Morphologic comparison of atherosclerotic lesions in native coronary arteries and saphenous vein graphs with intracoronary angioscopy in patients with unstable angina

In vivo morphologic comparison of saphenous vein grafts and native coronary arteries following non-ST elevation myocardial infarction

OBJECTIVE

This study aimed to assess the pathophysiological differences between saphenous vein grafts (SVG) and native coronary arteries (NCA) following presentation with non-ST elevated myocardial infarction (NSTEMI).

BACKGROUND

There is accelerated pathogenesis of de novo coronary disease in harvested SVG following coronary artery bypass (CABG) surgery, which contributes to both early and late graft failure, and is also causal in adverse outcomes following vein graft PCI. However in vivo assessment, with OCT imaging, comparing the differences between vein grafts and NCAs has not previously been performed.

METHODS

We performed a retrospective, observational, analysis in patients who underwent PCI with adjunctive OCT imaging following presentation with NSTEMI, where the infarct-related artery (IRA) was either in an SVG or NCA.

RESULTS

A total of 1550 OCT segments was analysed from thirty patients with a mean age of 66.3 (±9.0) years were included. The mean graft age of 13.9 (±5.6) years in the SVG group. OCT imaging showed that the SVG group had evidence of increased lipid pool burden (lipid pool quadrants, 2.1 vs 2.7; p = 0.021), with a reduced fibro-atheroma cap-thickness in the SVG group (45.0 μm vs 38.5 μm; p = 0.05) and increased burden of calcification (calcified lesion length = 0.4 mm vs 1.8 mm; p = 0.007; calcified quadrants = 0.2 vs 0.9; p = 0.001; arc of superficial calcium deposits = 11.6° vs 50.9°; p = 0.007) when compared to NCA.

CONCLUSION

This OCT study has demonstrated that vein grafts have a uniquely atherogenic environment which leads to the development of calcified, lipogenic, thin-capped fibro-atheroma's, which may be pivotal in the increased, acute and chronic graft failure rate, and may underpin the increased adverse outcomes following vein graft PCI.

Embolization after percutaneous coronary intervention in acute coronary syndrome. Saphenous vein grafts versus native coronary arteries

AIMS

The aim of this study was to assess the occurrence of distal embolization and to quantify the amount of embolic material captured during stent implantation in native coronary arteries, as compared with saphenous vein grafts (SVG) in patients at different time periods after an acute coronary syndrome.

PATIENTS AND METHODS

In all, 104 patients presenting with unstable or stable angina underwent percutaneous coronary intervention (PCI) in 107 vessels and stent implantation in 112 lesions, 53 % of which were in SVG.

RESULTS

Device deployment and retrieval was successful in 111 lesions. Embolic material was detected in 74 % of the protection devices. Early PCI, during a 2-week period after the last ischemic episode, was associated with larger embolic load, especially in the right coronary artery. The length of the lesion was the only preprocedural independent variable that was found to be a significant predictor for the presence of emboli (p = 0.002). The stent diameter and the maximum dilatation pressure were the two procedural variables found to be significant predictors for the presence of emboli (p = 0.025 and p = 0.008, respectively). The irregularity of the lesion and the number of stents deployed were found to have a predictive correlation to the total area of the embolic particles (p = 0.04 and p = 0.005, respectively).

CONCLUSION

Distal embolization of atherosclerotic debris is a frequent phenomenon after PCI not only in SVG but also in native vessels. The amount of embolic material seems to be related to the atherosclerotic burden of the vessel and to the early timing of the procedure as related to acute coronary syndrome.

Outcomes of patients with prior coronary artery bypass graft who present with acute coronary syndrome

Generally, patients with prior coronary artery bypass graft (CABG) are often under-represented in acute coronary syndrome (ACS) clinical trials. Nevertheless, there is growing global attention concerning their short- and long-term prognosis. Some reports suggest prior CABG as an independent risk factor for increased mortality, while others report an equal or a more favorable prognosis despite their adverse baseline clinical characteristics. The reasons for this 'risk-mortality paradox' need to be further evaluated. More recent reports showed a significant reduction in in-hospital morbidity and mortality over a 20-year period of follow up that may be attributed to the improvement in surgical CABG techniques and increased use of evidence-based therapies over the past two decades. In the current review we discuss the available literature regarding outcomes of prior CABG patients who are presenting with ACS.

