Lipoprotein-associated phospholipase A2 for early risk stratification in patients with suspected acute coronary syndrome: a multi-marker approach: the North Wuerttemberg and Berlin Infarction Study-II (NOBIS-II)

Lp-PLA2 as a biomarker and its possible associations with SARS-CoV-2 infection

Lp-PLA2 is an enzyme encoded by the PLA2G7 gene located at chromosome 6p12-21, which is included in different signal transduction pathways. The potential of serum levels of Lp-PLA2 as a marker of inflammation quantifying cardio-metabolic risk, renal impairment and oxidative stress has been explored in earlier studies. It has also been used in chronic obstructive pulmonary disease, hepatic disease, metabolic conditions and exercise tolerance. Additionally, it shows promising evidence for the assessment of risk for certain cardiovascular conditions in otherwise seemingly healthy individuals. COVID-19 has affected life and the economy globally. The identification of biomarkers to assess the sickness and treatment plan is the need of the hour. This review summarizes the pathophysiological inter-relationship between serum levels of Lp-PLA2 and COVID-19. The authors hypothesize that the estimation of Lp-PLA2 levels may help in the early identification of risk and thus may play a beneficial role in the proactive management of COVID-19.

Lipoprotein-associated phospholipase-A2 activity and its diagnostic potential in patients with acute coronary syndrome and acute ischemic stroke

BACKGROUND

The study examined the Lp-PLA₂ activity at the patients presented to the emergency department with acute coronary syndrome (ACS) or acute ischemic stroke (AIS), as well as its diagnostic value.

METHODS

The prospective study included consecutive male and female patients aged >18 years that presented to the our emergency department with ACS or AIS between November 2009 and January 2010. Blood samples were obtained immediately following diagnosis in the ACS and AIS groups. The diagnostic value of Lp-PLA₂ was determined based on receiver operating characteristic curves, sensitivity, specificity, predictive values, likelihood ratios and accuracy rates.

RESULTS

In all, 34 ACS and 32 AIS patients were included in the study, and the control group included 35 patients. Lp-PLA₂ enzyme activity was significantly lower in the ACS and AIS groups than in the control group (26.7 ± 13.8, 31.4 ± 13.6, and 41.4 ± 8.1 nmol min^-1·mL^-1, respectively; p < 0.0001, p = 0.022). In the ACS group the area under the curve (AUC) was 0.825 (95%CI: 0.722-0.929), sensitivity was 71% for an optimal Lp-PLA₂ cut-off value of 31.4 nmol min^-1·mL^-1, and specificity was 91%, whereas in the AIS group the AUC was 0.768 (95%CI: 0.652-0.884), sensitivity was 75% for an optimal Lp-PLA₂ cut-off value of 38.1 nmol min^-1·mL^-1, and specificity was 74%.

CONCLUSIONS

Lp-PLA₂ enzyme activity was significantly lower during the early stage of both ACS and AIS. The obtained statistic data suggest that low Lp-PLA₂ enzyme activity can be used for diagnostic purposes.

Evaluation of lipoprotein-associated phosholipase A2 and plaque burden/composition in young adults

OBJECTIVE

The total burden of subclinical coronary atherosclerosis is significant in young adults. Serum lipoprotein-associated phospholipase A2 (Lp-PLA2) is an established predictor of morbidity and mortality because of cardiovascular disease. The aim of the present investigation was to evaluate the relationship between subclinical coronary atherosclerosis and serum Lp-PLA2 concentrations in a population of young adults.

PATIENTS AND METHODS

A total of 261 individuals younger than 45 years of age who had undergone coronary computed tomography angiography were evaluated. The study group included 101 patients in whom coronary computed tomography angiography detected subclinical coronary atherosclerosis; the control group included 160 sex-matched and age-matched healthy control patients.

RESULTS

Serum Lp-PLA2 levels were increased significantly in the study group patients compared with the control patients (15.42±11.88 vs. 8.06±4.32 ng/ml, P<0.001). Furthermore, a positive correlation was identified between the Lp-PLA2 levels and the total number of plaques and diseased arteries (r=0.495, P<0.001, and r=0.621, P<0.001, respectively). The presence of mixed plaque composition was also correlated with the Lp-PLA2 levels (r=0.657, P<0.001). Multivariate regression analysis identified four independently significant predictors of subclinical coronary atherosclerosis: high-sensitivity C-reactive protein levels, tobacco use, uric acid levels, and serum Lp-PLA2 levels.

