Comparison of coronary lesions obtained by directional coronary atherectomy in unstable angina, stable angina, and restenosis after either atherectomy or angioplasty

CD31 as a Therapeutic Target in Atherosclerosis

The potential of CD31 as a therapeutic target in atherosclerosis has been considered ever since its cloning in the 1990s, but the exact role played by this molecule in the biologic events underlying atherosclerosis has remained controversial, resulting in the stalling of any therapeutic perspective. Due to the supposed cell adhesive properties of CD31, specific monoclonal antibodies and recombinant proteins were regarded as blocking agents because their use prevented the arrival of leukocytes at sites of acute inflammation. However, the observed effect of those compounds likely resulted from the engagement of the immunomodulatory function of CD31 signaling. This was acknowledged only later though, upon the discovery of CD31's 2 intracytoplasmic tyrosine residues called immunoreceptor tyrosine inhibitory motifs. A growing body of evidence currently points at a therapeutic potential for CD31 agonists in atherothrombosis. Clinical observations show that CD31 expression is altered at the surface of leukocytes infiltrating unhealed atherothrombotic lesions and that the physiological immunomodulatory functions of CD31 are lost at the surface of blood leukocytes in patients with acute coronary syndromes. On the contrary, translational studies using candidate therapeutic molecules in laboratory animals have provided encouraging results: synthetic peptides administered to atherosclerotic mice as systemic drugs in the acute phases of atherosclerotic complications favor the healing of wounded arteries, whereas the immobilization of CD31 agonist peptides onto coronary stents implanted in farm pigs favors their peaceful integration within the coronary arterial wall.

Tissue characterization of in-stent neointima using intravascular ultrasound radiofrequency data analysis

Using virtual histology and intravascular ultrasound (VH-IVUS), tissue characterization of restenotic in-stent neointima after drug-eluting stent (DES) and bare metal stent (BMS) implantation was assessed. VH-IVUS was performed in 117 lesions (70 treated with DESs and 47 treated with BMSs) with angiographic in-stent restenosis and intimal hyperplasia (IH) > 50% of the stent area. The region of interest was placed between the luminal border and the inner border of the struts and tissue composition was reported as percentages of IH area (percent fibrous, percent fibrofatty, percent necrotic core, percent dense calcium) at the 2 sites of maximal percent IH and maximal percent necrotic core. Mean follow-up times between stent implantation and VH-IVUS study were 43.5 ± 33.8 months for BMS-treated lesions and 11.1 ± 7.8 months for DES-treated lesions (p < 0.001). The 2 groups had greater percent necrotic core and percent dense calcium at maximal percent IH and maximal percent necrotic core sites, especially in stents that had been implanted for longer periods. In conclusion, this VH-IVUS analysis showed that BMS- and DES-treated lesions develop in-stent necrotic core and dense calcium, suggesting the development of in-stent neoatherosclerosis.

Histopathology of clinical coronary restenosis in drug-eluting versus bare metal stents

To characterize in-stent restenosis after the implantation of sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES), tacrolimus-eluting stents (TES), and zotarolimus-eluting stents (ZES), 25 patients treated with drug-eluting stents (DES; 9 PES, 10 SES, 4 TES, and 2 ZES) and 19 with bare-metal stents (BMS) underwent directional coronary atherectomy for in-stent restenosis 4 to 36 months after implantation. Restenosis after DES implantation was more frequently focal and associated with smaller specimens compared to that after BMS implantation. Light and confocal microscopy were used. Histologic features were similar in DES and BMS. In-stent restenotic lesions were composed mainly of neointima containing proteoglycan-rich smooth muscle cells and fibrolipidic regions. Small inflammatory infiltrates were observed, mostly in patients with unstable angina; CD18- and/or CD3(+) cells were detected in patients with BMS and DES. Different smooth muscle cell phenotypes were observed: synthetic was more frequent with BMS and PES, intermediate with ZES, contractile or intermediate with SES, and contractile with TES. The mean proliferation index was low and comparable among stent types; cyclins B1 and D1 were expressed in all DES. In conclusion, intra-DES and intra-BMS restenotic tissue was composed mainly of smooth muscle cells with different phenotypes, proliferating at a low rate. The different smooth muscle cell phenotypes within the stent types might suggest different mechanisms of restenosis.

Mild inflammatory activation of mammary arteries in patients with acute coronary syndromes

Acute coronary syndromes (ACS) are characterized by multiple unstable coronary plaques and elevated circulating levels of inflammatory biomarkers. The endothelium of internal mammary arteries (IMA), which are atherosclerosis resistant, is exposed to proinflammatory stimuli as vessels that develop atherosclerosis. Our study investigated the IMA endothelial expression of inflammatory molecules in patients with ACS or chronic stable angina (CSA). IMA demonstrated normal morphology, intact endothelial lining, and strong immunoreactivity for glucose transporter 1. E-selectin expression was observed more frequently in IMA of ACS patiention than CSA patients (ACS 61% vs. CSA 14%, P = 0.01). High fluorescence for major histocompatibility complex (MHC) was significantly more frequent on the luminal endothelium (ACS 66.7% vs. CSA 17.6%, P = 0.001 for class I; and ACS 66.7% vs. CSA 6.2%, P = 0.0003 for class II-DR) and on the vasa vasorum (ACS 92.9% vs. CSA 33.3% and 7.7%, P = 0.0007 and P < 0.0001 for class I and class II-DR, respectively) of ACS patients than CSA patients. ICAM-1, VCAM-1, Toll-like receptor 4, tissue factor, IL-6, inducible nitric oxide synthase, and TNF-alpha expression were not significantly different in ACS and CSA. Circulating C-reactive protein [ACS 4.8 (2.6-7.3) mg/l vs. CSA 1.8 (0.6-3.5) mg/l, P = 0.01] and IL-6 [ACS 4.0 (2.6-5.5) pg/ml vs. CSA 1.7 (1.4-4.0) pg/ml, P = 0.02] were higher in ACS than CSA, without a correlation with IMA inflammation. The higher E-selectin, MHC class I and MHC class II-DR on the endothelium and vasa vasorum of IMA from ACS patients suggests a mild, endothelial inflammatory activation in ACS, which can be unrelated to the presence of atherosclerotic coronary lesions. These findings indicated IMA as active vessels in coronary syndromes.

TH1/TH2 functional imbalance after acute myocardial infarction: coronary arterial inflammation or myocardial inflammation

OBJECTIVES

The study clarified whether the T-helper (Th)1/Th2 imbalance existed only in coronary arterial inflammation or in both coronary arterial inflammation and myocardial inflammation and explored the significance of the imbalance of Th1/Th2 function after acute myocardial infarction (AMI).

BACKGROUND

There are two different inflammatory processes in patients with AMI: the coronary arterial inflammation that leads to the pathogenesis of AMI and the myocardial inflammation after AMI that leads to ventricular remodeling, which are positively and negatively regulated by Th1 and Th2 lymphocytes, respectively.

METHODS

Peripheral blood mononuclear cells from 33 AMI patients, 22 unstable angina (UA) patients and splenocytes from 35 AMI Wistar rats were collected. Cytokine-producing Th cells were ambulatorily monitored by 3-color flow cytometry. Interferon (IFN)-gamma and interleukin (IL)-4 mRNA in the rat myocardium and chemokine receptors CCR3,CCR5 and CXCR3 mRNA on the surface of rat T-lymphocytes after AMI were measured by RT-PCR.

RESULTS

IFN-gamma-producing T-cells significantly increased in patients with AMI and UA within 24 hours after the onset of symptom. The high ratio of IFN-gamma-producing T-cells recovered 1 week after the onset in UA patients, while it could be examined 1 week and even 1 month after the onset in AMI patients. The up-regulation of Th1 cell function is consistent with bad heart function. There was no significant difference on the frequencies of IL-4-producing T-cells between each group. 1 week, 2 weeks and 1 month after AMI, IFN-gamma mRNA increased in the myocardium of rats, but there was no significant change on global Th cell functions.