Association of preprocedural low-density lipoprotein cholesterol levels with myocardial injury after elective percutaneous coronary intervention

BACKGROUND

Lower levels of low-density lipoprotein cholesterol (LDL-C) are associated with less cardiovascular risk in patients with coronary artery disease.

OBJECTIVES

To assess whether lower preprocedural LDL-C levels are associated with less risk of periprocedural myocardial injury in patients undergoing elective percutaneous coronary intervention (PCI).

METHODS

We enrolled 2529 consecutive patients with normal preprocedural cardiac troponin I (cTnI) who successfully underwent elective PCI. The association between preprocedural LDL-C levels and peak cTnI levels within 24 hours after PCI was evaluated.

RESULTS

Preprocedural LDL-C levels were correlated to postprocedural cTnI levels (r = 0.059, P = .003). In the multivariable model, preprocedural LDL-C levels between 70 and 99 mg/dL were associated with less risk of postprocedural cTnI elevation above 1 × upper limit of normal (ULN) (odds ratio [OR]: 0.804; 95% confidence interval [CI]: 0.663-0.975; P = .027) up to 15 × ULN (OR: 0.709; 95% CI: 0.530-0.949; P = .021) compared with preprocedural LDL-C levels ≥100 mg/dL. Moreover, preprocedural LDL-C levels <70 mg/dL were more strongly associated with less risk of postprocedural cTnI elevation above 1 × ULN (OR: 0.736; 95% CI: 0.584-0.927; P = .009) up to 15 × ULN (OR: 0.655; 95% CI: 0.452-0.950; P = .026).

CONCLUSIONS

Lower preprocedural LDL-C levels were associated with less risk of periprocedural myocardial injury in patients undergoing elective PCI.

Aspirate from human stented native coronary arteries vs. saphenous vein grafts: more endothelin but less particulate debris

Stent implantation into atherosclerotic coronary arteries releases particulate debris and soluble substances that contribute to impaired microvascular perfusion. Here we addressed the potential for microvascular obstruction in patients with stenotic native right coronary arteries (nRCA) compared with saphenous vein grafts on right coronary arteries (SVG-RCA). We enrolled symptomatic, male patients with stable angina pectoris and a flow-limiting stenosis in their nRCA or SVG-RCA ( n = 18/18). Plaque volume and composition were analyzed using intravascular ultrasound before stent implantation. Coronary aspirate was retrieved during stent implantation under protection with a distal occlusion/aspiration device and divided into particulate debris and plasma. The release of catecholamines, endothelin, serotonin, thromboxane B2, and tumor necrosis factor-α was measured. The response of rat mesenteric arteries with intact (+E) and denuded (−E) endothelium to aspirate plasma (without and with selective endothelin receptor blockade) was normalized to that by potassium chloride (KClmax = 100%). Plaque volume and composition were not different between nRCA and SVG-RCA. There was less particulate debris (65 ± 8 vs. 146 ± 23 mg; P < 0.05) and more endothelin release (5.8 ± 0.8 vs. 1.3 ± 0.7 pg/ml; P < 0.05) in nRCA than in SVG-RCA, whereas the release of the other mediators was not different. Aspirate from nRCA induced stronger vasoconstriction than that from SVG-RCA [nRCA, 78 ± 6% (+E)/84 ± 5% (−E); SVG-RCA, 59 ± 6% (+E)/68 ± 3% (−E); P < 0.05 nRCA vs. SVG-RCA], which was attenuated by a nonspecific endothelin and a specific endothelin receptor A antagonist. Thus coronary aspirate from stented nRCA is characterized by less debris but more endothelin and stronger vasoconstrictor response than that from SVG-RCA.

Degenerated Saphenous Vein Graft Intervention: Should We Target the Native Vessel instead?