CONCLUSION

The presence of subclinical coronary atherosclerosis is associated independently with Lp-PLA2, and it has potential utility as a novel indicator of cardiovascular disease risk in the young adult population.

Early discharge using single cardiac troponin and copeptin testing in patients with suspected acute coronary syndrome (ACS): a randomized, controlled clinical process study

AIMS

This randomized controlled trial (RCT) evaluated whether a process with single combined testing of copeptin and troponin at admission in patients with low-to-intermediate risk and suspected acute coronary syndrome (ACS) does not lead to a higher proportion of major adverse cardiac events (MACE) than the current standard process (non-inferiority design).

METHODS AND RESULTS

A total of 902 patients were randomly assigned to either standard care or the copeptin group where patients with negative troponin and copeptin values at admission were eligible for discharge after final clinical assessment. The proportion of MACE (death, survived sudden cardiac death, acute myocardial infarction (AMI), re-hospitalization for ACS, acute unplanned percutaneous coronary intervention, coronary artery bypass grafting, or documented life threatening arrhythmias) was assessed after 30 days. Intention to treat analysis showed a MACE proportion of 5.17% [95% confidence intervals (CI) 3.30-7.65%; 23/445] in the standard group and 5.19% (95% CI 3.32-7.69%; 23/443) in the copeptin group. In the per protocol analysis, the MACE proportion was 5.34% (95% CI 3.38-7.97%) in the standard group, and 3.01% (95% CI 1.51-5.33%) in the copeptin group. These results were also corroborated by sensitivity analyses. In the copeptin group, discharged copeptin negative patients had an event rate of 0.6% (2/362).

CONCLUSION

After clinical work-up and single combined testing of troponin and copeptin to rule-out AMI, early discharge of low- to intermediate risk patients with suspected ACS seems to be safe and has the potential to shorten length of stay in the ED. However, our results need to be confirmed in larger clinical trials or registries, before a clinical directive can be propagated.

Can lipoprotein-associated phospholipase A2 be used as a predictor of long-term outcome in patients with acute coronary syndrome?

Studies indicate that elevated plasma concentrations of lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with increased risk of cardiovascular disease. Lp-PLA2 seems to play a crucial role in the formation of plaques and acute inflammation, and plasma Lp-PLA2 could therefore potentially be used as a predictor of long-term outcome in ACS patients. To evaluate this, data concerning Lp-PLA2 as a predictor in ACS patients was gathered through a systematic literature review, and studies on this issue were extracted from relevant databases, incl. PubMed and Cochrane. A total of 14 articles were retrieved, but after thorough evaluation and elimination of irrelevant articles only seven studies were eligible for the literature review. All studies except two showed significant correlation between Lp-PLA2 and CV events in ACS patients. Only one study found an independent value to predict CV events 30 days after ACS. Altogether, there was inconsistency in the findings regarding the potential use of Lp-PLA2 and a lack of knowledge on several issues. Lp-PLA2 seems to give valuable information on which ACS patients are prone to new events and also provides important information on plaque size. However, more focused studies concerning genetic variations, time-window impact, patients with and without CV risk factors (e.g. diabetes), and treatment effects are needed. In conclusion, Lp-PLA2 offers new insight in the pathophysiological development of ACS, but until the aforementioned issues are addressed the biomarker will mainly be of interest in a research setting, not as a predictive parameter in a clinical setting.

