Prediction of restenosis after coronary balloon angioplasty. Results of PICTURE (Post-IntraCoronary Treatment Ultrasound Result Evaluation), a prospective multicenter intracoronary ultrasound imaging study

Influence of the angiotensin converting enzyme insertion or deletion genetic variant and coronary restenosis risk: evidence based on 11,193 subjects

The insertion/deletion (I/D) polymorphism of the gene encoding angiotensin converting enzyme is a controversial risk factor for restenosis after percutaneous transluminal coronary angioplasties (PTCA) in patients. Genetic association studies can be problematic to reproduce due to insufficient power, phenotypic heterogeneity, population stratification, small effect of the variant and even publication biases. To derive a more precise estimation of the relationship as well as to quantify the between-study heterogeneity and potential bias, a meta-analysis including 11,193 patients from 33 published cohort studies was performed. In a combined analysis, the summary per-allele odds ratio for restenosis was 1.31 (95% CI: 1.08-1.58, P = 0.006), and 1.22 (95% CI: 0.95-1.56, P = 0.12), for PTCA-stent and PTCA-balloon, respectively. In the subgroup analysis by ethnicity, significantly increased restenosis risks after PTCA-stent were found in Asians for the polymorphism; whereas no significant associations were found among Caucasians. As for restenosis risks after PTCA-balloon, no evidence of any gene-disease association was obtained in the stratified analyses according to ethnicity and study size. In conclusion, this meta-analysis demonstrated that the DD homozygous of ACE I/D polymorphism was significantly associated with elevated restenosis susceptibility after PTCA-stent among Asian populations.

Genetic polymorphism of angiotensin converting enzyme and risk of coronary restenosis after percutaneous transluminal coronary angioplasties: evidence from 33 cohort studies

Background

In the past decade, a number of cohort studies studies have been carried out to investigate the relationship between the insertion/deletion polymorphism of the gene encoding angiotensin-converting enzyme and risk of restenosis after percutaneous transluminal coronary angioplasties in patients. However, these studies have yielded contradictory results. Genetic association studies addressing this issue are frequently hampered by insufficient power. We therefore performed a meta-analysis of the published studies to clarify this inconsistency and to establish a comprehensive picture of the relationship between ACE I/D polymorphism and post-PTCA restenosis risk.

Methods

Databases including Pubmed, EMBASE, ISI Web of Science, EBSCO, Cochrane Library databases and CNKI were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. The random-effects model was applied, addressing heterogeneity and publication bias.

Results

A total of 33 cohort studies involving 11,099 subjects were included. In a combined analysis, the OR for post-PTCA restenosis of the ACE DD genotype was 1.61 (95% CI: 1.27–2.04; P<10⁻⁵). In the subgroup analysis by intervention, significantly increased risks were also found in PTCA-stent and PTCA-balloon for the DD genotype of the polymorphism.

Conclusions

Our meta-analysis showed that the DD genotype of ACE I/D polymorphism was significantly associated with increased risk of restenosis, particularly for PTCA-stent.

Impact of vessel calcification on outcomes after coronary stenting

BACKGROUND

Calcified coronary arteries have few viable smooth muscle cells capable of proliferating, and, subsequently, might exhibit less in-stent restenosis. We therefore studied the outcome of stenting in patients with different amounts of coronary calcification.

METHODS

Six hundred twenty-one patients who underwent bare metal stenting of calcific native coronary arteries were studied retrospectively. Pre- and postinterventional intravascular ultrasound (IVUS) and qualitative and quantitative coronary angiography (QCA) were performed in 662 lesions. The arc of calcium was measured, and arteries were grouped (A, B, C, and D) according to the calcium arc in IVUS (0-90 degrees , 91-180 degrees , 181-270 degrees , and 271-360 degrees , respectively). Arteries with a superficial calcium arc of < or =270 degrees (Group E) were compared to arteries with >270 degrees calcification (Group F).

RESULTS

Clinical and lesion characteristics were similar, and the major complication rate was low (1.9%) in all groups. In Groups A, B, C, and D, patients with more calcific arteries had more non-Q-wave myocardial infarction (MI) (P=.04-.002). Patients in Group F (more extensive superficial calcification) had an increased frequency of non-Q-wave MI compared to Group E. Malapposition of stents to vessel wall and use of rotational atherectomy were more frequent in Group F (P=.001). Late events including death, MI, and revascularization with either coronary artery bypass grafting or percutaneous coronary intervention (PCI) were not different among the groups. Extensive calcification of coronary arteries is associated with more frequent peri-procedural non-Q-wave MI.

CONCLUSION

Despite the scarcity of viable cells, the late event rate in severely calcified arteries is not different from mildly calcified arteries. This may be due to more frequent malapposition of stents to vessel wall and augmented trauma during PCI in severely calcified arteries.

Effect of preintervention remodeling type on subsequent coronary artery behavior after directional atherectomy

To evaluate the influence of preintervention remodeling on subsequent vessel behavior after directional coronary atherectomy (DCA) under intravascular ultrasound (IVUS) guidance, serial (before and after DCA and at 6-month follow-up) IVUS data were analyzed for 246 lesions that were classified into 2 categories: positive remodeling (PR) in 77 lesions versus intermediate or negative remodeling in 169 lesions. Although the 2 groups had similar baseline characteristics, IVUS data showed that the PR group had a greater acute lumen area (LA) gain without an increased late LA loss, resulting in a greater net (acute plus late) LA gain and follow-up LA. This suggests that IVUS-guided DCA may neutralize the negative impact of preintervention PR on late vessel patency.

