Coronary restenosis: what have we learned from angiography?

Periodontitis Is Associated With Risk of Conventional Stent Restenosis: Pilot Case-Control Study

Objectives: Percutaneous coronary angioplasty with stent implantation has been established as the main form of treatment of atherosclerosis. However, 16 to 44% of patients may evolve with stent restenosis. Periodontitis is an inflammatory condition associated with bacterial infection, that may lead to periodontal tissue destruction and tooth loss. This study aimed to evaluate the association between stent restenosis and periodontitis.

Materials and Methods: Coronary angiography exams presenting stent imaging with and without restenosis were analyzed. Patients meeting the inclusion and exclusion criteria were selected and allocated in 2 groups: case (restenosis) and control (without restenosis). We evaluated if systemic and periodontal variables were predictors of restenosis (primary outcome) using a multivariable stepwise logistic regression. Additionally, we compared clinical and periodontal conditions between the control and case groups (secondary outcomes) using Chi-square test and ANOVA test.

Results: Data from 49 patients (case n = 15; control n = 34) were analyzed. The results showed that stages III and IV periodontitis and lack of physical activity were significant predictors of stent restenosis (OR 5.82 and 5.98, respectively). Comparisons regarding the diagnosis of periodontal conditions between control and case groups did not present significant differences in the incidence of periodontitis and alveolar bone loss.

Conclusion: Stages III and IV periodontitis increased the incidence of stent restenosis. These findings suggest that advanced stages of periodontal disease might lead to the occurrence of negative outcomes after coronary angioplasty with stent placement.

Comparison of the linking arm effect on the biological performance of a CD31 agonist directly grafted on L605 CoCr alloy by a plasma-based multistep strategy

Stents are cardiovascular implants deployed on atherosclerotic arteries that aid in reopening, sustaining, and avoiding their collapse. Nevertheless, postimplantation complications exist, and the risk of the renewal of the plaque subsists. Therefore, enhanced properties are mandatory requirements for clinics. For that purpose, a novel approach allowing the direct-grafting of bioactive molecules on cobalt-chromium devices (L605) has been developed. This original strategy involves the direct plasma functionalization of metallic surfaces with primary amines (-NH₂). These groups act as anchor points to covalently graft biomolecules of interest, herein a peptide derived from CD31 (P23) with proendothelialization and antithrombotic properties. However, the biological activity of the grafted peptide could be impacted by its conformation. For this study, glutaric anhydride (GA), a short chain spacer, and polyethylene glycol (PEG) with antifouling properties were used as linking arms (LAs). The covalent grafting of the CD31 agonist on L605 by different LAs (GA-P23 and PEG-P23) was confirmed by XPS and ToF-SIMS analyses. The biological performance of these functionalized surfaces showed that, compared to the electropolished (EP) alloy, grafting the P23 with both LA increases adhesion and proliferation of endothelial cells (ECs) since day 1: EP = 68 ± 10%, GA-P23 = 101 ± 7%, and PEG-P23 = 106 ± 5% of cell viability. Moreover, ECs formed a complete monolayer at the surface, preventing clot formation (hemoglobin-free >80%). The potential of this plasma-based strategy for cardiovascular applications was confirmed by promoting a fast re-endothelialization, by improving the hemocompatibility of the alloy when coupled with the CD31 agonist and by its transfer onto commercial L605 stents, as confirmed by ToF-SIMS.

Current issues in coronary stent technology

Coronary artery stents have become the medical device of choice for the treatment of coronary artery disease. Since their introduction in 1987, significant advances in stent technology have taken place. A major objective of these developments was the reduction of in-stent restenosis, the formation of neointimal tissue inside the stent triggered by vessel injury and the inflammatory response, which results in renarrowing of the coronary artery. Improvements in strut configuration, thickness, and materials have enhanced deliverability and reduced vessel damage. Currently available drug-eluting stents release drugs that reduce neointimal formation through the arrest of cell proliferation. Drug-eluting stents have significantly reduced rates of in-stent restenosis. However, concerns have been raised with respect to their long-term safety, particularly in relation to the occurrence of late thrombosis. The post-procedural monitoring of stent-related complications is also of interest, including the relative suitability of invasive techniques such as angiography and intravascular ultrasound, and non-invasive techniques such as computed tomography and magnetic resonance imaging scanning. This paper reviews the current issues in stent technology.

Three-Dimensional Rotational Angiographic Detection of In-Stent Stenosis in Wide-Necked Aneurysms Treated with a Self-Expanding Intracranial Stent

OBJECTIVE

To determine the effect of Neuroform stent (Boston Scientific/Target, Fremont, CA) deployment on parent vessel lumen and detect in-stent changes in patients harboring wide-necked intracranial aneurysms treated with the stent-coil technique.

METHODS

Parent vessel dimensions were quantified before and after the procedure and at intermediate follow-up examinations by use of high-resolution three-dimensional rotational angiography. By use of shaded surface segmentation of the acquired volume, measurements of the parent vessel proximal to the stent (Point A), at three points within the stented vascular segment (Points B, C, and D), and distal to the stent (Point E) at each study time were compared by use of paired t tests. Correlation between degree of in-stent stenosis and reported ischemic events was estimated by use of a linear regression model.

RESULTS

Stent and coil deployment had no immediate effect on parent vessel dimensions. At angiographic follow-up, there was no significant change in vessel size proximal to the stent. Within the stent and distal to it, however, there was a statistically significant 0.31- to 0.41-mm reduction in average diameter (P < 0.001, P < 0.011, P < 0.003, and P < 0.014 for Points B, C, D, and E, respectively). The highest degree of stenosis occurred at Point B, with an average decrease in cross sectional surface area of 2.4 mm (P < 0.001), corresponding to a 19% stenosis and 52% estimated increase in focal hemodynamic resistance by Poiseuille's law. No clinical correlation was noted with the degree of in-stent stenosis.

