Predicting the Risk of Cardiovascular Disease

Association between Lp-PLA2 and coronary heart disease in Chinese patients

Objective

To evaluate the association between plasma lipoprotein-associated phospholipase A2 (Lp-PLA2; known to release inflammatory mediators that promote atherosclerosis) and coronary heart disease (CHD) in Chinese patients.

Methods

This observational, cross-sectional study included a patient cohort who were assessed by coronary angiography and divided into patients with coronary heart disease and patients with normal coronary angiography (controls). Data for several biochemical indicators were collected. Plasma Lp-PLA2 concentrations were measured by enzyme-linked immunosorbent assay. Univariate and multivariate logistic regression were used to analyse the association between Lp-PLA2 concentration and CHD.

Results

A total of 531 patients were included, comprising 391 with CHD and 140 with normal coronary angiography (controls). Plasma Lp-PLA2 concentration was significantly higher in patients with CHD versus controls (median, 251 µg/l versus 219 µg/l, respectively), and particularly among patients with acute myocardial infarction and stable angina pectoris (249 µg/l and 266 µg/l, respectively). Multivariate analysis showed that Lp-PLA2 ≥ 292 µg/l (upper quartile of the whole cohort) was independently associated with CHD (odds ratio 2.814, 95% confidence interval 1.519, 5.214).

Conclusion

Plasma Lp-PLA2 concentration was independently associated with CHD in Chinese patients.

The Importance of Age and Statin Therapy in the Interpretation of Lp-PLA2 in ACS Patients, and Relation to CRP

C-reactive protein (CRP) is a marker of arterial inflammation while lipoprotein-associated phospholipase A2 (Lp-PLA2) is related to plaque instability. The aim of this study was to evaluate the correlation between the risk of unstable plaque presenting as acute coronary syndrome (ACS) and Lp-PLA2, and to assess the influence of statins on interpretation of Lp-PLA2. A total of 362 consecutive patients presenting to the emergency department (ED) with acute chest pain suggestive of ACS were evaluated by cardiologists as STEMI, NSTEMI, or unstable angina, and non-ACS. Serum biomarkers measured on admission: troponin I, C-reactive protein (Abbott), and Lp-PLA2 (DiaDexus). Four groups were defined according to the final diagnosis and history of statin medication: ACS/statin−; ACS/statin+; non-ACS/statin−; non-ACS/statin+. Lp-PLA2 was highest in ACS/statin− group; statins decreased Lp-PLA2 both in ACS and non-ACS of about 20 %. Lp-PLA2 was higher in ACS patients in comparison with non-ACS patients group without respect to statin therapy (p<0.001). Lp-PLA2 predicted worse outcome (in terms of acute coronary syndrome) effectively in patients up to 62 years; limited prediction was found in older patients. C-reactive protein (CRP) failed to discriminate four groups of patients. Statin therapy and age should be taken into consideration while interpreting Lp-PLA2 concentrations and lower cut-off values should be used for statin-treated persons.

Cardiovascular disease risk prediction in women: is there a role for novel biomarkers?

BACKGROUND

Risk prediction is an integral part of the current US guidelines for cardiovascular disease in women. Although current risk prediction algorithms exist to identify women at increased 10-year risk of cardiovascular disease (CVD), clinicians and researchers have been interested in developing novel biomarkers that might improve predictive accuracy further. These biomarkers have led to important insights into the pathophysiology of CVD, but results for their ability to improve prediction or guide preventive therapy have been mixed. The incidence of CVD is lower in women than men, and the effects of a number of traditional biomarkers on CVD risk differ in women compared to men. Both of these factors influence the ability to accurately predict CVD risk.

CONTENT

We review the distinctive aspects of CVD risk prediction in women, discuss the statistical challenges to improved risk prediction, and discuss a number of biomarkers in varying stages of development with a range of performance in prediction.

SUMMARY

A variety of biomarkers from different pathophysiologic pathways have been evaluated for improving CVD risk. While many have been incompletely studied or have not been shown to improve risk prediction in women, others, such as high-sensitivity troponin T, have shown promise in improving risk prediction. Increasing inclusion of women in CVD studies will be crucial to providing opportunities to evaluate future biomarkers.