Randomized trial of Rotational Atherectomy Versus Balloon Angioplasty for Diffuse In-stent Restenosis (ROSTER)

BACKGROUND

Various autopsy and intravascular ultrasound (IVUS) studies have shown neointimal proliferation as the main mechanism of in-stent restenosis (ISR) responsible for >95% of luminal narrowing while stent struts are not compressed. ISR of diffuse type has a high incidence of recurrence (up to 70%) after balloon angioplasty (PTCA). Tissue ablation with percutaneous rotational coronary atherectomy (PRCA) may be more efficacious compared to tissue compression or extrusion after PTCA for the interventional treatment of diffuse ISR.

METHODS

The Rotational Atherectomy Versus Balloon Angioplasty for Diffuse In-Stent Restenosis (ROSTER) trial is a single-center, randomized trial comparing PRCA to PTCA (both with IVUS guidance) in the treatment of diffuse ISR in 200 patients. In the PRCA group (n = 100), rotablation was performed using a burr-to-artery ratio >0.7 followed by adjunctive balloon dilatation at low pressure (4-6 atm). In the PTCA group (n = 100), high-pressure (>12 atm) balloon dilatation was performed using an optimal size balloon. The study's primary end point was target lesion revascularization (TLR) at 9 months and secondary end points included clinical events at 1 year and angiographic restenosis in a substudy of the last 75 patients enrolled.

RESULTS

Baseline clinical and angiographic variables were comparable between the 2 groups with similar procedural and angiographic success, but a higher rate of repeat stenting occurred in the PTCA group (31% vs 10%; P <.001). Although the angiographic acute luminal gain was similar between the 2 groups, IVUS analysis revealed lower residual intimal hyperplasia area after PRCA versus PTCA (2.1 +/- 0.9 mm2 vs. 3.3 +/- 1.8 mm2; P =.005). At a mean follow-up of 12 +/- 2 months, there were 2 deaths, 3 myocardial infarctions, and 3 coronary artery bypass graft procedures in each group. TLR incidence was 32% in the PRCA group and 45% in the PTCA group (P =.042), with a similar trend noted in the angiographic substudy.

CONCLUSION

The ROSTER trial for diffuse ISR revealed both PRCA and PTCA to be safe and effective, but PRCA resulted in less residual intimal hyperplasia, lower repeat stent use, and decreased TLR.

Intracoronary ultrasound in acute coronary syndromes: from characterization of vulnerable plaques to guidance of percutaneous treatment of complex stenoses

Our current knowledge on the substrate and genesis of acute coronary syndromes (ACS) results from the integration of pathological, angiographic, and intracoronary imaging techniques. To summarize briefly the current paradigm, eight differentiated stages of development of atherosclerotic lesions are currently accepted, defined not only by the cellular elements involved, but also by the appearance of sudden alterations of plaque structure and coronary thrombosis. The latter constitutes not only the dominant substrate for the most devastating manifestations of coronary artery disease, but also accelerates plaque size at a faster pace than in earlier stages. The composition of atherosclerotic plaque varies significantly along the different evolutive stages, and thus includes cellular (macrophage, smooth muscle cells) and noncellular elements (glicosaminglycan or collagen-rich cellular matrix, extracellular lipid deposits, calcification, fresh, or organized thrombus) in a varying proportion. Furthermore, a dynamic process of vessel remodeling occurs along the atherosclerotic process, resulting, in most cases, in a protective mechanism against myocardial ischemia by preserving luminal dimensions during plaque enlargement. Intravascular ultrasound (IVUS) is one of the intracoronary imaging techniques that has contributed to the understanding of these changes in man. In addition, IVUS has the potential of being a useful clinical tool for predicting the chances of future acute coronary events by identifying vulnerable plaques, of characterizing which is the culprit lesion in ACS, and in guiding revascularization procedures in the treacherous field of thrombotic coronary syndromes. In this article, we review the current evidence on the potential of IVUS imaging for fulfilling these purposes.

Mechanisms of acute lumen gain following cutting balloon angioplasty in calcified and noncalcified lesions: an intravascular ultrasound study

Several studies have shown that mechanisms for lumen enlargement following conventional balloon angioplasty (BA) consist of plaque reduction and vessel expansion. To assess the mechanisms of lumen enlargement after Cutting Balloon (CB) angioplasty, intravascular ultrasound images were analyzed in 180 lesions (89 CB and 91 BA). External elastic membrane (EEM) cross-sectional area (CSA), lumen CSA, and plaque plus media (P+M) CSA were measured before and after angioplasty. In the CB group, lower balloon pressure was utilized (P < 0.0001). DeltaP+M CSA was significantly larger (P = 0.02) and deltalumen CSA showed a trend toward being larger (P = 0.07) compared to BA group. For noncalcified lesions, CB resulted in a larger deltaP+M CSA (P < 0.05) and a smaller deltaEEM CSA (P = 0.10) than BA. For calcified lesions, deltalumen CSA was significantly larger in the CB group (P < 0.05) without significant differences in deltaEEM CSA and deltaP+M CSA. Dissections complicated with calcified lesions were associated with larger deltalumen CSA for the CB group. In conclusion, for noncalcified lesions, CB achieves similar luminal dimensions with larger plaque reduction and less vessel expansion compared to BA. On the other hand, for calcified lesions, the CB achieves larger lumen gain, especially in lesions with evidence of dissections.

Down-regulation of the ERK1 and ERK2 mitogen-activated protein kinases using antisense oligonucleotides inhibits intimal hyperplasia in a porcine model of coronary balloon angioplasty

OBJECTIVE

Neointimal hyperplasia is a central feature in the pathogenesis of a variety of vascular pathologies. Mitogen-activated protein kinases (MAPK) are involved in the downstream transduction of signals from receptors for many of the molecules known to be instrumental in this process and thus represent a potential target for the modification of the proliferative response. We examined the hypothesis that down-regulation of MAPK would inhibit neointima formation in a porcine coronary injury model.

