Intravascular ultrasound predictors of restenosis after percutaneous transcatheter coronary revascularization

Comparison of Small Blood Vessel Diameter with Intravascular Ultrasound and Coronary Angiography for Guidance of Percutaneous Coronary Intervention

Major cardiovascular events (MACEs) are a cause of major mortality worldwide. The narrowing and blockage of coronary arteries with atherosclerotic plaques are diagnosed and treated with percutaneous coronary intervention (PCI). During this procedure, coronary angiography (CAG) remains the most widely used guidance modality for the evaluation of the affected blood vessel. The measurement of the blood vessel diameter is an important factor to consider in order to decide if stent colocation is suitable for the intervention. In this regard, a small blood vessel (<2.75 mm) is majorly left without stent colocation; however, small vessel coronary artery disease (SvCAD) is a significant risk factor for the recurrence of MACEs, maybe due to the lack of a standardized treatment related to the diameter of the affected blood vessel; therefore, a more precise measurement is needed. The use of CAG for the measurement of the blood vessel diameter has some important limitations that can be improved with the use of newer techniques such as intravascular ultrasound (IVUS), although at higher costs, which might explain its underuse. To address differences in blood vessel diameter measurements and identify specific cases where IVUS might be of additional benefit for the patient, we conducted a retrospective study in patients who underwent PCI for MACEs with affection for at least one small blood vessel. We compared the measurements of the affected small blood vessels' diameter obtained by CAG and IVUS to identify cases of reclassification of the affected blood vessel; additionally, we underwent a multivariate analysis to identify risk factors associated with blood vessel reclassification. We included information from 48 patients with a mean ± SD age of 69.1 ± 11.9 years; 70.8% were men and 29.2% were women. The mean diameter with CAG and IVUS was 2.1 mm (95% CI 1.9-2.2), and 2.8 (2.8-3.0), respectively. The estimated difference was of 0.8 mm (95% CI 0.7-0.9). We found a significant positive low correlation in diameter measurements of small blood vessels obtained with CAG and IVUS (r = 0.1242 p = 0.014). In total, 37 (77%) patients had a reclassification of the affected blood vessel with IVUS. In 21 cases, the affected blood vessel changed from a small to a medium size (2.75-3.00 mm), and in 15 cases, the affected vessel changed from a small to a large size (<3.00 mm). The Bland-Altman plot was used to evaluate agreement in measurements with CAG and IVUS. The change in blood vessel classification with IVUs was important for the decision of intervention and stent collocation. The only variable associated with reclassification of blood vessels after adjustment in a multivariate analysis was T2D (type 2 diabetes) (p = 0 0.035). Our findings corroborate that blood vessels might appear smaller with CAG, especially in patients with T2D; therefore, at least in these cases, the use of IVUS is recommended over CAG.

Outcomes following coronary artery bypass grafting with multiple arterial grafting by pump status in men and women

BACKGROUND

Multiple arterial grafting (MAG) and off-pump surgery are strategies proposed to improve outcomes with coronary artery bypass grafting (CABG). This study was conducted to determine the impact of off-pump surgery on outcomes after CABG with MAG in men and women.

METHODS

This cohort study used population-based data to identify all Ontarians undergoing isolated CABG with MAG between October 2008 and September 2019. The primary outcome was all-cause mortality. Secondary outcomes included major adverse cardiac and cerebrovascular events (MACCE; hospitalization for stroke, myocardial infarction hospitalization or heart failure, or repeat revascularization). Analysis used propensity-score overlap-weighted cause-specific Cox proportional hazard regression.

RESULTS

A total of 2989 women (1188 off-pump, 1801 on-pump) and 16,209 men (6065 off-pump, 10,144 on-pump) underwent MAG with a median follow-up of 5.0 years (interquartile range, 2.7-8.0) years. Compared to the on-pump approach, all-cause mortality was not changed with off-pump status (hazard ratio [HR] in women: 1.25 [95% CI, 0.83-1.88]; in men: 1.08 [95% CI, 0.85-1.37]). In women, the risk of MACCE was significantly higher off-pump (HR, 1.45; 95% CI, 1.04-2.03), with nonsignificantly increased risk observed for all component outcomes.

CONCLUSIONS

In patients undergoing CABG with MAG, this population-based analysis found no association between pump status and survival in either men or women. However, it did suggest that off-pump MAG in women may be associated with an increased risk of MACCE.

Fundamentals and role of intravascular ultrasound in percutaneous coronary intervention

Intravascular ultrasound (IVUS) is a catheter-based invasive imaging modality that has become an essential adjunctive tool to percutaneous coronary intervention (PCI) over the past 20 years. Clinical applications of IVUS in PCI include assessment of lesion severity, characterizing plaque morphology, optimization of acute stent results and clarification of mechanisms of stent failure. Numerous meta-analyses of large observational and randomized studies support the role of IVUS-guided PCI in reducing short and long-term adverse outcomes, including mortality and stent failure, particularly in patients receiving drug-eluting stents (DESs) and in complex lesion subsets. The current review provides a summary of the fundamental aspects and current clinical roles of IVUS in coronary intervention.

Recurrent atherosclerosis complications as a mechanism for stent failure

Stents are an indispensable tool in the percutaneous treatment of symptomatic coronary artery disease. Yet, stent failure due to restenosis or thrombosis may compromise their clinical benefit, carrying substantial morbidity and mortality. Despite improvements in device design and adjunctive medical treatment, stent failure still occurs during long-term follow-up, suggesting that this may be an issue that persists for many years, perhaps indefinitely. Numerous studies during the last decade have highlighted the previously underappreciated pivotal role of atherosclerosis in stent failure. We review evolving evidence on the role of atherosclerosis in stent restenosis and thrombosis, differentiating between de novo in-stent atherosclerosis development (i.e., neoatherosclerosis) and progression of pre-existing underlying atherosclerosis (i.e., paleoatherosclerosis), a distinction with potentially important clinical implications. We conclude with a concept that provides a unifying pathophysiology for these significant problems in the field of interventional cardiology based on the progression and destabilization of atherosclerosis.

Atherosclerotic plaque behind the stent changes after bare-metal and drug-eluting stent implantation in humans: Implications for late stent failure?

BACKGROUND AND AIMS

The natural history and the role of atherosclerotic plaque located behind the stent (PBS) are still poorly understood. We evaluated the serial changes in PBS following bare-metal (BMS) compared to first-generation drug-eluting stent (DES) implantation and the impact of these changes on in-stent neointimal hyperplasia (NIH).

METHODS

Three-dimensional coronary reconstruction by angiography and intravascular ultrasound was performed after intervention and at 6-10-month follow-up in 157 patients with 188 lesions treated with BMS (n = 89) and DES (n = 99).

RESULTS

There was a significant decrease in PBS area (-7.2%; p < 0.001) and vessel area (-1.7%; p < 0.001) after BMS and a respective increase in both areas after DES implantation (6.1%; p < 0.001 and 4.1%; p < 0.001, respectively). The decrease in PBS area significantly predicted neointimal area at follow-up after BMS (β: 0.15; 95% confidence interval [CI]: 0.10-0.20, p < 0.001) and DES (β: 0.09; 95% CI: 0.07-0.11; p < 0.001) implantation. The decrease in PBS area was the most powerful predictor of significant NIH after BMS implantation (odds ratio: 1.13; 95% CI: 1.02-1.26; p = 0.02).