Perspectives on the value of biomarkers in acute cardiac care and implications for strategic management

Biomarkers in acute cardiac care are gaining increasing interest given their clinical benefits. This study is a review of the major conditions in acute cardiac care, with a focus on biomarkers for diagnostic and prognostic assessment. Through a PubMed search, 110 relevant articles were selected. The most commonly used cardiac biomarkers (cardiac troponin, natriuretic peptides, and C-reactive protein) are presented first, followed by a description of variable acute cardiac conditions with their relevant biomarkers. In addition to the conventional use of natriuretic peptides, cardiac troponin, and C-reactive protein, other biomarkers are outlined in variable critical conditions that may be related to acute cardiac illness. These include ST2 and chromogranin A in acute dyspnea and acute heart failure, matrix metalloproteinase in acute chest pain, heart-type fatty acid binding protein in acute coronary syndrome, CD40 ligand and interleukin-6 in acute myocardial infarction, blood ammonia and lactate in cardiac arrest, as well as tumor necrosis factor-alpha in atrial fibrillation. Endothelial dysfunction, oxidative stress and inflammation are involved in the physiopathology of most cardiac diseases, whether acute or chronic. In summary, natriuretic peptides, cardiac troponin, C-reactive protein are currently the most relevant biomarkers in acute cardiac care. Point-of-care testing and multi-markers use are essential for prompt diagnostic approach and tailored strategic management.

Modulation of oxidative stress, inflammation, and atherosclerosis by lipoprotein-associated phospholipase A2

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), also known as platelet-activating factor acetylhydrolase (PAF-AH), is a unique member of the phospholipase A(2) superfamily. This enzyme is characterized by its ability to specifically hydrolyze PAF as well as glycerophospholipids containing short, truncated, and/or oxidized fatty acyl groups at the sn-2 position of the glycerol backbone. In humans, Lp-PLA(2) circulates in active form as a complex with low- and high-density lipoproteins. Clinical studies have reported that plasma Lp-PLA(2) activity and mass are strongly associated with atherogenic lipids and vascular risk. These observations led to the hypothesis that Lp-PLA(2) activity and/or mass levels could be used as biomarkers of cardiovascular disease and that inhibition of the activity could offer an attractive therapeutic strategy. Darapladib, a compound that inhibits Lp-PLA(2) activity, is anti-atherogenic in mice and other animals, and it decreases atherosclerotic plaque expansion in humans. However, disagreement continues to exist regarding the validity of Lp-PLA(2) as an independent marker of atherosclerosis and a scientifically justified target for intervention. Circulating Lp-PLA(2) mass and activity are associated with vascular risk, but the strength of the association is reduced after adjustment for basal concentrations of the lipoprotein carriers with which the enzyme associates. Genetic studies in humans harboring an inactivating mutation at this locus indicate that loss of Lp-PLA(2) function is a risk factor for inflammatory and vascular conditions in Japanese cohorts. Consistently, overexpression of Lp-PLA(2) has anti-inflammatory and anti-atherogenic properties in animal models. This thematic review critically discusses results from laboratory and animal studies, analyzes genetic evidence, reviews clinical work demonstrating associations between Lp-PLA(2) and vascular disease, and summarizes results from animal and human clinical trials in which administration of darapladib was tested as a strategy for the management of atherosclerosis.

Developing and assessing cardiovascular biomarkers

Atherosclerosis is a slow process that over time can lead to fatal events. Early identification and prediction of future risk can allow for preventive strategies to be instituted. There is an increasing interest in utilizing novel biomarkers in cardiovascular disease screening and management. These novel biomarkers may help in cardiovascular disease risk assessment and treatment monitoring, and some may be treatment targets. To be useful for risk prediction, novel biomarkers need to show a significant association with cardiovascular disease events and bring additional value in risk stratification when added to known risk prediction models. Biomarkers used for treatment monitoring need to show that they can serve as good surrogates of cardiovascular disease status. In this article, we present 3 biomarkers that are currently approved by the U.S. Food and Drug Administration for use in cardiovascular disease management and risk assessment: C-reactive protein, lipoprotein-associated phospholipase A2, and myeloperoxidase. Other new biomarkers have also been shown recently to help in cardiovascular disease risk prediction and management. In this article, we will review 2 of these new biomarkers: cardiac troponin T measured by a highly sensitive assay and brain natriuretic peptide.

[Cardiac biomarkers in the critically ill]

Cardiac biomarkers in intensive care medicine are an excellent complement to existing clinical and diagnostic information in specific diseases. Due to their lack of specificity, the diagnostic properties of common cardiac biomarkers, such as natriuretic peptides and cardiac troponins, remain ambiguous, while their prognostic value has already been proven. In addition, there are several promising new biomarkers that might contribute to a "multimarker strategy" in the critically ill patient in the future, but further evaluation is still required.