CONCLUSION

Intracranial stenting using a soft self-expanding stent without angioplasty induced a statistically, but not clinically, significant decrease in cross sectional area. Further research and longer-term follow-up are needed to elucidate the mechanism and clinical importance of this response.

The medicine, angioplasty, or surgery study (MASS-II): a randomized, controlled clinical trial of three therapeutic strategies for multivessel coronary artery disease

OBJECTIVES

We sought to evaluate the relative efficacies of three possible therapeutic strategies for patients with multivessel coronary artery disease (CAD), stable angina, and preserved ventricular function.

BACKGROUND

Despite routine use of coronary artery bypass graft surgery (CABG) and percutaneous coronary intervention (PCI), there is no conclusive evidence that either one is superior to medical therapy (MT) alone for the treatment of multivessel CAD.

METHODS

The primary end point was defined as cardiac mortality, Q-wave myocardial infarction (MI), or refractory angina requiring revascularization. All data were analyzed according to the intention-to-treat principle.

RESULTS

A total of 611 patients were randomly assigned to either a CABG (n = 203), PCI (n = 205), or MT (n = 203) group. The one-year survival rates were 96.0% for CABG, 95.6% for PCI, and 98.5% for MT. The rates for one-year survival free of Q-wave MI were 98% for CABG, 92% for PCI, and 97% for MT. After one-year follow-up, 8.3% of MT patients and 13.3% of PCI patients underwent to additional interventions, compared with only 0.5% of CABG patients. At one-year follow-up, 88% of the patients in the CABG group, 79% in the PCI group, and 46% in the MT group were free of angina (p < 0.0001).

CONCLUSIONS

Medical therapy for multivessel CAD was associated with a lower incidence of short-term events and a reduced need for additional revascularization, compared with PCI. In addition, CABG was superior to MT for eliminating anginal symptoms. All three therapeutic regimens yielded relatively low rates of cardiac-related deaths.

Myocardial perfusion imaging following percutaneous coronary intervention: the importance of restenosis, disease progression, and directed reintervention

Percutaneous coronary intervention (PCI) has become a mainstay in the treatment of patients with coronary artery disease. Currently, more than one million coronary angioplasty and stent implantation procedures are performed annually. Although increasingly complex lesions and higher risk patients are being successfully treated percutaneously, restenosis and disease progression continue to cause significant morbidity. Restenosis occurs in approximately one-third of patients, one-half of who remain asymptomatic, while disease progression occurs at rates approaching 7% per year. Despite technological advances, unadjusted mortality rates have actually increased since the mid-1980s, and the current annual risk of a major adverse cardiac event following PCI is 5% to 7%. Although randomized clinical trials are needed to more definitively show a benefit, when performed six or more months following PCI, myocardial perfusion imaging reliably identifies patients most at risk of a poor long-term outcome. Directed reintervention can have a salutary impact on the prognosis of these patients. In view of recent data showing a positive impact of imaging and reintervention in patients after PCI, current guidelines should be reassessed.

Prevention of postcoronary angioplasty restenosis by omega-3 fatty acids: main results of the Esapent for Prevention of Restenosis ITalian Study (ESPRIT)

BACKGROUND AND OBJECTIVE

Previous trials of omega-3 fatty acids (omega-3 FA) for restenosis prevention after percutaneous transluminal coronary angioplasty (PTCA) have yielded conflicting results. We tested the hypothesis that long-term administration of omega-3 FA before PTCA may have significant effects on restenosis.

METHODS

We randomized 339 patients in a double-blind, placebo-controlled study of omega-3 FA (as an ethyl ester preparation given as 6 1-g capsules providing 3 g eicosapentaenoic acid and 2.1 g docosahexaenoic acid/d started 1 month before PTCA and given for 1 month thereafter, then continued at half-dose for 6 months) versus an olive oil placebo. Of these, 257 patients (125 on omega-3 FA, 132 on placebo) well matched for risk factors underwent successful balloon-only PTCA (280 total lesions) and were evaluable at 6 months with repeat angiography. Restenosis was defined at quantitative angiography as a recurrence of >50% diameter stenosis in the dilated vessel (Definition I) and as >50% loss of the short-term gain immediately after PTCA (Definition II).

RESULTS

Restenosis rates per vessel were 29.4% and 31.6% in the omega-3 FA group, and 39.6% and 35.4% in the placebo group according to Definitions I (P =.04) and II (P = not significant), respectively. Restenosis rates per patient were 31.2% and 33.6% in the omega-3 FA group, and 40.9% and 37.1% in the placebo group according to Definitions I (P =.05) and II (P = not significant), respectively.

CONCLUSIONS

With a long treatment before PTCA, omega-3 FA produced a small but significant decrease in the restenosis rate compared with placebo.

Heparin reacts with and inactivates nitric oxide

Although heparin is a well-known anticoagulant, in some cases it promotes a prothrombotic state and does so through both antibody-dependent and antibody-independent platelet activation. In this study, heparin was found to reverse the antiplatelet effect of an NO donor. S-nitroso-glutathione (SNO-Glu), with an EC(50) of 1.8 U/mL. Ultraviolet/visible spectral analysis and the Griess assay showed that increasing heparin concentrations on a dose-dependent basis eliminated acidified NO(x) species. Since heparin is a heterogeneous mixture of glycosaminoglycans, the effects of six different heparin disaccharides were compared with various substitutions on the hexose rings to determine which functional group(s) of the polysaccharide interact with acidified NO(x). Among the six disaccharides tested, only types I-S and II-S had the effect, suggesting that the sulfamino-group at the C2 position of the glucosamine moiety was critical for the elimination of acidified NO(x) species. Mass spectrometry experiments gave results consistent with these observations, indicating that only the I-S and II-S heparin disaccharides were modified upon treatment with NaNO(2)/HCl. Negative-ion electro-spray ionization MS and tandem MS analyses of the native compounds and their deuterium-labeled analogs confirmed that the reaction products from nitrosation of these N-sulfated disaccharides had eliminated the C2-sulfamino-moiety and replaced it with methoxide derived from the solvent. Participation of the 6-sulfato-substituent appears to facilitate the elimination reaction. These data show that heparin can impair the antiplatelet properties of nitric oxide by interacting with the nitrosating species, and suggest that heparin-like glycosamino-glycans may interact with endothelium-derived nitric oxide in vivo to regulate the bioactivity of this important antiplatelet and vasorelaxant substance.

