Coronary plaque erosion without rupture into a lipid core. A frequent cause of coronary thrombosis in sudden coronary death

Coronary Artery Calcification Revisited

Calcification is a common finding in human coronary arteries. However, there is conflicting evidence for a link between calcification and plaque instability. Current intravascular ultrasound (IVUS) technology allows a definitive detection of the calcification and measurement of the vessel wall. Using preinterventional IVUS images, we clarified that in patients with acute myocardial infarction, small "spotty" calcifications prevailed, associated with a fibrofatty plaque and positive remodeling. Conversely, in patients with stable angina pectoris, extensive calcification was frequent. IVUS allows the detection of vulnerable plaques in coronary arteries, by identifying not only a large lipid core and positive remodeling, but also a spotty pattern of calcification.

Atherothrombosis and high-risk plaque: part I: evolving concepts

Atherothrombosis is a complex disease in which cholesterol deposition, inflammation, and thrombus formation play a major role. Rupture of high-risk, vulnerable plaques is responsible for coronary thrombosis, the main cause of unstable angina, acute myocardial infarction, and sudden cardiac death. In addition to rupture, plaque erosion may also lead to occlusive thrombosis and acute coronary events. Atherothrombosis can be evaluated according to histologic criteria, most commonly categorized by the American Heart Association (AHA) classification. However, this classification does not include the thin cap fibroatheroma, the most common form of high-risk, vulnerable plaque. Furthermore, the AHA classification does not include plaque erosion. As a result, new classifications have emerged and are reviewed in this article. The disease is asymptomatic during a long period and dramatically changes its course when complicated by thrombosis. This is summarized in five phases, from early lesions to plaque rupture, followed by plaque healing and fibrocalcification. For the early phases, the role of endothelial dysfunction, cholesterol transport, high-density lipoprotein, and proteoglycans are discussed. Furthermore, the innate and adaptive immune response to autoantigens, the Toll-like receptors, and the mechanisms of calcification are carefully analyzed. For the advanced phases, the role of eccentric remodeling, vasa vasorum neovascularization, and mechanisms of plaque rupture are systematically evaluated. In the final thrombosis section, focal and circulating tissue factor associated with apoptotic macrophages and circulatory monocytes is examined, closing the link between inflammation, plaque rupture, and blood thrombogenicity.

Serum levels of osteoprotegerin and RANKL in patients with ST elevation acute myocardial infarction

OPG (osteoprotegerin) has been suggested to have an important role in atherogenesis and vascular calcification. In the present study, we have investigated serum OPG and RANKL (receptor activator of nuclear factor kappaB ligand) concentrations in patients with ST elevation AMI (acute myocardial infarction) and established CAD (coronary artery disease). OPG and RANKL were measured in 58 male patients hospitalized in the coronary care unit with ST elevation AMI, in 52 asymptomatic male patients with an established diagnosis of CAD and in 52 healthy male controls. These last two groups were matched with the AMI patients for age and body mass index. OPG was significantly (P<0.05) higher in patients with AMI at 1 h after AMI (8.04+/-4.86 pmol/l) than in both patients with established CAD (4.92+/-1.65 pmol/l) and healthy subjects (3.15+/-1.01 pmol/l). Subjects with established CAD had significantly (P<0.05) increased OPG levels compared with controls. RANKL levels in patients with established CAD (0.02+/-0.05 pmol/l) and with AMI (0.11+/-0.4 pmol/l) were significantly (P<0.05) lower compared with controls (0.32+/-0.35 pmol/l). In the AMI group, OPG decreased significantly (P<0.05) at 1 and 4 weeks after infarction (8.04+/-4.86 compared with 6.38+/-3.87 and 6.55+/-2.6 pmol/l respectively), but OPG levels, either at 1 h or 1-4 weeks after AMI, remained significantly (P<0.05) higher compared with established CAD (4.92+/-1.65 pmol/l) and controls (3.15+/-1.01 pmol/l). Our data show for the first time that OPG levels are increased in ST elevation AMI within 1 h of infarction. Whether the increase in OPG is a consequence or a causal factor of plaque destabilization deserves further investigation.

Diabetes mellitus: clinical presentation and outcome in men and women with acute coronary syndromes. Data from the Euro Heart Survey ACS

AIMS

To study clinical presentation, in-hospital course and short-term prognosis in men and women with diabetes mellitus and acute coronary syndromes (ACS).

METHODS

Men (n = 6488, 21.2% with diabetes) and 2809 women (28.7% with diabetes) < or = 80 years old, with a discharge diagnosis of ACS were prospectively enrolled in the Euro Heart Survey of ACS.

RESULTS

Women with diabetes were more likely to present with ST elevation than non-diabetic women, a difference that became more marked after adjustment for differences in smoking, hypertension, obesity, medication and prior disease [adjusted odds ratio (OR) 1.46 (1.20, 1.78)], whereas there was little difference between diabetic and non-diabetic men [adjusted OR 0.99 (0.86, 1.14)]. In addition, women with diabetes were more likely to develop Q-wave myocardial infarction (MI) than non-diabetic women [adjusted OR 1.61 (1.30, 1.99)], while there was no difference between men with and without diabetes [adjusted OR 0.99 (0.85, 1.15)]. There were significant interactions between sex, diabetes and presenting with ST-elevation ACS (P < 0.001), and Q-wave MI (P < 0.001), respectively. Of the women with diabetes, 7.4% died in hospital, compared with 3.6% of non-diabetic women [adjusted OR 2.13 (1.39, 3.26)], whereas corresponding mortality rates in men with and without diabetes were 4.1% and 3.3%, respectively [OR 1.13 (0.76, 1.67)] (P for diabetes-sex interaction 0.021).

CONCLUSION

In women with ACS, diabetes is associated with higher risk of presenting with ST-elevation ACS, developing Q-wave MI, and of in-hospital mortality, whereas in men with ACS diabetes is not significantly associated with increased risk of either. These findings suggest a differential effect of diabetes on the pathophysiology of ACS based on the patient's sex.

Reducing the risks of sudden death and heart failure post myocardial infarction: utility of optimized pharmacotherapy

Current guidelines define the standard of care for patients after myocardial infarction (MI), with particular focus on patients with significant ventricular dysfunction. Inherent in these recommendations are assumptions about the relative risks and benefits, as well as the costs, of the available options. This review will consider strategies to prevent sudden death and heart failure post-MI by utilization of pharmacologic therapies--angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARB), aldosterone antagonists, statins, and beta-blockers--in parallel with the approaches reviewed elsewhere in this supplement. A patient-centric approach necessitates that drugs in each class be compared for efficacy within this patient population. Clinical trials have demonstrated the efficacy of several drugs, such as ACE inhibitors, beta-blockers, and aldosterone antagonists, in patients post-MI, yet these benefits do not seem to be reflected in the epidemiologic data. This may reflect underutilization of these therapies or, alternatively, support the notion that efficacy in clinical trials does not assure effectiveness in clinical practice. The latter point is a subject of ongoing investigation, while the former is being addressed through quality-of-care initiatives. In clinical practice, aggressiveness is key, starting with patient education. If patients understand their risks better, compliance and adoption of a more ideal lifestyle seem more likely. However, even with educational programs, human nature teaches us that marked change in behavior is difficult and therefore, to minimize risks, particularly of sudden death and heart failure post infarction, an optimized pharmacologic regimen serves as a powerful tool.