METHODS

Balloon angioplasty was performed on 38 coronary arteries from 23 large white pigs. Antisense oligonucleotides to the p42 and p44 MAPK were locally delivered to the site of injury immediately after balloon injury. At 7 or 21 days, arteries were harvested for morphometry, determination of cell proliferation and assessment of MAPK protein levels.

RESULTS

At 7 days, neointima formation was significantly reduced compared to controls (corrected intima/media ratio (IMR) 1.01+/-0.13 vs. 1.61+/-0.07, P<0.01) and this was associated with a 58% and 23% down-regulation of p42 and p44 protein levels, respectively. Intimal and medial proliferation rates were also reduced by 32% and 26%, respectively. At 21 days however, the effect of the treatment on MAPK protein levels was no longer significant and this correlated with a loss of the effects on IMR and cell proliferation.

CONCLUSIONS

Down-regulation of MAPK inhibits early smooth muscle cell (SMC) proliferation and neointimal thickening in response to arterial injury, implying that it plays an important role in determining the early vascular response to injury. Inhibitory effects were less apparent at 21 days after a single delivery of oligonucleotide, implying that more sustained local delivery may be required to achieve longer term therapeutic benefit.

Quinapril prevents restenosis after coronary stenting in patients with angiotensin-converting enzyme D allele

Restenosis after coronary artery stent implantation is attributed chiefly to intimal hyperplasia, which is prevented experimentally by angiotensin-converting enzyme (ACE) inhibitors. Therefore, the present study investigated whether the effect of quinapril, a tissue-specific ACE inhibitor, on the prevention of coronary restenosis differs according to ACE polymorphism. One hundred consecutive patients with successful stent implantation were randomly assigned to quinapril and control groups. Both follow-up angiography and ACE polymorphism analysis were obtained from 92 patients (control, 46; quinapril treatment, 46). The prevalence of risk factors did not differ statistically according to quinapril treatment or ACE genotypes. There was no statistically significant difference in the occurrence of restenosis 6 months after stenting between the groups. Quantitative coronary angiography revealed that quinapril treatment resulted in significantly higher minimal lumen diameter and significantly lower percent diameter stenosis (22.9 +/- 22.6 vs 37.1 +/- 19.7% in the control group, p < 0.05) in patients with the D allele although there was no difference in those with the II genotype. In addition, intravascular ultrasound revealed that quinapril treatment significantly prevented the loss of minimal lumen cross-sectional area and the increase in percent area stenosis (34.5 +/- 14.0 vs 53.3 +/- 16.4% in the control group, p < 0.05) in patients with the D allele compared to those with the II genotype. These results suggest that the administration of ACE inhibitors for the attenuation of lumen loss after coronary stent implantation is best for subjects with the D allele of the ACE genotype.

Cardiovascular risk factors do not predict clinically defined restenosis after percutaneous transluminal angioplasty for lower limb ischemia

The purpose of this study was to evaluate risk factors predicting restenosis and primary patency after percutaneous transluminal angioplasty. Follow-up data (including cardiovascular risk factor scores according to SCVIR criteria, preinterventional and postinterventional clinical data and patient history) of all patients who underwent successful percutaneous transluminal angioplasty for lower limb ischemia were analyzed retrospectively and patients, relatives, or referring physicians underwent a telephone interview. Patients with incomplete follow-up data were examined by means of a clinical examination, including Doppler measurements and treadmill test. Additionally all angiograms were evaluated to calculate lesion length, number of treated lesions, lesion type (SCVIR score), and runoff. The outcome was categorized into four groups: early recurrence (< 1 month, group I), mean recurrence (1-6 months, group II), late recurrence (>6 months, group III), and no recurrence (group IV). According to common concepts group I was defined as early (thrombotic) reocclusion, group II as clinically defined restenosis, and group III as progression of atherosclerosis. One hundred thirty-seven patients underwent percutaneous transluminal angioplasty of 148 extremities. The groups differ significantly only with respect to a higher diabetes score for group I in comparison to group IV (p=0.002, Kruskal-Wallis test), and a worse runoff of group I compared with group IV (p =0.008). There was a trend toward a higher diabetes score for group II in comparison to group IV (p = 0.014). There were no differences with regard to hyperlipemia, hypertension, and tobacco use between patient groups. Mean primary patency was 436 days. Predictors for lower patency rates were diabetes mellitus (p<0.001), runoff (p=0.005), and number of treated lesions (p=0.007) in a stepwise, multiple regression analysis. Patients with clinically defined restenosis showed no specific risk factor profile in this study. Predictors for lower primary patency were diabetes mellitus, number of treated lesions, and runoff.

Clinical and quantitative coronary angiographic predictors of coronary restenosis: a comparative analysis from the balloon-to-stent era

OBJECTIVES

We sought to assess whether coronary stents have modified the predictive value of demographic, clinical and quantitative coronary angiographic (QCA) predictors of coronary restenosis.

BACKGROUND

A systematic analysis in a large cohort of registries and randomized trials of the percutaneous transluminal coronary angioplasty (PTCA) and stent era has never been performed.

METHODS

A total of 9,120 treated lesions in 8,156 patients included in nine randomized trials and 10 registries, with baseline, post-procedural and six-month follow-up QCA analyses, were included in this study. Predictors of restenosis were identified with univariate and multivariate logistic regression analyses. Interaction terms were introduced in the regression equation to evaluate whether the predictors of restenosis were common to both eras or specific for either one of the revascularization techniques.