CONCLUSIONS

Th1/Th2 functional imbalance exists in both coronary arterial inflammation and myocardial inflammation processes. The up-regulation of Th1 cell-functions may participate in the immune-mediated ventricular remodeling after AMI.

Elevated serum neopterin predicts future adverse cardiac events in patients with chronic stable angina pectoris

AIMS

Serum levels of neopterin, an immune modulator secreted by activated macrophages, are elevated in patients with acute coronary syndromes compared with stable angina patients and control subjects. In unstable angina, serum neopterin levels correlate with the presence of vulnerable coronary stenosis, multiple complex coronary lesions, and patient outcome. The present study assessed the prognostic significance of raised serum neopterin concentrations in patients with stable angina pectoris.

METHODS AND RESULTS

We carried out a 1-year follow-up prospective study in 297 patients with chronic stable chest pain undergoing diagnostic coronary angiography. The primary study endpoint was the composite of non-fatal myocardial infarction, unstable angina, and cardiac death. Fifty-one patients (17.2%) had adverse coronary events during follow-up. Mean serum neopterin levels were significantly higher in patients with events compared with those without (P=0.02). On multiple regression analysis, neopterin levels (P=0.021), severity of coronary artery disease (P=0.009), and a history of previous myocardial infarction (P=0.001) were independent predictors of adverse events.

CONCLUSIONS

Serum neopterin is an independent predictor of major adverse coronary events in patients with chronic stable angina pectoris. This marker of macrophage activation may be useful for risk stratification in patients with chronic stable angina.

Pathogen burden, inflammation, proliferation and apoptosis in human in-stent restenosis. Tissue characteristics compared to primary atherosclerosis

Pathogenic events leading to in-stent restenosis (ISR) are still incompletely understood. Among others, inflammation, immune reactions, deregulated cell death and growth have been suggested. Therefore, atherectomy probes from 21 patients with symptomatic ISR were analyzed by immunohistochemistry for pathogen burden and compared to primary target lesions from 20 stable angina patients. While cytomegalovirus, herpes simplex virus, Epstein-Barr virus and Helicobacter pylori were not found in ISR, acute and/or persistent chlamydial infection were present in 6/21 of these lesions (29%). Expression of human heat shock protein 60 was found in 8/21 of probes (38%). Indicated by distinct signals of CD68, CD40 and CRP, inflammation was present in 5/21 (24%), 3/21 (14%) and 2/21 (10%) of ISR cases. Cell density of ISR was significantly higher than that of primary lesions (977 +/- 315 vs. 431 +/- 148 cells/mm(2); p < 0.001). There was no replicating cell as shown by Ki67 or PCNA. TUNEL(+) cells indicating apoptosis were seen in 6/21 of ISR specimens (29%). Quantitative analysis revealed lower expression levels for each intimal determinant in ISR compared to primary atheroma (all p < 0.05). In summary, human ISR at the time of clinical presentation is characterized by low frequency of pathogen burden and inflammation, but pronounced hypercellularity, low apoptosis and absence of proliferation.

Tenascin-C is associated with coronary plaque instability in patients with acute coronary syndromes

BACKGROUND

Tenascin-C (TNC) is an extracellular matrix glycoprotein that increases after inflammation and injury. In cultured cells TNC has been reported to markedly induce the expression of matrix metalloproteinase-9, which stimulates collagen degradation in the fibrous cap of human atherosclerotic plaque.

METHODS AND RESULTS

Immunohistochemical techniques were used to analyze the expression of TNC protein in 51 coronary atherectomy specimens obtained from patients with stable angina pectoris (SAP, n=23) or acute coronary syndromes (ACS) (n=28; unstable angina pectoris, n=20, acute myocardial infarction, n=8). Immunostaining for alpha-smooth muscle actin, CD68, CD45, and CD31 was also performed in serial sections to identify the cell types that express TNC protein. The %TNC + area (percentage of the area of immunostaining for TNC protein in the total surface area of the plaque) was larger in coronary samples with the plaque characteristics of thrombus, angiogenesis, intraplaque hemorrhage, and macrophage (CD68(+)), and lymphocyte (CD45 (+)) clusters than in coronary samples without them (52+/-3.4 vs 39+/-4.8, p<0.05; 57+/-3.7 vs 36+/-3.7, p<0.01; 51+/-3.6 vs 39+/-4.8, p<0.05; 53+/-3.4 vs 33+/-4.5, p<0.01; 56+/-4.1 vs 37+/-3.6, p<0.01, respectively). The presence of other components, such as dense fibrous tissue, neointimal hyperplasia, atheromatous gruel and calcification, was not significantly correlated with the %TNC + area. The %TNC + area was larger in coronary samples from patients with ACS than in samples from patients with SAP (56+/-3.2% vs 34+/-4.3%, p<0.01).

CONCLUSIONS

The results suggest that TNC may have specific functions in coronary plaque formation and may be involved in the pathogenesis of coronary lesions in ACS.

Multiple complex stenoses, high neutrophil count and C-reactive protein levels in patients with chronic stable angina

Inflammation plays an important role in atherosclerosis and the genesis of acute coronary syndromes, i.e., atheromatous plaque disruption. Neutrophil count and C-reactive protein (CRP) levels are markers of ongoing inflammation and predictors of cardiovascular risk. We sought to assess whether these inflammatory markers are associated with the presence of multiple complex stenoses in patients with chronic stable angina.

METHODS AND RESULTS

We assessed 150 patients with chronic stable angina, 121 with significant coronary artery stenosis (> or =50% diameter reduction) and 29 without. CRP levels and neutrophil count were assessed at study entry. Stenoses were classified as "complex" (irregular or scalloped borders, ulceration or filling defects) or "smooth" (absence of complex features). Eighty-eight percent of the complex lesions were of type C according to AHA/ACC classification whereas the rest were type B. Patients with > or =3 complex lesions were considered to have multiple complex stenoses. Extent of coronary artery disease was assessed using a validated score. Baseline neutrophil count (4.39 x 10(9) L (-1) +/- 28 versus 3.82 x 10(9) L (-1) +/- 0.77; P = 0.004) and CRP levels (2.15 mg/L (4.6-1) versus 0.39 mg/L (0.69-0.23); P < 0.0001) were higher in patients with significant stenoses compared to patients without. No association was found between disease extent and CRP levels or neutrophil count. Neutrophil count, however (but not CRP) correlated with stenosis complexity (r = 0.28; P = 0.002 ) and was also an independent predictor of the presence of multiple complex stenoses (OR: 4.05; CI 95% (1.9-10.4); P = 0.038).

CONCLUSIONS

CRP levels and neutrophil count are higher in angina patients with coronary stenoses compared to those without. Neutrophil count, but not CRP levels, correlates with angiographic stenosis complexity.

Relation of C-reactive protein to restenosis after coronary stent implantation and to restenosis after coronary atherectomy

To determine whether the inflammatory response is equally involved in the pathogenesis of restenosis after coronary stenting and directional coronary atherectomy, we assessed restenotic lesions with immunohistochemical methods. Levels of C-reactive protein and macrophages were greater in patients with in-stent restenosis than in those with restenosis after directional coronary atherectomy. This suggests that the inflammatory response is more involved in the pathogenesis of in-stent restenosis than in restenosis after directional coronary atherectomy.

