Circulating pregnancy-associated plasma protein a predicts outcome in patients with acute coronary syndrome but no troponin I elevation

Diagnostic evaluation of the MRP-8/14 for the emergency assessment of chest pain

Elevated levels of myeloid-related protein (MRP)-8/14 (S100A8/A9) are associated with first cardiovascular events in healthy individuals and worse prognosis in patients with acute coronary syndrome (ACS). The diagnostic utility of MRP-8/14 in patients presenting to the emergency room with symptoms concerning for ACS is uncertain. MRP-8/14 was measured in serial serum and plasma samples in a single center prospective cohort-study of patients presenting to the emergency room with non-traumatic chest pain concerning for ACS. Final diagnosis was adjudicated by an endpoint committee. Of patients with baseline MRP-8/14 results (n = 411), the median concentration in serum was 1.57 μg/ml (25th, 75th: 0.87, 2.68) and in plasma was 0.41 μg/ml (<0.4, 1.15) with only moderate correlation between serum and plasma (ρ = 0.40). A final diagnosis of MI was made in 106 (26%). Peak serum MRP-8/14 was higher in patients presenting with MI (p < 0.001). However, the overall diagnostic performance of MRP-8/14 was poor: sensitivity 28% (95% CI 20-38), specificity 82% (78-86), positive predictive value 36% (26-47), and negative predictive value 77% (72-81). The area under the ROC curve for diagnosis of MI with MRP-8/14 was 0.55 (95% CI 0.51-0.60) compared with 0.95 for cTnI. The diagnostic performance was not improved in early-presenters, patients with negative initial cTnI, or using later MRP-8/14 samples. Patients presenting with MI had elevated levels of serum MRP-8/14 compared to patients with non-cardiac chest pain. However, overall diagnostic performance of MRP-8/14 was poor and neither plasma nor serum MRP-8/14 offered diagnostic utility comparable to cardiac troponin.

Role of PAPP-A in aging and age-related disease

As suggested by its name, pregnancy-associated plasma protein-A (PAPP-A) plays an important role in pregnancy and fetal development (Brizot et al., 1996; Lin et al., 1974; Smith et al., 2002). On the opposite end of life's spectrum, recent studies using genetically-engineered mice indicate a newly recognized role for PAPP-A in aging and in the development of age-related disease. These latter studies will be reviewed in this article.

Assessment of serum leptin, pregnancy-associated plasma protein A and CRP levels as indicators of plaque vulnerability in patients with acute coronary syndrome

INTRODUCTION

A multifactorial aetiology of coronary artery disease (CAD) has been established in the recent past. Extensive research is now underway to understand the mechanisms responsible for plaque vulnerability. The identification of a novel biomarker that will help in the assessment of plaque status is urgently needed for the purpose of patient stratification and prognostication. The aim of the present study was to evaluate leptin, pregnancy-associated plasma protein A (PAPP-A) and C-reactive protein (CRP) levels in patients with acute coronary syndrome and to assess their diagnostic efficacy in the identification of vulnerable plaques.

METHODS

The study group comprised 105 patients who had chest pain along with ECG changes (ST elevation, ST depression, T inversion) and raised cardiac enzyme levels. Sixty-two patients with chest pain and ECG changes but with normal cardiac enzyme profiles were included in the control group. Lipid profiles, and leptin, PAPP-A and CRP levels were assessed in these two groups. Receiver operating characteristics (ROC) curves were plotted to determine the utility of the parameters under study as markers of plaque vulnerability.

RESULTS

Significantly higher levels of serum lipoprotein (a), leptin, PAPP-A and high-sensitivity CRP (hs-CRP) were observed in the cases than in the controls. A positive correlation was observed between CRP and PAPP-A levels as well as CRP and leptin concentrations. ROC curve analysis revealed similar efficacies of CRP and PAPP-A levels in their ability to detect unstable plaques with areas under the curve of 0.762 and 0.732, respectively. Multivariate analysis established the superiority of hs-CRP as a predictor of plaque instability.

CONCLUSIONS

Our study highlights the utility of both CRP and PAPP-A levels as determinants of plaque instability. Our findings necessitate population-based follow-up studies to establish the superiority of either of the two biomarkers in the field of preventive cardiology.