RESULTS

The restenosis rate was 35% after PTCA and 19% after angioplasty with additional stenting. In the univariate analysis, favorable predictors were previous coronary artery bypass graft surgery (CABG), stent use, stent length and a large pre-procedural minimal lumen diameter (pre-MLD); unfavorable predictors were weight, body mass index, diabetes mellitus, multi-vessel disease, lesion length and a high residual post-procedural diameter stenosis (post-DS). Predictors specific for the PTCA population were a large post-procedural MLD (post-MLD) as favorable and a severe pre-procedural DS (pre-DS) as unfavorable. Favorable predictors specific for the stent population were a large post-MLD and a large pre-procedural reference diameter (pre-RD). In the multivariate analysis, the best model included the following favorable predictors: stent use, a large post-MLD, previous CABG and the interaction term between stent use and a large post-MLD; unfavorable predictors were lesion length and diabetes mellitus.

CONCLUSIONS

There are no major differences in demographic and clinical predictors of coronary restenosis between PTCA and stent populations. In the modern (stent) era, a severe pre-DS is no longer an unfavorable predictor of restenosis. Still important, but more so in the stent population, is a large post-MLD (optimal result). Finally, a larger pre-RD became a favorable predictor with the advent of stenting.

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

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

Early lumen diameter loss after percutaneous transluminal coronary angioplasty is related to coronary plaque burden: a role for viscous plaque properties in early lumen diameter loss

OBJECTIVES

We tested the hypothesis that lumen diameter loss within 1 h after percutaneous transluminal coronary angioplasty is related to plaque volume parameters.

BACKGROUND

Early lumen diameter loss after coronary balloon angioplasty may predict restenosis and may paradoxically decrease late lumen diameter loss. Viscous properties of the vessel wall, as would be determined by tissue volume and composition, may be involved in early lumen diameter loss.

METHODS

Early lumen diameter loss was measured with quantitative coronary angiography as the loss in lesion lumen diameter (significant loss 0.4 mm) occurring between 5 min and a median of 40 min after successful coronary balloon angioplasty in 68 patients. Thirty-nine patients were evaluated with intravascular ultrasound at the narrowest lumen cross-section of the dilated lesion, 29 patients formed a control group without intravascular ultrasound imaging. We tested the relation between intravascular ultrasound parameters and early lumen diameter loss.

RESULTS

Early lumen diameter loss of > or = 0.4 mm was present in eight patients (12%), decreasing lumen diameter from 2.26 +/- 0.36 mm to 1.73 +/- 0.43 mm. There was no difference in the frequency of early lumen diameter loss between the groups with or without intravascular ultrasound imaging. Univariate intravascular ultrasound determinants of early lumen diameter loss were media bounded area (p = 0.01), maximal plaque thickness (p = 0.02), eccentricity index (p = 0.03) and the presence of hard lesions (p = 0.02).

CONCLUSION

Early lumen diameter loss in the first hour after successful coronary balloon angioplasty occurs in a small proportion of patients. It is related to hard lesion type, maximal plaque thickness and eccentricity index, favoring a role for viscous plaque properties in early lumen diameter loss.

Preintervention arterial remodeling affects clinical outcome following stenting: an intravascular ultrasound study

OBJECTIVES

The study was done to elucidate the relationship between baseline arterial remodeling and clinical outcome following stenting.

BACKGROUND

The impact of preintervention arterial remodeling on subsequent vessel response and clinical outcome has been reported following nonstent coronary interventions. However, in stented segments, the impact of preintervention remodeling on clinical outcome has not been clarified.

METHODS

Preintervention remodeling was assessed in 108 native coronary lesions by using intravascular ultrasound (IVUS). Positive remodeling (PR) was defined as vessel area (VA) at the target lesion greater than that of average reference segments. Intermediate or negative remodeling (IR/NR) was defined as VA at the target lesion less than or equal to that of average reference segment. Remodeling index expressed as a continuous variable was defined as VA at the target lesion site divided by that of average reference segments.

RESULTS

Positive remodeling was present in 59 (55%) and IR/NR in 49 (45%) lesions. Although final minimal stent areas were similar (7.76 +/- 1.80 vs. 8.09 +/- 1.90 mm2, p = 0.36), target vessel revascularization (TVR) rate at nine-month follow-up was significantly higher in the PR group (22.0% vs. 4.1%, p = 0.01). By multivariate logistic regression analysis, higher remodeling index was the only independent predictor of TVR (p = 0.02).

CONCLUSIONS

Lesions with PR before intervention appear to have a worse clinical outcome following IVUS-guided stenting. Intravascular ultrasound imaging before stenting may be helpful to stratify lesions at high risk for accelerated intimal proliferation.

Acute stent recoil: in vivo evaluation of different stent designs

This study sought to investigate the degree of acute recoil of four different stents by means of quantitative coronary angiography. Four hundred and six patients underwent stent implantation for single discrete coronary artery lesion: 105 received a 16 mm Paragon stent, 112 an 18 mm Multilink Duet, 97 a 16 mm NIR Primo stent, and 92 a 15 or 18 mm NIR Royal Advance. Elastic recoil was defined as the difference between mean balloon cross-sectional area (CSA) at the highest pressure and mean CSA after PTCA. The mean stent recoil was 13% +/- 10% CSA (P < 0.001), being statistically greater for the nitinol Paragon stent (21% +/- 11%), intermediate for the multicellular Multilink Duet stent (14% +/- 7%), and minimum for the NIR family (9% +/- 6% and 8% +/- 7%, respectively). The recoil was not homogeneously distributed along the stent length but was lower at the two ends (11% +/- 12% and 13% +/- 11%) and highest in the central part (15% +/- 12%)(P < 0.001). Thus, acute recoil is a significant phenomenon regardless of the mechanical properties and design of new-generation tubular stents.