Impact of an aggressive stenting strategy on initial and one-year follow-up costs in patients undergoing coronary angioplasty

BACKGROUND

Although stents have been shown in randomised trials to reduce restenosis rates compared with balloon angioplasty, there are concerns regarding the cost-effectiveness of an aggressive stenting strategy. Stents were shown to increase medical costs over 12 months in the early trials.

AIM

Our aim was to determine the economic impact of an aggressive stenting strategy using current stenting techniques compared with a conservative stenting strategy.

METHODS

Initial and one year follow-up costs were determined in all patients who underwent successful revascularisation during June to December 1996 (aggressive stenting, n = 401), and compared to all patients treated in the corresponding months in 1995 (conservative stenting, n = 347). All patients had clinical follow-up for one year.

RESULTS

The proportion of patients receiving a stent increased from 22.5% in 1995 to 66.1% in 1996 (p < 0.0001). Requirement for repeat procedures in the 1995 group compared with 1996 was coronary angiography in 31% vs 16% (p < 0.001), coronary angioplasty in 11% vs 6% (p = 0.0044) and bypass surgery in 4.8% vs 2.5% (p = 0.054). The mean initial cost of the procedure was higher in the aggressive stenting group ($4319 +/- 1276 in 1995 vs $5131 +/- 1491 in 1996, p < 0.0001), but after 12 months follow-up, total medical costs were equivalent ($5975 +/- 4143 in 1995 vs $5994 +/- 3476 in 1996, p = NS).

CONCLUSION

An aggressive coronary stenting strategy is associated with higher initial costs compared with a conservative strategy, but lower costs during follow-up due to reduced need for repeat procedures, resulting in equivalent one year total medical costs.

Angiographic deterioration of target coronary artery narrowing as a result of percutaneous balloon angioplasty

We evaluated the long-term angiographic outcome of balloon angioplasty by comparing original and follow-up target coronary narrowing. Rather than using restenosis to determine outcome, as in most angioplasty studies, we took an unusual approach and analyzed outcome in terms that are commonly used in progression and regression studies after medical interventions. Quantitative angiographic measurements were undertaken in 315 narrowings with an initial diameter stenosis <90% before and after angioplasty and at follow-up. Angiographic deterioration (>10% increase in follow-up diameter stenosis) was identified in 44 (14%) narrowings. Angiographic deterioration was not influenced by age, sex, risk factors, lipid profile, or the indication for angioplasty. Deterioration was also not predicted by the severity, length, or the location of the narrowing. The deteriorating narrowings had a higher recoil after dilatation compared with narrowings with angiographic improvement (21% +/- 31% vs 12% +/- 17%, p = 0.006); the residual stenosis after angioplasty was therefore higher. The late loss was also significantly increased compared with narrowings with angiographic improvement (65% +/- 26% vs 8% +/- 24%, p < 0.001). We conclude that the incidence of angiographic deterioration of coronary disease as a result of restenosis is uncommon but not negligible. Interventional cardiologists should resist the temptation to dilate mild, silent coronary narrowings because the procedure might have an unfavorable angiographic (and probably clinical) effect.

High-dose heparin decreases nitric oxide production by cultured bovine endothelial cells

BACKGROUND

Abrupt cessation of heparin therapy can lead to a recrudescence of thrombosis and acute ischemia. Endothelial NO is an important endogenous inhibitor of platelet-mediated thrombosis, yet biochemical studies examining the effect of heparin on NO production by the endothelium have heretofore been lacking.

METHODS AND RESULTS

In an attempt to address the effect of heparin on endothelial cell production of NO, confluent bovine aortic endothelial cells (BAECs) on microcarrier beads were incubated in the presence or absence of heparin. Results indicate that BAECs incubated with heparin were less able to inhibit platelet aggregation than control cells (P<.005 by ANOVA) and that this effect correlated with a decrease in NO production (36% decrease for heparin compared with control, P<.05). Dextran sulfate evoked the same response (67% decrease, P<.0001 compared with control), suggesting that the decrease in NO after heparin treatment is secondary to its negative charge rather than to a specific polysaccharide sequence. The decrease in NO production by heparin was accompanied by a 72% decrease in steady-state Nos 3 mRNA as well as a 49% decrease in immunodetectable endothelial NO synthase (eNOS) protein.

CONCLUSIONS

These data show that high-dose heparin at concentrations achieved in some acute cardiovascular settings increases in vitro platelet aggregation in media conditioned by endothelial cells by decreasing endothelial NO production through a mechanism that involves a decrease in steady-state Nos 3 mRNA and eNOS protein. These observations suggest a possible mechanism by which to explain in part the prothrombotic effects of heparin.

Anti-atherogenicity in women does not prevent restenosis after balloon angioplasty

To test the hypothesis that anti-atherogenicity in women exerts beneficial effects to prevent restenosis formation after coronary angioplasty, we studied 493 men (988 lesions) and 81 women (159 lesions), aged 40-60 years, who had undergone successful balloon angioplasty and had follow-up angiography, 4.9 +/- 4.1 months later. We compared the extent of restenosis between men and women, and between pre- and post-menopausal women, which was assessed by a categorical definition of restenosis (more than 50% diameter stenosis at follow-up) and by percent diameter measured immediately after angioplasty and at follow-up. Hypertension was more frequent in women and a significantly lower percentage of women smoked. In women, the levels of total cholesterol and low-density lipoprotein cholesterol were higher. The location of dilated lesions, frequency of angioplasty for lesions with chronic total occlusion, and frequency of emergency angioplasty in patients with unstable angina or acute myocardial infarction were similar in men and women. Restenosis formation, estimated by the categorical definition or percent diameter, did not differ between men and women, or between pre- and post-menopausal women. Menopausal status or sex was not an independent predictor of restenosis by multivariate analysis. Thus, the benefit of anti-atherogenicity in women does not play an important role in preventing restenosis after coronary angioplasty.