Key questions and answers about pregnancy-associated plasma protein-A

Twenty-five years after it was identified as a circulating protein of unknown function derived from the placenta, pregnancy-associated plasma protein-A (PAPP-A) was discovered to be a novel zinc metalloproteinase expressed by a variety of cell types. Great progress has been made in understanding the biology of PAPP-A and its regulation during recent years, especially in regard to physiological and pathophysiological inflammatory injury responses. However, much remains to be learned about this complex protein and its potential clinical implications outside pregnancy. In this article we address some of the outstanding questions about PAPP-A, in particular about its newly emerging role in the insulin-like growth factor (IGF) system.

Pregnancy associated plasma protein-A (PAPP-A) as an early marker for the diagnosis of acute coronary syndrome

AIMS AND OBJECTIVES

Pregnancy associated plasma protein-A (PAPP-A), a metalloproteinase plays a pivotal role in the pathogenesis of atherosclerosis. Recent studies have reported that elevated levels of PAPP-A, signal the onset of acute coronary syndrome (ACS). We, therefore, proposed to study the analytical competence of PAPP-A in patients admitted to the emergency department with chest pain and finally diagnosed as ACS.

METHODS AND RESULTS

Pregnancy associated plasma protein-A was measured using enzyme-linked immunosorbent assay (ELISA) in 485 patients admitted to emergency care unit, of which 89 patients were diagnosed as Non-cardiac chest pain (NCCP). Elevated levels of PAPP-A were observed in patients diagnosed as ACS on comparison with the controls. Receiver operator characteristic (ROC) curve analysis showed PAPP-A to be a good discriminator between ischaemic and non-ischaemic patients. The area under the curve was found to be 0.904, 95% CI (0.874-0.929) with 90% sensitivity and 85% specificity (P< 0.0001). The cut-off value from the ROC curve was 0.55 μg/mL above which PAPP-A was considered to be positive.

CONCLUSION

Pregnancy associated plasma protein-A seems to be a promising biomarker for identification and risk stratification for patients with ACS.

N-terminal and C-terminal fragments of IGFBP-4 as novel biomarkers for short-term risk assessment of major adverse cardiac events in patients presenting with ischemia

OBJECTIVES

Pregnancy Associated Plasma Protein A (PAPP-A)-derived N- and C-terminal fragments of IGF-binding protein-4 (NT- and CT-IGFBP-4) released from vulnerable atherosclerotic plaques are proposed to be used for cardiovascular risk assessment.

DESIGN AND METHODS

NT- and CT-IGFBP-4 were measured by novel immunoassays in EDTA-plasma of 180 patients admitted to the emergency department with symptoms of myocardial ischemia but without ST-segment elevation. Six-month incidence of major adverse cardiac events (MACE), including myocardial infarction, cardiac death, percutaneous coronary interventions, and coronary artery bypass grafting was recorded.

RESULTS

Sixteen patients met the endpoint. NT- and CT-IGFBP-4 were strong predictors of MACE: area under ROC curve (AUC) 0.856 and 0.809, respectively. NT-IGFBP-4 concentrations≥214μg/L and CT-IGFBP-4 concentrations≥124μg/L were associated with increased risk of future MACE: adjusted hazard ratio 13.79 and 7.93, respectively.

CONCLUSIONS

IGFBP-4 fragments can be utilized as biomarkers for MACE prediction in patients with suspected myocardial ischemia.

Pregnancy-associated plasma protein A as an independent mortality predictor in long-term hemodialysis patients

BACKGROUND/AIMS

Pregnancy-associated plasma protein A (PAPP-A) is a biomarker related to vascular damage. The aim of the study was to focus on PAPP-A and related parameters and their relationship to the prognosis of long-term hemodialysis (HD) patients.

METHODS

This is a prospective observational cohort study which included 261 long-term HD patients followed up for 5 years and 66 healthy subjects. PAPP-A, placental growth factor (PlGF), matrix metalloproteinase 2 and 9 (MMP-2, MMP-9), insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein-4 (IGFBP-4), and cardiac, nutritional and inflammatory parameters were measured at the beginning of the study and tested as predictors of mortality.

RESULTS

PAPP-A, PlGF, IGF-1, IGFBP-4 and MMP-2 were significantly increased in HD patients compared to controls (PAPP-A 27.6 ± 15.5 mIU/l in HD vs. 9.4 ± 2.5 mIU/l in controls, p < 0.001). Increased PAPP-A was a significant independent predictor of overall mortality and mortality due to infection in the multivariate Cox analysis [HR (95% CI): 1.237 (1.060-1.444), p = 0.007, and 1.416 (1.115-1.798), p = 0.004, per standard deviation, respectively]. PAPP-A was not related to cardiovascular mortality.