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

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

Beneficial application of quantitative coronary angiography (edge detection algorithm) in analysis of dissected coronary arteries to predict long-term patency

The present study evaluated the application of quantitative coronary angiography (edge detection algorithm) for the analysis of coronary dissection lesions after balloon angioplasty. Acute and late results were obtained by the edge detection algorithm in 60 patients with 66 dissected lesions (NHLBI types B-C). The edge detection algorithm delineated the border of the true lumen in 32 lesions (group with automated analysis alone, 48.5%) and included the dissection cap in the analysis in 34 lesions in which manual editing was adjuncted (group with manual editing, 51.5%). In both groups, the minimal lumen diameter after balloon angioplasty obtained by initial automated analysis was correlated to that obtained at the 5.3-month follow-up similarly (r=0.554, p=0.0010 for the group with automated analysis alone and r=0.613, p=0.0001 after automated analysis for the group with manual editing). However, additional manual editing reduced the correlation coefficient (r=0.240, p=0.1707) in the latter group. Thus, in terms of predicting long-term patency, it is reasonable to let the edge detection algorithm decide the measurements in types B and C dissected lesions.

Reproducibility of calcified lesion quantification: a longitudinal intravascular ultrasound study

In view of a prospective intravascular ultrasound (IVUS) study, the reproducibility of the extent of the calcified lesion in IVUS images derived from separate pull-back maneuvers was assessed. Patients (n = 34) were imaged with IVUS before and after percutaneous transluminal angioplasty (PTA) and at 1-y follow-up. In the presence of a calcified lesion, the largest arc and the length of the matched calcified lesions was assessed. Interobserver differences in arc measurements were low (< or = 0.7%), with low coefficients of variation (< or = 5.8%). Similarly, interexamination differences in arc and length measurements were small (< or = 1.1%), with low coefficients of variation (< or = 3.2%). At follow-up, a nonsignificant increase in both the arc (1.9%) and length (1.7%) of the calcified lesion was observed. This study showed that measurements of the calcified lesion are highly reproducible; changes seen at 1-y follow-up were not significant. We conclude that IVUS may be used to monitor the effect of medical intervention on the extent of the calcified lesion in a longitudinal study.

The Insertion/Deletion Polymorphism of the Angiotensin-Converting Enzyme Gene and the Risk for Restenosis After PTCA

The therapeutic benefit of percutaneous transluminal coronary angioplasty (PTCA) is limited by restenosis in about 30% of patients. The underlying mechanisms are currently not well understood. Besides clinical and angiographic variables, genetic factors may be involved. We determined the angiotensin I-converting enzyme (ACE) I/D genotype as a possible risk factor for restenosis in 511 consecutive patients who had undergone successful PTCA and follow-up angiography. Clinical and angiographic variables were also considered as possible predictors of restenosis. One hundred sixty patients had restenosis as defined by a greater than 50% progression of residual stenosis of the dilated segment at follow-up angiography. There were significantly more patients with the ACE DD genotype in the restenosis than in the no-restenosis group. This difference did not remain statistically significant in an analysis of covariance that included genetic and clinical variables. Patients who subsequently developed restenosis had a higher degree of stenosis and more severe lesions before PTCA as well as less residual stenosis immediately after PTCA. We conclude that the ACE DD genotype is not an independent risk factor for restenosis after PTCA.

The role of intravascular ultrasound imaging in vascular brachytherapy

Intracoronary brachytherapy has recently emerged as a new therapy to prevent restenosis. Initial experimental work was achieved in animal models and the results were assessed by histomorphometry. Initial clinical trials used angiography to guide dosimetry and to assess efficacy. Intravascular ultrasound (IVUS) permits tomographic examination of the vessel wall, elucidating the true morphology of the lumen and transmural components, which cannot be investigated on the lumenogram obtained by angiography. This paper reviews the use of IVUS in the clinical studies of brachytherapy conducted to date. IVUS allows clinicians to make a thorough assessment of the remodeling of the vessel and appears to have a major role to play in facilitating understanding of the underlying mechanisms of action in this emerging field. The authors propose that state-of-the-art IVUS techniques should be employed to further knowledge of the mechanisms of action of brachytherapy in atherosclerotic human coronary arteries.

Greater late lumen loss after successful coronary balloon angioplasty in the proximal left anterior descending coronary artery is not explained by extent of vessel wall damage or plaque burden

OBJECTIVES

We investigated whether the greater late lumen loss after coronary balloon angioplasty in the proximal left anterior descending artery (P-LAD) compared with that in other segments might be related to differences in vascular dimensions or morphology as determined by angiography and intravascular ultrasound imaging.

BACKGROUND

The greater late lumen loss after angioplasty in the P-LAD that has been observed in several studies has not been explained.

METHODS

We studied 178 patients and 194 coronary artery lesions by quantitative angiography and 30 MHz intravascular ultrasound imaging after successful balloon angioplasty. Vessel wall morphology was compared among three proximal and three nonproximal segments. Follow-up quantitative angiography for late lumen loss calculation was performed in 168 lesions. Multivariate analysis was used to determine predictors of late lumen loss.

RESULTS

Absolute and relative late loss were significantly greater at the P-LAD compared with the pooled group of other segments (0.42 +/- 0.60 mm vs. 0.10 +/- 0.48 mm, p = 0.0008 and 0.14 +/- 0.24 vs. 0.03 +/- 0.17, p < 0.001). Also, a greater percentage of calcific lesions (65% vs. 44%, p = 0.034), a lower incidence of rupture (51% vs. 74%, p = 0.009) and a larger reference segment plaque area (5.4 +/- 2.2 mm2 vs. 4.7 +/- 1.9 mm2, p = 0.05) were found in the P-LAD. In multivariate analysis however, these variables were not predictive of late loss.