CONCLUSIONS

The decrease in PBS area after stent implantation is significantly associated with the magnitude of NIH development at follow-up. This finding raises the possibility of a communication between the lesion within the stent and the underlying native atherosclerotic plaque, and may have important implications regarding the pathobiology of in-stent restenosis and late/very late stent thrombosis.

Predictors of Plaque Progression in Hypertensive Angina Patients with Achieved Low-Density Lipoprotein Cholesterol Less Than 70 mg/dL after Rosuvastatin Treatment

We evaluated the impact of achieved low-density lipoprotein cholesterol (LDL-C) concentrations <70 mg/dL on plaque progression in statin-treated hypertensive angina patients by use of virtual histology-intravascular ultrasound (VH-IVUS). The effects of 10 mg of rosuvastatin on plaque progression were evaluated in 78 patients who achieved LDL-C <70 mg/dL with statin treatment. The patients were divided into plaque progressors (n=30) and plaque regressors (n=40) on the basis of the baseline minimum lumen area (MLA) site at the 9-month follow-up. The prevalence of chronic kidney disease (CKD) [creatinine clearance (CrCl) <60 mL/min)] and current smoking was higher in progressors than in regressors (90.0% vs. 31.3%, p<0.001, and 40.0% vs. 12.5%, p=0.005, respectively). Baseline CrCl was significantly lower and baseline apolipoprotein (apo) B/A1 was significantly higher in progressors than in regressors (21±13 mL/min vs. 70±20 mL/min, p<0.001, and 0.77±0.23 vs. 0.65±0.16, p=0.011, respectively). Absolute and relative fibrotic areas at the MLA site increased in progressors; by contrast, these areas decreased in regressors from baseline to follow-up. CKD [odds ratio (OR): 2.13, 95% confidence interval (CI): 1.77-2.53, p=0.013], smoking (OR: 1.76, 95% CI: 1.23-2.22, p=0.038), and apoB/A1 (OR: 1.25, 95% CI: 1.12-1.40, p=0.023), but not any VH-IVUS parameters, were independent predictors of plaque progression at follow-up. In conclusion, clinical factors including CKD, smoking, and apoB/A1 rather than plaque components detected by VH-IVUS are associated with plaque progression in hypertensive angina patients who achieve very low LDL-C after statin treatment.

The role of noninvasive and invasive diagnostic imaging techniques for detection of extra-cranial venous system anomalies and developmental variants

The extra-cranial venous system is complex and not well studied in comparison to the peripheral venous system. A newly proposed vascular condition, named chronic cerebrospinal venous insufficiency (CCSVI), described initially in patients with multiple sclerosis (MS) has triggered intense interest in better understanding of the role of extra-cranial venous anomalies and developmental variants. So far, there is no established diagnostic imaging modality, non-invasive or invasive, that can serve as the "gold standard" for detection of these venous anomalies. However, consensus guidelines and standardized imaging protocols are emerging. Most likely, a multimodal imaging approach will ultimately be the most comprehensive means for screening, diagnostic and monitoring purposes. Further research is needed to determine the spectrum of extra-cranial venous pathology and to compare the imaging findings with pathological examinations. The ability to define and reliably detect noninvasively these anomalies is an essential step toward establishing their incidence and prevalence. The role for these anomalies in causing significant hemodynamic consequences for the intra-cranial venous drainage in MS patients and other neurologic disorders, and in aging, remains unproven.

Preferential secretion of collagen type 3 versus type 1 from adventitial fibroblasts stimulated by TGF-β/Smad3-treated medial smooth muscle cells

Restenosis, or arterial lumen re-narrowing, occurs in 30-50% of the patients undergoing angioplasty. Adaptive remodeling is the compensatory enlargement of the vessel size, and has been reported to prevent the deleterious effects of restenosis. Our previous studies have shown that elevated transforming growth factor (TGF-β) and its signaling protein Smad3 in the media layer induce adaptive remodeling of angioplastied rat carotid artery accompanying an increase of total collagen in the adventitia. In order to gain insights into a possible role of collagen in Smad3-induced adaptive remodeling, here we have investigated a mechanism of cell-cell communication between medial smooth muscle cells (SMCs) and adventitial fibroblasts in regulating the secretion of two major collagen subtypes. We have identified a preferential collagen-3 versus collagen-1 secretion by adventitial fibroblasts following stimulation by the conditioned medium from the TGF-β1-treated/Smad3-expressing medial smooth muscle cells (SMCs), which contained higher levels of CTGF and IGF2 as compared to control medium. Treating the TGF-β/Smad3-stimulated SMCs with an siRNA to either CTGF or IGF2 reversed the effect of conditioned media on preferential collagen-3 secretion from fibroblasts. Moreover, recombinant CTGF and IGF2 together stimulated adventitial fibroblasts to preferentially secrete collagen-3 versus collagen-1. This is the first study to identify a preferential secretion of collagen-3 versus collagen-1 from adventitial fibroblasts as a result of TGF-β/Smad3 stimulation of medial SMCs, and that CTGF and IGF2 function together to mediate this signaling communication between the two cell types.

Mechanisms of post-intervention arterial remodelling

It has been appreciated over the past two decades that arterial remodelling, in addition to intimal hyperplasia, contributes significantly to the degree of restenosis that develops following revascularization procedures. Remodelling appears to be an adventitia-based process that is contributed to by multiple factors including cytokines and growth factors that regulate extracellular matrix or phenotypic transformation of vascular cells including myofibroblasts. In this review, we summarize the currently available information from animal models as well as clinical investigations regarding arterial remodelling. The factors that contribute to this process are presented with an emphasis on potential therapeutic methods to enhance favourable remodelling and prevent restenosis.

Usefulness of minimum stent cross sectional area as a predictor of angiographic restenosis after primary percutaneous coronary intervention in acute myocardial infarction (from the HORIZONS-AMI Trial IVUS substudy)

HORIZONS-AMI was a prospective dual-arm randomized trial of different antithrombotic regimens and stent types in patients with ST-segment elevation myocardial infarction. A formal intravascular ultrasound (IVUS) substudy enrolled 464 patients with baseline and 13-month follow-up at 36 centers. Of them, 318 patients with 355 lesions were evaluated for this study. Angiographic restenosis occurred in 45 of 355 lesions (12.7%). Bare-metal stent use (45.5% vs 21.2%, p <0.001) and diabetes mellitus (29.5% vs 10.9%, p <0.001) were more prevalent in patients with versus without restenosis. Postprocedure IVUS minimum lumen area (5.6 mm(2), 5.0 to 6.1, vs 6.7 mm(2), 6.5 to 6.9, p <0.001), minimum stent area (5.7 mm(2), 5.1 to 6.3, vs 6.9 mm(2), 6.6 to 7.1, p <0.001), and reference average lumen area (7.7 mm(2), 6.8 to 8.6, vs 9.7 mm(2), 9.3 to 10.1, p <0.001) were smaller in restenotic versus nonrestenotic lesions. By multivariable analysis, minimum stent area was an independent predictor of angiographic restenosis (odds ratio 0.75, 95% confidence interval 0.61 to 0.93, p = 0.009) in addition to diabetes, bare-metal stent use, and longer stent length. Attenuated plaque behind the stent struts had a trend to predict less binary restenosis (p = 0.07). In conclusion, a smaller IVUS minimum stent area was an independent predictor of angiographic restenosis after primary percutaneous intervention in patients with ST-segment elevation myocardial infarction, similar to patients with stable coronary artery disease.