Determinants of plaque instability in atherosclerotic vascular disease

BACKGROUND

Despite numerous advances in the understanding of the pathogenesis of atherosclerosis, the factors that determine atheromatous plaque instability remain unclear. The prediction of the vulnerability of a plaque to rupture and subsequent thrombosis would be useful in guiding development of diagnostic and therapeutic approaches.

METHODS

Aortas with areas of gross atherosclerosis were obtained from seven autopsy cases. These were then serially sectioned at 3-mm intervals, analyzed histologically, and scored as to plaque size, calcification, lipid content, intraplaque hemorrhage, inflammation, plaque disruption, and plaque thrombosis. Bivariate correlations and binary multivariate regression analyses were performed using SPSS software.

RESULTS

Plaque instability was highly correlated with intraplaque hemorrhage, lipid content, and plaque size. Weaker but statistically significant correlations were found with inflammation and calcification. However, in multivariate regression analyses, only plaque size, intraplaque hemorrhage, and lipid content, independent predictors of plaque instability, were significant.

CONCLUSIONS

Atheromatous plaques may be rendered unstable by increases in size, increased intra- and extracellular lipid accumulation, and intraplaque hemorrhage. Based on these results, diagnostic modalities that detect plaque size, plaque hemorrhage, and/or lipid content are most likely to be useful in predicting unstable plaques.

High glucose-induced apoptosis through store-operated calcium entry and calcineurin in human umbilical vein endothelial cells

Diabetes mellitus causes multiple cardiovascular complications. Previous studies have shown that prolonged exposure (96 h) of human umbilical vein endothelial cells (HUVECs) to hyperglycemia causes a significant increase in apoptosis. We report here that this increase in apoptosis is associated with an increase in Ca(2+) current (whole cell patch-clamp recorded) resulting from Ca(2+) entry mediated by store-operated channels (SOCs). The number of apoptotic cells after prolonged high glucose (HG, 30 mmol/L) exposure was significantly reduced in the presence of the SOC inhibitor 2-APB or of La(3+). A marked increase (approximately 80%) in Ca(2+)-dependent calcineurin (CN-A) phosphatase activity also occurred after prolonged HG exposure. Prolonged HG exposure-induced increase in CN-A activity was prevented by 2-APB, and selective CN-A phosphatase inhibition by FK506 or calmodulin inhibition by calmidazolium decreased HG-induced apoptosis. Blocking hydrogen peroxide production using catalase or inhibiting the tyrosine kinase pp60(src) during prolonged exposure to HG, resulted in a marked decrease in apoptosis and was further associated with a significant reduction in CN-A phosphatase activity. The results demonstrate a significant role for Ca(2+) entry in HG-induced apoptosis in HUVECs, and suggest that this role is mediated via H(2)O(2) generation and the action of the Ca(2+)-activated protein phosphatase calcineurin.

C-reactive protein increase in unstable coronary disease cause or effect?

A crucial point in understanding the clinical and pathophysiologic meaning of C-reactive protein (CRP) elevation in acute coronary syndromes (ACS) is whether CRP release is predominantly a response to even small amounts of myocardial necrosis, for which troponin is a sensitive and specific marker, or is an independent indicator of the inflammatory process occurring in that clinical condition. Whereas troponin is a good predictor of both mortality and myocardial infarction (MI), although the highest values are associated with a decreased probability of MI, CRP predicts mortality but has no relation with the early or late occurrence of MI. The large variability of CRP values in ACS may depend on the different response of this inflammation marker to various stimuli, some patients being particularly hyperresponsive, especially those with elevated CRP values at baseline. We hypothesize that myonecrosis, as detected by troponin increases, would represent the strongest stimulus for CRP increase in ACS, causing in some patients, especially those with already-elevated CRP values at baseline, a disproportionate increase of this marker. Accordingly, the highest CRP values during ACS are likely to be observed in patients with already-elevated CRP values at baseline (which would increase the probability of having death and MI in the follow-up) and the highest troponin values (which would increase the probability of death in the follow-up, but not of subsequent MI). This hypothesis would explain why high CRP levels in unstable coronary disease are good predictors of death, but not of MI.

Update on using coronary calcium screening by computed tomography to measure risk for coronary heart disease

Coronary artery disease (CAD) is the number one killer of adults in the United States, claiming one-half million deaths annually. Early detection and prevention strategies clearly remain a top priority for health care providers in order to reduce the high mortality rate of heart disease. As an unequivocal reflection of arteriosclerosis, coronary arterial calcium (CAC) may provide a means to qualitatively assess the overall disease severity and likewise serve as a means to assess risk for CHD. It is known that patients with heavy calcium burdens have more advanced CAD, a concomitantly a higher likelihood of coronary stenoses, and a concomitant higher risk for acute cardiac events. Computed tomography has been shown to be an accurate, non-invasive method to quantify coronary calcification burden in patients. Evidence shows that calcium measurements by CT correlate well with histological plaque analyses, and that CAC measurements accurately reflect disease severity and can be useful to assess individual risk for CHD. The purpose of this article is to summarize the currently available evidence that has attempted to validate CAC screening as a screening exam and risk predictor for coronary heart disease.

Alteplase treatment affects circulating matrix metalloproteinase concentrations in patients with ST segment elevation acute myocardial infarction

INTRODUCTION

Matrix metalloproteinases (MMPs) are expressed in atherosclerotic plaques. Acute coronary syndromes may be precipitated by MMPs through degradation of the fibrous cap and subsequent plaque disruption. Serine proteases such as plasmin activate MMPs and may contribute to plaque events. Thrombolysis with recombinant tissue plasminogen activator (rtPA) is widely used for treatment of acute ST segment elevation myocardial infarction (STEMI). In the present study we assessed whether thrombolytic therapy with rtPA in patients with STEMI influences serum levels of MMP-2 and MMP-9.

METHODS

We recruited 108 patients (92 men, mean age 64 +/- 12 years) with STEMI, of whom 84 (78%) received thrombolytic treatment with rtPA and 24 (22%) did not. MMP-2 and MMP-9 levels were assessed at hospital admission (baseline), and at 24 and 72 h after admission, using a commercially available ELISA.

RESULTS

Overall, MMP-9 levels were higher in the thrombolysis group compared to patients without thrombolysis (p < 0.001). Thrombolysis treatment significantly affected the change in MMP-9 levels during the 72-h study period (p < 0.001).

CONCLUSIONS

The present study showed that thrombolysis could affect circulating levels of MMP-9 in STEMI patients. Whether this effect may lead to plaque instability deserves further investigation.