CONCLUSIONS

Greater late lumen loss after coronary balloon angioplasty of the P-LAD is not explained by differences in atherosclerotic plaque burden or in vessel wall damage.

Preintervention lesion remodelling affects operative mechanisms of balloon optimised directional coronary atherectomy procedures: a volumetric study with three dimensional intravascular ultrasound

AIMS

To classify atherosclerotic coronary lesions on the basis of adequate or inadequate compensatory vascular enlargement, and to examine changes in lumen, plaque, and vessel volumes during balloon optimised directional coronary atherectomy procedures in relation to the state of adaptive remodelling before the intervention.

DESIGN

29 lesion segments in 29 patients were examined with intravascular ultrasound before and after successful balloon optimised directional coronary atherectomy procedures, and a validated volumetric intravascular ultrasound analysis was performed off-line to assess the atherosclerotic lesion remodelling and changes in plaque and vessel volumes that occurred during the intervention. Based on the intravascular ultrasound data, lesions were classified according to whether there was inadequate (group I) or adequate (group II) compensatory enlargement.

RESULTS

There was no significant difference in patient and lesion characteristics between groups I and II (n = 10 and 19), including lesion length and details of the intervention. Quantitative coronary angiographic data were similar for both groups. However, plaque and vessel volumes were significantly smaller in group I than in II. In group I, 9 (4)% (mean (SD)) of the plaque volume was ablated, while in group II 16 (11)% was ablated (p = 0.01). This difference was reflected in a lower lumen volume gain in group I than in group II (46 (18) mm(3) v 80 (49) mm(3) (p < 0.02)).

CONCLUSIONS

Preintervention lesion remodelling has an impact on the operative mechanisms of balloon optimised directional coronary atherectomy procedures. Plaque ablation was found to be particularly low in lesions with inadequate compensatory vascular enlargement.

Relation of coronary artery size to one-year clinical events after new device angioplasty of native coronary arteries (a New Approach to Coronary Intervention [NACI] Registry Report)

The influence of vessel size on clinical and angiographic outcomes after new device angioplasty has not been well documented. We reviewed clinical and angiographic outcomes of 2,044 patients undergoing new device angioplasty of native vessels enrolled in the New Approaches to Coronary Interventions (NACI) Registry. Quantitative angiography was performed using standard methods. Patients were divided into 3 groups according to reference vessel diameter (RVD) (<2.75, 2.75 to 3.25, and >3.25 mm). Patients with the smallest vessels had a higher incidence of diabetes (26% vs. 16%, p<0.01), multivessel disease (50% vs. 45%, p<0.01), left anterior descending coronary artery disease (61% vs. 39% p<0.01), and in general, more severe baseline lesion characteristics than patients with larger (>3.25 mm) vessels. Absolute baseline and final minimal lumen diameter (MLD) was also smaller in patients with RVD <2.75 mm despite similar final percent diameter stenosis. Although in-hospital events were similar, patients who underwent interventions in vessels <2.75 mm had an increased incidence of death (p<0.01), surgical revascularization (p<0.05), and target lesion revascularization (TLR) (p<0.01) at 1 year. Multivariate analysis by vessel size showed a stepwise increase in the risk of TLR by 1 year in patients with the smaller RVD (p = 0.0001) and the combined end point of 1 year death/Q wave-myocardial infarction/TLR (p = 0.02). Thus, despite similar early clinical events among patients undergoing new device angioplasty, patients who underwent treatment of smaller vessels had a significantly increased risk of major adverse clinical events and particularly TLR by 1 year after new device angioplasty of native coronary arteries.

Acute and chronic tissue response to coronary stent implantation: pathologic findings in human specimen

OBJECTIVES

The aim of our study was to analyze the cellular components of neointimal tissue regeneration after coronary stenting.

BACKGROUND

High restenosis rates are a major limiting factor of coronary stenting. To reduce the occurrence of restenoses, more insights into the mechanisms leading to proliferation and expression of extracellular matrix are necessary.

METHODS

Twenty-one autopsy cases with coronary stents implanted 25 h to 340 days before death were studied. The stented vessel segments were analyzed postmortem by light microscopy and immunohistochemical staining.

RESULTS

In the initial phase stents are covered by a thin multilayered thrombus. Alpha-actin-positive smooth muscle cells (SMCs) are found as the main cellular component of the neointimal tissue. Later (>6 weeks) extracellular matrix increases and fewer SMCs can be found. In every phase the SMC layers are loosely infiltrated by inflammatory cells (T lymphocytes). In the early postinterventional phase all endothelial cells are destroyed. The borderline between the vessel lumen and the vascular wall is constituted by a thin, membranous thrombus. Six weeks after stenting, SMCs form the vessel surface. Complete reendothelialization is first found 12 weeks after stenting.

CONCLUSIONS

Stent integration is a multifactorally triggered process with proliferating SMCs generating regenerative tissue. In the early phase predominantly thrombotic material can be observed at the site of stenting, followed by the invasion of SMCs, T lymphocytes and macrophages. The incidence of delayed reendothelializations and the occurrence of deep dissections may be associated with excessive SMC hyperplasia.

Inadvertent stenting of left main coronary artery complicated by later in-stent restenosis

Stenting of both the protected and unprotected left main coronary artery has been described. This case presents a patient who had inadvertent left main stent deployment. A 47-year-old female presented with a non-Q-wave infarction and subsequent angina leading to angiography and angioplasty of her proximal ramus intermedius artery. Recurrent angina and ECG changes necessitated repeat coronary angiography and angioplasty on the same day with Wiktor stent deployment to treat a resultant dissection. Poststent deployment pictures revealed that the stent had been partially deployed in the left main coronary artery. Additional balloon dilatations were performed at the ostia of the left anterior descending and circumflex arteries through the stent. Three months later the patient presented with progressive angina and was discovered to have severe distal left main stenosis. In a case such as this, stent removal may be preferable to leaving an unnecessary stent within the left main coronary artery. Cathet. Cardiovasc. Intervent. 48:194-197, 1999.