Relation of fractional flow reserve after drug-eluting stent implantation to one-year outcomes

Patients still present with drug-eluting stent (DES) failure despite an angiographically successful implantation. The aim of the present study was to investigate the relation between the fractional flow reserve (FFR) measured after DES implantation and the clinical outcomes at 1 year. A total of 80 patients (mean age 62 years, 74% men, 99 DESs) underwent coronary pressure measurement at maximum hyperemia after successful DES implantation. The composite of major adverse cardiac events (MACE), including death, myocardial infarction, and ischemia-driven target vessel revascularization was evaluated at 1 year. The patients were divided into 2 groups (low-FFR group, FFR ≤0.90 and high-FFR group, FFR >0.90) according to the median FFR. The mean poststent percent diameter stenosis was 11 ± 5% in the low-FFR group and 12 ± 3% in the high-FFR group (p = 0.31). Left anterior descending coronary artery lesions were more frequent in the low-FFR group than in the high-FFR group (82% vs 55%, p = 0.02). The mean stent length was greater in the low-FFR group than in the high-FFR group (38 ± 18 vs 28 ± 13 mm, p = 0.01). Six cases (7.5%) of MACE occurred during the 1-year follow-up. The rate of MACE was 12.5% in the low-FFR group and 2.5% in the high-FFR group (p <0.01). Receiver operating characteristic curves revealed 0.90 as the best cutoff of FFR after DES implantation for the prediction of 1-year MACE. In conclusion, a poststent FFR of ≤0.90 correlated with a greater adverse event rate at 1 year.

Intravascular Ultrasound Classification of Plaque Distribution in Left Main Coronary Artery Bifurcations

Background— Angiographic classifications of the location and severity of disease in the main vessel and side branch of coronary artery bifurcations have been proposed and applied to distal left main coronary artery (LMCA) bifurcation.

Methods and Results— We reviewed 140 angiograms of distal LMCA and ostial left anterior descending (LAD) and left circumflex (LCX) artery lesions with preintervention intravascular ultrasound (IVUS) of both the LAD and LCX arteries as well as the LMCA. Of 140 patients, 92.9% had at least 1 cross section with ≥40% IVUS plaque burden versus 57.2% of patients with an angiographic diameter stenosis ≥50%. Contrary to angiographic classifications, IVUS showed that bifurcation disease was rarely focal and that both sides of the flow divider were always disease-free. Continuous plaque from the LMCA into the proximal LAD artery was seen in 90%, from the LMCA into the LCX artery in 66.4%, and from the LMCA into both the LAD and LCX arteries in 62%. Plaque localized to either the LAD or LCX ostium and not involving the distal LMCA was seen in only 9.3% of LAD arteries and 17.1% of LCX arteries. Plaque distribution was not influenced by the LAD/LCX angiographic angle, lesion severity, LMCA length, or remodeling. We proposed an IVUS classification for bifurcation lesions illustrating longitudinal and circumferential spatial plaque distribution.

Conclusions— Angiographic classification of LMCA bifurcation lesions is rarely accurate. IVUS shows that the carina is always spared and that the disease is diffuse rather than focal.

Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180466.

Molecular imaging in atherosclerosis

Atherosclerosis is the major cause of cardiovascular disease, which still has the leading position in morbidity and mortality in the Western world. Many risk factors and pathobiological processes are acting together in the development of atherosclerosis. This leads to different remodelling stages (positive and negative) which are both associated with plaque physiology and clinical presentation. The different remodelling stages of atherosclerosis are explained with their clinical relevance. Recent advances in basic science have established that atherosclerosis is not only a lipid storage disease, but that also inflammation has a fundamental role in all stages of the disease. The molecular events leading to atherosclerosis will be extensively reviewed and described. Further on in this review different modalities and their role in the different stages of atherosclerosis will be discussed. Non-nuclear invasive imaging techniques (intravascular ultrasound, intravascular MRI, intracoronary angioscopy and intravascular optical coherence tomography) and non-nuclear non-invasive imaging techniques (ultrasound with Doppler flow, electron-bean computed tomography, coronary computed tomography angiography, MRI and coronary artery MR angiography) will be reviewed. After that we focus on nuclear imaging techniques for detecting atherosclerotic plaques, divided into three groups: atherosclerotic lesion components, inflammation and thrombosis. This emerging area of nuclear imaging techniques can provide measures of biological activity of atherosclerotic plaques, thereby improving the prediction of clinical events. As we will see in the future perspectives, at present, there is no special tracer that can be called the diagnostic tool to diagnose prospective stroke or infarction in patients. Nevertheless, we expect such a tracer to be developed in the next few years and maybe, theoretically, it could even be used for targeted therapy (in the form of a beta-emitter) to combat cardiovascular disease.

Intravascular ultrasound: principles and cerebrovascular applications

Intravascular sonography is a valuable tool for the morphologic assessment of coronary atherosclerosis and the effect of pharmacologic and nonpharmacologic interventions on the progression or stabilization of atherosclerosis. An analysis of the different modes, applications, and limitations is provided on the basis of review of existing data from multiple clinical case studies, trials, and mechanistic studies. Intravascular sonography has been used to assess the outcomes of different percutaneous interventions, including angioplasty and stent implantation, and to provide detailed characterization of atherosclerotic lesions, aneurysms, and dissections within the cerebrovascular circulation. Evolution of intravascular sonographic technology has led to the development of more sophisticated diagnostic tools such as color-flow, virtual histology, and integrated backscatter intravascular sonography. The technologic advancement in intravascular sonography has the potential of providing more accurate information prior, during, and after a medical or endovascular intervention. Continued assessment of this diagnostic technique in both the intracranial and extracranial circulation will lead to increased use in clinical practice with the intent to improve outcomes.

Disease progression in nonintervened saphenous vein graft segments a serial intravascular ultrasound analysis

OBJECTIVES

We used serial intravascular ultrasound (IVUS) to assess disease progression in nonintervened saphenous vein graft (SVG) segments to determine the natural rate of disease progression in SVG.

BACKGROUND

There are no serial IVUS studies of disease progression or luminal compromise in SVGs.

METHODS

We assessed serial (baseline and follow-up at 16.2 +/- 7.4 months) IVUS findings in 50 nonintervened SVG segments in 44 patients. The SVG age was 13.5 +/- 3.6 years.