Biomechanical interaction between cap thickness, lipid core composition and blood pressure in vulnerable coronary plaque: impact on stability or instability

BACKGROUND

A 'thin' fibrous cap atheroma is the typical morphological characteristic of vulnerable plaque. Yet the very pathological studies that have provided these descriptions have also shown the actual prediction of plaque rupture to be rather less exact. Other relevant characteristics must be involved in the mechanisms of plaque rupture--blood pressure loading (P) and the material properties of the soft atheromatous core--as predictors of the distribution of the peak circumferential stress (PCS) locations.

METHODS AND RESULTS

We used a computational structural analysis based on three typical in-vivo intravascular ultrasound images of fibrous cap atheroma in which we decreased the cap thickness (CTh). With different soft atheromatous core Young's moduli (Ecore), 414 simulations were performed under eight different physiological loading blood pressures. The transition from plaque stability to plaque instability was defined by a threshold of 300 kPa and is a feature of vulnerability. It was found that (1) irrespective of plaque geometry and composition, CTh < 60 microm exposed the plaque to PCSs in excess of 300 kPa; (2) the exponential variations in PCS with change in CTh and Ecore values show that very slight structural changes are enough to tilt a vulnerable plaque from stability to instability or vice versa; and (3) the relationship between P and PCS is proportional with P acting as trigger or as protector.

CONCLUSION

The present study shows why, in clinical practice, mere morphological detection by imaging techniques of thin-cap fibro-atheroma is not in itself enough for the prediction of future rupture.

Association between cardiac troponin T elevation and angioscopic morphology of culprit lesion in patients with non-ST-segment elevation acute coronary syndrome

BACKGROUND

It is well known that cardiac troponin T (TnT) elevation on admission indicates a high-risk subgroup among patients with non-ST-segment elevation acute coronary syndrome (NSEACS). Although the mechanism of TnT elevation is speculated to be the microthromboembolism from unstable plaques, it has not been clarified. The aim of this study is to clarify the association between the serum TnT elevation and the angioscopically evaluated morphology of culprit lesion in the patients with NSEACS.

METHODS

Among 113 patients with NSEACS who had significant coronary stenosis, 62 patients with successful angioscopic examination were prospectively and consecutively enrolled from October 2001 to August 2002. Patients were divided into 2 groups according to the serum TnT level measured before percutaneous coronary intervention: TnT-positive or TnT-negative group. Thrombus and plaque color at culprit lesion were evaluated by angioscopy and were compared between the groups. Plaque color was determined as yellow or white, and thrombus as none, small, or large. Three different definitions for TnT-positive (> or =0.1, > or =0.03, and > or =0.01 ng/mL) were used and the sensitivity and specificity for detecting thrombus was compared.

RESULTS

Prevalence of thrombus, large thrombus, and yellow plaque were all higher in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Angiographic slow-flow occurred more frequently after percutaneous coronary intervention in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Sensitivity/specificity of detecting large thrombus were 33%/100%, 44%/91%, and 56%/83% when TnT-positive was defined as TnT > or = 0.1, > or =0.03, and > or =0.01 ng/mL, respectively.

CONCLUSIONS

Serum TnT level was significantly associated with the prevalence of thrombus and yellow plaque at the culprit lesions of NSEACS. Troponin T, when positive was defined as > or =0.01 ng/mL, still have a high specificity for detecting intracoronary thrombus.

Intravascular ultrasound study of patterns of calcium in ruptured coronary plaques

Coronary calcium is intimately associated with coronary atherosclerotic plaque development, although it is controversial as to whether coronary calcium is associated with plaque instability. We analyzed 101 IVUS-detected ruptured plaques and compared them with 101 computer-matched control plaques without evidence of plaque rupture. The arc of calcium was measured every 0.5 mm within 10-mm-long segments that spanned the minimum lumen cross-sectional area, and the number and length of calcium deposits were assessed. Ruptured plaques had a significantly larger number of individual calcium deposits than control plaques (3.5 +/- 1.7 vs 1.8 +/- 1.1, p <0.001). However, the arc of the largest calcium deposit was smaller and the length of the largest calcium deposit in each plaque was shorter in ruptured plaques compared with control plaques (67.3 degrees +/- 41.4 degrees vs 114.9 degrees +/- 77.4 degrees , p <0.001, and 1.6 +/- 1.3 vs 4.0 +/- 2.7 mm, p <0.001, respectively). There was no difference in the number of superficial calcium deposits between the 2 groups, although ruptured plaques had significantly smaller arcs of superficial calcium compared with control plaques (56.2 degrees +/- 35.5 degrees vs 95.8 degrees +/- 65.2 degrees , p <0.001). Conversely, the number of deep calcium deposits was significantly larger in ruptured plaques than in control plaques (1.8 +/- 1.4 vs 0.3 +/- 0.6, p <0.001), although the arc of deep calcium was similar in the 2 groups. Ruptured plaques had quantitatively less calcium, especially superficial calcium, but a larger number of small calcium deposits, especially deep calcium deposits. In conclusion, ruptured plaques are associated with a larger number of calcium deposits within an arc of <90 degrees , a larger number of deep calcium deposits, and a remodeling index.

Relation of number of complex coronary lesions to serum C-reactive protein levels and major adverse cardiovascular events at one year

This study investigated the relation among serum C-reactive protein (CRP), number of complex coronary lesions, and adverse cardiovascular events at 1 year. Univariate and multivariate analyses were performed. Of 283 patients who had acute coronary syndrome, a single complex lesion was present in 32%, multiple complex lesions were identified in 23%, and no complex lesion was documented in 45%. On multivariate analysis, CRP was independently associated with the presence of multiple complex coronary lesions (p <0.0001); there was a striking association between increments in CRP titers and number of complex lesions (CRP levels of 0.22 mg/dl in patients who had 0 lesion, 0.53 mg/dl in patients who had 1 lesion, and 1.85 mg/dl in patients who had multiple complex lesions, p <0.0001), and high serum CRP levels independently predicted adverse outcome (p = 0.03). In conclusion, the presence of multiple complex plaques was the most powerful predictor of adverse outcome (hazard ratio 2.88, p = 0.0007), predominantly in those who had high CRP levels (p = 0.004).

Thrombus of the ascending aorta

We present two cases of a thrombus in the ascending aorta causing an acute myocardial infarction (AMI) and review the 10 other cases previously reported in the literature. This life-threatening condition appears to be more common in female smokers in their fifth decade. Suspicion should be raised in individuals at low risk for atherosclerotic disease with coronary angiographic findings not in keeping with the clinical presentation. The diagnosis may be obtained by transesophageal echocardiography, and we generally recommend surgical thrombectomy.

Perioperative myocardial infarction—aetiology and prevention

Perioperative myocardial infarction (PMI) is one of the most important predictors of short- and long-term morbidity and mortality associated with non-cardiac surgery. Prevention of a PMI is thus a prerequisite for an improvement in overall postoperative outcome. The aetiology of PMI is multifactorial. The perioperative period induces large, unpredictable and unphysiological alterations in coronary plaque morphology, function and progression, and may trigger a mismatch of myocardial oxygen supply and demand. With many diverse factors involved, it is unlikely that one single intervention will successfully improve cardiac outcome following non-cardiac surgery. A multifactorial, step-wise approach is indicated. Based on increasing knowledge of the nature of atherosclerotic coronary artery disease, and in view of the poor positive predictive value of non-invasive cardiac stress tests, and the considerable risk of coronary angiography and coronary revascularization in high-risk patients, the paradigm is shifting from an emphasis on extensive non-invasive preoperative risk stratification to a combination of selective non-invasive testing and aggressive pharmacological perioperative therapy. Perioperative plaque stabilization by pharmacological means may be as important in the prevention of PMI as an increase in myocardial oxygen supply or a reduction in myocardial oxygen demand.

