study

Interventional therapy for coronary artery disease.

generation stents have been associated with restenosis rates of Since the introduction of percutaneous coronary intervention in approximately 15% in selected patient populations. the 1970s, its use has increased dramatically. An estimated The United States Food and Drug Administration initially 650,000 patients underwent percutaneous coronary intervention approved stents for use in emergency situations when balloon in 1999 (1), and the American College of Cardiology and the angioplasty was complicated by severe dissection or abrupt vesAmerican Heart Association guidelines now designate the qualsel closure. Currently, however, coronary stents are used as firstity of the evidence of benefit for high-risk patients as 1A. Balloon line treatment in as many as 80% of percutaneous coronary angioplasty allows for minimally invasive treatment of coronary interventions. The one lesion subset for which coronary stents artery disease but has limitations when used alone. These limitahave not been convincingly shown to improve on balloon angiotions include abrupt vessel closure (caused by vessel recoil or plasty is diseased vessels with diameters of less than 2.5 mm (4). persistent intimal dissection) in up to 5% of patients and restenoThese lesions are often treated with balloon angioplasty alone. sis requiring repeat angioplasty or coronary artery bypass sur-

Standards in interventional therapy of coronary artery disease

This review provides an overview of current percutaneous coronary interventional techniques (PCI) in patients with acute and chronic coronary artery disease. The indications for PCI have expanded during the past two decades, and no absolute contraindications remain. The chief limitations to event free survival following balloon angioplasty have been abrupt vessel closure in the short term and restenosis in the long term. The therapeutic effect of arterial vessel enlargement through PCI is accompanied by various degrees of arterial injury with exposure of thrombogenic components. Depending on the degree of activation of the coagulation cascade, as well as platelet adhesion and aggregation, this may result in intracoronary thrombus formation and subsequent ischemic sequelae. Therefore, inhibition of platelets and the coagulation system has always been central to interventional investigations. Restenosis has been the most important long-term limitation of PCI. Coronary artery stents have become an important adjunct to conventional balloon angioplasty owing to their dual function of reducing acute complications and the long term risk of restenosis. Although coronary artery stents serve as antirestenosis devices and reduce target vessel revascularisation requirements compared with balloon angioplasty, they themselves become a source of restenosis. In-stent restenosis is a major challenge for the interventionalist. None of the available interventional modalities provides optimal acute results, and long-term results are even poorer. This is especially true for diffuse in-stent restenosis lesions which have high recurrence rates. Thus, mechanical treatment modalities for evolved in-stent restenosis can only be one step in a comprehensive strategy for prevention and treatment. Brachytherapy as an adjunct seems to be especially promising, but late thrombosis, delayed restenosis and the potential for very late fibrosis are matters of concern. As attention has turned towards the prevention of in-stent restenosis new techniques such as drug delivering stents and gene therapy to inhibit the biological reaction of the vessel wall are likely to obtain greater importance.

The role of thrombin inhibition during percutaneous coronary intervention.

Acute coronary syndromes encompass a spectrum of conditions, including myocardial infarction and unstable angina. These syndromes are related to the formation and disruption of atherosclerotic plaque. Rupture of plaque leads to thrombin generation, fibrin deposition, and platelet aggregation, ultimately resulting in restriction of blood flow and ischemia of cardiac tissue. Percutaneous coronary intervention (PCI), including angioplasty and coronary stent placement, has been developed to open occluded arteries. The frequency with which these procedures are performed speaks to their largely successful outcomes. However, the mechanical manipulations of PCI result in additional plaque rupture and damage to the vessel wall, exposing subendothelial components to blood and resulting in the initiation of the clotting cascade and in platelet activation. Left unchecked, these intertwined processes lead to formation of arterial thrombi at the site of endothelial damage, and potentially to abrupt vessel closure or embolization of thrombi into the distal microcirculation. Thrombin plays a central role in thrombus formation and platelet activation, and its inhibition significantly reduces thrombus-related sequelae. Current antithrombotic strategies during PCI are based on the traditional indirect thrombin inhibitor heparin. Heparin has several limitations in efficacy and safety, due in part to its indirect mechanism of action. Bivalirudin, a direct thrombin inhibitor, offers significant improvement over heparin in the clinical outcomes and risks associated with PCI.