RESULTS

Overall, from baseline to follow-up, plaque area increased (Delta = +0.58 +/- 1.25 mm(2), p = 0.003), and SVG and minimum lumen area (MLA) decreased (Delta = -0.50 +/- 1.14 mm(2), p = 0.002, and Delta = -1.08 +/- 1.28 mm(2), p < 0.001, respectively). The MLA decreased in 34 lesions (Delta = -1.67 +/- 1.08 mm(2)), and MLA increased in 16 lesions (Delta = +0.19 +/- 0.47 mm(2)). Compared with lesions with an increase in MLA, lesions with a decrease in MLA were associated with: 1) larger baseline SVG and plaque areas and plaque burden (15.57 +/- 3.90 mm(2) vs. 11.55 +/- 2.30 mm(2), p < 0.001; 7.97 +/- 3.77 mm(2) vs. 4.27 +/- 1.92 mm(2), p < 0.001; and 48.7 +/- 14.2% vs. 36.0 +/- 13.4%, p = 0.004, respectively); and 2) a greater decrease in SVG area (Delta = -0.96 +/- 1.05 mm(2) vs. +0.48 +/- 0.58 mm(2), p < 0.001) and greater increase in plaque area (Delta = +0.71 +/- 1.47 mm(2) vs. +0.29 +/- 0.45 mm(2), p < 0.001). The DeltaMLA correlated with both Deltaplaque area (r = -0.589, p < 0.001) and DeltaSVG area (r = 0.470, p = 0.001), and Deltaplaque area correlated with DeltaSVG area (r = 0.436, p = 0.002). There were linear relations between both the Deltaplaque area (r = 0.519, p < 0.001) and Deltalumen area (r = -0.500, p < 0.001) versus follow-up low-density lipoprotein (LDL) cholesterol; a follow-up LDL cholesterol of 100 mg/dl predicted no plaque increase.

CONCLUSIONS

Lumen loss in nonintervened SVG segments correlated with an increase in plaque area and a decrease in SVG area (plaque growth and negative remodeling) with a linear relationship between plaque growth versus follow-up LDL cholesterol leading to long-term lumen loss.

Regulation of arterial remodeling and angiogenesis by urokinase-type plasminogen activatorThis article is one of a selection of papers from the NATO Advanced Research Workshop on Translational Knowledge for Heart Health (published in part 2 of a 2-part Special Issue)

A wide variety of disorders are associated with an imbalance in the plasminogen activator system, including inflammatory diseases, atherosclerosis, intimal hyperplasia, the response mechanism to vascular injury, and restenosis. Urokinase-type plasminogen activator (uPA) is a multifunctional protein that in addition to its fibrinolytic and matrix degradation capabilities also affects growth factor bioavailability, cytokine modulation, receptor shedding, cell migration and proliferation, phenotypic modulation, protein expression, and cascade activation of proteases, inhibitors, receptors, and modulators. uPA is the crucial protein for neointimal growth and vascular remodeling. Moreover, it was recently shown to be implicated in the stimulation of angiogenesis, which makes it a promising multipurpose therapeutic target. This review is focused on the mechanisms by which uPA can regulate arterial remodeling, angiogenesis, and cell migration and proliferation after arterial injury and the means by which it modulates gene expression in vascular cells. The role of domain specificity of urokinase in these processes is also discussed.

Intravascular ultrasound assessment of expansion of the sirolimus-eluting (cypher select) and paclitaxel-eluting (Taxus Express-2) stent in patients with diabetes mellitus

Patients with diabetes have a higher risk for in-stent restenosis after coronary stent implantation. Drug-eluting stents (DES) are highly effective in reducing in-stent restenosis. Once neointimal hyperplasia is suppressed with DES, the impact of stent underexpansion becomes magnified. The aim of this study was to evaluate DES expansion in patients with diabetes. Ninety-five patients with diabetes were randomized to Cypher Select (n = 48) or Taxus Express-2 (n = 47) stent implantation. Intravascular ultrasound was performed after stent implantation. Stent expansion was defined as the ratio of measured to predicted minimum stent diameter. There was a trend for lower stent expansion in the Cypher Select stent group (0.74 +/- 0.08 vs 0.78 +/- 0.11 in the Taxus Express-2 stent group, p = 0.061). Cypher Select stents achieved a final minimal stent cross-sectional area of 5.5 +/- 1. 8 mm2, compared with 6.4 +/- 1.9 mm2 for Taxus Express-2 stents (p = 0.015). For stents with nominal diameters > or =2.75 mm (Cypher Select n = 40, Taxus Express-2 n = 38), 42.5% of the Cypher Select stents and 10.5% of the Taxus Express-2 stents did not achieve a final minimum stent area of 5 mm2 (p = 0.002). Insulin treatment (relative risk 0.31, 95% confidence interval 0.10 to 0.95, p = 0.041) and stent type (relative risk 0.15, 95% CI 0.04 to 0.53, p = 0.003) were independent predictors of not achieving a minimum stent area >5.0 mm2. In conclusion, an important percentage of DES in patients with diabetes fail to achieve the manufacturers' predicted final minimal stent diameter. Cypher Select stent and insulin treatment were independent predictors of not achieving a minimum stent area >5.0 mm2.

Comparison of intravascular ultrasound and angiographic assessment of coronary reference segment size in patients with type 2 diabetes mellitus

During percutaneous coronary intervention, the reference segment is assessed angiographically. This report described the discrepancy between angiographic and intravascular ultrasound (IVUS) assessment of reference segment size in patients with type 2 diabetes mellitus. Preintervention IVUS was used to study 62 de novo lesions in 41 patients with type 2 diabetes mellitus. The lesion site was the image slice with the smallest lumen cross-sectional area (CSA). The proximal and distal reference segments were the most normal-looking segments within 5 mm proximal and distal to the lesion. Plaque burden was measured as plaque CSA/external elastic membrane (EEM) CSA. Using IVUS, the reference lumen diameter was 2.80 +/- 0.42 mm and the reference EEM diameter was 4.17 +/- 0.56 mm. The angiographic reference diameter was 2.63 +/- 0.36 mm. Mean difference between the IVUS EEM diameter and angiographic reference diameter was 1.56 +/- 0.55 mm. The mean difference between the IVUS reference lumen diameter and angiographic reference lumen diameter was 0.18 +/- 0.44 mm. Plaque burden in the reference segment correlated inversely with the difference between IVUS and quantitative coronary angiographic reference lumen diameter (slope = -0.12, 95% confidence interval -0.17 to -0.07, p <0.001), but it was not related to the absolute angiographic reference lumen diameter. Thus, reference segment diameters in type 2 diabetic patients were larger using IVUS than angiography, especially in the setting of larger plaque burden. In conclusion, these findings combined with inadequate remodeling may explain the angiographic appearance of small arteries in diabetic patients.

Influence of a Pressure Gradient Distal to Implanted Bare-Metal Stent on In-Stent Restenosis After Percutaneous Coronary Intervention

Background— Fractional flow reserve predicts cardiac events after coronary stent implantation. The aim of the present study was to assess the 9-month angiographic in-stent restenosis rate in the setting of optimal stenting and a persisting gradient distal to the stent as assessed by a pressure wire pullback recording in the entire length of the artery.

Methods and Results— In 98 patients with angina pectoris, 1 de novo coronary lesion was treated with a bare-metal stent. After stent implantation, pressure wire measurements (P d =mean hyperemic coronary pressure and P a =mean aortic pressure) were performed in the target vessel: (1) P d /P a as distal to the artery as possible (fractional flow reserve per definition); (2) P d /P a just distal to the stent; (3) P d /P a just proximal to the stent; and (4) P d /P a at the ostium. Residual abnormal P d /P a was defined as a pressure drop between P d /P a measured at points 1 and 2. Fractional flow reserve distal to the artery after stenting was significantly lower (0.88±0.21 versus 0.97±0.05; P <0.001), and angiographic in-stent binary restenosis rate was significantly higher (44.0% versus 8.1%; P <0.001) in vessels with a residual abnormal P d /P a . Residual abnormal P d /P a (odds ratio, 4.39; 95% confidence interval, 1.10 to 18.16; P =0.034), reference vessel size (odds ratio, 0.17; 95% confidence interval, 0.04 to 0.69; P =0.013), and stent length (odds ratio, 1.11; 95% confidence interval, 1.03 to 1.21; P =0.009) were predictors of angiographic in-stent restenosis after 9 months.