Initial thrombosuction with subsequent angioplasty in primary coronary intervention—comparison with conventional strategy

BACKGROUND

Large thrombus burden remains challenging in the setting of acute myocardial infarct. Initial thrombosuction (IT) followed by actual angioplasty may be advantageous over conventional strategy in primary percutaneous coronary intervention (PCI).

METHODS

With a case-control design, 22 consecutive patients receiving primary PCI with IT were designated as group 1. Another 22 well-matched patients undergoing primary PCI with conventional strategy in the same period were enrolled as group 2. Clinical and angiographic outcomes, procedural parameters and resource usage were compared.

RESULTS

Baseline characteristics were comparable, including the symptom onset-to-needle time (250+/-101 vs. 261+/-149 min, p = NS). Total procedure time (33+/-14 vs. 47+/-20 min, p = 0.011), fluoroscopy time (10+/-6 vs. 16+/-10 min, p = 0.014) and contrast medium consumption (140+/-40 vs. 170+/-50 ml, p = 0.024) were all significantly reduced with group 1. No-reflow occurred less frequently with group 1 (5% vs. 32%, p = 0.046) during intervention, and TIMI 3 flow was established more quickly (19+/-10 vs. 30+/-20 min, p = 0.024). Final TIMI 3 flow rates and stent rates were similar. The time to myocardial enzyme peak was shorter with group 1 (9.7+/-3.1 vs. 12.8+/-6.3 h, p = 0.048), but no difference was found in 3 months cumulative major cardiac adverse event rates.

CONCLUSIONS

Primary PCI with IT achieves earlier reperfusion and is more efficient in terms of time and resource, comparing to conventional strategy.

Multislice spiral computed tomographic angiography of coronary arteries in patients with suspected coronary artery disease: an effective filter before catheter angiography?

BACKGROUND

Despite impressive image quality, it is unclear if noninvasive coronary angiography with multislice spiral computed tomography (CT) is powerful enough to act as a filter before invasive angiography (INV-A) in symptomatic patients.

METHODS AND RESULTS

We therefore studied 133 consecutive symptomatic patients with suspected coronary artery disease (CAD) and an indication for INV-A (chest pain and signs of ischemia in conventional stress tests). Patients with known CAD, acute coronary syndrome, or a calcium volume score >1000 were excluded. In all patients, both INV-A and multislice CT angiography (MSCT-A) (Philips MX 8000 multislice spiral CT, scan time 250 milliseconds, slice thickness 1.3 mm, 120 mL of contrast agent, 4 mL/s, retrospective gating) were directly compared by 2 independent investigators using the American Heart Association 15-segment model. Altogether, we studied 1596 segments, 74% had diagnostic image quality. Multislice CT angiography correctly identified 68 significant stenoses of the 75 stenoses seen with INV-A (sensitivity 91%). In 945 of 1185 diagnostic segments, stenosis could correctly be ruled out with MSCT-A. There were 3 times more stenoses seen with MSCT-A compared with INV-A (positive predictive value 29%) mainly because of misclassification of nonobstructive plaques as stenosis. The per-patient analysis allowed to exclude significant CAD in 42 (32%) of 133 patients. In only 6 of 53 patients, MSCT-A failed to detect significant stenosis, 4 of those were in small segments not requiring intervention. Calcium scoring alone was less suited as a filter before angiography: 25 patients (18% of study group) had a calcium score = 0, and 8 of these patients turned out to have significant stenoses.

CONCLUSION

Multislice CT angiography, but not calcium scoring alone, offers promise to reduce the number of INV-A in symptomatic patients with suspected CAD by up to one third with minimal risk for the patient.

Noninvasive in vivo measurement of vascular inflammation with F-18 fluorodeoxyglucose positron emission tomography

BACKGROUND

Fluorine 18 fluorodeoxyglucose (FDG) has been shown to accumulate in inflamed tissues. However, it is not known whether vascular inflammation can be measured noninvasively. The aim of this study was to test the hypothesis that vascular inflammation can be measured noninvasively by use of positron emission tomography (PET) with FDG.

METHODS AND RESULTS

Inflamed atherosclerotic lesions were induced in 9 male New Zealand white rabbits via balloon injury of the aortoiliac arterial segment and exposure to a high cholesterol diet. Ten rabbits fed standard chow served as controls. Three to six months after balloon injury, the rabbits were injected with FDG (1 mCi/kg), after which aortic uptake of FDG was assessed (3 hours after injection). Biodistribution of FDG activity within aortic segments was obtained by use of standard well gamma counting. FDG uptake was also determined noninvasively in a subset of 6 live atherosclerotic rabbits and 5 normal rabbits, via PET imaging and measurement of standardized uptake values over the abdominal aorta. Plaque macrophage density and smooth muscle cell density were determined by planimetric analysis of RAM-11 and smooth muscle actin staining, respectively. Biodistribution of FDG within nontarget organs was similar between atherosclerotic and control rabbits. However, well counter measurements of FDG uptake were significantly higher within atherosclerotic aortas compared with control aortas (P < .001). Within the upper abdominal aorta of the atherosclerotic group (area of greatest plaque formation), there was an approximately 19-fold increase in FDG uptake compared with controls (108.9 +/- 55.6 percent injected dose [%ID]/g x 10(3) vs 5.7 +/- 1.2 %ID/g x 10(3) [mean +/- SEM], P < .001). In parallel with these findings, FDG uptake, as determined by PET, was higher in atherosclerotic aortas (standardized uptake value for atherosclerotic aortas vs control aortas, 0.68 +/- 0.06 vs 0.13 +/- 0.01; P < .001). Moreover, macrophage density, assessed histologically, correlated with noninvasive (PET) measurements of FDG uptake (r = 0.93, P < .0001). In contrast to this finding, FDG uptake did not correlate with either aortic wall thickness or smooth muscle cell staining of the specimens.

CONCLUSION

These data show that FDG accumulates in macrophage-rich atherosclerotic plaques and demonstrate that vascular macrophage activity can be quantified noninvasively with FDG-PET. As such, measurement of vascular FDG uptake with PET holds promise for the noninvasive characterization of vascular inflammation.

Sex differences in outcome after ventricular fibrillation in out-of-hospital cardiac arrest

INTRODUCTION

Previous studies have shown that early defibrillation programs improve survival after an out-of-hospital cardiac arrest (OHCA). Reports also suggest that women fare worse than men do after cardiovascular events, but there is no population-based study of sex differences after an OHCA with early defibrillation. We, therefore, compared the short- and long-term survival and quality-of-life (QOL) in women and men after an OHCA.