Coronary interventions of degenerated saphenous vein grafts (SVGs) continue to present a management challenge. Although repeat coronary artery bypass grafting (CABG) remains a significant risk factor for operative mortality, percutaneous coronary intervention (PCI) is still associated with a high risk for periprocedural events. There is a lack of consensus on the optimal treatment strategy for patients with severe stenosis of SVGs. It is imperative to review the characteristics of native versus SVG disease, risk factors for complications after SVG intervention, procedural treatment strategies important to the decision on which therapeutic strategy to follow, and measures to mitigate the risks of periprocedural complications.

Coronary aspirate TNFα reflects saphenous vein bypass graft restenosis risk in diabetic patients

BACKGROUND

Patients with diabetes mellitus (DM) have an increased risk for periprocedural complications and adverse cardiac events after percutaneous coronary intervention. We addressed the potential for coronary microvascular obstruction and restenosis in patients with and without DM undergoing stenting for saphenous vein bypass graft (SVG) stenosis under protection with a distal occlusion/aspiration device.

METHODS

SVG plaque volume and composition were analyzed using intravascular ultrasound before stent implantation. Percent diameter stenosis was determined from quantitative coronary angiography before, immediately after and 6 months after stent implantation. Coronary aspirate was retrieved during stent implantation and divided into particulate debris and plasma. Total calcium, several vasoconstrictors, and tumor necrosis factor (TNF)α in particulate debris and coronary aspirate plasma were determined.

RESULTS

Patients with and without DM had similar plaque volume, but larger necrotic core and greater particulate debris release in patients with than without DM (20.3±2.7 vs. 12.7±2.6% and 143.9±19.3 vs. 75.1±10.4 mg, P<0.05). The TNFα concentration in particulate debris and coronary aspirate plasma was higher in patients with than without DM (15.9±6.6 vs. 5.1±2.4 pmol/mg and 2.2±0.7 vs. 1.1±0.2 pmol/L, P<0.05), whereas total calcium and vasoconstrictors were not different. Patients with DM had a greater percent diameter stenosis 6 months after stent implantation than those without DM (22.17±5.22 vs. 6.34±1.11%, P<0.05). The increase in TNFα immediately after stent implantation correlated with restenosis 6 months later (r=0.69, P<0.05).

CONCLUSION

In diabetics, particulate debris and coronary aspirate plasma contained more TNFα, which might reflect the activity of the underlying atherosclerotic process.

TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov/ct2/results?term=NCT01430884; unique identifier: NCT01430884.

Saphenous vein aorto-coronary graft atherosclerosis in patients with chronic kidney disease: more plaque calcification and necrosis, but less vasoconstrictor potential

Atherosclerotic coronary arteries are more calcified in patients with than without chronic kidney disease (CKD). We addressed the potential for coronary microvascular obstruction in patients with and without CKD during stenting for saphenous vein aorto-coronary graft (SVG) stenosis under protection with a distal occlusion/aspiration device. In patients with and without CKD (n = 20/20), SVG plaque composition was analyzed from virtual histology using intravascular ultrasound analysis before stent implantation. There was more dense calcium and more necrotic core in patients with than without CKD (14 ± 3 vs. 3 ± 1 % and 21 ± 3 vs. 12 ± 2 % of plaque volume, respectively). Coronary aspirate was retrieved during stent implantation and divided into particulate debris and plasma. Patients with CKD had more particulate debris and calcium release than patients without CKD. In contrast, the release of serotonin was less in patients with than without CKD (0.4 ± 0.1 vs. 1.2 ± 0.3 μmol/L), whereas that of catecholamines, endothelin, tissue factor, thromboxane, tumor necrosis factor α, and C reactive protein was not significantly different. Confirming the biochemical results, aspirate plasma from patients with CKD induced less vasoconstriction of rat mesenteric arteries than that from patients without CKD (with endothelium (+E), 26 ± 7 %; without endothelium (-E): 28 ± 7 % vs. +E, 68 ± 12 %; -E: 95 ± 16 % of maximum KCl-induced vasoconstriction). Graft atherosclerosis of patients with CKD is more degenerated and releases more particulate debris and calcium, but the aspirate has surprisingly less serotonin and vasoconstrictor potential.