Cardiac Angiotensin II Participates in Coronary Microvessel Inflammation of Unstable Angina and Strengthens the Immunomediated Component

Angiotensin (Ang) II is now recognized to be a mediator of a wide variety of inflammatory processes. This study investigated renin-angiotensin system (RAS) components and a number of inflammatory mediators in left ventricular biopsies from 2-vessel disease unstable angina (UA) (n=43) and stable angina (SA) (n=15) patients undergoing coronary bypass surgery. Biopsy samples from 6 patients undergoing valve replacement for mitral stenosis served as controls. UA patients were randomly assigned to angiotensin-converting enzyme (ACE)-inhibitor (ramipril), AT1 antagonist (valsartan), or placebo and treated during the 5 days preceding coronary bypass surgery, performed from 6 to 9 days after coronary angiography. During coronary angiography coronary blood flow was measured and samples were obtained from aorta and coronary sinus for determination of Ang I and Ang II gradients. The hearts of UA patients produced Ang II in a greater amount than in SA patients ( P <0.01). UA biopsy samples showed numerous DR + cells, identified as lymphocytes, macrophages, and endothelial cells. Reverse-transcriptase polymerase chain reaction showed overexpression of AGTN, ACE, and AT1-R genes, as well as upregulation of TNF-α, IL-6, IFN-γ, and iNOS genes ( P <0.01), with no differences between nonischemic and potentially ischemic areas. AGTN, ACE, and cytokine genes were mainly localized on endothelial cells. Ramipril and valsartan markedly decreased the expression levels of TNF-α, IL-6, and iNOS, and, to a lesser extent, of IFN-γ genes, but did not affect the number of DR + cells, with no significant difference between the 2 treatments. These results show that locally generated Ang II amplifies the immunomediated inflammatory process of coronary microvessels occurring in unstable angina.

Comparison of frequency of interferon-gamma-positive CD4+ T cells before and after percutaneous coronary intervention and the effect of statin therapy in patients with stable angina pectoris

We investigated the effect of statin therapy on T-cell activation in patients who underwent percutaneous coronary intervention by using flow cytometric analysis. The increased frequency of interferon-gamma-positive CD4(+) T cells after percutaneous coronary intervention was significant in the group treated without statins but not in the group treated with statins.

Immunomediated and ischemia-independent inflammation of coronary microvessels in unstable angina

This study investigated whether the myocardium is involved in the acute inflammatory reaction associated with bursts of unstable angina (UA). We looked for the presence of activated DR+ inflammatory cells and the expression patterns, localization, and immunostaining identification of genes for cytokines (IL-1beta, TNF-alpha, IL-6, and IFN-gamma), MCP-1, and iNOS in the left ventricle biopsies from 2-vessel disease anginal patients, 24 with UA and 12 with stable angina (SA), who underwent coronary bypass surgery. Biopsy specimens from 6 patients with mitral stenosis who underwent valve replacement were examined as control hearts (CHs). Plasma levels of IL-2 soluble receptor (sIL-2R) were measured as a marker of systemic immune reaction. In CHs, DR+ cells were undetectable, and cytokine and iNOS mRNA expression were negligible. UA patients had higher sIL-2R levels than SA patients (P<0.01), and their biopsy specimens showed both numerous DR+ cells identified as lymphocytes, macrophages, endothelial cells, and elevated expression levels of cytokine and iNOS genes (from 2.4- to 6.1-fold vs SA; P<0.01). Cytokine and iNOS genes and proteins were localized in endothelial cells without involvement of myocytes. IL-1beta and MCP-1 mRNAs were nearly undetectable. No significant differences were found in the number of DR+ cells, levels of cytokine, and iNOS genes between potentially ischemic and nonischemic left ventricle areas. In SA specimens, DR+ cells were very rare and only mRNAs for TNF-alpha and iNOS genes were overexpressed versus CHs. These results indicated that an acute immunomediated inflammatory reaction, essentially involving coronary microvessels, is demonstrable in UA patients.

Variants of toll-like receptor 4 modify the efficacy of statin therapy and the risk of cardiovascular events

BACKGROUND

Atherosclerosis is increasingly considered to be a chronic inflammatory process. We examined whether genetic variants of the toll-like receptor 4 (TLR4), which are correlated with impaired innate immunity and with progression of carotid atherosclerosis, are also associated with coronary atherosclerosis and predict the risk of cardiovascular events.

METHODS AND RESULTS

Two polymorphisms of the TLR4 gene (Asp299Gly and Thr399Ile) were determined in 655 men with angiographically documented coronary atherosclerosis. All patients participated in a prospective cholesterol-lowering trial evaluating the effect on coronary artery disease and were randomly assigned to either pravastatin or placebo for 2 years. There were no significant differences between genetically defined subgroups with respect to baseline risk factors, treatment, or in-trial changes of lipid, lipoprotein, or angiographic measurements. Genotype was not associated with progression of atherosclerosis. In the pravastatin group, 299Gly carriers had a lower risk of cardiovascular events during follow-up than noncarriers (2.0% versus 11.5%, P=0.045). Among noncarriers, pravastatin reduced the risk of cardiovascular events from 18.1% to 11.5% (P=0.03), whereas among 299Gly carriers this risk was strikingly reduced from 29.6% to 2.0% (P=0.0002, P=0.025 for interaction).

CONCLUSIONS

Among symptomatic men with documented coronary artery disease, the TLR4 Asp299Gly polymorphism was associated with the risk of cardiovascular events. This variant also modified the efficacy of pravastatin in preventing cardiovascular events, such that carriers of the variant allele had significantly more benefit from pravastatin treatment.

Involvement of C-reactive protein obtained by directional coronary atherectomy in plaque instability and developing restenosis in patients with stable or unstable angina pectoris

We investigated whether positive immunohistochemical staining of C-reactive protein (CRP) in initial culprit lesions is related to coronary plaque instability and whether it could affect the outcome of directional coronary atherectomy (DCA). The plasma level of CRP is a reliable marker of the risk of coronary events and restenosis after percutaneous coronary intervention. However, the influence of tissue CRP in atheromatous plaque on plaque vulnerability and restenosis remains unknown. Samples of DCA obtained from 12 patients with stable angina pectoris and 15 patients with unstable angina pectoris were immunohistochemically stained with a monoclonal antibody against CRP. We performed follow-up coronary angiography on 22 of 27 patients to evaluate the presence of restenosis after DCA. Immunoreactivity to CRP was localized to macrophages, smooth muscle cells, and necrotic areas. The ratio of CRP positive cells to total cells was significantly higher in DCA samples from patients with unstable (17.9 +/- 2.0%) than with stable angina (11.0 +/- 2.5%) (p <0.05). Follow-up coronary angiography showed that 12 of 22 patients developed restenosis after DCA. The ratio was also significantly higher in DCA specimens from patients with restenosis (19.3 +/- 2.8%) compared with those without restenosis (11.0 +/- 2.0%) (p <0.05). In addition, the ratio significantly correlated with late luminal loss (r = 0.428, p <0.05) and loss index (r = 0.636, p = 0.0011) after DCA. Immunoreactivity to CRP in coronary atheromatous plaque increases in culprit lesions of unstable angina, and it affects restenosis after DCA. These findings suggest that CRP in atheromatous plaque plays an important role in the pathogenesis of unstable angina and restenosis after coronary intervention.

Anti-inflammatory and immunomodulatory effects of statins

Anti-inflammatory and immunomodulatory effects of statins. 3-Hydroxy-3-methyl-gutaryl coenzyme A (HMG-CoA) reductase inhibitors or statins constitute the most powerful class of lipid-lowering drugs. Clinical trials have demonstrated a marked reduction in cardiovascular mortality in patients treated with statins. However, the benefits observed with statin therapy appear to be related, at least in part, with their cholesterol-lowering independent effects. Extensive research carried out mainly in the last decade suggests that the clinical benefits of these drugs could be related to an improvement in endothelial dysfunction, a reduction in blood thrombogenicity, anti-inflammatory properties, and, recently, immunomodulatory actions. In this sense, statins decrease T cell activation, the recruitment of monocytes and T cells into the arterial wall, and enhance the stability of atherosclerotic lesions. Many of these effects are related with the inhibition of isoprenoid synthesis, which serve as a lipid attachment for a variety of proteins implicated in intracellular signaling. In fact, small G proteins, whose proper membrane localization and function are dependent on isoprenylation, may play an important role in the lipid-lowering independent effects of HMG-CoA reductase inhibitors. This article summarizes the anti-inflammatory and immunomodulatory effects of statins and their participation in the different steps of atherosclerotic lesion formation.