Systematic Review of the Association between Lipoprotein-Associated Phospholipase A2 and Atherosclerosis

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a novel inflammatory biomarker. Basic research has shown that Lp-PLA2 is involved in the pathogenesis of atherosclerosis. In the past decade, an increasing number of epidemiological studies have investigated the association of Lp-PLA2 with atherosclerosis, but its roles in the different stages of atherosclerosis are not established. By undertaking a systematic review of the epidemiological studies on the relationship between Lp-PLA2 and atherosclerotic cardiovascular disease (CVD)/subclinical atherosclerosis, we tried to evaluate the relationship between Lp-PLA2 and the different stages of atherosclerosis. MEDLINE, Cochrane Library, and National Knowledge Infrastructure (CNKI) were searched up to September 1st, 2011. The references in all the located articles were manually searched. Epidemiological studies on the association of Lp-PLA2 with CVD and subclinical atherosclerosis, with total CVD, coronary heart disease (CHD), stroke, and subclinical atherosclerosis as their observation endpoints or outcome variables, were included in this study. Studies which did not assess the hazard ratio (HR), relative risk (RR), or odds ratio (OR) of Lp-PLA2 or which did not adjust for other known risk factors were excluded. The general information, study design, sample size, outcome variables and their definitions, follow-up duration, Lp-PLA2 measurements, variables adjusted in the multivariate analysis and main results in the literatures were retrieved. Thirty-nine studies were enrolled in this systematic review. Thirty-three studies (49, 260 subjects) investigated the relationship between Lp-PLA2 and CVD, among which 31 showed that increased Lp-PLA2 is associated to high risk for incidence or mortality of CVD: HR/RR per 1 standard deviation (SD) increase = 1.17-1.40; RR for the highest as compared with the lowest quartile was 1.41-3.75 (1.8-2.5 in most studies). Six studies (four cross-sectional studies and two case-control studies, with an overall sample size of 5,537) explored the relationship between Lp-PLA2 and subclinical atherosclerosis; among them, two studies demonstrated that Lp-PLA2 was associated with coronary artery calcification in young adults and men. In conclusion, many epidemiological studies have demonstrated that Lp-PLA2 increases the risk of clinical CVD events. However, whether there is a similar association between Lp-PLA2 and subclinical atherosclerosis remains unclear. Whether Lp-PLA2 exerts its effect during the occurrence of clinical events promoted by unstable plaques or at the early stage of atherosclerosis needs to be clarified in further prospective studies.

Lipoprotein-associated phospholipase A2: a new therapeutic target

Lipoprotein-associated phospholipase A2 is an enzyme produced by inflammatory cells, which binds to apolipoprotein B-containing lipoproteins and degrades oxidatively modified phospholipids in low-density lipoprotein cholesterol particles, leading to formation of proinflammatory and cytotoxic products. Experimental studies suggest a role for lipoprotein-associated phospholipase A2 in the formation of advanced rupture-prone atherosclerotic lesions, and epidemiological investigations have linked it to increased cardiovascular risk. Ongoing trials are evaluating the role of novel pharmacological inhibitors of this enzyme, such as darapladib, in the management of high-risk coronary artery disease patients.

Altered nitric oxide/cGMP platelet signaling pathway in platelets from patients with acute coronary syndromes