Vasoconstrictor Potential of Coronary Aspirate From Patients Undergoing Stenting of Saphenous Vein Aortocoronary Bypass Grafts and Its Pharmacological Attenuation

Rationale:

Stent implantation into atherosclerotic plaques releases, apart from particulate debris, soluble substances that contribute to impaired microvascular perfusion.

Objective:

To quantify the release of vasoconstrictors and to determine the efficacy of coronary dilators to attenuate their action.

Methods and Results:

Using a distal protection/aspiration device, coronary arterial blood was retrieved before and during stenting in 22 patients with severe saphenous vein aorto-coronary bypass stenoses. The release of catecholamines, endothelin, serotonin, thromboxane B 2 , and tumor necrosis factor (TNF)α was measured. The response of rat mesenteric arteries with intact (+E) and denuded (−E) endothelium to aspirate plasma was normalized to that by KCl. Responses to selective receptor blockade, adenosine, nitroprusside, and verapamil against the aspirate-induced constriction were determined. The coronary arterial plasma withdrawn before stenting induced 21±5% and the aspirate plasma after stenting induced 95±8% of maximum KCl-induced vasoconstriction. Serotonin, thromboxane B 2 , and TNFα release into aspirate plasma increased by 1.9±0.2 μmol/L, 25.6±3.1 pg/mL, and 19.7±6.1 pg/mL, respectively, during stenting. The aspirate-induced vasoconstriction was largely antagonized by selective serotonin receptor blockade, with little further antagonism by additional thromboxane receptor blockade. TNFα did not induce constriction per se but potentiated the constriction with serotonin and the thromboxane-analog U-46619 in arteries +E. The concentrations to induce half-maximal vasodilation were comparable for nitroprusside (+E, 3.3×10 −8 ; −E, 1.9×10 −8 mol/L) and verapamil (+E, 8.3×10 −8 ; −E, 7.8×10 −8 mol/L), and the vasoconstriction was eventually eliminated. The vasodilator response to adenosine was dependent on functional endothelium and weaker.

Conclusion:

Serotonin is the main coronary vasoconstrictor after stenting, and thromboxane and TNFα somewhat potentiate the serotonin response. Nitroprusside and verapamil are more potent than adenosine to attenuate the aspirate plasma-induced vasoconstriction, and they are not dependent on functional endothelium.

Pathophysiology of aortocoronary saphenous vein bypass graft disease

Aortocoronary saphenous vein bypass grafting relieves anginal pain in patients with coronary artery disease. However, its effectiveness is limited due to graft failure; the 10-year patency rate is 50%-60%. Early, 1-year and late graft failure may be due to thrombosis, fibrointimal hyperplasia and atherosclerosis, respectively. There is general agreement that vein graft atherosclerosis differs from arterial lesions in terms of temporal and histological changes. Vein graft atherosclerosis is more rapid, with diffuse concentric changes and a less noticeable fibrous cap, making venous plaques more vulnerable to rupture and subsequent thrombus formation. Despite progress in understanding the pathophysiology, some aspects of vein graft atherosclerosis need to be clarified. This review focuses on the pathophysiologic aspects of this widespread, costly and disabling disease, with emphasis on late graft occlusion and distinctions between arterial and venous atherosclerosis in terms of histology, pathophysiology and risk factors.

Multidetector CT and coronary artery bypass grafts

The aim of this review is to provide--starting from anatomical, surgical and pathophysiological data--elements for evaluating the status of coronary artery bypass grafts with multidetector computed tomography (CT), taking into consideration the most common conduits used (left and right internal mammary arteries, saphenous vein, radial artery, gastroepiploic artery) and early and late complications (stenosis or obstruction, vasospasm, aneurysms and pseudoaneurysms, malposition). Some of the major problems regarding the examination technique and image analysis are also discussed. Finally, we offer general guidelines for reporting the examination results.

Myocardial infarction: contemporary management strategies

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

Evidence based medicine: role of multidetector CT in the follow-up of patients receiving coronary artery bypass graft

PURPOSE

The aim of this study was to define the role of multidetector computed tomography (MDCT) in the follow-up assessment of patients undergoing coronary artery bypass grafting (CABG) using an evidence-based medicine (EBM) approach.