Inflammation and immune system response against unstable angina and its relationship with coronary angiographic findings

The aim of this study was to assess the relations between inflammation, immune response, and coronary angiographic findings in patients with unstable angina pectoris (UAP). Recent studies suggest a role for inflammation in the pathophysiology of UAP. Although activation of neutrophils, monocytes and lymphocytes has been shown in UAP, no studies have correlated the activation findings with clinical and angiographic features of patients with UAP. Seventy-three patients undergoing coronary angiography were classified according to their ischaemic syndrome, stable angina pectoris (SAP) (n = 25) and UAP (n = 48). Patients with UAP were classified using the Braunwald classification; UAP class I (n = 15), UAP class II (n = 15), and UAP class III (n = 18). Patients with UAP were also classified into a progression to myocardial infarction (MI (+)) group (n = 15) and a non-progression to myocardial infarction (MI(-)) group (n = 33). Venous blood samples were taken from all patients. Cell surface receptors (CD4, CD8, CD3, CD14, CD45, CD56+16, and HLA-DR) were detected by flow cytometry using monoclonal antibodies tagged with fluorescent markers and serum levels of C-reactive protein (CRP) were measured. The serum levels of CRP and the percentages of HLA-DR, CD14, and CD16+56 were higher in UAP than SAP. The serum levels of CRP and percentages of HLA-DR, CD14, and CD16+56 were higher in UAP class II than UAP class I. The serum levels of CRP and percentages of HLA-DR, CD14, and CD16+56 were higher in UAP class III than UAP class II and UAP class I. The serum levels of CRP and percentages of CD16+56 were higher in the MI(+) group than the MI(-) group. The CRP levels in serum and the percentages of cell surface antigens had no correlation with extent of coronary artery disease (no differences among one, two or three vessels) but Type C lesion had significantly higher percentages of HLA-DR, CD14, CD16+56 and the serum levels of CRP than Type A and Type B lesions. This investigation shows that inflammatory and immunologial components may be detectable in UAP and were correlated with the clinical severity, progression to myocardial infarction, and lesion morphology, but were not correlated with the extent of coronary artery disease.

Plaque composition in plexogenic and thromboembolic pulmonary hypertension: the critical role of thrombotic material in pultaceous core formation

BACKGROUND

Patients with pulmonary hypertension develop intimal plaques in large pulmonary arteries.

OBJECTIVE

To test the hypothesis that the composition of such plaques differs depending on whether the aetiology of the disease is thromboembolic or hypertensive.

DESIGN

Chronic thromboembolic and plexogenic pulmonary hypertension (primary and secondary (Eisenmenger syndrome)) were investigated. These are spontaneous human models and were used to examine the independent role of thrombus and hypertension in plaque composition.

SETTING

A national tertiary referral centre for lung transplantation and pulmonary thromboendoarterectomy.

PATIENTS

Thirty nine patients with chronic thromboembolic pulmonary hypertension who had undergone thromboendoarterectomy (n = 32) or lung transplantation (n = 7), 28 with plexogenic diseases (nine primary and 19 Eisenmenger), and three with Eisenmenger syndrome complicated by thromboembolic events.

INTERVENTIONS

The lung and thromboendoarterectomy samples were sectioned, stained with Movat pentachrome, and immunostained with antibodies for fibrin, platelets, inflammatory cells, smooth muscle cells, and erythrocyte membrane glycophorin A.

MAIN OUTCOME MEASURE

Composition of the plaques affecting large pulmonary arteries.

RESULTS

Two types of intimal lesion were distinguished in chronic thromboembolic pulmonary hypertension: fibrous plaques with angioneogenesis; and core-rich atherosclerotic plaques with pultaceous cores largely consisting of glycophorin immunoreactive material, with cholesterol clefts (61.5%), CD68 positive macrophages (84.6%), T lymphocytes (87%), and calcification (46.1%). The samples from the patients with Eisenmenger syndrome and thromboembolic complications had similar characteristics, whereas those from patients with uncomplicated primary pulmonary hypertension had core-free fibrous plaques, spotted with macrophages and T lymphocytes.

CONCLUSIONS

Chronic thromboembolic pulmonary hypertension is associated with atherosclerotic plaques with glycophorin-rich pultaceous cores, and plexogenic pulmonary hypertension with fibrous plaques. Thromboembolic material thus plays a critical role in the formation of pultaceous cores, of which erythrocyte membrane derived glycophorin is a major component.

Histopathologic evaluation of coronary artery thrombi obtained by directional coronary atherectomy in patients with restenosis-induced unstable angina pectoris

The pathogenesis of unstable angina pectoris (UAP) following percutaneous transluminal coronary angioplasty (PTCA) or directional coronary atherectomy (DCA) has not been adequately investigated, so the present study aimed to determine whether thrombi are present in restenotic lesions. The study group comprised 14 patients (16 arterial branches) with angina pectoris in whom either PTCA or DCA was performed and who had developed UAP associated with restenosis, and who then underwent DCA of the restenosed lesion (R-UAP group). The control groups comprised individuals with UAP undergoing DCA with no prior history of PTCA or DCA (P-UAP group; n=29, 29 branches), patients with acute myocardial infarction (AMI group; n=34, 34 branches), and patients with stable angina pectoris (SAP group; n=31, 33 branches). The presence of thrombi was determined by light microscopy of histologic specimens. Thrombus was present in only 1 of the 16 (6.3%) branches in the R-UAP group. 21 of the 29 (72.4%) branches in the P-UAP group, and in 25 of the 34 (73.5%) in the AMI group. In the SAP group, it was detected in only 2 of the 33 (7.1%) branches. The incidence of thrombus was significantly lower in the R-UAP group than in the P-UAP group. In conclusion, the role of thrombus is limited in causing post-interventional UAP at restenosed sites.

Physiological concentration of 17beta-estradiol retards the progression of severe atherosclerosis induced by a high-cholesterol diet plus balloon catheter injury: role of NO

The molecular mechanisms of the antiatherosclerotic effects of estrogen are not yet known. We evaluated the effects of 17beta-estradiol (E(2)) on high cholesterol diet- (HCD; standard diet and 1% cholesterol) and balloon injury-induced atherosclerosis in female New Zealand White rabbits. The abdominal aortas of 40 oophorectomized (Groups 1 through 5) and 8 nonoophorectomized (Group 6) rabbits were injured by balloon catheter, and the animals were then divided into the following groups and treated for 10 weeks: Group 1, standard diet; Group 2, standard diet plus a moderate dose of E(2) (100 microg x kg(-1) x d(-1)); Group 3, HCD; Group 4, HCD plus a moderate dose of E(2); Group 5, HCD plus a low dose of E(2) (20 microg x kg(-1) x d(-1)); and Group 6, HCD in nonoophorectomized rabbits. After the treatment phase, plasma E(2) was increased up to 282.2+/-45.5 pg/mL in Group 2, 263.0+/-41.5 pg/mL in Group 4, 87. 9+/-18.8 pg/mL in Group 5, and 45.6+/-7.3 pg/mL in Group 6. HCD-mediated increases in plasma lipid levels were not changed by E(2) treatment, whereas E(2) decreased the aortic intimal thickening in Group 2 animals compared with those in Group 1 and reduced atherosclerosis in the thoracic and abdominal aortas of Group 4, 5, and 6 rabbits compared with those in Group 3. E(2) restored the impaired abdominal aortic endothelium-dependent relaxation of balloon-injured and HCD-supplemented rabbits, and E(2) increased basal nitric oxide (NO) release. The basal NO-releasing effect showed a significant, inverse relation with the severity of atherosclerosis. Plasma E(2) concentration also showed a significant, inverse relation with atherosclerotic area. In conclusion, physiological concentrations of E(2) can retard the progression of severe atherosclerosis and stabilize atheromas induced by HCD and balloon injury. The retardation may be partially mediated by endothelial NO function in vessels treated with E(2).