Inhibition of thrombin attenuates stenosis after arterial injury in minipigs

OBJECTIVES

We sought to determine whether brief, profound inhibition of thrombin or prothrombin activation by factor Xa limits neointimal formation and stenosis after arterial injury.

BACKGROUND

Thrombin has been implicated as a mediator of neointimal formation, but adjunctive administration of anticoagulant agents has not proven effective to decrease restenosis in patients undergoing coronary angioplasty.

METHODS

We infused recombinant desulfatohirudin (r-hirudin, bolus of 2 mg/kg body weight followed by 2 mg/kg per h, n = 9), heparin (100 U/kg per h, n = 6) or recombinant tick anticoagulant peptide (rTAP, 1-mg/kg bolus followed by 3 mg/kg per h, n = 5), a specific inhibitor of factor Xa, intravenously, beginning 15 min before and for up to 3 h after repetitive balloon hyperinflations sufficient to disrupt the internal elastic lamina in a carotid artery of minipigs with hypercholesterolemia induced by feeding them an atherogenic diet.

RESULTS

Partial thromboplastin time was increased six- to sevenfold over baseline levels at the end of the infusions of the anticoagulant agents. Lumen stenosis measured histologically 4 weeks after balloon-induced carotid injury was 29 +/- 16% (mean +/- SEM) in r-hirudin-treated, 52 +/- 19% in rTAP-treated and 76 +/- 18% in heparin-treated pigs (p < 0.02 for r-hirudin vs. heparin treatment).

CONCLUSIONS

The marked reduction of stenosis in r-hirudin-treated animals indicates that thrombin plays a major role in neointimal formation after balloon-induced arterial injury. A relatively brief interval of profound, direct inhibition of thrombin may be particularly effective to attenuate restenosis after balloon angioplasty.

Fish oils and low-molecular-weight heparin for the reduction of restenosis after percutaneous transluminal coronary angioplasty. The EMPAR Study

BACKGROUND

Percutaneous transluminal coronary angioplasty (PTCA) is complicated by restenosis within 6 months in > 40% of patients. Theoretical, animal experimental, and human epidemiological and clinical trial findings have suggested that fish oils (n-3) might reduce restenosis. Low-molecular-weight heparin (LMWH) has reduced cellular proliferation and restenosis in several experimental systems.

METHODS AND RESULTS

We randomized 814 patients to fish oils (5.4 g n-3 fatty acids) or placebo a median of 6 days before PTCA and continued for 18 weeks. At the time of sheath removal, 653 patients with at least one successfully dilated lesion were randomized to LMWH (30 mg SC BID) or control for 6 weeks in a 2 x 2 factorial design. Follow-up with quantitative coronary angiography (QCA; target, 18 weeks) was interpretable on 96% of these patients. Restenosis rates per patient were for n-3, 46.5%; placebo, 44.7%; LMWH, 45.8%; and control, 45.4%. Restenosis rates per lesion were for n-3, 39.7%; placebo, 38.7%; LMWH, 38%; and control, 40.4%. At follow-up QCA, mean minimal lumen diameters were (mm) for n-3, 1.12; placebo, 1.10; LMWH, 1.12; and control, 1.10. Fifteen percent of patients permanently discontinued n-3/placebo before study completion, and 21% of patients discontinued LMWH early. There were no significant differences in the occurrences of ischemic events. Bleeding was more common with LMWH, usually was mild, and led to early discontinuation of study medication in only 0.9% of patients. Gastrointestinal side effects were more common in patients receiving n-3 than placebo.

CONCLUSIONS

There is no evidence for a clinically important reduction of PTCA restenosis in this trial by either n-3 or LMWH. Evaluation of the results for n-3 in the context of previously published data on the reduction of PTCA restenosis indicates that n-3 is not efficacious and that further trials are unwarranted.

Intracoronary stenting without intravascular ultrasound guidance followed by antiplatelet therapy with aspirin alone in selected patients

One hundred selected patients with 103 lesions were treated with the deployment of 117 Palmaz-Schatz stents without the use of intravascular ultrasound, followed by antiplatelet therapy with aspirin alone. Angiographic and clinical follow-up revealed 2 stent thromboses; 3 stents required redilation, and 3 patients required intervention for disease progression elsewhere, suggesting that this approach can be applied effectively in selected patients.

Tissue factor mediates prolonged procoagulant activity on the luminal surface of balloon-injured aortas in rabbits

BACKGROUND

Activation of coagulation has been implicated in both acute thrombotic occlusion and restenosis after balloon angioplasty. However, concomitant administration of antithrombotic agents has thus far failed to prevent these complications. Importantly, the factors contributing to procoagulant activity of balloon-injured arteries over time have not been defined. This study was designed to determine the duration of procoagulant activity on the luminal surface of balloon-injured arteries and the relative roles of tissue factor and thrombin in this response.

METHODS AND RESULTS

Abdominal aortas in rabbits were subjected to repetitive balloon hyperinflations sufficient to disrupt the internal elastic lamina. Aortas were excised at < 1, 2, 4, 8, 16, 24, 48, and 72 hours and 1, 2, and 4 weeks after injury; divided into segments; and perfused with recalcified human pooled plasma (n = 58) or plasma depleted of vitamin K-dependent coagulation factors (n = 27) or first incubated with a monoclonal antibody to rabbit tissue factor (n = 33) followed by perfusion with human plasma. Samples of the effluent and plasma perfusate were collected over 10 minutes and assayed for fibrinopeptide A (FPA) as an index of the rate of thrombin-induced fibrin formation. FPA in the effluent from segments perfused with recalcified plasma, expressed as a percentage of FPA in the perfusate, was elevated for 16 hours after balloon-induced injury and exhibited two distinct increases occurring < 1 hour (1297 +/- 473%, mean +/- SD, n = 5) and 8 hours (1052 +/- 330%, n = 6) after injury (P < or = .000001 versus uninjured vessels). Preincubation of segments at these intervals with an antibody to tissue factor markedly attenuated the increases in FPA, as did perfusion of segments with plasma depleted of vitamin K-dependent coagulation factors, indicating that the observed increases in FPA in whole plasma did not result from performed thrombin bound to the injured vessel wall.