METHODS

All patients with a ventricular fibrillation (VF) OHCA who received early defibrillation in Olmstead County, Minnesota between November 1990 and December 2000 were included. Using medical records and the cardiac arrest database, the short- and long-term survival and QOL based on a SF-36 survey of each sex were compared. Adjusted QOL scores were obtained by using age- and sex-specific norms from a sample of the general U.S. population; an adjusted score of 50 (normalized mean) was considered normal.

RESULTS

Thirty-seven female and 163 male patients presented with a VF OHCA and early defibrillation. Survival to hospital admission was significantly better for women than men [30 female survivors to admission (81%), 112 male (69%), p = 0.04]. Paradoxically, survival to discharge among those admitted was worse for women [13 female survivors to discharge (43%), 66 male (61%), p = 0.04]. The average length of follow-up was 4.8+/-3.0 years. The 5-year expected survival was 83% in women and 78% in men (p = 0.48). There was no difference in call-to-shock time (6+/-2, 6+/-2 min, p = 0.6) or whether the arrest was witnessed (86, 82%, p = 0.64). There was no statistical difference between women and men in age (64+/-17, 65+/-14 years), ejection fraction (40+/-17, 40+/-18%), diabetes (17, 29%, p = 0.16), hypertension (23, 28%, p = 0.58) or known CAD (27, 48%, p = 0.06). Adjusted QOL scores were similar between women and men in terms of pain (52+/-9, 52+/-10) vitality (47+/-11, 40+/-9), general health (49+/-9, 44+/-7), social function (51+/-10, 51+/-8), and mental health (50+/-10, 49+/-6).

CONCLUSION

Women are more likely to survive to hospital admission following an OHCA. However, admitted women less likely to survive their hospital stay. Long-term survival and QOL are equally favorable in both sexes.

Cardiovascular disease in women: Sex differences in presentation, risk factors, and evaluation

Cardiovascular disease (CVD) is the leading cause of mortality in women. Pathophysiology, risk factors, clinical presentation, and outcomes of coronary artery disease (CAD) differ in women, and a better understanding of the sex differences in these factors will potentially lead to a slowing of this epidemic in women. Often forgotten, women have higher complication rates post revascularization and higher in-hospital mortality post myocardial infarction compared with men despite a smaller burden of disease in women. Though overall women share the same risk factors as men in the development of CAD, certain risk factors appear to be particularly ominous, such as the presence of diabetes mellitus, low values of high-density lipoprotein cholesterol, high triglycerides, and psychologic depression. Disease detection in advanced CAD is more accurate with stress echocardiography (ECG) and perfusion single-photon emission computed tomography imaging in women than with stress ECG. Subclincial atherosclerotic disease detection with carotid artery intima media thickness assessment provides an opportunity to target preventive measures in women. This article focuses on some of the sex-specific differences.

Detection of coronary plaque by computed tomography with a novel plaque analysis system, 'Plaque Map', and comparison with intravascular ultrasound and angioscopy

BACKGROUND

Previous reports suggest that plaque may be characterized by the computed tomography (CT) number, but there is not a comprehensive method for evaluating the gray-scale CT image of the coronary artery obtained by multi-detector row CT (MDCT).

METHODS AND RESULTS

Forty-five patients with acute coronary syndrome (ACS) underwent MDCT either 3-4 weeks after the onset of acute myocardial infarction (n=24) or within 1 week after percutaneous coronary intervention in patients with unstable angina (UA; n=21). The cross-sections obtained at intervals of 5 mm were converted to numerical data and a 'plaque map' was drawn using the color-based isometric line method and bird's eye view. 'Plaque map' was compared with the findings of intravascular ultrasound (IVUS) and angioscopy. Of 662 slices of 78 vessels, soft, intermediate or calcified plaque was detected in 144, 134, and 84 slices, respectively. Compared with IVUS, the sensitivities were 92%, 87%, and 89%, respectively, and compared with angioscopy, sensitivity was 80% and specificity was 87%.

CONCLUSIONS

MDCT with the 'Plaque Map' system can noninvasively characterize plaque in patients with ACS.

Proportion of fibrin and platelets differs in thrombi on ruptured and eroded coronary atherosclerotic plaques in humans

OBJECTIVE

To determine the proportion of platelets and fibrin in coronary thrombi.

DESIGN

Immunohistochemical and morphometric means to examine the coronary arteries of 31 patients who died of acute myocardial infarction.

RESULTS

Fresh thrombi were detected in the feeding arteries of infarction areas in 23 cases (74%) and were associated with plaque rupture in 18 (78%) and plaque erosion in 5 (22%). An immunohistochemical study showed that the thrombi consisted of a mixture of fibrin and platelets as well as some other types of blood cells. The fibrin and platelet positive areas in the thrombi associated with plaque rupture accounted for 74 (19)% and 35 (20)% (p < 0.01) and those associated with erosion accounted for 51 (6)% and 70 (21)%, respectively, of the total areas. Areas of positive immunoreactivity for tissue factor and C reactive protein were also significantly greater in ruptured than in eroded plaques.

CONCLUSION

These results indicate that the proportions of fibrin and of platelets differ in coronary thrombi on ruptured and eroded plaques. Higher proportions of tissue factor and C reactive protein contribute more significantly to thrombus formation on plaque rupture than on plaque erosion.

Angioscopic follow-up study of coronary ruptured plaques in nonculprit lesions

OBJECTIVES

Changes of ruptured plaques in nonculprit lesions were evaluated using coronary angioscopy.

BACKGROUND

The concept of multiple coronary plaque ruptures has been established. However, no detailed follow-up studies of ruptured plaques in nonculprit lesions have yet been reported.

METHODS

Forty-eight thrombi in 50 ruptured coronary plaques in nonculprit lesions in 30 patients were identified by angioscopy. The percent diameter stenosis (%DS) at the target plaques on quantitative coronary angiographic analysis and the serum C-reactive protein (CRP) level were measured.

RESULTS

The mean angioscopic follow-up period was 13 +/- 9 months. Thirty-five superimposed thrombi still remained at follow-up, and the predominant thrombus color changed from red (56%) at baseline to pinkish-white (83%) at follow-up. The healing rate increased according to the angioscopic follow-up period (23% at </=12 months vs. 55% at >12 months, p = 0.044). The %DS at the healed plaque increased from baseline to follow-up (12.3 +/- 5.8% vs. 22.7 +/- 11.6%, respectively; p = 0.0004). The serum CRP level in patients with healed plaques (n = 10) was lower than that in those without healed plaques (n = 19; 0.07 +/- 0.03 mg/dl vs. 0.15 +/- 0.11 mg/dl, respectively; p = 0.007).

CONCLUSIONS

The present study demonstrated that: 1) ruptured plaques in nonculprit lesions tend to heal slowly with a progression of angiographic stenosis; and 2) the serum CRP level might reflect the disease activity of the plaque ruptures.