Plaque inflammation in restenotic coronary lesions of patients with stable or unstable angina

OBJECTIVES

To evaluate immunohistochemically various parameters of inflammation in coronary atherectomy specimens obtained from restenotic culprit lesions of patients presenting with either stable or unstable angina (UA).

BACKGROUND

There is no information regarding the relationship between atherosclerotic plaque inflammation and the severity of the coronary syndromes in patients with restenotic coronary lesions.

METHODS

A total of 37 patients with either stable angina or UA underwent directional coronary atherectomy for restenotic coronary lesions. Cryostat sections of atherectomy specimen were immunohistochemically stained with monoclonal antibodies CD68 (macrophages [MACs]), CD3 (T-lymphocytes) and alpha-actin (smooth muscle cells [SMCs]). Smooth muscle cell contents and MAC contents were planimetrically quantified as the percentage immunopositive tissue area of the total tissue area. T-lymphocytes were counted at 100-X magnification throughout the entire section and expressed as number of cells per mm2.

RESULTS

Restenotic coronary lesions of patients with UA or stable angina showed no significant difference in SMC areas (31.9%+/-16.3% vs. 38.5%+/-18.8%, respectively; p = NS). However, restenotic coronary lesions of patients presenting with unstable angina contained significantly more MACs (24.4%+/-15.1% vs. 10.5%+/-5.8%, p = 0.001) and T-lymphocytes (18.8 cells/mm2+/-15.1 cells/mm2 vs. 8.6 cells/mm2+/-9.8 cells/mm2; p = 0.034) than patients with stable angina.

CONCLUSIONS

These results suggested that inflammation appears to affect plaque instability in restenotic coronary lesions resulting in unstable coronary syndromes.

Histologic comparison of coronary and iliac atherectomy tissue from cases of in-stent restenosis

Pathologically, restenotic lesions after stenting were investigated by use of atherectomized tissues of seven coronary and seven iliac arteries. The mean interval of the stent deployment to restenosis was 9.1 months for the coronary artery and 33.7 months for the iliac artery, indicating a 3.7-fold longer interval for the latter. This study does not include cases of acute thrombotic occlusion. The atherectomized tissue from restenotic coronary arteries showed abundant neointima with alpha-actin-positive and ultrastructually synthetic-type smooth muscle cells in a rich myxomatous extracellular matrix. In the iliac arteries, the predominant component of restenosis consisted of organized thrombi. The neointima of the iliac arteries was mature, and only a small amount of spindle cells were observed in the hyalinized matrix. The tissue that developed restenosis after stenting was different in the coronary and iliac arteries included in this series. This study on the atherectomized tissue suggests that even in the chronic stage, a major cause of in-stent restenosis among the larger caliber vessels such as the iliac artery is not neointima but stent thrombosis.

Expression of the angiogenic protein, platelet-derived endothelial cell growth factor, in coronary atherosclerotic plaques: In vivo correlation of lesional microvessel density and constrictive vascular remodeling

Recent information indicates that platelet-derived endothelial cell growth factor (PD-ECGF), a 45-kDa angiogenic protein, is expressed in the endothelium of various tissues and that its level of expression is correlated with the number of microvessels in human tumors. Because the formation of neovessels is also thought to play a role in atherosclerotic vascular remodeling, we analyzed PD-ECGF expression in fresh, coronary plaque tissues obtained by directional coronary atherectomy. Specimens from 31 patients were collected and analyzed by reverse transcription-polymerase chain reaction, histochemical staining, immunohistochemistry, and in situ hybridization with the use of PD-ECGF-specific primers and probes. Lesional vascular remodeling was assessed by intravascular ultrasound. PD-ECGF immunoreactivity and mRNA were found in plaque macrophages, endothelial cells of plaque neovessels, and stellate smooth muscle cells of 20 atherectomy specimens (64.5%). PD-ECGF immunoreactivity was correlated with the number of lesional microvessels and mast cells. Double-staining experiments revealed a close spatial proximity of PD-ECGF-positive cells and mast cells. Furthermore, the numbers of microvessels and mast cells were significantly higher in lesions lacking compensatory enlargement. The data indicate that PD-ECGF is expressed within cells of the atherosclerotic plaque and may be involved in driving angiogenesis in concert with mast cells.

From plaque biology to clinical setting

Coronary atherosclerosis may cause acute and chronic ischemic syndromes; the former are caused by "acute plaque events," mostly thrombosis complicating vulnerable ruptured plaques, namely severe lesions with large core, thin cap, and weak shoulder infiltrated by activated inflammatory cells. Plaque rupture may also occur in nonischemic settings and is not obligatorily complicated by thrombosis. Furthermore, plaque rupture is not the only thrombus substrate in acute ischemic syndromes: Superficial erosion of fibrous plaques is found in 44% of acute thrombi in sudden coronary deaths and in 25% of those in acute myocardial infarctions. Coronary thrombosis appears to be triggered by superficial intimal inflammation in plaque ulceration and by neointimal hyperplasia in plaque erosion. "Endogenous" and, recently, exogenous factors, particularly infective intracellular organisms, have been proposed as major contributors to plaque inflammation, activation, and vulnerability. Possible exogenous triggers are DNA and RNA viruses and intracellular bacteria such as Chlamydia pneumoniae, which has been identified with microbiological, ultrastructural, immunohistochemical, and molecular tools in a consistent proportion of human plaque samples. Chlamydia increases local thrombogenicity and is associated with an atherogenic lipid profile. Systemic indexes of inflammation, such as PCR, SAA, and fibrinogen, are also increased in acute syndromes and common infectious diseases with high morbidity and minimal clinical impact are good candidates; Helicobacter pylori is a major one. Infectious agents could link local and systemic inflammation: White cells infected in its target tissue could circulate into the flow and be captured, on a specific local trigger, into vessel walls thus stimulating local inflammation.

Histological evaluation of coronary plaque in patients with variant angina: relationship between vasospasm and neointimal hyperplasia in primary coronary lesions

OBJECTIVES

This study was designed to determine whether coronary vasospasm in patients with variant angina pectoris (VAP) may produce focal organic lesions at the site of vasospasm that would contribute to disease progression.

BACKGROUND

Recent clinical angiographic and experimental studies have demonstrated the potential role of vasospasm in the worsening of organic coronary stenosis.

METHODS

We studied histologically the coronary plaques obtained at atherectomy in 202 patients with moderate to severe coronary stenosis. This population included 22 patients with VAP, 100 patients with chronic stable angina and 80 patients with restenosis following angioplasty or atherectomy. Diagnosis of VAP was based on both the clinical feature of angina at rest associated with ST elevation and a positive response to acetylcholine provocation test.

RESULTS

The most common histological appearance in 92% of patients with stable angina was hypocellular fibroatheromatous plaques, whereas neointimal hyperplasia was the characteristic feature of the plaque observed in 90% of patients with restenosis. The coronary specimens at the site of spasm in 15 of the 22 patients (68%) with VAP demonstrated intimal injuries such as neointimal hyperplasia (15), thrombus formation (2), and intimal hemorrhage (3). Neointimal hyperplasia was significantly more common in the patients with VAP as compared with those with stable angina (68% vs. 8%; p < 0.0001). A rapid progression of organic stenosis within three years was angiographically found in 5 of the 22 patients with variant angina. In all five cases, neointimal hyperplasia was the main contributor to the worsening of the organic lesion at the site of spasm. These histological findings in patients with VAP extremely resembled those in restenosis. Except for vasospasm, no factors significantly predicted the presence of neointimal formations in primary coronary lesions.

CONCLUSIONS

Coronary vasospasm may provoke vascular injury that leads to the formation of neointima in VAP patients similar to that seen with restenosis. Coronary spasm may thus play a key role in the rapid coronary stenosis progression in certain patients with VAP.