CONCLUSIONS

Tissue factor-mediated coagulation appears to be primarily responsible for prolonged procoagulant activity of balloon-injured arteries.

The effect of lovastatin on early restenosis

The effect of lovastatin given before percutaneous coronary angioplasty (PTCA) on early restenosis was investigated in men with mild to moderate hypercholesterolemia. Thirty-four hypercholesterolemic patients (serum LDL cholesterol 130-200 mg/dL) undergoing their first PTCA completed a 6-month prospective, double-blind, placebo-controlled trial. Eighteen received lovastatin 20 mg/day (Lo group) and 16 placebo (P1 group), beginning 10 to 21 days before PTCA. All underwent a thallium-201 quantitative exercise test 5 to 7 days after PTCA. Endpoints for restenosis were either 50% narrowing of the dilated artery on coronary angiography, performed in symptomatic patients or, in asymptomatic patients, the appearance of newly developed reversible filling defects in the vascular territory of the dilated artery on a second thallium scan done 6 months after PTCA. The hypocholesterolemic change observed in the Lo group was not accompanied by a reduction in early restenosis risk. The authors conclude that effective hypocholesterolemic therapy before PTCA does not affect early restenosis rate in men with mild to moderate hypercholesterolemia.

Restenosis after experimental angioplasty. Intimal, medial, and adventitial changes associated with constrictive remodeling

Predicting and preventing arterial restenosis after angioplasty has failed despite considerable research into mechanisms and techniques. We examined the roles of chronic constriction, neointimal-medial growth, and adventitial changes in restenosis in atherosclerotic rabbits. Angioplasty was performed on femoral artery lesions 4 weeks after lesion induction by air drying and cholesterol-supplemented diet. Angiographic and histological evaluation was conducted 3 to 4 weeks after angioplasty. The angiographic minimum luminal diameter (MLD) increased from 1.31 +/- 0.21 to 1.73 +/- 0.41 mm after angioplasty. Loss in MLD by 3 to 4 weeks was 0.95 +/- 0.64 mm. Initial gain and late loss correlated (P = .008). Late residual stenosis, defined histologically as the difference between the luminal areas of a proximal reference site and lesion site normalized by the luminal area of the reference site, was 52 +/- 32%. Histological indices of chronic constriction, neointimal-medial growth, and adventitial growth were defined on the basis of the areas of these arterial wall layers at the lesion site relative to the reference site. Another parameter defined as the ratio of adventitial area to the area of intima+media at the lesion site allowed evaluation of the relative importance of these layers. Surprisingly, late residual stenosis correlated with chronic constriction (P = .0003) but not with neointimal-medial growth or adventitial growth. The ratio of adventitial area to the area of intima+media at the lesion site also correlated with chronic constriction (P = .01). These findings suggest that factors related to arterial remodeling rather than neointimal-medial growth may dominate the response to angioplasty.

Role of the thrombin receptor in restenosis and atherosclerosis

Thrombus generation is central to thrombosis at vascular lesion sites, including post-PCTA acute reocclusion and chronic restenosis. Thrombin stimulates platelet activation, monocyte and neutrophil chemotaxis, and endothelial production of prothrombotic factors. The varied physiologic effects of thrombin are due to the widespread presence of thrombin receptors in many cell types. The receptor is uniquely activated: thrombin binds to the receptor at the thrombin anion-binding exosite, the receptor ligand ("tethered ligand") apparently being a sequence of 6 amino acids (SFLLRN). Thus, peptides corresponding to the sequence of the tethered ligand can stimulate almost all functions of native thrombin itself. Several intracellular signaling pathways have been identified as important in the restenosis process: the G protein-related pathway, cyclic adenosine monophosphate (cAMP) mediator pathway, and tyrosine kinase activation pathway. In situ hybridization has demonstrated an increase in thrombin receptor mRNA throughout the period of neointimal and vascular lesion development. The mechanism of this increase is unknown, but may be mediated by multiple inflammatory modulators. Several strategies have been tested in animal models for inhibiting thrombin: (1) Hirudin not only prevents thrombin from cleaving fibrinogen, but also prevents thrombin receptor activation. (2) Thrombin receptor antagonist peptides block platelet aggregation effects of thrombin. (3) Mono- and polyclonal antibodies inhibit thrombin receptor activation. (4) Antisense oligonucleotides block thrombin receptor expression.

Long-term follow-up after peripheral and coronary angioplasty in patients undergoing both types of procedure

Restenosis rates after peripheral and coronary angioplasties have been assessed only in patients who had either peripheral angioplasty or coronary angioplasty but never in patients who had both types. Among the 6364 angioplasties performed in the authors' institution since 1980, they studied 38 patients (36 men, 2 women, mean age fifty-five years, range thirty-four to seventy-seven) who had both peripheral and coronary angioplasty. The peripheral angioplasties were most often performed on iliac artery stenoses. They were performed before coronary angioplasty in 22 patients (58%) and after coronary angioplasty in 16 patients (42%). The follow-up after peripheral angioplasty was based on clinical data; ultrasound investigation was performed when the result of the clinical follow-up was poor (maximal walking distance lower than 500 meters). Follow-up after coronary angioplasty was assessed by a systematic coronary angiography at six months and with long-term clinical follow-up. The mean durations of the follow-up after peripheral or coronary angioplasty were not significantly different (respectively fifty-six +/- eleven and forty-two +/- nine months [mean +/- 2 SEM]). No patient was lost to clinical follow-up; 17 (45%) ultrasound investigations, 12 (32%) peripheral angiographies, and 34 (89%) coronary angiographies were performed. The restenosis rate after peripheral angioplasty was 18% and that after coronary angioplasty was 34%. These rates are similar to the classic rates observed in the literature. In conclusion, as reported for either procedure alone, the restenosis rates after peripheral angioplasty and after coronary angioplasty are different when assessed in patients who undergo both types of angioplasty.