Vulnerable plaque: Definition, detection, treatment, and future implications

Atherosclerosis continues to account for significant morbidity and mortality in most of the world. The major proportion of atherosclerosis mortality is related to atherosclerotic coronary artery disease, yet there still is not an optimal method for making the diagnosis of vulnerable plaque in vivo. The search for such an undefined method, along with studies on amelioration of currently available technology, gains special significance when the association between the qualitative definition of lesions in an individual and cardiovascular risks are considered. We, therefore, start by defining the critical lesion of coronary atherosclerosis and review the advantages and potential for clinical use of various methods to detect the vulnerable plaque and comment on possible future implications in this field.

The use of myeloperoxidase as a risk marker for atherosclerosis

The mechanisms of atheroma formation and their ensuing complications and methods by which these can be detected have been the focus of several in vitro, in vivo, and clinical studies. Myeloperoxidase (MPO) is a microbicidal hemoprotein that serves as a part of the neutrophils' armory in host defense. However, the oxidation products generated by MPO have now been shown to be related to various stages of atheroma development. MPO and its oxidant products have been shown to be capable of modifying low-density lipoprotein cholesterol and to be enriched in human atheromas and rupture-prone plaques. Clinical studies have suggested an association between levels of MPO and the presence of coronary artery disease and endothelial dysfunction, and have shown a possible additional role to troponin in patients with chest pain.

Plaque erosion in the culprit lesion is prone to develop a smaller myocardial infarction size compared with plaque rupture

BACKGROUND

Acute myocardial infarction (MI) stems from a disruption of the plaque in the coronary artery. Based on postmortem examinations, such plaque disruption has been classified as either a rupture or an erosion. Unfortunately, it has been difficult to clinically identify plaque ruptures and plaque erosions during the development of acute MI. To elucidate the relationships between clinical features and the morphological characteristics of the infarct-related lesions, we observed the culprit lesions in patients with acute MI by coronary angioscopy and intravascular ultrasound.

METHODS

We examined culprit lesions in 107 patients with acute MI using coronary angioscopy and intravascular ultrasound immediately before performing percutaneous coronary intervention. The lesions were then classified as plaque ruptures or nonruptured erosions, and their clinical features were compared.

RESULTS

Among the lesions studied, 44 were classified as plaque ruptures, 28 were classified as plaque erosions, and 35 were unclassified. Patients with nonruptured eroded plaques had more preinfarction angina before the onset of MI than those with ruptured plaques (53.6% vs 22.7%, P = .0074). They also had less ST-segment elevation MI (71.4% vs 93.2%, P = .0185), lower peak creatine kinase levels (2029 +/- 1517 vs 4033 +/- 2699 IU/L, P = .0009), less distal embolization after percutaneous coronary intervention (3.6% vs 36.4%, P = .0014), and less Q-wave MI 1 month after onset (40.7% vs 88.4%, P < .0001).

CONCLUSION

Patients with eroded plaque lesions have smaller infarctions than those with ruptured plaque lesions, suggesting that an eroded plaque is less potently thrombogenic than a ruptured plaque.

Prognostic implications of elevated troponin in patients with suspected acute coronary syndrome but no critical epicardial coronary disease: a TACTICS-TIMI-18 substudy

OBJECTIVES

The purpose of this study is to determine whether there is clinical significance to elevated troponin I in patients with suspected acute coronary syndromes (ACS) with non-critical angiographic coronary stenosis.

BACKGROUND

Elevation of troponin in patients admitted with ACS symptoms with non-critical coronary artery disease (CAD) may result from coronary atherothrombosis not evident using standard angiography or from other ischemic and non-ischemic causes that may confer increased risk for future events.

METHODS

Patients with ACS enrolled in the Treat Angina With Aggrastat and Determine Cost of Therapy With Invasive or Conservative Strategy-Thrombolysis In Myocardial Infarction (TACTICS-TIMI)-18 were included. Of 2,220 patients enrolled in the trial, 895 were eligible. Patients were divided into four groups according to troponin status on admission and presence of significant angiographic stenosis. Baseline brain natriuretic peptide (BNP) and C-reactive protein (CRP) were obtained on all patients.

RESULTS

The median troponin I levels were 0.71 ng/ml in patients with CAD compared with 0.02 ng/ml in patients without CAD (p <0.0001). Troponin-positive patients with or without angiographic CAD had higher CRP and BNP levels compared with troponin-negative patients (p <0.01 for both). The rates of death or reinfarction at six months were 0% in troponin-negative patients with no CAD, 3.1% in troponin-positive patients with no CAD, 5.8% in troponin-negative patients with CAD, and 8.6% in troponin-positive patients with CAD (p=0.012).

CONCLUSIONS

Elevated troponin in ACS is associated with a higher risk for death or reinfarction, even among patients who do not have significant angiographic CAD. The mechanisms conferring this adverse prognosis merit further study.

What causes acute coronary syndromes? Applying Koch's postulates

The term "acute coronary syndromes" (ACS) is used to describe a heterogeneous spectrum of clinical conditions. This includes myocardial infarction, non-ST-elevation myocardial infarction, and unstable angina. These conditions are linked by a similar constellation of signs and symptoms but not necessarily by a common pathophysiology. They are syndromes. Several different hypotheses exist that have attempted to explain the pathological mechanisms that are involved in these conditions, however, it is not clear whether ACS are caused by variations of a single disease process or by several disease processes. The contribution of both vessel wall- and blood-related factors in the pathogenesis of acute coronary syndromes is herein discussed with the guidance of Koch's postulates.

The pathogenesis of atherosclerosis

Worldwide, more people die of the complications of atherosclerosis than of any other cause. It is not surprising, therefore, that enormous resources have been devoted to studying the pathogenesis of this condition. This article attempts to summarize present knowledge on the events that take place within the arterial wall during atherogenesis. Classical risk factors are not dealt with as they are the subjects of other parts of this book. First, we deal with the role of endothelial dysfunction and infection in initiating the atherosclerotic lesion. Then we describe the development of the lesion itself, with particular emphasis on the cell types involved and the interactions between them. The next section of the chapter deals with the events leading to thrombotic occlusion of the atherosclerotic vessel, the cause of heart attack and stroke. Finally, we describe the advantages--and limitations--of current animal models as they contribute to our understanding of atherosclerosis and its complications.

Computed tomography coronary calcium screening and myocardial perfusion imaging

Cardiac computed tomography (CT) has seen an exponential increase in interest as applications expanded from identification of coronary artery calcification to noninvasive coronary angiography and, more recently, identification of soft and noncalcified plaques. The interest arises from the well-known fact that cardiovascular disease remains the most prevalent cause of death in the Western hemisphere and the fact that in a large proportion of patients the initial event is either sudden death or a disabling myocardial infarction or stroke. Although traditional risk factors are extremely helpful in determining risk in a population, the prognostic ability of risk factors alone in the individual patient is limited. Hence, researchers have turned their attention to noninvasive modalities to image the atherosclerotic plaque in its preclinical stages, hoping to better address this ailment at its inception and change the natural history of the disease. Measurements of coronary artery calcium (CAC) serve as a quantitative reflection of the severity of coronary artery atherosclerosis, and greater calcium burdens correlate with more advanced disease. Indeed, CAC has been shown to add prognostic value to traditional risk factors in patients at intermediate risk, and in this group of patients, it is most cost-effective. Furthermore, CAC measurements providing an assessment of coronary atherosclerotic plaque burden appear to be complementary to myocardial perfusion single photon emission computed tomography that offers information regarding inducible ischemia. In this manner, a better assessment of risk in a patient suspected of harboring preclinical or early coronary artery disease can be achieved. In this article we review the most relevant literature regarding the utilization of CAC testing as a tool to refine risk assessment and use several case studies to exemplify the combination of CT imaging and functional myocardial perfusion studies, which may provide a better identification of patients in need of aggressive medical therapy and those needing invasive assessment for possible coronary revascularization.

