Role of plaque rupture in acute coronary syndromes

Association between the CD14-260C>T gene polymorphism and susceptibility to myocardial infarction: Evidence from case-control studies

Numerous published studies have investigated the relationship between the CD14-260C>T (rs2569190) polymorphism and the risk of myocardial infarction (MI). However, the results are still conflicting and inconclusive. Potentially eligible published articles were searched in four databases including PubMed, Web of Science, EMBASE and Chinese Biomedical Database (CBM). The odds ratio (OR) with its 95% confidence interval (CI) was used to estimate the strength of the associations. Thirteen papers including 17 case-control studies were included, reporting a total of 6,443 MI patients and 6,315 controls. A significant increase in overall MI susceptibility was identified in the homozygote model. In the subgroup analysis, with respect to the type of MI, a significantly increasing acute MI susceptibility was found in the homozygote model. In the subgroup analysis for ethnicity, a significant increased susceptibility was found in Asian populations in allele, homozygote, recessive and dominant models. However, no significant association was found among Caucasian populations. In conclusion, there may be a moderate association between the CD14-260C>T polymorphism and acute MI susceptibility. This association may be different between ethnicities with the CD14-260C>T polymorphism being a risk factor for myocardial infarction in Asian populations.

Plasma C-Reactive Protein and Lipoprotein Levels, and Progression of Coronary Artery Disease after Myocardial Infarction Treated with Thrombolysis

BACKGROUND

There is a paucity of studies using quantitative coronary angiography (QCA) to determine progression of coronary artery disease (CAD) after an acute coronary event. Furthermore, despite a great interest in effects of inflammation and 'early' lipid lowering therapy, no data have been published on the role of plasma C-reactive protein (CRP) and lipoprotein levels in CAD progression after myocardial infarction.

METHODS

Seventy-two patients with myocardial infarction treated with thrombolysis, but not with statins, were investigated with QCA during admission and after 6 months. Plasma CRP concentrations were measured by a high sensitive method 2 days after the acute event, and plasma high-sensitive CRP and lipoprotein levels were determined 3 months after myocardial infarction.

RESULTS

Overall, there was no significant progression of CAD, but when stenoses were grouped into those reducing the lumen diameter greater or less than 50%, progression was seen in stenoses originally <50%, whereas regression was seen in stenoses >50%. No consistent associations were seen between plasma CRP, lipoprotein lipid or lipoprotein(a) levels and CAD.

CONCLUSIONS

Progression of stenoses <50% might be of clinical importance since these stenoses are more prone to rupture. Furthermore, the lack of associations between change in minimum lumen diameter and plasma CRP and lipoprotein concentrations suggests that positive effects on CAD progression of early treatment with anti-inflammatory or lipid-lowering drug therapy may not be expected in this subset of patients.

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.

Association study of CD14 polymorphism with myocardial infarction in a Japanese population

There have been many studies investigating the association between gene polymorphisms and coronary artery disease (CAD) including myocardial infarction (MI), and some studies have shown that certain gene polymorphisms are associated with CAD/MI. However, the results of the association have sometimes been controversial. The reason may be that the contribution of genetic risk factors to CAD/MI varies depending on the ethnic, environmental, and habitual backgrounds, and differs between males and females. In this study, we analyzed 17 polymorphisms in 12 candidate genes for MI in 136 patients and 200 to 235 controls, and found that there is a significant association of MI with the polymorphisms in the genes for E-selectin and CD14 receptor. To further explore the association, we investigated the C-260 T polymorphism in the promoter region of the CD14 gene in 502 MI patients and 527 control subjects. The genotype distributions of the CD14 polymorphism were as follows: patients; T/T 32.5%, C/T 48.2%, C/C 19.3%, and controls; T/T 25.4%, C/T 52.8%, C/C 21.8%. The frequencies of the T/T homozygotes were significantly higher in the patients (OR = 1.41, P = 0.013) than in the control group, confirming the association of CD14 polymorphism with MI in Japanese. Stratification analyses further demonstrated that the association was more prominent in females and in patients with a relatively low body mass index, suggesting that the contribution of the CD14-linked genetic risk to MI differs with respect to gender and habitual background.

Pharmacologic plaque passivation for the reduction of recurrent cardiac events in acute coronary syndromes