Long-term histologic patency after percutaneous transluminal coronary angioplasty is predicted by the creation of a greater lumen area

OBJECTIVES

This study assessed the relation between histologic acute and long-term lumen size after coronary angioplasty.

BACKGROUND

Angiographic studies suggest that the creation of a larger acute lumen is associated with a reduced incidence of restenosis. Histologic evaluation of the influence of the acute lumen on late outcome has not been previously reported.

METHODS

Detailed histologic examination and planimetry were performed in 28 postmortem coronary arteries subjected to angioplasty at an average of 71 weeks antemortem. The lumen area on each histologic segment was defined as the final lumen area. The lumen area immediately after angioplasty, the acute lumen area, was defined by the sum of the neointimal area plus final lumen. A final lumen area > or = 25% of the arterial area was considered a long-term success; a final lumen area < 25% was considered a long-term failure.

RESULTS

Arterial size and neointimal area were similar in long-term successes and failures. In successes, the mean (+/- SD) acute lumen area was greater than in failures (4.1 +/- 1.9 vs. 2.7 +/- 1.4 mm2, respectively, p < 0.001). The acute lumen area as a percent of arterial area was 46 +/- 10% in successes versus 27 +/- 11% in failures (p < 0.0001). The corresponding estimated mean acute lumen diameter stenosis was 24 +/- 8% in successes versus 42 +/- 12% in failures (p < 0.0001). Plaque area was greater in failures (7.1 +/- 3.2 mm2) than in successes (4.8 +/- 2.4 mm2, p < 0.002).

CONCLUSIONS

Neointimal proliferation after angioplasty occurs in all dilated coronary arteries, and the amount of neointimal growth is independent of vessel size. The creation of a larger lumen and a larger lumen as a percent of vessel size were associated with an improved long-term histologic patency.

Low molecular weight heparin in prevention of restenosis after angioplasty. Results of Enoxaparin Restenosis (ERA) Trial

BACKGROUND

Heparin, an anticoagulant, possesses antiproliferative effects and has been shown to reduce neointimal proliferation and restenosis following vascular injury in experimental studies.

METHODS AND RESULTS

The primary aim of this double-blind multicenter study was to determine if 40 mg Enoxaparin, a low molecular weight heparin, administered subcutaneously once daily for 1 month after successful angioplasty would reduce the incidence of restenosis. Four hundred fifty-eight patients were randomized at nine clinical centers (231 to placebo and 227 to Enoxaparin). The primary end point was angiographic or clinical restenosis. Angiographic restenosis was defined as a loss of 50% of the initial gain as measured by quantitative coronary angiography (QCA) at a core laboratory. In the absence of QCA, clinical evidence of restenosis was defined as death, myocardial infarction, repeat revascularization, or worsening angina. Using the intention-to-treat analysis for all patients, restenosis occurred in 51% of the placebo group and 52% of the Enoxaparin group (relative risk, 1.07, P = .625). Likewise, no difference in restenosis was evident when the change in minimal lumen diameter or other angiographic definitions of restenosis were used. Adverse clinical events were infrequent and did not differ between the groups with the exception of minor bleeding complications, which were more common in the Enoxaparin group.

CONCLUSIONS

Enoxaparin (40 mg/d SC for 1 month) following successful angioplasty did not reduce the incidence of angiographic restenosis or the occurrence of clinical events over 6 months. The treatment was well tolerated, although in-hospital minor bleeding was more common with active treatment.

Coronary angioplasty for isolated non-dominant left circumflex coronary artery disease

The study describes the clinical findings and results of coronary balloon angioplasty in 134 patients with non-dominant left circumflex coronary artery disease. The immediate angiographic success rate was 97% versus 95% for left anterior descending (P = NS), and 90% for right coronary lesions (P < 0.002). There was no hospital mortality in the circumflex group versus 1.2% in the left anterior descending (P < 0.01), and 0.4% in the right coronary artery group (P = NS). Major non-fatal cardiac complications were significantly lower in the non-dominant left circumflex coronary artery patients (no new Q-wave versus 3% in the left anterior descending, P < 0.0002, and 3% in the right coronary artery group, P < 0.01; no urgent coronary artery bypass grafting versus 2% in the left anterior descending, P < 0.001, and 1% in the right coronary artery group, P = NS). The freedom from chest pain was 63% in 112 patients (84%) with follow-up data available at 24 +/- 18 months, and mean angina class diminished to 0.7 +/- 1.3 (P < 0.001). Consumption of antianginal and other cardiac drugs was diminished during follow-up, and the number of patients on no such drugs increased from 5 to 32% (P < 0.001). Restenosis was found in 19 of 32 patients with repeat coronary angiography (59%). Repeat angioplasty was required in 22 patients during follow-up and in 4 of them (18%) it was done for new lesions. Angioplasty for isolated non-dominant left circumflex coronary artery disease yields excellent immediate and long-term results.

Clinical and angiographic predictors of immediate recoil after successful coronary angioplasty and relation to late restenosis

The effect of immediate recoil on the results of balloon angioplasty was examined in a group of 416 patients (596 lesions) who underwent successful coronary angioplasty. Immediate recoil was responsible for loss of 0.42 +/- 0.64 mm from the potentially achievable lesion diameter, and represented 23% of the actual gain in diameter. The immediate recoil was determined mainly by the degree of arterial stretch, which is best represented by the balloon to normal artery size ratio (correlation coefficient 0.49, p < 0.0001). Classic risk factors for coronary artery disease did not affect immediate recoil, except for a trend toward lower values in patients with history of hypercholesterolemia. There was a tendency for lower recoil in patients with residual coronary thrombus and in those who underwent angioplasty within 1 week of acute myocardial infarction. Recoil was larger in the left anterior descending artery than in the circumflex or the right coronary artery. Patients with more immediate recoil developed more restenosis (> 50% stenosis at follow-up). However the late loss of luminal diameter due to the restenotic process was smaller in those who had larger initial recoil. It is concluded that immediate recoil after balloon angioplasty is an elastic phenomenon that is related mainly to the degree of arterial stretch. The relative importance of immediate recoil in determining the late outcome of coronary angioplasty is at least as important as the late restenotic process.