Immune system activation follows inflammation in unstable angina: pathogenetic implications

OBJECTIVES

The aim of this study was to assess the relations between inflammation, specific immune response and clinical course in unstable angina (UA).

BACKGROUND

Several studies suggest that either inflammation and/or T-cell activation might have a pathogenetic role in UA, but neither their potential reciprocal connection nor their relation to the clinical course is known.

METHODS

Serum levels of C-reactive protein (CRP) (inflammation), IgG, IgA, IgM, C3, C4 (humoral immunity), IL-2 and the percentage of CD4+, CD8+ and CD3+/DR+ T-cells (cell-mediated immunity) were measured in 35 patients with UA and 35 patients with chronic stable angina (CSA) during a period of 6 months.

RESULTS

The CRP levels and the main specific immune markers (CD4+ and CD3+/DR+ cells, IL-2 and IgM) were higher in unstable than in stable angina. In UA, the serum levels of IgM and IL-2 and the percentage of double positive CD3+/DR+ significantly increased at 7 to 15 days, and returned to baseline at 6 months. The increment of circulating activated T cells (CD3+/ DR+) in UA was inversely related to the admission levels of CRP (r=-0.63, p=0.003) and associated with a better outcome.

CONCLUSIONS

Our data suggest that the inflammatory component systemically detectable in UA may be antigen-related and that the magnitude of the immune response correlates with the clinical outcome of instability.

Apoptosis in restenosis versus stable-angina atherosclerosis: implications for the pathogenesis of restenosis

Decreases in programmed cell death (apoptosis) may contribute to restenotic hyperplasia by prolonging the life span of intimal cells. Apoptotic events were compared in restenotic versus primary lesions, by using atherectomy samples from 16 restenotic and 30 primary human peripheral and coronary lesions from patients presenting with stable angina. We used transmission electron microscopy to identify apoptosis, quantify its frequency, distinguish apoptosis from necrosis, and relate these events to cellular composition. Smooth muscle cell (SMC) density was higher in restenotic versus primary lesions (P<0.0001), whereas the number of macrophages was significantly reduced (P<0.01) and the number of lymphocytes was lower, but not significantly (P=0.06). As the main finding, restenotic lesions contained fewer apoptotic cells compared with primary lesions (3% versus 13%, P=0.002), whereas no differences were found for cellular necrosis. With regard to cell type, the lower frequency of apoptotic cells observed in restenotic tissue was attributable to both SMCs and macrophages. The key finding of less apoptosis in restenotic versus primary lesions was in agreement with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) analysis (2% versus 9%, P<0.001). For all lesions analyzed, significant inverse correlations were observed between the density of SMCs and the frequency of apoptotic cell death (r=-0.60, P<0.001) as well as the density of SMCs and that of macrophages (r=-0.74, P<0.001). No relationship was seen between the frequency of apoptosis and the density of macrophages. In conclusion, the data of the present study indicate that a low level of apoptosis may be an important mechanism leading to restenotic intimal lesion development after interventional procedures.

Directional coronary atherectomy (DCA): a report from the New Approaches to Coronary Intervention (NACI) registry

Directional coronary atherectomy (DCA) with the Simpson coronary atherocath seeks to debulk rather than simply displace obstructive tissue and is a means of enlarging the stenotic coronary lumen. This report from the New Approaches to Coronary Intervention (NACI) registry describes the experience of 1,196 patients who underwent DCA as the sole treatment for either native vessel or vein graft lesions. Device success (post-DCA residual stenosis <50% and > or =20% improvement) was achieved in 87.8%, with a lesion success rate (postprocedural residual stenosis <50% and > or =20% improvement) of 94.0%. The mean resultant stenosis after all interventions (by core laboratory) was 19%. Significant in-hospital complications occurred in 2.8% of patients with DCA attempts, including death 0.6%, Q-wave myocardial infarction (MI) 1.5%, and emergent coronary artery bypass graft surgery (CABG) 2.8%. At 1-year follow-up, cumulative mortality was 3.6%, with repeat revascularization in 28% (repeat percutaneous transluminal coronary angioplasty, 20.1%; CABG, 10.6%). This reflected percutaneous or surgical revascularization of the original lesion (target lesion revascularization) in 22.6% of patients. Subgroup analysis showed a lower lesion success rate and an increased complication rate for unplanned use, vein graft treatment, and treatment of a de novo (vs a restenotic) lesion. Multivariate analysis shows that diabetes mellitus, unstable angina, treatment of a restenotic lesion, and greater residual stenosis after the initial procedure were independent predictors of the composite endpoint of death/Q-wave MI/target lesion revascularization by 1-year follow-up. Among these generally favorable acute and 1-year results, the NACI directional atherectomy data confirm the "bigger is better" hypothesis: that lesions with a lower residual stenosis after a successful procedure had significantly fewer target lesion revascularizations between 30 days and 1 year, with no increase in major adverse events.

Role of inflammation in the pathogenesis of unstable coronary artery disease

In this article, the clinical, angiographic, and postmortem features of unstable angina are reviewed and its pathogenesis is discussed. Coronary plaque inflammation may play a key role in the pathogenesis of unstable angina and the evidence for this assertion is examined. Finally, the therapeutic implications of the involvement of inflammation in acute coronary syndromes are outlined.

Enhanced angiogenesis and unfavorable remodeling in injured porcine coronary artery lesions: effects of local basic fibroblast growth factor delivery

There is interest in the role of growth factors in the genesis of arterial remodeling. We studied local administration of basic fibroblast growth factor (bFGF) to coronary lesions to determine whether there is a difference in remodeling and whether neovascularization could be induced in such stenoses and distal myocardium. Pigs were randomized to balloon infusion of either saline or bFGF at each thermally injured arterial site. After the animals were killed, their internal elastic lamina, neointima, and lumen areas were measured. Capillaries were counted in the arteries and myocardium. There was a greater loss of lumen and internal elastic in the bFGF group. The neointima, media, and myocardium in the bFGF treated arteries had statistically more capillaries. This study showed that local intracoronary bFGF, at a dose that results in arterial luminal revascularization in injured segments, adversely affects arterial remodeling. Thus, the angiogenic response to exogenous bFGF may be offset by concomitant shrinkage of injured arterial segments.

Pathology of unstable plaque: correlation with the clinical severity of acute coronary syndromes

OBJECTIVES

The aim of this study was to relate the various clinical presentations of acute coronary syndromes to the underlying plaque morphology as assessed from histopathologic analysis of plaque fragments obtained by directional coronary atherectomy (DCA).

BACKGROUND

Autopsy studies have shown that unstable angina and infarction are related to plaque instability and involve events such as fissure or rupture of the fibrous cap, thrombosis and inflammation. The clinical severity and prognosis of acute coronary syndromes can be estimated by the Braunwald classification of unstable angina. Whether plaque morphology can be related to the Braunwald classification has not been evaluated.

METHODS

Plaque fragments were obtained by DCA in 75 patients: 38 with unstable angina, 19 with stable angina and 18 with no symptoms after infarction. The presence of fibrous tissue, thrombus, high cellularity, inflammatory cells, atheroma, neovessels and "stellar-shaped" smooth muscle cells was evaluated in 7-micron thick sections by appropriate staining. The patients were classified according to clinical presentation without knowledge of the results of pathologic examination, and a plaque instability score was assigned. The risk of further cardiac events was classified as low, medium or high.

RESULTS

Increasing severity of the score of unstable angina was associated with increasing prevalence of thrombus, high cellularity, atheroma and neovessels. Plaque from patients with unstable angina considered to be at low risk of further events appeared very similar to that of patients with stable angina, whereas the specific morphologic characteristics of plaque instability were more frequently observed as the clinical score and the risk of further events increased. After thrombolyzed infarction, plaque morphology depends on the delay between the acute event and DCA. Within 1 week after infarction, plaque still showed the morphologic characteristics of instability, whereas late DCA provided samples with morphologic features similar to those observed in patients with stable angina.