This study was aimed at evaluating whether the nitric oxide (NO)/cyclic GMP (cGMP) signaling pathway is altered in platelets from patients with an acute coronary syndrome (unstable angina and acute myocardial infarction). We investigated 10 patients with unstable angina (UA), 14 with acute myocardial infarction (AMI) and 14 age and sex-matched healthy subjects. The serum markers of platelet activation (sP-selectin), inflammation (TNF-alpha and erythrocyte sedimentation rate), thrombotic state (fibrinogen) and plaque disruption were significantly higher in both UA and AMI patients compared to the healthy controls. In their platelets we assessed the cGMP levels in basal conditions and after stimulation with sodium nitroprusside (SNP), and performed Western blot analysis of homogenates to measure the expression of soluble guanylate cyclase isoforms. Basal levels of cGMP (pmol/10(10) platelets) were significantly higher in platelets from UA patients (1,097 +/- 111; p < 0.0001) and AMI (1,122 +/- 77; p < 0.0001) compared to those collected from healthy controls (497 +/- 80). The platelets of AMI patients exhibited a lack of cGMP increase after SNP stimulation in comparison with UA patients. The phosphorylation of upstream (Akt1 protein kinase alpha and endothelial NO synthase) and downstream (vasodilator-stimulated phosphoprotein, VASP) signaling proteins of the NO/cGMP pathway was investigated: serine phosphorylation in Akt1, eNOS and VASP was enhanced in platelets from UA and AMI patients when compared to controls. Furthermore, in AMI patients the inhibitors of guanylate cyclase and cGMP-dependent protein kinase did not revert the VASP phosphorylation. These data suggest that platelets from AMI patients are more resistant to SNP stimulation, not only as cGMP production, but also in terms of VASP activation. From these ex vivo results we hypothesize that the increased inflammatory state which often accompanies patients with cardiovascular diseases might promote a platelet preactivation resulting in their reduced sensitivity to NO.

Lp-PLA2 Inhibition-The Atherosclerosis Panacea?

Based on the complex pathophysiology of atherosclerosis, a large number of biomarkers that relate to lipids, inflammation, immunity, thrombosis and hemostasis, have been investigated experimentally, in epidemiologic studies and in clinical trials. Interest focuses on their potential role to aid in risk stratification, as possible surrogate markers of atherosclerosis, and potential targets for therapy. More recently, one lipid associated biomarker, lipoprotein-associated phospholipase A2 (Lp-PLA₂), has gained considerable interest. In addition to a plausible pathophysiological role by generating pro-inflammatory and pro-atherogenic compounds from oxidized LDL in the vessel wall, there is a large, fairly consistent epidemiological database indicating that increased levels of Lp-PLA₂ mass or activity are associated with increased risk for cardiovascular outcomes; such data further suggest that it might improve risk stratification. In addition, clinical studies indicate that increased Lp-PLA₂ levels are associated with endothelial dysfunction. Moreover, it may also serve as an interesting therapeutic target, since a specific inhibitor of the enzyme is available with promising animal data and initial positive data in humans. Recent experimental data from a hyperlipidemic diabetic pig model strongly suggest that increased Lp-PLA₂ in the vessel wall is associated with a more vulnerable plaque phenotype which can be modulated by inhibiting Lp-PLA₂ activity. A biomarker study in more than 1,000 patients with CHD over three months has demonstrated a positive effect on various inflammatory molecules. In addition, an imaging study using IVUS based modalities (greyscale, virtual histology, and palpography) together with a panel of biomarkers (IBIS-2) has been done in more than 300 patients with CHD treated over 12 months and results indicate that the progression of the necrotic core of the plaque can be retarded. Inhibition of the pro-atherogenic and pro-inflammatory effects of Lp-PLA₂ may therefore contribute to decrease the residual risk in high risk patients already on polypharmacotherapy. This hypothesis is now being tested in two large phase 3 clinical trials. Thus, Lp-PLA₂ indeed may represent a biomarker and a promising target for intervention.

A cross-sectional study of intima-media thickness, ethnicity, metabolic syndrome, and cardiovascular risk in 2268 study participants

OBJECTIVE

To describe the association between intima-media thickness (IMT) and metabolic syndrome (MetS) and to examine if the addition of IMT to a traditional MetS definition adds value to the assessment of predicted cardiovascular disease (CVD) risk in a large multiethnic population.

PARTICIPANTS AND METHODS

In this cross-sectional study, carotid IMT was measured in 2268 men and women as part of a wellness physical examination between August 1, 2000, and October 1, 2001. The wellness examination included a fasting lipid panel, physical examination, and medical history. Mean IMT was described by sex, ethnicity, and the MetS. Predicted risk for CVD was determined with IMT as a component of the diagnostic criteria for MetS.