Conclusions— A residual abnormal P d /P a distal to a bare-metal stent was an independent predictor of in-stent restenosis after implantation of a coronary bare-metal stent.

Incidence and predictors of target vessel revascularization after sirolimus-eluting stent treatment for proximal left anterior descending artery stenoses among 2274 patients fromthe prospectivemulticenter German Cypher Stent Registry

BACKGROUND

Involvement of the proximal LAD is considered an indication for coronary artery bypass graft (CABG) surgery due to the high restenosis rates associated with this location after percutaneous coronary interventions (PCI). This seems to be different, however, when using sirolimus-eluting stents, a finding if proven to be true could have a major impact on clinical decision making regarding the optimal revascularization strategy for these patients.

METHODS

We analyzed 2274 patients treated for proximal LAD stenoses using SES from the German Cypher Stent Registry. The incidence of TVR and other major clinical adverse events were determined and independent predictors of TVR were specified using a multiple logistic regression model.

RESULTS

Event-free survival was achieved in 89.5% of patients. TVR was performed in 179 patients (7.9%) and the combined incidence of all cause death, myocardial infarction and TVR was 10.5% (231 patients). Independent predictors of TVR were multivessel disease (OR 1.74, 95% CI 1.16-2.62, p = 0.008), stent diameter < or = 2.75 mm (OR 1.61, 95% CI 1.10-2.40, p = 0.02) and the administration of GP IIb/ IIIa antagonists (OR 1.60, 95% CI 1.05-2.60, p = 0.03). TVR rate was as high as 11.2% for 2.5 mm SES and as low as 4.0% for 3.5 mm SES (p < 0.001 for trend test).

CONCLUSION

TVR among patients treated with SES for proximal LAD stenoses is low and is related in part to operator dependent factors. Treatment with SES should be considered as an effective treatment for these patients.

Estrogen decreases neointimal hyperplasia and improves re-endothelialization in pigs

BACKGROUND

17-Beta-estradiol inhibits smooth muscle cell proliferation and migration and accelerates endothelial cell repair in response to balloon injury. The aim of this study was to determine whether administration of estrogen is associated with decreased neointimal hyperplasia after stenting in the porcine model.

METHODS AND RESULTS

Twenty-two farm female pigs 7 months old were oophorectomized and at the third day normal saline (11 pigs) or 20 mg of estradiol valerate (11 pigs), modified release, were administered intramuscularly. At the 10th day after oophorerectomy, 1 or 2 stainless steel stents were implanted in the right coronary artery in each pig, and at the 17th day, normal saline or 10 mg estradiol valerate, modified release, were administered intramuscularly in the two groups. Pigs were sacrificed 28 days after stent implantation and histomorphometric analysis of the coronary arteries was performed (20 stents from the estrogen and 18 stents from the control groups). In the estrogen group, neointimal proliferation area was 1.42+/-0.55 mm(2), whereas in the control group, 1.96+/-0.89 mm(2) (p=0.02). Area stenosis was 39+/-13% and 49+/-16% in the two groups, respectively (p=0.07). Re-endothelialization was 2.67+/-0.34 and 2.22+/-0.46 in the two groups, respectively (p<0.010). The injury score was similar between the two groups.

CONCLUSIONS

These data suggest that intramuscular administration of estrogen accelerates the endothelial cell repair in response to injury and reduces intimal hyperplasia in the porcine model.

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.

Drug-Eluting Coronary Stents

The introduction and widespread use of coronary stents have been the most important advancement in the percutaneous treatment of coronary artery disease since the introduction of balloon angioplasty. Coronary artery stents reduce the rate of angiographic and clinical restenosis compared to balloon angioplasty. This angiographic restenosis was further reduced with the introduction of drug-eluting stents and hence further reduction in the frequency of major adverse cardiac events. Herein we present a comprehensive and up-to-date review about the use of drug-eluting stents in the treatment of coronary artery disease.

Clinical Significance of Fractional Flow Reserve for Evaluation of Functional Lesion Severity in Stent Restenosis and Native Coronary Arteries

OBJECTIVE

Fractional flow reserve (FFR) is a valid surrogate for hemodynamic significance in stenotic native coronary arteries, but its validity in patients with coronary stent restenosis is unknown.

DESIGN

Prospective.

SETTING

University hospital.

PATIENTS

We studied 42 patients (mean age +/- 1 SD, 62 +/- 10 years) with stent restenosis and 57 patients (mean age, 61 +/- 12 years) with a native coronary lesion. All patients demonstrated a single coronary lesion of intermediate severity (stenosis diameter, 40 to 70%). Determination of FFR and quantitative angiography of the stenosis were performed.

RESULTS

Stenosis diameter was comparable in both groups (native, 52 +/- 11%; stent, 52 +/- 9%; not significant [NS]). FFR was lower in stent restenosis (0.77 +/- 0.15 vs 0.82 +/- 0.12, p < 0.05) and more often pathologic with an FFR < 0.75 (48% vs 26%, p < 0.05) compared to native coronary stenosis. However, the area under the receiver operating characteristic curve for native stenosis was 0.82 (95% confidence interval [CI], 0.71 to 0.94) and for stent restenosis was 0.84 (95% CI, 0.71 to 0.97; NS). In patients with an FFR > 0.75, there was no adverse coronary event that was related to the stented lesion in the subsequent 6 months.

CONCLUSIONS

The threshold of stenosis diameter of coronary lesions for pathologic FFR measurement (FFR < 0.75) is similar for stent restenosis and native coronary stenosis. Thus, FFR measurement seems to be applicable for decision making in patients with stent restenosis.

The importance of gender on coronary artery size: in-vivo assessment by intravascular ultrasound

BACKGROUND

It remains controversial whether women have smaller coronary arteries than men because of a gender-specific trait, or whether the observed differences are primarily due to a difference in body size. Intravascular ultrasound (IVUS), with its ability to provide unique coronary images that allow precise measurement of arterial size in vivo, is ideally suited to address this issue.

HYPOTHESIS

Female gender, independent of body size, is associated with smaller coronary artery size as measured by intracoronary ultrasound.

METHODS

Intravascular ultrasound images of normal left main arteries were identified retrospectively from a single center database. Associations between demographic and clinical characteristics (including body size) and left main coronary dimensions were assessed with univariant and multivariate regression analyses.

RESULTS

We identified 257 completely normal left main arteries. Mean left main arterial areas were smaller in women than in men (17.2 vs. 20.6 mm2, p < 0.001), as were mean luminal areas (14.0 vs. 16.7 mm2, p < 0.001). By multiple regression analysis, the independent predictors of left main lumen were body surface area (p < 0.001) and gender (p = 0. 003).

CONCLUSIONS

Body surface area and gender are both independent predictors of coronary artery size, although body size has a greater influence than gender.