Restenosis after Angioplasty in Patients with Left Ventricular Dysfunction

Clinical and angiographic rates of restenosis after angioplasty were compared in 80 patients (group A) with ejection fractions below 40% (mean, 28.3% ± 5.2%) and 50 (group B) with ejection fractions above 50% (mean, 58% ± 5.4%). Mean angina class improved to the same degree in both groups after angioplasty. Recurrence of significant angina within 6 to 12 months affected 30 patients (38%) in group A compared to 12 (24%) in group B (p > 0.05). Angiographic restenosis occurred in 42 patients (53%) in group A compared to 14 (28%) in group B (p = 0.006). Restenosis after single-vessel angioplasty was 46% in group A and 25% in group B (p > 0.05), after multivessel angioplasty it was 62% in group A and 33% in group B (p = 0.05). In group A, restenosis was more frequent in the left anterior descending coronary artery (46%) compared to the right coronary (41%) or circumflex (30%). Higher rates of restenosis occurred in patients with prior coronary artery bypass grafting (64%) or recanalization of chronic total occlusion (61%). Angina was a less reliable indication of restenosis in group A. We attribute the higher rate of restenosis in patients with low ejection fractions partly to low coronary perfusion pressure.

Clinical implications of online and off-line interobserver variability in intracoronary ultrasound-guided interventions

Intracoronary ultrasound (ICUS)-guided interventions imply online decision making. We investigated the on- and off-line interobserver variability in ICUS measurements and evaluated the clinical implication of the interobserver variability for ICUS-guided interventions in 40 lesions (38 patients). On the same recorded ICUS images, an online and an off-line observer independently selected and analyzed the proximal and distal reference images, the most severe stenosis image before intervention and the minimal lumen area (MLA) image after intervention. In addition, the off-line observer analyzed the online selected images. The interobserver variability (percentage difference between the two observers) of ICUS measurements was determined on images independently selected by both observers (Analysis A) and on images selected by the online observer (Analysis B). The balloon size was determined from ICUS measurements according to the CLOUT trial. After intervention, the CLOUT and MUSIC criteria for MLA by ICUS had to be fulfilled for PTCA and stent procedures, respectively. In Analysis A, the on- and off-line interobserver variability in diameter and area measurements was maximally 9% and 18%, respectively. In Analysis B, the on- and off-line interobserver variability was maximally 6% and 11%, respectively. The off-line observer would have chosen a balloon size differing by more than 0.25 mm in 25 % (10 of 40) and 12.5% (5 of 40) of the procedures in Analysis A and B, respectively. After PTCA or stenting, the off-line observer would have taken different procedural decisions in 19% or 15% and in 13% or 7% of the procedures in Analysis A and B, respectively.

IN CONCLUSION

when the same location was selected, the on- and off-line interobserver variability was low. When different locations were selected, however, the interobserver variability resulted in different balloon sizing in 25 % of the cases. Interobserver variability may be a confounding factor in the analysis of ICUS-guided interventions.

Intravascular ultrasound for evaluation of initial vessel patency and early outcome following directional coronary atherectomy

Elastic recoil and thrombus formation may potentially occur following directional coronary atherectomy (DCA) confounding the assessment of late vascular remodeling. Since intravascular ultrasound (IVUS) data on early outcome of DCA is not available, we used IVUS to investigate whether elastic recoil or thrombus formation can affect early (4 hr) outcome. Quantitative coronary angiography (QCA) and IVUS were performed in high-grade coronary lesions in 32 consecutive patients before, immediately after, and 4 hr after DCA. Late clinical follow-up was obtained after a maximum interval of 2 years. Significant acute elastic recoil was observed by both IVUS (19%+/-14%) and QCA (19%+/-12%), but there was no further recoil after 4 hr. DCA reduced plaque area by 51%+/-13%, an effect that was stable after 4 hr, indicating the absence of relevant thrombus formation. Residual area stenosis by IVUS was not related to the occurrence of late clinical events (n = 8). Mechanical recoil or thrombus formation do not hamper initial lumen gain achieved by DCA. Although QCA significantly underestimated residual plaque burden after DCA when compared to IVUS, the degree of residual area stenosis did not identify patients suffering from cardiac events on follow-up.

New developments in intravascular ultrasound

Intravascular ultrasound (IVUS) is a dynamic imaging modality that provides real-time in vivo visualization of atherosclerosis and other vascular pathology. The tomographic image presentation of IVUS permits detailed assessment of plaque morphology and its corresponding responses to interventional therapy. IVUS studies have confirmed vascular remodeling in vivo, have proposed a high-pressure stent implantation strategy and have shown two key mechanisms of restenosis after angioplasty: plaque proliferation and vessel shrinkage (negative remodeling). IVUS also provides accurate quantitative information regarding lumen size, vessel size and plaque burden. These observations, essential to achieving improved outcomes, have drastically changed the understanding of atherosclerotic artery disease and interventional procedures. IVUS has matured into an essential complement to daily peripheral and coronary interventional practice and is routinely incorporated as part of the interventional arsenal in the catheterization laboratory. A variety of new imaging techniques are currently being designed and tested. These include combined therapeutic devices, further miniaturization, 3-D applications and tissue characterization. These techniques may evolve to provide increased favorable clinical outcomes and more accurate information of vessel geometry and plaque composition.