Frequency of abrupt vessel closure and side branch occlusion after percutaneous coronary intervention in a 6.5-year period (1994 to 2000) at a single medical center

The aims of this study were to analyze the contemporary trends in the changing incidence of abrupt vessel closure (AVC) after percutaneous coronary intervention (PCI), to determine the impact of intracoronary stenting and glycoprotein IIb/IIIa inhibitors (GPIs) on complication rates and etiologies, and to determine the incidence of side branch occlusion (SBO) as the etiology of AVC in the stent era, complications occurring during 3,300 consecutive PCIs performed from April 1994 to December 2000 at a single referral institution. In this consecutive patient cohort of PCI cases collected over a 6.5-year period, AVC occurred in 103 of 3,300 cases (3.12%). Linear regression analysis over this time frame documented a steadily decreasing incidence of AVC from 5.9% in 1994 to 1.1% in 2000 (−0.76%/per year, 95% confidence interval −0.99 to 0.52, p <0.05). Analysis using Pearson’s correlation showed that the decreasing incidence of AVC was inversely correlated with the increasing percentage of intracoronary stents placed over this time period (r = −0.94, p <0.001). Additionally, GPI use increased from 0% in 1995 to 36.0% in 2000 (p = 0.009). The absolute incidence of SBO of a major branch vessel remained relatively stable over this 6.5-year period. However, SBO appeared to be increasing as the etiology of AVC, and accounted for 9.0% of AVC in 1995 compared with 28.0% of AVC in 2000. This increasing trend of the percentage of SBO as the etiology of AVC appeared to correlate with the increased use of stents (r = 0.85, p = 0.015). Thus, the incidence of AVC steadily decreased over the 6.5-year time period, and was associated with the increased use of stents and GPIs; conversely, SBO accounted for an increasing percentage of AVC over this time period.

Vascular Intervention: A Clinical Approach

Bruce A. Perler and Gary J. Becker 733 pp. New York, NY: Theime Medical Publishers; 1998. $139.00. ISBN 0-86577-694-6 The surge in the diagnosis and treatment of endovascular disease can be attributed to the proliferation of stents. Stents are metallic scaffolds that reduce abrupt vessel closure and provide superior long-term results. They have revolutionized the management of vascular disease, fueled the growth of endovascular procedures, led to the creation of “vascular physicians,” and provided …

Immediate stent implantation versus conventional techniques for the treatment of abrupt vessel closure or symptomatic dissections after coronary balloon angioplasty

Background Coronary stenting was initially designed to treat a bailout scenario. Prospective randomized trials comparing stent implantation with standard techniques, including emergency coronary artery bypass grafting, are lacking. The aim of this trial was to test the superiority of immediate stent implantation compared with standard techniques for the treatment of abrupt or threatening closure after coronary balloon angioplasty. Methods In a prospective trial, 100 patients with abrupt vessel closure or symptomatic dissections causing objective signs of ischemia were randomly assigned to treatment with immediate placement of stents (n = 51) versus standard techniques such as prolonged dilatation or emergency bypass surgery (n = 49). The primary end point was the achievement of successful stabilization not requiring crossover to the other study group. Secondary end points included event-free survival and restenosis. Results Successful stabilization was achieved in 94% of patients in the stent group compared with 78% of patients in the standard treatment group (P =.038). Two patients died in each group, and there was a trend toward a higher incidence of myocardial infarction (16% vs 8%; P =.163) and a significantly increased creatine phosphokinase level (245 IU/L [95% confidence interval, 217-265 IU/L] vs 179 IU/L [confidence interval 140-212 IU/L]; P =.0002) in the standard treatment group. Event-free survival after 250 days was 72% in the stent group compared with 29% in the standard treatment group (P =.001). The angiographic restenosis rate was 30% in the stent group versus 59% in the standard treatment group (P =.01). Conclusions Immediate stenting, if technically feasible, shows superior short- and long-term results compared with standard treatment options. (Am Heart J 2000;140:e26.)