RESULTS

Intima-media thickness increased with each additional component of the MetS, increasing from 0.516 mm for 0 components to 0.688 mm for 4 or more components (P<.001). In each ethnic group (non-Hispanic whites, blacks, Hispanics, and Asians), those with the MetS had higher mean IMT (increased by 0.084 mm to 0.134 mm) than those without MetS. The addition of IMT as a "new" component in the diagnosis of MetS allowed us to identify 78 (3.4%) participants who were not previously diagnosed as having MetS but who had a high 10-year estimated risk of MetS as measured by the Framingham risk score (11.67%).

CONCLUSION

The addition of IMT to the traditional criteria for the diagnosis of the MetS may help identify individuals who otherwise would not have been identified to be at high risk of CVD.

A cross-sectional study of intima-media thickness, ethnicity, metabolic syndrome, and cardiovascular risk in 2268 study participants

OBJECTIVE

To describe the association between intima-media thickness (IMT) and metabolic syndrome (MetS) and to examine if the addition of IMT to a traditional MetS definition adds value to the assessment of predicted cardiovascular disease (CVD) risk in a large multiethnic population.

PARTICIPANTS AND METHODS

In this cross-sectional study, carotid IMT was measured in 2268 men and women as part of a wellness physical examination between August 1, 2000, and October 1, 2001. The wellness examination included a fasting lipid panel, physical examination, and medical history. Mean IMT was described by sex, ethnicity, and the MetS. Predicted risk for CVD was determined with IMT as a component of the diagnostic criteria for MetS.

RESULTS

Intima-media thickness increased with each additional component of the MetS, increasing from 0.516 mm for 0 components to 0.688 mm for 4 or more components (P<.001). In each ethnic group (non-Hispanic whites, blacks, Hispanics, and Asians), those with the MetS had higher mean IMT (increased by 0.084 mm to 0.134 mm) than those without MetS. The addition of IMT as a "new" component in the diagnosis of MetS allowed us to identify 78 (3.4%) participants who were not previously diagnosed as having MetS but who had a high 10-year estimated risk of MetS as measured by the Framingham risk score (11.67%).

CONCLUSION

The addition of IMT to the traditional criteria for the diagnosis of the MetS may help identify individuals who otherwise would not have been identified to be at high risk of CVD.

Lipoprotein-associated phospholipase A2: a cardiovascular risk predictor and a potential therapeutic target

Lipoprotein-associated phospholipase A2 (Lp-PLA2), present in the circulation and in atherosclerotic plaque, is an inflammatory marker with potential use as a predictor of cardiovascular risk and as a therapeutic target. Although Lp-PLA2 is associated with both LDL and HDL, it is important to determine whether Lp-PLA2 has a predominantly pro- or anti-atherogenic effect. Increasing evidence suggests a proatherogenic role for Lp-PLA2. ©iEpidemiologic and clinical evidence suggests Lp-PLA2 is an independent predictor of risk and may be superior to other inflammatory markers owing to its specificity and minimal biovariation. Lp-PLA2 inhibitors currently being investigated in clinical trials are promising novel anti-inflammatory agents with a specificity for the vascular bed and a potential for decreasing plaque vulnerability.

Lipoprotein-associated and secretory phospholipase A2 in cardiovascular disease: the epidemiological evidence

INTRODUCTION

Among other lipid related biomarkers, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and type II secretory phospholipase A(2) (sPLA(2)) represent emerging candidates for refined assessment of future cardiovascular disease (CVD) risk. Indeed, emerging evidence from more than prospective 15 studies conducted since 2000, clearly demonstrate the prognostic ability of increased Lp-PLA(2) concentrations or elevated activity for risk of future coronary heart disease (CHD) and stroke. Moreover, Lp-PLA(2) might have similar predictive power for both, incident CHD in initially healthy subjects, as well as for recurrent events in those with clinically manifest atherosclerosis.

DISCUSSION

By contrast, to date, there are only few prospective studies that have investigated the relationship of sPLA(2) with future CVD risk. However, most of them show a positive association between increased mass or elevated activity and future atherosclerotic complications. Nonetheless, since inhibitors of Lp-PLA(2) and sPLA(2) have already been developed, these enzymes may be considered as novel therapeutic targets to treat residual risk in certain high risk patient groups.

CONCLUSION

This review summarizes the epidemiologic evidence on the association between increased mass or elevated activity of these two phospholipases and risk of CVD.