MATERIALS AND METHODS

We performed a literature search of the most reputable studies published in the period 1990-2005 on the clinical follow-up of patients after myocardial revascularisation by CABG. Relevant studies were ranked according to levels of evidence using EBM criteria. A similar search was also conducted on the Internet to identify and review the guidelines posted by the major international scientific societies.

RESULTS

A total of 29 papers meeting the basic reliability requirements of EBM were identified. The reported sensitivity and specificity for electrocardiogram (ECG) testing, stress echocardiography and radionuclide myocardial perfusion imaging were 45% and 82%, 86% and 90%, and 68% and 84%, respectively. All 16 CT studies (one retrospective, the remaining prospective) were validation studies comparing MDCT with conventional coronary angiography. The total number of patients and graft segments studied were 705 and 1,974, respectively. The total number of assessable graft segments were 62%-100%, with a sensitivity and specificity of 75%-100% and 76.9%-100%, respectively.

CONCLUSIONS

The applications of MDCT in the follow-up assessment of patients after CABG are derived from indirect evidence only. The efficacy of the method should be evaluated in randomised clinical trials comparing MDCT not only with conventional coronary angiography but also with other noninvasive stress imaging methods. On the basis of the clinical evidence reported in the literature, the indications for the use of MDCT are still limited. In our view, the completion of such randomised trials combined with the development of new-generation scanners is required to correctly define the role of MDCT in the follow-up assessment of patients who have undergone CABG.

Passive immunization with monoclonal IgM antibodies against phosphorylcholine reduces accelerated vein graft atherosclerosis in apolipoprotein E-null mice

Phosphorylcholine (PC) headgroup is one of the neoantigens exposed by LDL oxidation that can elicit an immune response. Active immunization with Streptococcus pneumoniae, which bears PC on its cell wall, reduced atherosclerosis in hypercholesterolemic mice and this effect was attributed to an immune response to PC. In this study we tested the hypothesis that passive immunization with a monoclonal anti-PC IgM antibody can be athero-protective in a murine model of native aortic and vein graft atherosclerosis. Inferior vena cava from 16-week-old donor male apoE-null mice was grafted into right carotid artery of age-matched male recipient apoE-null mice. Anti-PC IgM titers were evaluated before and 4 weeks after surgery. For the immunization protocol, a separate group of mice received weekly intraperitoneal injection of monoclonal anti-PC IgM (400 microg) for 4 weeks, starting the day of surgery. Controls received PBS or pooled polyclonal IgM. Anti-PC IgM titres significantly increased at 4 weeks following surgery. Passive immunization with anti-PC IgM reduced vein graft plaque size and neointimal thickness resulting in a larger luminal area; in addition immunization reduced the inflammatory cell content of the plaques. There was no significant effect on the established native aortic atherosclerotic lesions. Immunization did not affect circulating cholesterol levels. Taken together our data suggest that passive immunization with anti-PC IgM significantly reduces vein graft lesion size with less inflammatory phenotype without affecting cholesterol levels, indicating an athero-protective immune response to PC. Lack of effect on established native aortic lesions may have been due to short duration of therapy and/or reduced efficacy in established lesions as compared to evolving lesions of vein graft atherosclerosis.

Comparison of ruptured plaques in native coronary arteries and in saphenous vein grafts: an intravascular ultrasound study