CONCLUSION

Increased PAPP-A is a significant independent predictor of overall mortality and mortality due to infection but it was not related to cardiovascular mortality in this study.

Human matrix metalloproteinases: an ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes.

Pregnancy-associated plasma protein A in obese children: relationship to markers and risk factors of atherosclerosis and members of the IGF system

BACKGROUND

Pregnancy-associated plasma protein A (PAPPA) is a large placenta-derived glycoprotein, which serves as a protease of several IGF-binding proteins (IGFBPs). In non-pregnant adults, measurable PAPPA levels were detected and have been implicated in the pathophysiology of atherosclerotic plaques. However, data in children is lacking.

OBJECTIVE

To study the relationship between PAPPA, markers of atherosclerosis, and members of the IGF system in pediatric obesity.

PATIENTS AND DESIGN

Eighty-two obese and 52 nonobese children and 1-year longitudinal follow-up study for obese cohort.

INTERVENTION

Outpatient 1-year intervention program based on exercise, behavior, and nutrition therapy.

MAIN OUTCOME MEASURES

Changes in PAPPA levels, carotid intima media thickness (IMT), weight, blood pressure, lipids, metabolic markers, and members of IGF system.

RESULTS

Baseline PAPPA (PAPPA(BL)) serum levels did not differ between obese and lean subjects. PAPPA(BL) correlated significantly with IGF1, IGFBP1, and serum cholesterol. During the 1-year-program mean IMT decreased from 0.66 ± 0.01 to 0.63 ± 0.01 mm (P<0.05) and PAPPA from 1.83 ± 0.12 to 1.58 ± 0.11 μU/l (P<0.00). In linear regression analysis with IMT after intervention as dependent variable, PAPPA contributed significantly to the observed variance. The longitudinal change of PAPPA correlated significantly with the change of serum triglycerides.

CONCLUSION

In this cohort of obese children, PAPPA serum levels correlated significantly with other cardiovascular risk factors. The lack of a direct correlation between PAPPA and IMT suggests that the described association of atherosclerotic plaques and increased PAPPA levels might reflect an indirect mechanism of PAPPA with cardiovascular risk factors such as serum lipids rather than a direct effect on the vasculature.

Gender-specific differences in biomarkers responses to acute coronary syndromes and revascularization procedures

A growing body of gender-related research in coronary artery disease is beginning to gradually elucidate differences between women and men. In patients presenting with acute coronary syndromes (ACS), these sex differences include varying risk factor profiles, accuracy of diagnostic testing, clinical presentations, treatment practices and outcomes. There is also a differential expression of cardiac biomarkers by sex, which remains unexplained. This paper reviews all the available information on the effect of gender on cardiac biomarkers by search of MEDLINE using the terms gender differences, biomarkers, ACS and revascularization procedures. A better understanding of the sex disparities in biomarkers along with all other clinical information is essential to optimal management and patient care in the future.

Diagnostic performance of high-sensitivity troponin T, myeloperoxidase, and pregnancy-associated plasma protein A assays for triage of patients with acute myocardial infarction

Background

Early diagnosis is the cornerstone of management of acute myocardial infarction (AMI). We aimed to compare the diagnostic accuracy of high-sensitivity troponin T (hs-cTnT) with myeloperoxidase (MPO) and pregnancy-associated plasma protein A (PAPP-A) for early diagnosis of AMI in patients at the time of presentation to the emergency department (ED).

Methods

We enrolled 289 patients who presented at the ED of the National Institute of Heart Disease (NIHD) Rawalpindi, Pakistan, within 4 hr of onset of chest pain. Clinical assessment, electrocardiography (ECG), and angiography were carried out. Blood samples were collected at 0, 3, 6, and 12 hr. Analyses of plasma hs-cTnT, MPO, and PAPP-A were carried out using commercial kits.

Results

Out of 289 subjects who presented to the ED, we diagnosed 180 patients with coronary heart disease as having AMI (N= 61) and 119 as without AMI (stable coronary artery disease, N=61; unstable angina, N=58). Compared to non-AMI patients, the patients with AMI had significantly higher levels (represented here as median [inter quartile range]) of plasma hs-cTnT (136 [39-370] vs. 12 [7-21] ng/L), MPO (906 [564-1,631] vs. 786 [351-1,299] pmol/L) and PAPP-A (5.78 [2.67-13.4] vs. 2.8 [1.8-4.9] mIU/L). Receiver operator characteristic curves (95% CI) for hs-cTnT (0.952 [0.909-0.978]) were significantly higher (P<0.001) than those for MPO (0.886 [0.830-0.929]) and PAPP-A (0.797 [0.730-0.854]), with AMI sensitivity and specificity percentages of 87% and 98% (hs-cTnT), 82% and 84% (MPO), and 65% and 87% (PAPP-A), respectively.