Lipoprotein-associated phospholipase A2: an independent predictor of coronary artery disease events in primary and secondary prevention

In recent years, atherosclerosis has become recognized as an inflammatory disease whose activity can be assessed by circulating biomarkers. Along with C-reactive protein (CRP), lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) may now be considered as a biomarker with sufficient accumulated evidence to support its application in clinical practice. Lp-PLA(2) is especially appealing because of its vascular specificity, which directly derives from its role in plaque pathophysiology. This article reviews the highlights of the >25 prospective epidemiologic studies now published on Lp-PLA(2) as a risk marker in primary or secondary prevention. These trials demonstrate generally consistent correlations between elevated Lp-PLA(2) levels and the increased risk for cardiovascular events, even after multivariable adjustment for traditional risk factors, with roughly a doubling of risk associated with upper quantile levels. Furthermore, Lp-PLA(2) as a risk predictor has been shown to be independent of and complementary to high-sensitivity CRP. These study results combined with recommendations from the American Heart Association/Centers for Disease Control (AHA/CDC) and the National Cholesterol Education Program III (NCEP III) suggest that Lp-PLA(2) might best be used in current clinical practice to refine risk prediction in those at intermediate cardiovascular risk. An increasingly prevalent group at intermediate risk shown to benefit from Lp-PLA(2) risk modification is the population with the cardiovascular metabolic syndrome, clinically identified as overweight patients with features of mixed dyslipidemia, dysglycemia, and hypertension. An additional application supported by these studies is further risk stratification of high- (often secondary-) risk patients into a group at very high risk, for whom a more aggressive target for low-density lipoprotein of <70 mg/dL (1 mg/dL = 0.02586 mmol/L) is now recommended as a reasonable therapeutic goal.

Lipoprotein-associated phospholipase A2: a risk marker or a risk factor?

Multiple cardiovascular biomarkers are associated with increased cardiovascular disease (CVD) risk. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) appears to be relatively unique in its high specificity for and the causal pathway of plaque inflammation. In both primary and secondary prevention study populations, Lp-PLA(2) was consistently associated with higher cardiovascular risk, and the risk estimate appears to be relatively unaffected by adjustment for conventional CVD risk factors. Risk ratios were similar, whether the mass concentration or activity of the enzyme was measured. The purpose of this article is to review the evidence for the clinical utility of Lp-PLA(2), both as a risk marker and as a risk factor involved in the causal pathway of plaque inflammation and the formation of rupture-prone plaque.

Review of the evidence for the clinical utility of lipoprotein-associated phospholipase A2 as a cardiovascular risk marker

A substantial body of peer-reviewed studies has been published validating the role of inflammation in atherogenesis and supporting lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) as a cardiovascular risk marker independent of and additive to traditional risk factors. As with elevated high-sensitivity C-reactive protein, an elevated Lp-PLA(2) level approximately doubles the risk for primary and secondary cardiovascular events. Interestingly, when both inflammatory markers are increased together, they provide an even greater predictive capability to help identify very-high-risk individuals who would benefit most from aggressive lipid-lowering therapy. High levels of Lp-PLA(2) are present in inflamed, rupture-prone plaques, and it appears that Lp-PLA(2) is released from these plaques into the circulation. Over 25 prospective epidemiologic studies have demonstrated the association of elevated Lp-PLA(2) levels with future coronary events and stroke-11 of 12 prospective studies have shown a statistically significant association between elevated Lp-PLA(2) and primary coronary or cardiovascular events, 12 of 13 have shown a statistically significant association with recurrent coronary or cardiovascular events, and 6 studies have shown a positive association with stroke. Lp-PLA(2) should be viewed today as an important cardiovascular risk marker whose utility is as an adjunct to the major risk factors to adjust absolute risk status and thereby modify low-density lipoprotein cholesterol goals. The low biologic fluctuation and high vascular specificity of Lp-PLA(2) makes it possible to use a single measurement in clinical decision making, and it also permits clinicians to follow the Lp-PLA(2) marker serially. Ultimately, Lp-PLA(2) may also be classified as a risk factor, but this should not detract from its utility today as a risk marker.