Terrein: a new melanogenesis inhibitor and its mechanism

Terrein is a bioactive fungal metabolite whose effects are almost unknown. In this study, we found for the first time that terrein has a strong hypopigmentary effect in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment of Mel-Ab cells with terrein (10-100 microM) for 4 days significantly reduced melanin levels in a dose-dependent manner. In addition, terrein at the same concentration also reduced tyrosinase activity. We then investigated whether terrein influences the extracellular signal-regulated protein kinase (ERK) pathway and the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. Terrein was found to induce sustained ERK activation and MITF down-regulation, and luciferase assays showed that terrein inhibits MITF promoter activity in a dose-dependent manner. To elucidate the correlation between ERK pathway activation and a decreased MITF transcriptional level, PD98059, a specific inhibitor of the ERK pathway, was applied before terrein treatment and found to abrogate the terrein-induced MITF attenuation. Terrein also reduced the tyrosinase protein level for at least 72 h. These results suggest that terrein reduces melanin synthesis by reducing tyrosinase production via ERK activation, and that this is followed by MITF down-regulation.

Review of the Ability of Optical Coherence Tomography to Characterize Plaque, Including a Comparison with Intravascular Ultrasound

Over the last 50 years the introduction of several imaging technologies have been pivotal in reducing mortality associated with coronary artery disease. However coronary disease continues to be the leading cause of mortality in the industrialized world. Optical coherence tomography (OCT) has recently been introduced for micron scale intravascular imaging. It is analogous to ultrasound, measuring the intensity of back-reflected infrared light instead of sound. Some of the advantages of OCT include its resolution, which is higher than any currently available imaging technology and acquisition rates are near video speed. Unlike ultrasound, OCT catheters consist of simple fiber optics and contain no transducers within their frame, thereby making imaging catheters both inexpensive and small. Currently, the smallest catheters have a cross-sectional diameter of 0.014". OCT systems are compact and portable and can be combined with a range of spectroscopic techniques. We review the application of OCT to intracoronary imaging.

Mast cells in vulnerable coronary plaques: potential mechanisms linking mast cell activation to plaque erosion and rupture

PURPOSE OF REVIEW

A novel link between inflammation and acute coronary syndromes is emerging, in that infiltrating inflammatory cells may convert a clinically silent coronary plaque into a dangerous and potentially lethal plaque. The majority of acute atherothrombotic events now relate to erosion or rupture of such unstable plaques. Here we summarize the molecular mechanisms by which activated mast cells may contribute to plaque erosion or rupture.

RECENT FINDINGS

In-vitro experiments have revealed a multitude of paracrine effects exerted by activated mast cells. By secreting heparin proteoglycans and chymase, activated mast cells efficiently inhibit the proliferation of smooth muscle cells in vitro, and reduce their ability to produce collagen by a transforming growth factor beta-dependent and -independent mechanism. Mast cell chymase and tryptase are capable of activating matrix metalloproteinases types 1 and 3, causing degradation of the extracellular matrix component, collagen, necessary for the stability of the plaque. Activated mast cells also secrete matrix metalloproteinases types 1 and 9 themselves. Furthermore, chymase induces SMC apoptosis by degrading fibronectin, a pericellular matrix component necessary for SMC adhesion and survival, with the subsequent disruption of focal adhesions and loss of outside-in survival signaling. By secreting chymase and tumour necrosis factor alpha, activated mast cells also induce endothelial cell apoptosis.

SUMMARY

Locally activated mast cells may participate in the weakening of atherosclerotic plaques by secreting heparin proteoglycans, chymase, and cytokines, which affect the growth, function and death of arterial endothelial cells and smooth muscle cells, thereby predisposing to plaque erosion or rupture.

The accumulation of specific types of proteoglycans in eroded plaques: a role in coronary thrombosis in the absence of rupture

PURPOSE OF REVIEW

Although fibrous cap rupture is the primary cause of coronary thrombosis, plaque erosion is responsible for 30%-40% of acute thrombotic events. The interface of the eroded surface involves a denuded endothelium allowing direct contact of the platelet/fibrin thrombus with the underlying lesion. This review discusses the putative role of extracellular matrix molecules, in particular proteoglycans/hyaluronan, in the development of acute coronary thrombosis associated with erosion.

RECENT FINDINGS

The plaque/thrombus interface in erosion presents a unique surface since it consists of predominantly SMCs and proteoglycans with minimal or no inflammation. The lack of significant inflammation raises the possibility that erosion represents chronic wounding rather than true atherogenesis. The abundance of proteoglycan and hyaluronan matrix suggests their potential role in the development of thrombosis. Matrix changes may contribute to endothelial loss, the magnitude of the thrombotic event, or both. Versican facilitates platelet adhesion at low shear and cooperates with collagen to promote platelet aggregation. Further, versican may, in part, regulate water content and in turn support coagulation because water-dependent functionality of anticoagulation molecules. Finally, experimental models of plaque erosion are currently being developed guided by the premise that the loss of surface endothelium together with other procoagulant factors may underlie the development of platelet-rich thrombi.

SUMMARY

The loss of endothelium and exposure of a potentially procoagulant versican-hyaluronan matrix may be largely responsible for plaque erosion. The development of relevant animal models should allow further insight into the pathophysiology of coronary thrombosis in the absence of rupture.

Focal and multi-focal plaque macrophage distributions in patients with acute and stable presentations of coronary artery disease

OBJECTIVES

This study was designed to utilize optical coherence tomography (OCT) images of coronary atherosclerotic plaque macrophages to investigate the relationship between macrophage distributions and clinical syndrome.

BACKGROUND

The relative significance of focal macrophage infiltration and generalized coronary inflammation for predicting acute coronary events is a currently a source of considerable controversy in cardiology. Lack of a high-resolution cross-sectional imaging modality has limited macrophage evaluation in vivo.

METHODS

Intracoronary OCT imaging was performed at culprit and non-culprit plaques in patients presenting with stable angina pectoris, unstable angina pectoris,and ST-segment elevation myocardial infarction. Macrophage densities were quantified from these images and analyzed with respect to the clinical presentations of the patients under investigation.

RESULTS

A significantly greater macrophage density was found in unstable patients, both for fibrous and lipid-rich plaques (p = 0.025 and p = 0.002, respectively). Within each patient, the macrophage densities at culprit and non-culprit lesions correlated significantly (r = 0.66, y = 0.88x + 0.43, p = 0.01). Sites of plaque rupture demonstrated a greater macrophage density than non-ruptured sites (6.95 +/- 1.60%, 5.29 +/- 1.17%; p = 0.002). Surface macrophage infiltration was a stronger predictor of unstable clinical presentation than subsurface infiltration for culprit lesions (p = 0.035) but not for remote lesions (p = 0.80).