Intravascular ultrasound (IVUS) has been used to describe ruptured plaques in saphenous vein grafts (SVGs) and native coronary arteries. We compared clinical, angiographic, and IVUS features of ruptured atherosclerotic plaques in SVGs and native coronary arteries. We identified 95 plaque ruptures in 76 SVGs in 73 patients. These lesions and patients were matched with 95 lesions and patients from a database of 468 native artery ruptures. The matching criterion was IVUS mean reference lumen area. Patients with ruptured SVG plaques were older (68.4 +/- 10.1 vs 65.0 +/- 10.6 years, p = 0.021), more often had hypercholesterolemia (92% vs 74%, p = 0.015) and hypertension (78% vs 62%, p = 0.059), and more often had a history of a remote myocardial infarction (57% vs 32%, p = 0.002). In contrast, anginal symptoms were similar in the 2 groups (70% to 75% of each group had an acute coronary syndrome). Most (90% to 95%) ruptured plaques in each group were classified as angiographically complex. However, ruptured SVG lesions more often had an angiographically visible intimal flap (71% vs 38%, p <0.001). More than 70% of lesions in the 2 groups had positive arterial remodeling by IVUS, but there was a tendency for a higher remodeling index in ruptured plaque SVG lesions (1.18 +/- 0.30 vs 1.11 +/- 0.20, p = 0.085). The site of the initial tear occurred mainly (in approximately 70%) at the plaque shoulders in the 2 groups. In conclusion, although patients with SVG plaque ruptures are older and have more co-morbidities, the clinical presentation and angiographic and IVUS features are remarkably similar to those of native artery plaque ruptures.

Distal Protection Improved Reperfusion and Reduced Left Ventricular Dysfunction in Patients With Acute Myocardial Infarction Who Had Angioscopically Defined Ruptured Plaque

Background— Distal protection, in the Saphenous Vein Graft Angioplasty Free of Emboli (SAFER) trial, is demonstrated to prevent distal embolism in the percutaneous coronary intervention of saphenous vein graft. However, in the Enhanced Myocardial Efficacy and Recovery by Aspiration of Liberated Debris (EMERALD) trial, it was not effective in the percutaneous coronary intervention of native coronary arteries in patients with acute myocardial infarction (AMI). We hypothesized that its effectiveness would be determined by lesion characteristics. Therefore, we classified the type of culprit lesion by angioscopy and examined its influence on the effectiveness of distal protection, comparing patients with AMI treated with and without distal protection.

Methods and Results— Consecutive patients with AMI treated without distal protection (n=110) from July 2000 to July 2002 and those treated with distal protection (n=81) from July 2002 to July 2004 were included. Patients in each group were subdivided according to whether or not they had angioscopically defined ruptured plaque at culprit lesion. Among those groups, incidence of no-reflow phenomenon, ST-segment resolution, myocardial blush grade, and left ventricular ejection fraction at 6 months were compared. Aspirated samples by distal protection were semiquantitatively and histologically analyzed and compared between patients with and without ruptured plaque. No-reflow phenomenon was most frequently ( P <0.05) observed in patients with ruptured plaque treated without distal protection. ST-segment resolution (68±15% versus 40±21%, P <0.001), myocardial blush grade (2.6±0.5 versus 1.8±0.3, P <0.001), and left ventricular ejection fraction (47.2±6.7% versus 41.0±9.7%, P <0.01) were improved by distal protection among patients with ruptured plaque but not among patients without ruptured plaque. Aspirated samples >1 mm were detected more frequently (97.3% versus 78.5%, P <0.05) in patients with ruptured plaque than those without ruptured plaque. Histologically, aspirated samples contained plaque debris (95.3% versus 31.1%, P <0.05) more frequently in patients with ruptured plaque than in those without ruptured plaque.

Conclusions— Distal protection reduced microcirculation damage and left ventricular dysfunction in patients with AMI who had angioscopically defined ruptured plaque. Distal embolization of plaque debris was detected more frequently in patients with ruptured plaque. These results suggest that microcirculation damage and left ventricular dysfunction are increased mainly by distal embolization of plaque debris rather than of thrombus.

Incidence and Clinical Correlates of Ruptured Plaques in Saphenous Vein Grafts

OBJECTIVES

The goal of this study was to assess the incidence, clinical correlates, and angiographic appearance of ruptured atherosclerotic plaques detected in saphenous vein grafts (SVGs).

BACKGROUND

Ruptured atherosclerotic plaques in native coronary arteries but not in SVGs have been well described with intravascular ultrasound (IVUS).

METHODS

We reviewed 791 pre-intervention IVUS SVG studies and identified 95 ruptured plaques in 76 SVGs in 73 patients. Standard clinical, angiographic, and IVUS measurements were collected and/or measured. Ruptured plaques were compared with nonruptured plaques in 276 randomly selected patients.