Impact of residual plaque burden on clinical outcomes of coronary interventions

In this study, we summarize the role of residual plaque burden, as determined by intravascular ultrasound, on the development of restenosis following percutaneus coronary interventions. Several clinical trials have shown that the amount of residual plaque is a consistent and independent predictor of subsequent restenosis. The impact of residual plaque burden on late lumen loss is particularly augmented by negative vessel remodeling that is commonly seen after balloon angioplasty and atherectomy. However, early evidence suggests that the importance of plaque burden also applies in the context of stenting. The cotreatment of debulking may further improve the long-term outcome of stenting by maximizing an acute lumen gain with less vessel stretching, preventing stent edge problems and possibly reducing the cell source involved in the intimal hyperplastic process. Evaluation of residual plaque burden with on-line intravascular ultrasound could lead to definitive therapies via risk stratification of the treated segments.

Enhanced secretion of insulin plays a role in the development of atherosclerosis and restenosis of coronary arteries: elective percutaneous transluminal coronary angioplasty in patients with effort angina

OBJECTIVES

We investigated the relation between insulin and coronary atherosclerosis and restenosis of the coronary arteries, by performing elective percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Insulin is known to promote atherosclerosis of the arteries and has been implicated in the development of restenosis after PTCA.

METHODS

Of 210 angina patients who underwent PTCA, newly detected lesions in 35 consecutive nondiabetic subjects without previous intervention on the same main coronary arteries were analyzed after a 75-g oral glucose tolerance test (OGTT) and follow-up coronary angiography. Atherosclerotic lesions were evaluated by pattern, severity and extent. Restenosis was defined as loss of gain, the percentage of loss of the initial gain in the coronary diameter achieved by PTCA > or = 50%.

RESULTS

Patients with restenosis had a significantly higher extent index (a marker of atherosclerosis), insulin area, ratio of insulin area to glucose area, insulinogenic index and minimal lumen diameter after PTCA than those without restenosis (p=0.001, 0.011, 0.002, 0.016 and 0.041, respectively). Simple regression analysis revealed that only the ratio of insulin area to glucose area (a relative marker of enhanced insulin secretion) significantly correlated with the extent index (p=0.035). Extent index, insulin area, the ratio of insulin area to glucose area and insulinogenic index significantly correlated with loss of gain (p=0.001, 0.010, 0.002 and 0.032, respectively). Stepwise multiple regression analyses revealed that extent index and the ratio of insulin area to glucose area significantly correlated with loss of gain.

CONCLUSIONS

Enhanced secretion of insulin during the OGTT might be useful as a predictor of coronary atherosclerosis and of restenosis after elective PTCA in nondiabetic patients with effort angina.

Intravascular ultrasound predictors of restenosis after balloon angioplasty of the femoropopliteal artery

OBJECTIVES

To determine intravascular ultrasound parameters related to restenosis following percutaneous transluminal balloon angioplasty (PTA) of the femoropopliteal artery.

DESIGN

Prospective study.

MATERIALS AND METHODS

Patients were studies with intravascular ultrasound before and after angiographic successful PTA (n = 114). Intravascular ultrasound cross-sections obtained with 1 cm interval in the dilated segment were analysed. A distinction was made between anatomic (duplex scanning) and clinical (Rutherford criteria) restenosis assessed within 1 month and at 6 months after PTA.

RESULTS

Intravascular ultrasound predictors of 1 month anatomic outcome were lumen area stenosis after PTA, lumen area increase, plaque area decrease, and area stenosis decrease; predictor of 6 months anatomic outcome was area stenosis after PTA. Multivariate analysis revealed that area stenosis after PTA was the only independent predictor of both 1 and 6 months anatomic outcome. Intravascular ultrasound predictors of 1 month clinical outcome were the presence of hard lesion and the mean arc of hard lesion. Multivariate analysis revealed that the mean arc of hard lesion was the only independent predictor of 1 month clinical outcome. No predictors for 6 months clinical outcome were found.

CONCLUSIONS

Intravascular ultrasound can elucidate parameters predictive of restonosis after PTA. The strongest intravascular ultrasound parameter predictive of anatomic restenosis was a large area stenosis after PTA.

Atherosclerotic coronary lesions with inadequate compensatory enlargement have smaller plaque and vessel volumes: observations with three dimensional intravascular ultrasound in vivo

OBJECTIVE

To compare vessel, lumen, and plaque volumes in atherosclerotic coronary lesions with inadequate compensatory enlargement versus lesions with adequate compensatory enlargement.

DESIGN

35 angiographically significant coronary lesions were examined by intravascular ultrasound (IVUS) during motorised transducer pullback. Segments 20 mm in length were analysed using a validated automated three dimensional analysis system. IVUS was used to classify lesions as having inadequate (group I) or adequate (group II) compensatory enlargement.

RESULTS

There was no significant difference in quantitative angiographic measurements and the IVUS minimum lumen cross sectional area between groups I (n = 15) and II (n = 20). In group I, the vessel cross sectional area was 13.3 (3.0) mm2 at the lesion site and 14.4 (3.6) mm2 at the distal reference (p < 0.01), whereas in group II it was 17.5 (5.6) mm2 at the lesion site and 14.0 (6.0) mm2 at the distal reference (p < 0.001). Vessel and plaque cross sectional areas were significantly smaller in group I than in group II (13.3 (3.0) v 17.5 (5.6) mm2, p < 0.01; and 10.9 (2.8) v 15.2 (4.9) mm2; p < 0.005). Similarly, vessel and plaque volume were smaller in group I (291.0 (61.0) v 353.7 (110.0) mm3, and 177.5 (48.4) v 228.0 (92.8) mm3, p < 0.05 for both). Lumen areas and volumes were similar.

CONCLUSIONS

In lesions with inadequate compensatory enlargement, both vessel and plaque volume appear to be smaller than in lesions with adequate compensatory enlargement.