Acute coronary syndrome (ACS) is often associated with the rupture of vulnerable atherosclerotic plaque, coronary thrombus formation, and abrupt limitation of blood flow, leading to adverse outcomes. Passivation of vulnerable plaque represents a therapeutic concept that has the potential to prevent or limit the magnitude of a new rupture in order to reduce the recurrence or severity of events. Plaque passivation can be defined as a process by which the structure or content of the atherosclerotic plaque is changed to reduce the risk of subsequent rupture and thrombosis. This may be achieved by using strategies that address different components of the plaque or the endothelium. The following factors can affect the susceptibility of plaque to rupture: macrophage infiltration; accumulation of inflammatory cells; paracrine secretion of enzymes that may cause degradation of the fibrous cap of coronary plaque; shear stress; circadian rhythm variation in stress hormone release; and infectious agents. The use of pharmacologic agents to reduce plaque vulnerability by passivation has been explored. Clinical studies demonstrate that lipid-modifying agents (e.g., statins), antiplatelet agents (acetylsalicylic acid, thienopyridines, thianopyridines, glycoprotein IIb/IIIa inhibitors), and antithrombotic agents (unfractionated heparin and low-molecular-weight heparin) can reduce the occurrence of acute coronary events in ACS patients. In addition, angiographic studies suggest that statins may also promote regression of atherosclerosis. Angiotensin-converting enzyme inhibitors, niacin, and calcium antagonists may also contribute to plaque passivation. This article reviews atherosclerotic plaque development and vulnerability and discusses some clinical studies highlighting the role of plaque passivation in the management of ACS patients.

Early statin therapy for acute coronary syndromes

OBJECTIVE

To review the clinical benefit of statins in the early management of acute coronary syndromes (ACSs) and their possible mechanisms of benefit.

DATA SOURCES

A MEDLINE search (1966-September 2001) was conducted using the following terms: pravastatin, lovastatin, simvastatin, atorvastatin, cerivastatin, fluvastatin, statins, hydroxymethylglutaryl coenzyme A reductase inhibitor, acute coronary syndromes, unstable angina, and myocardial infarction. Pertinent articles referenced in these publications were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

French- and English-language human and animal studies were selected and analyzed.

DATA SYNTHESIS

In addition to their lipid-lowering properties, statins produce several nonlipid-related properties. These pleiotropic properties include improved endothelial function, reduction of inflammation at the site of the atherosclerotic plaque, inhibition of platelet aggregation, and anticoagulant effects, all of which may result in clinical benefit during ACSs. Preliminary studies and retrospective analyses of large clinical trials support the hypothesis that statins may be of benefit in ACSs. A recently published randomized, double-blind, multicenter trial evaluated the clinical impact of high-dose atorvastatin in patients with ACSs. Use of atorvastatin resulted in a decrease in a combined endpoint of cardiovascular events. Furthermore, initiation of statin therapy during hospitalization improves long-term compliance and may significantly improve clinical outcome.

CONCLUSIONS

Early use of statins in ACSs appears to decrease cardiovascular events. We believe statin therapy should be initiated early (at the latest before hospital discharge) in all patients who have been hospitalized for ACSs. Ongoing studies will clarify the benefit of these agents in ACSs, the importance of their nonlipid-lowering properties, and the optimal cholesterol-target concentrations.

Dyslipidemia and the vulnerable plaque

In the last decade, an increasingly sophisticated understanding of the pathogenesis of atherosclerosis and its cardiovascular consequences has emerged. The characteristics of the unstable atherosclerotic plaque, the substrate for the majority of acute coronary events, have been well defined: mild-to-moderate stenosis, a lipid-rich pool, few smooth muscle cells, a friable fibrous cap, and macrophage infiltration. Lipid modification, an important cardiovascular risk reduction strategy, induces a number of effects at the vascular level that may contribute to the clinical benefits seen in large-scale, prospective prevention trials. New developments in imaging technologies may afford improved opportunities to visualize the at-risk plaque and may provide new insights into the optimal management of the unstable plaque.

Polymorphisms in the platelet-endothelial cell adhesion molecule-1 (PECAM-1) gene, Asn563Ser and Gly670Arg, associated with myocardial infarction in the Japanese

We examined three missense polymorphisms of platelet-endothelial cell adhesion molecule-1 (PECAM-1), Val125Leu, Asn563Ser, and Gly670Arg, in 136 Japanese patients with myocardial infarction and 235 healthy Japanese controls. We found that these polymorphisms were in linkage disequilibrium with each other and that frequencies of 125Leu, 563Ser, and 670Arg alleles were significantly increased in patients compared with controls (0.522 vs 0.447, p = 0.048; 0.585 vs 0.502, p = 0.030; and 0.577 vs 0.492, p = 0.032, respectively). The frequencies of homozygotes for 563Ser and 670Arg alleles were also significantly increased in the patients (33.1% vs 23.4%, odds risk [OR] = 1.62, p = 0.040, 95% confidence interval [95%CI] = 1.01-2.58; and 32.4% vs 23.0%, OR = 1.60, p = 0.048, 95%CI = 1.00-2.57, respectively). These observations suggest that the 563Ser/Ser genotype and 670Arg/Arg genotype of PECAM-1 are novel genetic risk factors of myocardial infarction in Japanese. Stratification analysis of the patients showed that the associations of these PECAM-1 genotypes with myocardial infarction were preferentially found in male and younger patients (age of onset of myocardial infarction less than 60 years). In addition, the associations were stronger in patients with three-vessel disease than in the others and appeared independent of conventional risk factors including smoking, hypertension, diabetes mellitus, hyperlipidemia, and obesity.