Lipoprotein-Associated Phospholipase A2

The role of inflammation in atherosclerosis continues to emerge. Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), a novel plasma biomarker, circulates in the blood bound mainly to low-density lipoprotein (LDL) and promotes vascular inflammation. Several epidemiological studies have shown that circulating levels of Lp-PLA(2) are an independent risk factor for cardiovascular events. Recent studies demonstrate that Lp-PLA(2) is also associated with endothelial dysfunction and early atherosclerosis. This review provides an overview of these studies, suggests plausible mechanisms for the association between endothelial dysfunction and Lp-PLA(2), and highlights future potential therapies.

Clinical utility of lipoprotein-associated phospholipase A₂ for cardiovascular disease prediction in a multiethnic cohort of women

BACKGROUND

Findings regarding the association of lipoprotein-associated phospholipase A₂ (Lp-PLA2) activity and mass with incident cardiovascular disease (CVD) have been inconsistent, and their role in risk prediction is uncertain.

METHODS

A case-cohort sample from the Women's Health Initiative Observational Study (WHI-OS) comprised 1821 CVD cases and a reference subcohort of 1992 women. We used Cox regression models with inverse sampling weights to assess the association of Lp-PLA2 mass and activity with CVD (myocardial infarction, stroke, and CVD mortality).

RESULTS

Subcohort means were 184.3 mmol/min/mL for Lp-PLA2 activity and 499.2 μg/L for Lp-PLA2 mass, with 99% having mass above 200 μg/L, the clinically recommended cut point. Both activity and mass were positively associated with incident CVD in age- and race/ethnicity-adjusted analyses. Following adjustment according to CVD risk factors, the association with activity became null (hazard ratio = 1.02 for top vs bottom quartile, 95% CI = 0.79-1.33, P for trend = 0.65), but the association with mass remained (hazard ratio = 1.84, 95% CI = 1.45-2.34, P for trend < 0.0001). In contrast to blood pressure, HDL, and hsCRP, reclassification statistics for Lp-PLA2 mass did not suggest improvement for overall CVD after full adjustment.

CONCLUSIONS

In the WHI-OS Lp-PLA2 mass, but not activity, was independently associated with CVD. However, model fit did not significantly improve with Lp-PLA2 mass, and assay calibration remains a clinical concern.

Update on integrated biomarkers for assessment of long-term risk of cardiovascular complications in initially healthy subjects and patients with manifest atherosclerosis

Risk stratification for cardiovascular diseases (CVD) remains suboptimal even after the introduction of global risk assessment by various scores. This has prompted the search for additional biomarkers which might help to improve risk stratification. Basically, there are blood biomarkers representing various pathophysiological pathways of atherosclerosis, and markers of subclinical disease. Since inflammatory processes accompany all stages of atherosclerosis, measurement of plasma/serum concentrations of circulating inflammatory biomarkers have received great attention. Such biomarkers can be measured systemically by sensitive assays, and elevated concentrations in the circulation have been shown to be associated with future CVD events. Thus, they might add to the predictive value of the atherogenic lipoprotein phenotype to further improve CVD risk assessment. In addition, several non-invasive imaging techniques are available for which also a predictive value for CVD could be established. However, for most of these biomarkers the clinical utility has not yet been firmly established. This review attempts to give an update on the potential use of biomarkers for risk stratification in initially healthy subjects and patients with manifest, chronic atherosclerosis, particularly focusing on the integrated value of the combination of these markers.

Identification of a domain that mediates association of platelet-activating factor acetylhydrolase with high density lipoprotein

The plasma form of platelet-activating factor (PAF) acetylhydrolase (PAF-AH), also known as lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) inactivates potent lipid messengers such as PAF and modified phospholipids generated in settings of oxidant stress. In humans, PAF-AH circulates in blood in fully active form and associates with high and low density lipoproteins (HDL and LDL). Several studies suggest that the location of PAF-AH affects both the catalytic efficiency and the function of the enzyme in vivo. The distribution of PAF-AH among lipoproteins varies widely among mammals. Here, we report that mouse and human PAF-AHs associate with human HDL particles of different density. We made use of this observation in the development of a binding assay to identify domains required for association of human PAF-AH with human HDL. Sequence comparisons among species combined with domain-swapping and site-directed mutagenesis studies led us to the identification of C-terminal residues necessary for the association of human PAF-AH with human HDL. Interestingly, the region identified is not conserved among PAF-AHs, suggesting that PAF-AH interacts with HDL particles in a manner that is unique to each species. These findings contribute to our understanding of the mechanisms responsible for association of human PAF-AH with HDL and may facilitate future studies aimed at precisely determining the function of PAF-AH in each lipoprotein particle.