RESULTS

The IVUS-detected ruptured plaques had angiographically complex morphology (95%) with ulceration (79%), intimal flap (71%), and sometimes aneurysm formation (14%). Compared with control SVG lesions, ruptured plaques occurred more often in patients with acute coronary syndromes, in older SVGs (12.3 +/- 5.0 years vs. 8.6 +/- 5.2 years, p < 0.001), and in patients with hypercholesterolemia (92% vs. 81%, p = 0.021) and hypertension (78% vs. 63%, p = 0.015). Multiple ruptured plaques were identified in 22 patients in 19 grafts, more often in diabetic patients (55% vs. 29%, p = 0.054). A tear in the fibrous cap could be identified in 59% of plaques; in 70% it occurred at the shoulder of the plaque and in 30% at the center of the plaque. The IVUS features of ruptured plaques included positive remodeling in 71%, which was more common than in control plaques (40%, p < 0.001).

CONCLUSIONS

Ruptured atherosclerotic plaques occur in old SVGs with an incidence of 9.7%. These lesions have a complex angiographic appearance and positive remodeling characteristics. This is similar to ruptured plaques in native arteries.

Differential effects of apolipoprotein A-I-mimetic peptide on evolving and established atherosclerosis in apolipoprotein E-null mice

BACKGROUND

Apolipoprotein (apo) A-I and apoA-I-mimetic peptides showed promise to prevent atherosclerosis development. Using a bypassed vein graft model in apoE-null mice, we evaluated the effects of oral or intraperitoneal administration of an apoA-I-mimetic peptide on evolving atherosclerotic lesions in the vein graft and compared such effects on the established atherosclerotic lesions in aortic sinus in the same mice.

METHODS AND RESULTS

We used apoE-null mice in which a segment of inferior vena cava was grafted into the right carotid artery at 16 weeks of age. Native aortic atherosclerotic lesions (established atherosclerosis) and vein-graft atherosclerotic lesions (evolving atherosclerosis) were assessed 4 weeks after daily oral (0.3 mg/mL) or intraperitoneal (50 microg in 200 microL saline) administration of an apoA-I-mimetic peptide, D4F. Mice receiving saline or water without D4F served as controls. Both oral and intraperitoneal administration of D4F reduced vein-graft atherosclerotic (evolving lesions) plaque size by 43% and 42%, plaque lipid by 70% and 49%, and macrophage immunoreactivity by 63% and 62%, respectively, compared with controls. In contrast, D4F had no effect on the native aortic sinus atherosclerotic lesions (established lesions).

CONCLUSIONS

Oral and intraperitoneal administration of the apoA-I-mimetic peptide D4F significantly reduced rapidly evolving atherosclerotic lesions in vein grafts but not established atherosclerotic lesions in aortic sinus. These observations suggest that the type of atherosclerotic lesions and the time of initiation during the course of lesion evolution modulate the beneficial effects of apoA-I-mimetic peptides on atherosclerosis.

Cholesterol-fed ovariectomized monkeys are good animal models for human atherosclerosis of postmenopausal women

Although it is well known that the incidence of atherosclerosis is markedly increased in postmenopausal women, antiatherosclerotic effects of estrogen replacement therapies are not clear. One of the reasons for this is due to the lack of appropriate animal models for atherosclerosis of postmenopausal women. Therefore, we attempted to develop an animal model for atherosclerosis of postmenopausal women and examined the antiatherosclerotic effects of estrogen replacement therapy. Adult ovariectomized Japanese monkeys were fed 2% cholesterol diet alone (C-group) or in combination with conjugated estrogen (CE-group) for 30 months. The serum estradiol-17beta levels of the CE-group were varied between 10 and 204.5 ng/dl during treatment. In the C-group, the serum total cholesterol levels were increased from 110 to 270 mg/dl, and atheroma was first observed after 3-months treatment with angioscopy. In the CE-group, the levels of the serum total cholesterol during treatment were 30% lower than those of the C-group, and the aortic lesions were first observed after 12-months treatment with angioscopy. The aortic intimal thickness of the CE-group was 58% of the C-group. This finding showed good agreement with the angioscopic observation. The aortic lesions were of a fibromuscular type in both groups. In conclusion, a cholesterol-fed ovariectomized monkey is an appropriate animal model for atherosclerosis of postmenopausal women. Furthermore, angiofiberscopic and histopathological observations suggested that estrogen replacement therapy was valid for atherosclerosis of postmenopausal women.