Prevention of restenosis after coronary angioplasty

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Stent-based Controlled Release of Intravascular Angiostatin to Limit Plaque Progression and In-Stent Restenosis

PURPOSE

To evaluate the importance of angiogenesis in plaque progression after stent placement, this study examines stent-based controlled delivery of the antiangiogenic agent, angiostatin, in a rabbit model.

MATERIALS AND METHODS

Controlled release biodegradable microspheres delivering angiostatin or polymer-only microspheres (polylactic-co-glycolic-acid-polyethylene glycol; PLGA/PEG) were loaded in channeled stents, anchored, and deployed in the aorta of adult New Zealand white rabbits (n = 6 animals per group, three each per time point). The stented aortas were harvested at 7 days and 28 days and evaluated for neovascularization, local inflammation, vascular smooth muscle cell proliferation, and in-stent plaque progression.

RESULTS

At 7 days, neovascularization was significantly decreased in the angiostatin groups (1.6 +/- 1.6 neovessels per mm(2) plaque) versus the control group (15.4 +/- 2.6 neovessels per mm(2) plaque; P =.00081), as were local inflammation where angiostatin-treated groups demonstrated significantly lower macrophage recruitment per cross section (34.9 +/- 4.9 cells per cross section) relative to the control group (55.2 +/- 3.84 cells per cross section; P =.0037). And a significant decrease in the overall vascular smooth muscle cell proliferation (143.8 +/- 26.3 Ki-67 positive cells per mm(2)) relative to the control group (263.2 +/- 16.6 Ki-67 positive cells per mm(2); P =.00074). At both 7 and 28 days, in-stent plaque progression in the angiostatin groups was successfully limited relative to the control group by 54% (0.255 +/- 0.019% of cross section; P =.00016) and 19% (1.981 +/- 0.080; P =.0033) respectively and resulted in reduction of in-stent restenosis relative to the control group.

CONCLUSION

Angiostatin-eluting stents may limit neovascularity after arterial implantation, offer insight into in-stent restenosis, and allow future refinement of bioactive stent designs and clinical strategies, particularly in light of evidence that intimal smooth muscle cells may in part be marrow-derived.

Clinical impact of stent construction and design in percutaneous coronary intervention

Convincing end point data demonstrating the anatomic and clinical superiority of stent placement compared with balloon angioplasty together with significant improvement in stenting technique and poststent management have resulted in an explosion in stenting procedures and the emergence of more than 40 stent types with disparate designs and material composition in clinical use. Structural nuances in design, composition, and coating of different stent models, however, have been shown to have a major influence on the risk of stent thrombosis, the degree of vessel wall injury, and subsequent intimal proliferation in the experimental model. There is now substantial amount of evidence to indicate that the same relationship between stent structural characteristics and vessel wall outcome holds true in humans. This article provides an up-to-date overview of the clinical impact of stent construction and design, including the clinical performance of drug-eluting stents.

Arterial remodeling patterns before intervention predict diffuse in-stent restenosis

OBJECTIVES

The aim of this retrospective study was to determine the predictors of diffuse in-stent restenosis (ISR) among the lesions causing the first ISR by intravascular ultrasound (IVUS) studies.

BACKGROUND

Although some predictors of diffuse ISR have been reported, parameters on IVUS relating to diffuse ISR are not well characterized.

METHODS

We classified 52 ISR lesions that had undergone successful stent implantation and led to restenosis into two types--focal and diffuse ISR--using quantitative coronary angiography. Restenosis was defined as > or =50% diameter stenosis, and diffuse ISR as lesion length > or =10 mm at follow-up. The remodeling index (RI) was defined as the vessel area at the target lesion divided by that of averaged reference segments.

RESULTS

There were no significant differences in patient, angiographic, and procedural characteristics between the focal (n = 25) and diffuse (n = 27) ISR groups. Baseline RI was significantly greater in the diffuse ISR group (1.03 +/- 0.18 vs. 0.88 +/- 0.24, p = 0.0159). Negative remodeling, defined as RI <0.9, was detected in 60% of the focal ISR group and in only 26% of the diffuse ISR group. By logistic regression analysis, baseline RI was the only independent predictor of diffuse ISR (p = 0.0341). Moreover, volumetric analyses revealed that lesions developing into diffuse ISR had less capacity to compensate for further plaque growth.

CONCLUSIONS

Among the first ISR lesions, baseline positive remodeling was the most powerful predictor of diffuse ISR. Measuring pre-interventional arterial remodeling patterns by IVUS may be helpful to stratify lesions at higher risk.

Evaluation of vascular injury following percutaneous transluminal coronary angioplasty: a comparison of the accuracy of two- and three-dimensional intracoronary ultrasound imaging

BACKGROUND

Following percutaneous transluminal coronary angioplasty (PTCA), the extent of vascular injury is underestimated by angiographic assessment. Conventional intracoronary ultrasound (ICUS) imaging provides additional information with regard to the extent of dissections but requires mental reconstruction of consecutive images. Three-dimensional ICUS reconstruction overcomes this limitation and may provide more accurate assessment of the extent of vascular injury. This study compares conventional two-dimensional ICUS imaging to combined two- and three-dimensional ICUS information in the assessment of vascular injury following PTCA.

METHODS

Atherosclerotic, human coronary arteries (n=24) were studied in a specially constructed flow system. Balloon dilatation of significant stenoses was performed followed by assessment using two- and three-dimensional ICUS imaging methods. Treated arteries were submitted for histological assessment after pressure fixation. Dissection depth and length measurements were made from obtained images and compared to histomorphometric assessments.

RESULTS

Of the 20 arterial segments confirmed histologically to contain dissection, 11 (55%) and 18 (90%) were identified by two-dimensional ICUS and combined two- and three-dimensional ICUS respectively. The kappa values for correlation of dissection type were 0.29 (0.23-0.35) and 0.64 (0.57-0.71) respectively indicating better agreement using combined two- and three-dimensional ICUS. Two-dimensional ICUS consistently underestimated dissection length (3.52+/-1.75 mm compared with 6.54+/-2.42 mm, P<0.001) and depth (0.61+/-0.24 mm compared with 0.92+/-0.32 mm, P=0.001). Combined two- and three-dimensional ICUS produced accurate dissection length (6.13+/-2.29 mm compared with 6.54+/-2.42 mm, P=0.09) and depth (0.86+/-0.32 mm compared with 0.92+/-0.32 mm, P=0.28) estimations.

CONCLUSION

Computerized three-dimensional reconstruction of ICUS images provides improved accuracy compared to conventional ICUS imaging in the detection and quantitation of arterial dissection. This technique would be a useful adjunct to angiography for the precise assessment of vascular injury following PTCA.