CONCLUSIONS

The morphologic features of plaque fragments vary at different stages of acute coronary disease. The specific features of plaque instability correlate with the clinical scoring system of the Braunwald classification.

Acute T-cell activation is detectable in unstable angina

BACKGROUND

Recent studies suggest a role for inflammation in the pathophysiology of unstable angina. This study was designed to investigate whether circulating lymphocytes are involved in the inflammatory reaction associated with the episodes of unstable angina.

METHODS AND RESULTS

Twenty-nine patients with proven unstable angina, 36 with stable angina, and 30 healthy subjects were studied. Both early and short-lived (interleukin-2 receptor [IL-2R], alpha-chain CD25, and transferrin receptor CD71) and late antigen (HLA-DR) expression were investigated by flow cytometric analysis. Soluble IL-2R (sIL-2R) was also measured in plasma by ELISA. Lymphocyte activation was studied at day 1 of hospital admission and after 7, 15, 30, 60, and 90 days. In patients with unstable angina, the number of HLA-DR+ CD3 lymphocytes and levels of sIL-2R were higher (P < .001) than in patients with stable angina and control subjects. Both CD4+ and CD8+ lymphocytes expressed HLA-DR antigens. No differences were found among the different groups of subjects in regard to the expression of CD25 and CD71. Lymphocyte activation was more marked in patients with urgent revascularization. No relationships were found between the number of HLA-DR+ lymphocytes and either the severity of coronary angiographic lesions or the number of ischemic episodes. Observations over time showed a gradual decrease in the number of HLA-DR+ lymphocytes and sIL-2R levels from weeks 3 through 8 to 12.

CONCLUSIONS

The present results indicate that (1) CD4+ and CD8+ circulating lymphocytes are activated in patients with unstable angina, and their activation state lasts 6 to 8 weeks; and (2) activation of lymphocytes is not a consequence of myocardial ischemia. These results support the immune system-mediated inflammatory nature of unstable angina.

Electron microscopic studies of phenotypic modulation of smooth muscle cells in coronary arteries of patients with unstable angina pectoris and postangioplasty restenosis

BACKGROUND

Proliferation and matrix protein secretion of coronary smooth muscle cells (SMCs) have been suggested as one of the mechanisms responsible for the development of postangioplasty restenosis and an alternative cause of unstable angina. Phenotypic modulation of SMCs may produce a pool of cells potentially responsive to growth stimulation that can synthesize abundant extracellular matrix. This study tested the hypothesis that phenotypic modulation of SMCs occurred during the evolution of postangioplasty restenosis and unstable angina.

METHODS AND RESULTS

The SMCs of coronary atherectomy specimens from 24 patients were identified under electron microscope. Volume fractions of synthetic organelles (VFSOs) and other features related to phenotypic modulation of SMCs were measured. The results showed that the VFSO in SMCs from 5 patients with unstable angina (group 2) resembled those from 9 patients with postangioplasty restenosis (group 3; 0.42 +/- 0.13 versus 0.36 +/- 0.10; P = NS), and both were significantly higher than those from 6 patients with stable angina (group 1; 0.21 +/- 0.11). Four patients with restenosis lesions who underwent angioplasty > 6 months ago (group 4) also had a low VFSO in SMCs (0.19 +/- 0.05). This value was significantly less than those in groups 2 and 3 (P < .05) but similar to that in group 1.

CONCLUSIONS

The coronary lesions from patients with unstable angina resembled those from patients with postangioplasty restenosis in terms of the phenotypic modulation and VFSO in SMCs. Our findings therefore suggest that after phenotypic modulation, the SMCs may become responsive to growth stimulation, with an ability to massively proliferate and synthesize abundant extracellular matrix. These processes may lead to plaque expansion and eventually to the development of unstable angina and restenosis.

Impact of restenosis after optimal directional coronary atherectomy on regional left ventricular function

To assess the effect of optimal directional coronary atherectomy (DCA) on restenosis and left ventricular (LV) function, 95 patients who underwent DCA and adjunctive balloon angioplasty for de novo lesions were prospectively followed for 6 months. Absolute and relative coronary lumen measurements were analyzed with online quantitative coronary angiography. LV volumes, ejection fraction, and segmental wall motion were measured off-line according to the radial method for LV cineangiograms acquired in a right anterior oblique projection. Target vessels were the left anterior descending artery in 63 patients and right coronary artery in 32. Mean (+/- SD) reference diameter was 3.58 +/- 0.65 mm. Mean lumen diameter improved significantly after DCA from 1.19 +/- 0.44 to 3.03 +/- 0.45 mm, yielding a 14 +/- 10% residual stenosis. Overall angiographic restenosis rate (> 50% stenosis in diameter) at control was 23%. In patients without restenosis, there were no significant changes in LV volumes or in LV pressures. In this subgroup, ejection fraction improved significantly in the left anterior descending group (mean difference 3 +/- 10%, p < 0.04). Moreover, there was an increase in fractional shortening of all anterior segments (mean difference 11 +/- 16%, p < 0.005). Improvement in fractional shortening was less marked in the right coronary artery group even without restenosis. We conclude that: (1) optimal DCA can achieve a low restenosis rate in selected large vessels, (2) long-term beneficial effects on regional LV function are possible, particularly in patients with left anterior descending disease and in the absence of coronary restenosis.

Absence of correlation between coronary thrombosis and postatherectomy restenosis

This study endeavored to assess whether thrombus in directional coronary atherectomy was correlated with later subsequent restenosis. We concluded that the presence of thrombus in native plaque is not correlated with the occurrence of postatherectomy restenosis.

Association of coronary plaque rupture and atherosclerotic inflammation

Coronary plaque inflammation may promote plaque rupture and thrombosis. To test this hypothesis, 351 coronary plaques from 83 patients were formalin-fixed and stained with haematoxylin and eosin. There were six groups: (1) ruptured plaques; (2) intact plaques from recently infarcted hearts; (3) plaques from hearts with severe coronary atherosclerosis without identifiable thrombosis; (4) native explanted hearts with severe coronary atherosclerosis; (5) cardiac transplant atherosclerosis; and (6) fatalities unrelated to coronary atherosclerosis. Selected arteries were immunostained for leukocyte markers and serially sectioned to identify plaque rupture. There were infiltrates of CD68-positive macrophages and CD3- and CD8-positive T cells adjacent to all plaque ruptures. Labelling with HLA-DR and CD30 indicated inflammatory cell activation. Plaque rupture was strongly statistically associated with the severity and frequency of superficial plaque inflammation but not that of deep plaque inflammation. Although atherosclerotic inflammation has been identified adjacent to rupture, this is its first comparison with control plaques. These results support the concept that inflammation in the fibrous cap is particularly associated with plaque rupture.

Neovascularization in human coronary atherosclerotic lesions

Neovessels within human coronary atherosclerotic lesions are frequently observed, but their pathophysiological significance is still subject to debate. Also, the origin of these vessels and their pathways in the arterial wall are not well-known. In this study, we describe the transmural pathway and the frequency of neovessels both in vivo and in autopsy cases. Atherosclerotic coronary arteries were obtained during autopsy in 10 subjects without previous cardiovascular symptoms. In 25 patients undergoing percutaneous intervention for either stable or unstable angina, plaque fragments were retrieved by directional coronary atherectomy. In the autopsy study, at least one coronary artery in each case showed some degree of neointimal proliferation, characterized by smooth muscle cells in a dense extracellular matrix. A neovascularization process was seen in 17.5% of the 40 samples analyzed. In 2 cases, the transmural pathway of the neovessels could be tracked: serial sections revealed the emergence of an arteriole from the adventitia of the coronary artery, its transmedial course as a capillary, and its opening into the coronary arterial lumen. In symptomatic patients who underwent atherectomy, neovessels were found in 1 of 9 patients with stable angina (11%) and in 8 of 16 patients with unstable angina (50%, P < 0.05). Mostly, the neovessels appeared as capillaries cut in their short axis. In 2 cases, however, the capillary was seen in its longitudinal axis, and its pathway could be traced through the atherosclerotic lesion to its opening in the coronary lumen, as in the autopsy study. Therefore, neovessels frequently develop in the atherothrombotic plaque, both in asymptomatic and anginal patients. In the latter group, the proliferation of neovessels is more frequent in acute coronary syndromes. These findings have several implications, in particular for percutaneous coronary angioplasty and related procedures, such as local drug delivery.