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.

Accelerated atherosclerosis in saphenous vein bypass grafts: a spectrum of diffuse plaque instability

Our understanding of plaque instability may be extended to vein graft atherosclerosis, which appears to represent the end of a continuum of plaque instability. Compared with plaque in native coronary arteries, vein graft atheroma is more diffuse and vulnerable to rupture, and the consequences of plaque rupture in vein grafts seem to be associated with almost certain thrombotic occlusion within 7 to 12 years after surgery.

Percutaneous intervention of old degenerated saphenous vein grafts

The treatment of failing bypass grafts is difficult because repeat surgery carries a higher mortality rate than a first operation. Percutaneous intervention is more difficult because mechanical manipulation of these soft, friable atherosclerotic plaques have been associated with a significant rate of distal embolization, myocardial infarction, late restenosis and death. Balloon angioplasty alone has proven to have serious limitations in the treatment of older degenerated saphenous vein grafts (SVG). Although directional atherectomy yielded a higher angiographic success in a randomized trial, the restenosis rate was similar, and the procedural complications higher. The transluminal extraction catheter (TEC) has also shown significant limitations for the treatment of degenerated or thrombotic vein grafts with a significant procedural complication rate. A randomized trial comparing stenting versus balloon angioplasty in focal SVG lesions showed a higher freedom from major adverse cardiovascular events in the stent group, but there was no significant difference in the angiographic restenosis rates. More recently, rheolytic thrombectomy and mechanical thrombolysis have proven useful in treating thrombotic lesions in SVG. In addition, the recent development of distal protection devices appears very promising and will probably contribute to decreased distal embolization during percutaneous revascularization of these conduits.

Aspirin, warfarin, or the combination for secondary prevention of coronary events in patients with acute coronary syndromes and prior coronary artery bypass surgery

BACKGROUND

Patients with a non-ST-elevation acute coronary syndrome and prior CABG are at high risk of a recurrent ischemic event despite aspirin therapy. This trial investigated the potential benefit of secondary prevention with warfarin.

METHODS AND RESULTS

In a double-blind randomized trial, 135 patients with unstable angina or non-ST-segment elevation myocardial infarction, with prior CABG, and who were poor candidates for a revascularization procedure received therapy with aspirin and placebo+warfarin, warfarin and placebo+aspirin, or aspirin and warfarin for 12 months. Warfarin was titrated to an international normalized ratio of 2.0 to 2.5. The primary end point (death or myocardial infarction or unstable angina requiring hospitalization 1 year after randomization) occurred in 14.6% of the patients in the warfarin-alone group, in 11.5% of patients in the aspirin-alone group, and in 11.3% of patients randomized to the combination therapy (P=0.76). Subgroup analyses by risk features provided no indications that warfarin alone or in combination with aspirin could be of benefit over aspirin alone. Bleeding was more frequent in the 2 groups of patients administered warfarin.

CONCLUSIONS

Moderate-intensity oral anticoagulation alone or combined with low-dose aspirin does not appear to be superior to low-dose aspirin in the prevention of recurrent ischemic events in patients with non-ST-elevation acute coronary syndromes and previous CABG.

Interesting cases from the University of Texas Medical Branch

This article discusses the cases for four patients with unstable angina. The first case is an example of the "high-risk" patient with widespread ECG changes, heart failure, and enzymatic elevations during an episode of chest pain. The second patient illustrates an unusual cause of unstable angina in a young women. The third patient had a large thrombus visible on angiography and management strategies for dealing with intracoronary thrombus are discussed. The final patient had an extensive past cardiac history with two prior coronary artery bypass operations and we discuss the recent advances made in the treatment of degenerative vein graft disease.