Intravascular ultrasound imaging of myocardial-infarction-related arteries after percutaneous transluminal coronary angioplasty reveals significant plaque burden and compensatory enlargement

We studied patients with acute myocardial infarction (MI) by intravascular ultrasound (IVUS) to elucidate the controversy as to the amount and severity of the atherosclerotic disease at the culprit lesion site in acute MI, as discrepancies exist between angiographic and pathological reports. Twenty-five consecutive patients (age 56 3 10.5 years), with acute MI, underwent IVUS study of the MI-related artery immediately following successful PTCA to the culprit lesion. The IVUS images were analyzed quantitatively and qualitatively and were compared with the angiography of the same arteries. At the PTCA site, 64% of the lesions had an area stenosis of 50-70% and the plaque cross-sectional area (CSA) averaged 0.5 3 0.18 of the arterial CSA. IVUS-defined atherosclerosis was found also in 72% of the segments proximal and distal to the culprit lesion with a plaque/artery CSA ratio of 0.25 3 0.2. The angiogram revealed only 30% of these segments to be abnormal (P 3 0.001). Sixty-nine per cent of all the plaques were defined as 'soft' (low echo-genecity) versus 31% 'hard' (high echo-genecity). The hard plaques were larger than the soft plaques (0.5 3 1.6 versus 0.37 3 0.19 CSA index, respectively, P 3 0.01). With the increase in plaque area there was a significant increase in arterial cross-sectional area. This was demonstrated for all the diseased segments with a correlation coefficient of 0.49 (P 3 0.0001) and for the diseased reference sites a similar correlation coefficient of 0.49 (P 3 0.003) was found. Contrary to coronary angiographic-based reports, this IVUS study revealed a significant atheromatous plaque burden at the culprit lesion of MI-related arteries as well as diffuse atherosclerosis in the reference segments proximal and distal to the lesion. The detection of compensatory enlargement may explain the discrepancies between the histopathological and the angiographic studies.

Long-term clinical outcome after stent implantation in coronary arteries

The long-term clinical outcome after planned and unplanned stent implantation was assessed in a single-center, observational study in 178 patients who underwent coronary stent implantation between November 1986 and July 1994. Main outcome measures were survival and event-free survival at 5 years (Kaplan-Meier method). Independent predictors for event-free survival were determined by using multivariate logistic regression analysis. Patients underwent planned (group 1, n 3 101) or unplanned (group 2, n 3 77) stent implantation. During the in-hospital period, there were no deaths. The incidence of Q-wave and non-Q-wave acute myocardial infarction (AMI), coronary artery bypass graft (CABG) and repeat percutaneous transluminal coronary angioplasty (PTCA) was 5.0%, 2.0% and 4.0%, respectively, in group 1, versus 32.5%, 23.4% and 10.4%, respectively, in group 2. During the follow-up period (median 4.0 years, range 0.29-9.8 years), the incidence of death, AMI, and repeat revascularization (CABG and PTCA) was 5.9%, 8.9% and 40.6%, respectively, in group 1, versus 1.3%, 5.2% and 36.4%, respectively, in group 2. Survival and event-free survival at 5 years was 73 (7%) and 47 (7%), respectively, for patients who underwent planned stent implantation. It was 98 (0.1%) and 34 (6%), respectively, for patients who underwent unplanned stent implantation. At the end of follow-up, 31.9% of patients had angina pectoris class III or IV (Canadian Cardiovascular Society). The long-term clinical outcome after both planned and unplanned stent implantation was characterized by a high incidence of repeat revascularization. It is conceivable that changes in stent design and implantation techniques, in addition to novel therapeutic approaches addressing neointima formation and progression of atherosclerosis, may improve the long-term clinical outcome.

Clinical restenosis after coronary stenting: perspectives from multicenter clinical trials

OBJECTIVES

We sought to evaluate clinical restenosis in a large population of patients who had undergone coronary stent placement.

BACKGROUND

One-year success after coronary stenting is limited mainly by restenosis of and requirement for repeat revascularization of the treated lesion. We studied 6,186 patients (6,219 lesions) pooled from several recently completed coronary stent trials. Clinical restenosis was defined using three different definitions: target lesion revascularization (TLR) beyond 30 days, target vessel revascularization (TVR) beyond 30 days, and target vessel failure (TVF), defined as TVR, any death, or myocardial infarction (MI) of the target vessel territory after hospital discharge.

RESULTS

By one year, 638 (12.2%) patients had TLR, 748 (14.3%) had TVR, and 848 (16.0%) had TVF, more than two-thirds higher than the rate of these end points at six months. The severity of angiographic restenosis (> or =50% follow-up diameter stenosis [DS]) in 419 of 1,437 (29%) patients undergoing routine angiographic follow-up correlated directly with the likelihood of TLR (73% vs. 26% for >70% DS compared with <60% DS). Smaller pretreatment minimum lumen diameter (MLD), smaller final MLD, longer stent length, diabetes mellitus, unstable angina, and hypertension were independent predictors of TLR. Prior MI and current smoking were negative predictors.

CONCLUSIONS

At one year after stenting, most clinical restenosis reflected TLR, which was predicted by the same variables previously associated with an increased risk of angiographic restenosis. The lower absolute rate of clinical restenosis relative to angiographic restenosis was due to infrequent TLR in lesions with less severe (<60% DS) angiographic renarrowing.

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.

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

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

Measurement of the ultrasonic properties of human coronary arteries in vitro with a 50-MHz acoustic microscope

Ultrasonic attenuation coefficient, wave propagation speed and integrated backscatter coefficient (IBC) of human coronary arteries were measured in vitro over the -6 dB frequency bandwidth (36 to 67 MHz) of a focused ultrasound transducer (50 MHz, focal distance 5.7 mm, f/number 1.7). Corrections were made for diffraction effects. Normal and diseased coronary artery sub-samples (N = 38) were obtained from 10 individuals at autopsy. The measured mean +/- SD of the wave speed (average over the entire vessel wall thickness) was 1581.04 +/- 53.88 m/s. At 50 MHz, the average attenuation coefficient was 4.99 +/- 1.33 dB/mm with a frequency dependence term of 1.55 +/- 0.18 determined over the 36- to 67-MHz frequency range. The IBC values were: 17.42 +/- 13.02 (sr.m)-1 for thickened intima, 11.35 +/- 6.54 (sr.m)-1 for fibrotic intima, 39.93 +/- 50.95 (sr.m)-1 for plaque, 4.26 +/- 2.34 (sr.m)-1 for foam cells, 5.12 +/- 5.85 (sr.m)-1 for media and 21.26 +/- 31.77 (sr.m)-1 for adventitia layers. The IBC results indicate the possibility for ultrasound characterization of human coronary artery wall tissue layer, including the situations of diseased arteries with the presence of thickened intima, fibrotic intima and plaque. The mean IBC normalized with respect to the mean IBC of the media layer seems promising for use as a parameter to differentiate a plaque or a thickened intima from a fibrotic intima.

Coronary disease morphology and distribution determined by quantitative angiography and intravascular ultrasound--re-evaluation in a cooperative multicenter intravascular ultrasound study (COMIUS)

Although previous studies have demonstrated that even quantitative coronary angiography (QCA) can not provide accurate disease morphology, there has not been a systematic comparison of disease morphology determined by QCA and intravascular ultrasound (IVUS), particularly in Japanese patients. Therefore, the present study prospectively examined patients in a multicenter cooperative study. A total of 491 coronary sites from 562 patients (446 men, 116 women; mean age, 64+/-11 years) who underwent coronary interventions were enrolled. The target lesions (>50% diameter stenosis) were evaluated pre-operatively by both QCA and IVUS operating at 30-40 MHz and the percent area stenosis, eccentricity index (EI) and lesion length were determined. The minimal (min) and maximal (max) distances from the center of the stenotic lesion to the outline of the vessel wall were measured, and the EI was calculated by the formula: [(max - min)/max]. By QCA, lesion length was determined by measuring the distance between the proximal and distal shoulders of the lesion. When the lesions were observed by IVUS with a motorized pull-back system, the length was calculated by multiplying the time for observation of the disease and 0.5 or 1 mm/s. Although the severity of the stenosis determined by QCA (86+/-10%, mean +/- SD) did not differ from that by IVUS (83+/-13%), there was no correlation between them (r=0.32, y=0.25x+65) and the correlation did not improve when lesions with remodeling, enlargement (n=176) or shrinkage (n=79) were omitted from the calculation. The EIs by QCA and IVUS were 0.51+/-0.26 and 0.52+/-0.22, respectively (NS), and there was no correlation between them (r=0.30, y=0.36x+33). However, when the lesions with remodeling were excluded, the correlation greatly improved (r=0.80, y=0.84x+10.6, p<0.05). Lesion length determined by QCA (12.4+/-6.1 mm) was significantly shorter than that by IVUS (16.3+/-8.9 mm, p<0.01). These results demonstrate that coronary angiography significantly misinterprets disease morphology in terms of severity, eccentricity and length, in part because of vessel remodeling that can be accurately determined only by IVUS.