Clinically stable angina pectoris is not necessarily associated with histologically stable atherosclerotic plaques

OBJECTIVE

To investigate the extent of plaque inflammation in culprit lesions of patients with chronic stable angina.

DESIGN

Retrospective study.

SETTING

Amsterdam reference centre.

SUBJECTS

89 consecutive patients who underwent directional coronary atherectomy, 58 of whom met the following inclusion criteria: chronic stable angina (Canadian Cardiovascular Society classification 1-3 (group 1, n = 28)); unstable angina (Braunwald class II (group 2, n = 18)); unstable angina (Braunwald class III (group 3, n = 12)).

INTERVENTIONS

Directional atherectomy in patients with angina pectoris.

MAIN OUTCOME MEASURES

Tissue areas of culprit lesions occupied by inflammatory cells and smooth muscle cells related to clinically defined ischaemic syndrome.

RESULTS

Areas (% of total surface area (mean (SEM)) rich in smooth muscle cells were larger in patients with chronic stable angina (group 1, 51.2 (20.9)) than in those with unstable angina (group 2, 42.1 (20.5); group 3, 29.5 (19.4)) (1 v 2 and 2 v 3, NS; 1 v 3, P < 0.004). Macrophage rich areas were significantly smaller in patients with stable angina (group 1, 21.8 (11.9)) than in those with unstable angina (group 2, 31.5 (14.6); group 3, 46.4 (16.7)) (1 v 2, P < 0.02; 2 v 3, P < 0.02; 1 v 3, P < 0.001). Mean numbers of T cells per mm2 were as follows: group 1, 17 (9.4); group 2, 25 (15.9); group 3, 41 (30.6) (1 v 2, P 0.04; 2 v 3, P 0.07; 1 v 3, P < 0.001). Areas with HLA-DR positive cells showed the same pattern as macrophages and T cells and were smaller in stable (29.9 (12.4)) than in unstable angina (group 2, 40.4 (17.6); group 3, 52.4 (12.0)) (1 v 2, P < 0.02; 2 v 3, P < 0.05; 1 v 3, P < 0.001).

CONCLUSION

The inverse relation between the extent of inflammatory activity in plaque tissues of culprit lesions and the clinical stability of the ischaemic syndrome supports the concept that reduction of inflammation favours plaque stabilisation. At the same time, the considerable overlap between groups indicates that patients with clinically stable angina do not all have histologically stable plaques.

Expression of neutrophil and monocyte CD11B/CD18 adhesion molecules at different sites of the coronary tree in unstable angina pectoris

To assess the site of leukocyte activation in unstable angina, the expression of neutrophil and monocyte CD11B/CD18 adhesion molecules in 26 patients was measured from blood samples taken from the coronary ostium, the coronary sinus, and the coronary artery just distal to the culprit lesion (postobstructive chamber). CD11B/CD18 adhesion molecules detected by direct immunofluorescence evaluated by flow cytometry were significantly higher in the coronary sinus blood than in both the coronary ostium and the postobstructive chamber blood, suggesting that leukocyte activation takes place at the microcirculatory interface with the injured myocardium, probably as the result of short but repeated episodes of myocardial ischemia.

Correlation between clinical and morphologic findings in unstable angina

This study was undertaken to verify the hypothesis that the discrepant findings in published reports on the prevalence of thrombus in unstable angina depend on the inclusion of different clinical subsets in the various studies. We therefore correlated the clinical characteristics of patients included under the label of unstable angina with the morphologic features assessed by coronary angiography and intravascular ultrasound, and with histopathologic findings of atherectomy specimens. Fifty-eight patients with unstable angina (class B of the Braunwald classification) undergoing coronary arteriography followed by either coronary angioplasty (n = 20) or directional coronary atherectomy (n = 38) were studied. Fifteen patients were in class IB and 43 were in class II to IIIB. Among these 43 patients with angina at rest, 28 had ST-segment elevation during pain, and 15 had ST-segment depression, and 26 developed negative T waves on the baseline electrocardiogram (ECG) as a result of prolonged or repeated episodes of resting chest pain. Intravascular ultrasound examination of the culprit lesion was performed in 43 patients before the interventional procedure, and histopathologic analysis of atherectomy specimens was performed in 38 patients. Complex lesion morphology by angiography was observed in 31 patients (53%) without any significant relation to various clinical subsets. Patients in Braunwald class IB had more calcific plaques than patients in class II to IIIB (p < 0.001). Among patients with angina at rest, those with negative T waves on the baseline ECG, as well as those with transient ST elevation during pain, had a significantly higher incidence of noncalcific lesions (p = 0.001 for both). Analysis of atherectomy specimens revealed acute coronary lesions (thrombus and/or intraplaque hemorrhage) in 18 patients (47%). The incidence of acute coronary lesions was significantly higher in patients with than without negative T waves on the baseline ECG (p = 0.005), and increased further when negative T waves were combined with ST elevation during pain (p = 0.001). Multivariate analysis revealed that the presence orf negative T waves on the baseline ECG was the only explanatory variable related to the presence of acute coronary lesions by histology (p = 0.03). Patient subsets included in the broad spectrum of unstable angina have different morphologic features and incidence of acute coronary lesions by histology. These data provide an explanation for the discrepant findings in published reports on the relevance of thrombus formation in the pathogenesis of unstable angina.

Angiotensin converting enzyme gene deletion allele is independently and strongly associated with coronary atherosclerosis and myocardial infarction

OBJECTIVE

To investigate the association of the three angiotensin converting enzyme (ACE) genotypes, DD, ID, and II, with the occurrence or absence of coronary atherosclerosis and with myocardial infarction and hypertension.

DESIGN

Cohort analysis study.

SETTING

North-Italy reference centre.

SUBJECTS

388 white Italian patients (281 males; mean age 60.7 (SD 12.5) years) with proven coronary atherosclerosis (n = 255) or with angiographically normal coronary arteries (n = 133). A further group of 290 healthy blood donors was tested for allele frequency comparison.

INTERVENTIONS

ACE/ID polymorphism was analysed with polymerase chain reaction on DNA from white blood cells.

MAIN OUTCOME MEASURES

Coronary atherosclerosis, myocardial infarction, hypertension.

RESULTS

The D and I allele frequencies were respectively 0.63 and 0.37 in the overall healthy blood donor group and 0.66 and 0.34 in the overall study group. In the latter, univariate analysis showed (1) that coronary atherosclerosis (255 patients) was associated with the deletion allele, with an odds ratio (OR) of 5.78 for DD/II, P < 0.001, and 2.39 for ID/II, P = 0.006; and (2) that myocardial infarction (154 patients) was associated with the DD genotype (OR DD/II = 2.56, P = 0.007), but not with the ID genotype (OR DD/II = 1.96, P = 0.056). Finally, hypertension proved to be unrelated with the ACE genotype. The distribution between the three genotypes of known risk factors for coronary artery disease was similar. Logistic regression modelling, performed to test the association of the selected risk factors simultaneously with coronary atherosclerosis and myocardial infarction, showed that the deletion allele (whether DD or ID) was the strongest risk factor for atherosclerosis, and that the D allele was significantly associated with the risk of infarction (although to a lesser extent than with coronary atherosclerosis).

CONCLUSION

ACE deletion polymorphism is strongly and independently associated with coronary atherosclerosis and, to a lesser extent, with myocardial infarction. As such, the results are analogous to what has already been reported in French white, Japanese, and Welsh coronary patients.