Factors determining late success after mitral balloon valvulotomy

Mitral balloon valvulotomy (MBV) has proved to be an effective method in the treatment of patients with mitral stenosis. Although several factors determining an optimal immediate result have been described, there is little information regarding long-term follow-up, as well as factors influencing late success after MBV. This study analyzes 350 patients (mean age 46 +/- 12 years) treated by MBV who were clinically followed up between 6 months and 6 years. At least 1 echo-Doppler follow-up study was obtained in 298 patients 28 +/- 14 months after MBV; hemodynamic reevaluations were performed in 66 patients after 23 +/- months. Late success was considered if the patient was in functional class I to II and free of major events (death, restenosis and valve surgery). Restenosis was defined as a 50% loss of initial gain with regard to valve area by echocardiography, which was confirmed hemodynamically. After a mean follow-up of 38 +/- 15 months, 296 patients (84%) remained in functional class I to II, without surgery or the need for an increase in medical treatment. The 5-year Kaplan-Meier survival rate was 94 +/- 1%, whereas restenosis, valve surgery and major event-free probability were 90 +/- 3%, 91 +/- 2% and 85 +/- 2%, respectively. Multivariate study (Cox regression model) identified the presence of sinus rhythm (p < 0.001) and the absence of calcium at fluoroscopy (p < 0.003) as the only independent factors of late success.(ABSTRACT TRUNCATED AT 250 WORDS)

Time course of restenosis during the first year after emergency coronary stenting

BACKGROUND

Prevention of abrupt vessel closure after percutaneous transluminal coronary angioplasty (PTCA) represents one of the current indications for intracoronary stent implantation. After the procedure, the stented segment undergoes luminal changes that may lead to late restenosis. This study was undertaken to assess the time course of luminal changes during the first year after emergency placement of coronary stents.

METHODS AND RESULTS

Coronary stenting was indicated in patients with present or threatened vessel closure secondary to large dissections after PTCA. From June 1989 to May 1991, 82 patients who received Palmaz-Schatz stents and did not have early vessel occlusion after stenting were enrolled into a serial angiographic follow-up study. Coronary normal reference diameter and minimal luminal diameter were measured with an automated edge detection technique. Patients who underwent repeat PTCA for restenosis were excluded from further serial angiography. The restudy rate at 3, 6, and 12 months was 96%, 81%, and 90% of the eligible patients, respectively. The incidence of restenosis (defined as a diameter stenosis > or = 50%) was 22.0% at 3 months, 31.9% at 6 months, and 33.2% at 12 months. Minimal luminal diameter was increased from 0.66 +/- 0.32 mm before to 2.85 +/- 0.43 mm immediately after stenting. It was 0.46 +/- 0.31 mm smaller than the diameter of the maximally inflated balloon during the procedure. The reduction in minimal luminal diameter was 0.80 +/- 0.69 mm (p = 0.0001) for the first 3 months, 0.29 +/- 0.52 mm (p = 0.0001) between 3 and 6 months, and 0.13 +/- 0.32 mm (p = 0.01) for the last 6 months. The percentage of patients who presented a significant change in minimal luminal diameter (defined as > 0.60 mm) declined from 50.6% during the first 3 months and 18.9% between 3 and 6 months to 6.5% for the period between 6 and 12 months.

CONCLUSIONS

The incidence and the time course of restenosis after emergency coronary stenting are similar to that reported for conventional PTCA. Coronary lumen dimensions demonstrated a peak change at 3 months and remained mostly stable after the first 6 months.

Pathophysiological mechanisms for restenosis following coronary angioplasty: possible preventive alternatives

Restenosis after successful percutaneous transluminal coronary angioplasty (PTCA) remains an unsolved medical problem. The search for the underlying pathophysiological mechanisms have identified intimal proliferation of smooth muscle cells (SMC) to be the prevailing cause of late restenosis, with endothelial cells (EC) and platelets being important participators in the process. According to the most accepted present theory, SMC would be stimulated to migrate and proliferate shortly after the angioplasty by the release of growth factors from injured EC and accumulated platelets. However, clinical trials of agents interfering with these mechanisms have not significantly diminished the rate of restenosis, which suggest both that our knowledge of the process is incomplete, and that new ways of administering the agents may be required.

Matching based on quantitative coronary angiography as a surrogate for randomized studies: comparison between stent implantation and balloon angioplasty of native coronary artery lesions

Although intracoronary stenting has been advocated as an adjunct to balloon angioplasty to circumvent late restenosis, its effectiveness has not yet been verified. Therefore the aim of this study was to determine the differences in the immediate and long-term changes in stenosis geometry between Wallstent implantation and balloon angioplasty in native coronary artery lesions. To obtain two study populations with identical baseline stenosis characteristics, patients were matched for lesion site, vessel size, and minimal luminal diameter. Only patients undergoing elective and successful coronary intervention of a native coronary artery, in whom a control angiographic study had been performed, were included. A total of 186 patients (93 in each group) were selected. The coronary angiograms were analyzed with the computer-assisted cardiovascular angiographic analysis system. Matching was considered adequate, since there was an equal number of lesion sites in each study population and there were no differences in baseline reference diameter and minimal luminal diameter. Wallstent implantation resulted in a significantly greater increase in minimal luminal diameter (from 1.22 +/- 0.34 mm to 2.49 +/- 0.40 mm, p < 0.00001) compared with balloon angioplasty (from 1.21 +/- 0.29 mm to 1.92 +/- 0.35 mm, p < 0.00001). Despite a greater decrease in minimal luminal diameter after Wallstent implantation (0.48 +/- 0.74 mm) than after balloon angioplasty (0.20 +/- 0.46 mm), the minimal luminal diameter at follow-up was significantly greater after stent implantation (2.01 +/- 0.75 mm vs 1.72 +/- 0.54, p < 0.0001). It was concluded that Wallstent implantation results in a superior immediate and long-term increase in minimal luminal diameter compared with balloon angioplasty. The larger initial gain after stent implantation compensates for the late loss, and thus an improved initial result and not lessened neointimal hyperplasia is responsible for a reduced incidence of restenosis. Studies based on matching of angiographic variables are a surrogate for randomized studies, forecasting their results and offering insight into the effects of different interventional techniques. Moreover, these studies yield statistical information that may be helpful for the proper design of a randomized study (sample size, type II error).