Coronary pressure measurement after stenting predicts adverse events at follow-up: a multicenter registry

BACKGROUND

Coronary stenting is associated with a restenosis rate of 15% to 20% at 6-month follow-up, despite optimum angiographic stent implantation. In this multicenter registry, we investigated the relation between optimum physiological stent implantation as assessed by poststent fractional flow reserve (FFR) and outcome at 6 months.

METHODS AND RESULTS

In 750 patients, coronary pressure measurement at maximum hyperemia was performed after angiographically apparently satisfactory stent implantation. Poststenting FFR was calculated and related to major adverse events (including need for repeat target vessel revascularization) at 6 months. In 76 patients (10.2%), at least 1 adverse event occurred. Five patients died, 19 experienced myocardial infarction, and 52 underwent at least 1 repeat target vessel revascularization. By multivariate analysis, FFR immediately after stenting was the most significant independent variable related to all types of events. In 36% of the patients, FFR normalized (>0.95), and event rate was 4.9% in that group. In 32% of the patients, poststent FFR was between 0.90 and 0.95, and event rate was 6.2%. In 32% of patients, poststent FFR was <0.90, and event rate was 20.3%. In 6% of the patients, FFR was <0.80, and event rate was 29.5% (P<0.001).

CONCLUSIONS

FFR after stenting is a strong independent predictor of outcome at 6 months.

Early angioplasty in acute coronary syndromes without persistent ST-segment elevation improves outcome but increases the need for six-month repeat revascularization: an analysis of the PURSUIT Trial. Platelet glycoprotein IIB/IIIA in Unstable angina: Receptor Suppression Using Integrilin Therapy

OBJECTIVES

We explored the effect of timing of percutaneous coronary intervention (PCI) in acute coronary syndromes (ACS) without persistent ST-segment elevation on the need for repeat revascularization, and we related this effect to other events.

BACKGROUND

Percutaneous coronary intervention is widely used to treat ACS without persistent ST-segment elevation. Moreover, restenosis and subsequent revascularization after PCI are more frequent in ACS than in stable angina. The optimal timing of PCI in ACS without persistent ST-segment elevation is unknown.

METHODS

In the Platelet glycoprotein IIB/IIIA in Unstable angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) database, patients were stratified by the time of PCI. In the PURSUIT trial, 9,461 patients received a platelet glycoprotein IIb/IIIa inhibitor, eptifibatide or placebo for 72 h. The investigators decided on other treatments.

RESULTS

A total of 2,430 patients underwent PCI within 30 days. Repeat revascularization (during 165 days) was notably higher for PCI within 24 h of enrollment (n = 620 [19%]) than for PCI at 24 to 72 h (n = 624 [16.7%]), 3 to 7 days (n = 614 [13.2%]), or 8 to 30 days (n = 561 [7.7%]; p < 0.001), regardless of eptifibatide use. This gradual reduction in the revascularization rate for later PCI was also observed after multivariate analysis correcting for baseline characteristics and with time as a continuous variable.

CONCLUSIONS

Percutaneous coronary intervention within 24 is associated with improved outcome (other analysis) but more repeat revascularization. Prospective analyses are needed to test the hypothesis that rapid PCI in ACS with a platelet glycoprotein IIb/IIIa receptor antagonist reduces myocardial infarction (and possibly death) and is therefore most suited for patients at highest risk of infarction, despite a higher need for repeat revascularization.

Role of plaque proliferation in late lumen loss after directional coronary atherectomy

Previous reports suggest that vessel remodeling is the most important factor in late lumen loss in non-stented lesions, but because results of directional coronary atherectomy (DCA) show that increased plaque area (PA) is also important, the aim of this study was to redefine the mechanism of late lumen loss after DCA. One hundred and twenty lesions that underwent DCA with intravascular ultrasound (IVUS) guidance and serial IVUS analysis were studied, and vessel area (VA), lumen area (LA), PA (VA-LA) and corrected values (each value divided by the value of VA pre procedure to correct the vessel size) were analyzed. During follow-up, corrected VA (cVA) decreased by 0.058 +/- 0.191, whereas corrected PA (cPA) increased by 0.087 +/- 0.159. Though the %PA (PA/VA) after the procedure showed significant negative correlation with the subsequent change in cPA, it did not correlate with the subsequent change in cVA. In conclusions, the mechanism of late lumen loss after DCA consists of both arterial remodeling and plaque proliferation, and the residual %PA after the procedure determines the subsequent lumen loss. With a lower %PA, a change in the PA contributes more to late lumen loss than do changes in VA. With a high %PA, a change in the VA contributes more to late lumen loss.

Relation between residual plaque burden after stenting and six-month angiographic restenosis

The degree of residual plaque burden outside of a stent might be correlated with the degree of intimal hyperplasia. However, the relation between residual plaque burden and angiographic restenosis are still unknown in a large number of patients. Therefore, we evaluated the effect of residual plaque burden after stenting on 6-month angiographic restenosis. Intravascular ultrasound (IVUS)-guided coronary stenting was successfully performed in 723 patients with 785 native coronary lesions. Six-month follow-up angiograms and evaluation of residual plaque burden by IVUS were available in 566 patients (78.3%) with 622 lesions (79.2%). Results were evaluated using conventional methods. The overall angiographic restenosis rate was 23.0% (143 of 622 lesions). There was no significant difference in residual plaque burden between the lesions with and without restenosis (52% vs 51%, respectively, p = 0.148). The angiographic restenosis rate was 20.8% (11 of 53 lesions), 21.6% (51 of 236 lesions), 22.0% (55 of 250 lesions), and 31.3% (26 of 83 lesions) in the lesions with residual plaque burden < 40%, between 40% and 50%, between 50% and 60%, and > 60%, respectively (p = 0.284). Using multivariate logistic regression analysis, the only independent predictor of angiographic restenosis was the IVUS stent area (odds ratio 0.807, 95% confidence intervals 0.69 to 0.95, p = 0.011). Furthermore, even in the lesions with residual plaque burden > 60%, the restenosis rate was 37.3% (23 of 61 lesions) versus 13.6% (3 of 22 lesions ) in IVUS stent areas of < 7 and > or =7 mm(2), respectively (p = 0.031). In conclusion, residual plaque burden outside the stent might not predict angiographic restenosis. IVUS stent area was the only independent predictor of angiographic restenosis.