CONCLUSIONS

Our results demonstrate that increases in both multi-focal and focal macrophage densities are highly correlated with symptom severity. By providing a means of detecting increases in plaque macrophage content before an acute event, this technique may aid in determining prognosis and guiding preventive therapy.

Angiographic aspects of ruptured plaque in patients with acute myocardial infarction: correlation with clinical and laboratory variables

In patients with acute myocardial infarction (AMI), little is known about the correlation between prognostic variables and aspects of ruptured plaque at the coronary angiography. Five hundred patients with acute myocardial infarction were studied in a consecutive and prospective manner; of these, 264 patients were excluded mainly because of the presence of an occluded culprit coronary artery. The remaining 236 patients were divided according to the presence (113, 52%) or absence (126, 48%) of angiographic aspects suggestive of ruptured plaque, and correlated with 49 clinical, electrocardiographic, in-hospital complications, procedures, and other angiographic prognostic variables. The variables that correlated significantly and independently with angiographic aspects of ruptured plaque were: presence of thrombi and higher degree of residual stenosis at the culprit coronary artery, as well as white ethnic group.

Oxidation of LDL, atherogenesis, and apoptosis

A plethora of studies in cultured cells have established that oxidized low-density lipoprotein (oxLDL) may enhance arterial apoptosis that involves both mitochondrial and death receptor pathways (Fas/FasL, TNF receptors I and II), thereby activating caspase cascade and other proteases. When apoptosis is inhibited by Bcl-2 overexpression, oxLDL may trigger necrosis through a calcium-dependent pathway. Despite this effort, the pathophysiological relevance of apoptosis in vivo remains to be elucidated. In principle, apoptosis occurring in atherosclerotic areas could be involved in endothelial cell lining defects, necrotic core formation, and plaque rupture or fissuring. This complex pathogenic framework may favor coronary atherothrombotic events. To date, the pathogenic role of apoptosis in thrombosis is attractive, but a solid evidence is still needed. When the precise role of oxLDL in vascular programmed cell death occurring in vivo is clarified, this may aid in the development of novel therapeutic approaches to adverse atherogenesis and its clinical sequelae.

Treatment of intracoronary thrombus using tirofiban in a patient with normal coronary arteries

We report a 64-year-old Turkish man who presented with unstable angina pectoris. Coronary angiography revealed massive intracoronary thrombus, which completely occluded the distal part of the left circumflex coronary artery. The thrombotic segment and the rest of the coronary tree were free of atherosclerosis. The patient was treated with intravenous tirofiban, a glycoprotein IIb/IIIa inhibitor. A control angiography was performed one week later and showed total dissolution of the thrombus with tirofiban therapy.

Atherothrombosis: Epidemiology, Pathophysiology, and Prevention

OBJECTIVES

To review the pathophysiology of atherothrombosis (atherosclerosis with superimposed platelet-rich thrombus formation) and the measures that can be taken to prevent its clinical sequelae through lifestyle modifications and pharmacotherapy, with emphasis on the role of antiplatelet agents.

DATA SOURCES

Recent (1995-2003) published scientific literature, as identified by the authors through Medline searches using the terms atherothrombosis, pathophysiology, risk factors, prevention, and reviews on treatment.

STUDY SELECTION

Recent systematic English-language review articles were screened for relevant material.

DATA SYNTHESIS

Atherothrombosis is a generalized and diffuse progressive process affecting multiple vascular beds; its clinical consequences, including acute coronary syndromes (unstable angina, acute myocardial infarction, and sudden cardiac death), ischemic stroke, and peripheral arterial disease, are unpredictable in their time course and potentially life-threatening. Atherothrombosis rather than arterial stenosis appears to account for most of the acute ischemic manifestations of the atherosclerotic process. Interventions that can favorably influence atherosclerotic progression include lifestyle modifications (dietary control, exercise, and smoking cessation) and pharmacotherapy (lipid-lowering, antihypertensive, antiglycemic, and antiplatelet drugs). The pivotal role played by the platelet in thrombus formation provides the rationale for employing antiplatelet drugs with complementary modes of action (e.g., aspirin, clopidogrel) to prevent atherothrombosis.

CONCLUSION

Ischemic cerebrovascular, coronary, and peripheral arterial disease can be regarded as diverse manifestations of a common underlying systemic pathology, namely atherothrombosis. Secondary prevention of an ischemic event in an affected arterial bed confers the added benefit of primary prevention against potential ischemic events in other arterial beds.

Rôle de l’immunité dans l’athérosclérose et dans les syndromes coronariens aigus

Cardiovascular diseases represent one of the most important causes of death in the world. The underlying pathogenetic process is atherosclerosis which leads to the progressive reduction of the arterial lumen and therefore to the ischemia of the perfused organs. Atherogenesis results from the interaction between the biology of the arterial wall and the various stress stimuli present in the circulating blood. The first steps of atherogenesis occur very early, already during the fetal life. Those arterial segments that are subjected to the initiating causes (including hemodynamic stress) show altered endothelial permeability and allow the infiltration of macromolecules, like lipoproteins, in the subintimal space. At the same time, the smooth muscle cells that are subjected to the same local factors produce proteoglycans able to bind lipoproteins and to promote their oxidation. Oxidized lipoproteins induce the expression of chemokines and adhesion molecules on the luminal surface of the endothelium, which then allow the local recruitment of monocytes-macrophages and T lymphocytes. This is a local inflammatory process that, in theory, should contribute to reestablish the homeostasis of the vascular wall by promoting the elimination of injured tissue and its repair. Unfortunately, for unknown reasons, the immuno-inflammatory reaction persists and autoamplifies, the various components of the immune response finally contributing to the pathogenesis of atherosclerosis as well as of atherosclerotic complications.

Multiple plaque morphologies in a single coronary artery: insights from volumetric intravascular ultrasound

Intravascular ultrasound provides detailed information on vessel wall and plaque morphology. This report illustrates the use of three-dimensional volumetric IVUS reconstruction images to characterize different patterns of plaque morphology, including vulnerable and ruptured plaques, within a single coronary artery in a patient with unstable angina.

Imaging of coronary calcification by computed tomography

As an unequivocal biomarker for arteriosclerosis, the presence of coronary calcium serves as a qualitative reflection of the severity of coronary artery disease (CAD). Greater calcium burdens correlate with more advanced disease, a higher likelihood of coronary stenoses, and a higher risk for coronary heart disease (CHD). Empirically, the quantification of coronary calcium not only provides an accurate reflection of disease severity, but also has great potential as a screening tool for CHD. Computed tomography (CT) has been shown to be capable of providing accurate, noninvasive measurements of coronary calcification. Evidence shows that calcium measurements by CT correlate well with histological plaque analyses, and that calcium burdens accurately reflect disease severity and can be used to assess individual risk for CHD. The purpose of this review article is to examine the accumulated evidence that has attempted to validate CT as a diagnostic tool for CAD and as a screening exam for CHD.