Angiographic and clinical outcome of intracoronary stenting: immediate and long-term results from a large single-center experience

OBJECTIVES

The purpose of this study was to determine the immediate and long-term angiographic and clinical results of coronary stenting.

BACKGROUND

Although preliminary trials of endovascular stenting have demonstrated promising results, lack of long-term follow-up has limited the critical evaluation of the role of coronary stenting in the treatment of obstructive coronary artery disease.

METHODS

A total of 250 procedures using the Palmaz-Schatz stent, performed in 220 patients between June 1988 and July 1991, were examined. Minimal lumen diameter of the treated segments was measured on angiograms obtained before, after and 6 months after intervention.

RESULTS

Stent placement was successful in 246 (98%) of 250 lesions, reducing diameter stenosis from 77% to -2.5%. There were no deaths or Q wave myocardial infarctions. One patient (0.4%) required emergency bypass surgery and one (0.4%) developed subacute thrombosis. Femoral vascular complications occurred in 36 patients (16%). Six-month angiographic follow-up was obtained in 91% of eligible patients. The overall angiographic restenosis rate (stenosis greater than or equal to 50%) was 25%. By univariable analysis, the rate of restenosis was significantly higher for stents in the left anterior descending versus the right coronary artery (44% vs. 12%; p = 0.002); in diabetic patients (56% vs. 20%; p = 0.006), and in vessels with post-stent lumen diameter less than 3.31 mm (34% vs. 16%; p = 0.05). Stenting of the left anterior descending artery was the strongest predictor (p = 0.01) of restenosis in a multivariable model. Total survival was 97% and event-free survival (freedom from death, myocardial infarction or revascularization) was 70% at 36 months.

CONCLUSIONS

Palmaz-Schatz stents can be placed successfully with a low incidence of major complications. The angiographic restenosis rate was 25%, and 70% of patients remained free of cardiovascular events at 3 years. Diabetes, small postprocedure lumen diameter and stenting of the left anterior descending artery are associated with higher rates of restenosis.

Novel approach to the analysis of restenosis after the use of three new coronary devices

Restenosis after coronary intervention has remained a vexing problem despite the introduction of nearly 24 newer coronary interventional devices. To more clearly evaluate the potential impact of three such new devices on restenosis, coronary lumen diameters were measured before, immediately after and at 6 months after intervention, and restenosis was analyzed using continuous geometric techniques. Lumen diameters were measured before and immediately after intervention in 223 coronary vessels treated with one of three new devices: a single Palmaz-Schatz stent (n = 87), directional atherectomy (n = 125) and laser balloon angioplasty (n = 11); 184 (83%) of the patients underwent follow-up angiography 6 months after treatment. The immediate increase in lumen diameter produced by the intervention (acute gain) and the subsequent reduction in lumen diameter between the time of intervention to 6 month follow-up study (late loss) were examined. For each of the three interventions, the restenosis rate at follow-up study was analyzed using a traditional dichotomous definition (greater than or equal to 50% diameter stenosis), as well as a novel graphic technique. Although the apparent restenosis rates differed significantly among the three interventions (19% for stents, 31% for atherectomy and 50% for laser balloon angioplasty; p = 0.02), late loss among the three interventions was equivalent (average 1 mm; p = 0.91). There were, however, marked differences in the acute gain achieved by the three interventions: 2.6 mm for stents, 2.2 mm for atherectomy and 2 mm for laser balloon angioplasty; p less than 0.001). It was these differences in acute gain rather than late loss that explained the observed differences in restenosis rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Wiktor stent implantation in patients with restenosis following balloon angioplasty of a native coronary artery

Intracoronary stenting has been introduced as an adjunct to balloon angioplasty aimed at overcoming its limitations, namely acute vessel closure and late restenosis. This study reports the first experience with the Wiktor stent implanted in the first 50 consecutive patients. All patients had restenosis of a native coronary artery lesion after prior balloon angioplasty. The target coronary artery was the left anterior descending artery in 26 patients, the circumflex artery in 7 patients and the right coronary artery in 17 patients. The implantation success rate was 98% (49 of 50 patients). There were no procedural deaths. Acute or subacute thrombotic stent occlusion occurred in 5 patients (10%). All 5 patients sustained a nonfatal acute myocardial infarction. Four of these patients underwent recanalization by means of balloon angioplasty; the remaining patient was referred for bypass surgery. A major bleeding complication occurred in 11 patients (22%): groin bleeding necessitating blood transfusion in 6, gastrointestinal bleeding in 3 and hematuria in 2. Repeat angiography was performed at a mean of 5.6 +/- 1.1 months in all but 1 patient undergoing implantation. Restenosis, defined by a reduction of greater than or equal to 0.72 mm in the minimal luminal diameter or a change in diameter stenosis from less than to greater than or equal to 50%, occurred in 20 (45%) and 13 (29%) patients, respectively. In this first experience, the easiness and high technical success rate of Wiktor stent implantation are overshadowed by a high incidence of subacute stent occlusion and bleeding complications.(ABSTRACT TRUNCATED AT 250 WORDS)