Conclusions

The diagnostic performance of hs-cTnT was superior to that of MPO and PAPP-A for early triage and diagnosis of AMI among patients of coronary heart disease presenting with chest pain to the ED.

Pregnancy-associated plasma protein A values in patients with stable cardiovascular disease: use of a new monoclonal antibody-based assay

BACKGROUND

PAPP-A is promising in improving risk stratification and invasive treatment decisions in stable cardiovascular patients. We evaluated the prognostic value of pregnancy-associated plasma protein A (PAPP-A) measured by a novel assay in stable cardiovascular patients.

METHODS

We investigated 228 stable cardiovascular outpatients. Blood was drawn for PAPP-A measurement after echocardiography and ergometry prior to heart catheterization. Angiographically we determined severity as well as qualitative characteristics suspect for vulnerability of coronary lesions. After 1108±297 days, follow-up information was obtained by questionnaire mailings and interviews by phone.

RESULTS

104 patients had coronary stenosis≥70%, 75 had B-type lesions≥50%, 46 showed complex lesions, and 68 were suspected to have vulnerable lesions. Median PAPP-A was 1.76 (interquartile range 1.21, 2.63) μIU/ml in the entire cohort. PAPP-A concentrations did not differ in dependence on coronary artery findings. A cutpoint of 2.7 μIU/ml was derived from receiver-operator characteristics for outcome measures. For this cutoff, Cox proportional hazard models with 19 further clinical variables showed that PAPP-A was predictive for all-cause death (HR 4.73, 95% CI 1.46-15.31, p=0.01), all-cause death or nonfatal infarction (HR 4.01, 95% CI 1.58-10.13, p=0.003) and all-cause death, nonfatal myocardial infarction or hospitalization (HR 1.96, 95% CI 1.03-3.70, p=0.04). The predictive value of PAPP-A did not change substantially after correction for values of cardiac troponin, using a highly sensitive cardiac troponin I research assay.

CONCLUSIONS

PAPP-A, measured by a new, monoclonal antibody-based assay is a promising prognostic marker in patients with stable cardiovascular disease and an indication for heart catheterization.

Comparative endocrinology of aging and longevity regulation

Hormones regulate growth, development, metabolism, and other complex processes in multicellular animals. For many years it has been suggested that hormones may also influence the rate of the aging process. Aging is a multifactorial process that causes biological systems to break down and cease to function in adult organisms as time passes, eventually leading to death. The exact underlying causes of the aging process remain a topic for debate, and clues that may shed light on these causes are eagerly sought after. In the last two decades, gene mutations that result in delayed aging and extended longevity have been discovered, and many of the affected genes have been components of endocrine signaling pathways. In this review we summarize the current knowledge on the roles of endocrine signaling in the regulation of aging and longevity in various animals. We begin by discussing the notion that conserved systems, including endocrine signaling pathways, "regulate" the aging process. Findings from the major model organisms: worms, flies, and rodents, are then outlined. Unique lessons from studies of non-traditional models: bees, salmon, and naked mole rats, are also discussed. Finally, we summarize the endocrinology of aging in humans, including changes in hormone levels with age, and the involvement of hormones in aging-related diseases. The most well studied and widely conserved endocrine pathway that affects aging is the insulin/insulin-like growth factor system. Mutations in genes of this pathway increase the lifespan of worms, flies, and mice. Population genetic evidence also suggests this pathway's involvement in human aging. Other hormones including steroids have been linked to aging only in a subset of the models studied. Because of the value of comparative studies, it is suggested that the aging field could benefit from adoption of additional model organisms.

Positive correlation between pregnancy-associated plasma protein-A level and OX40 ligand expression in patients with acute coronary syndromes

OBJECTIVE

Increasing evidence show that serum pregnancy-associated plasma protein-A (PAPP-A) and OX40 ligand (OX40L) expression have been implicated in acute coronary syndromes (ACS). We investigated the relationship between PAPP-A level and OX40L in serum and membrane-bound OX40L in patients with ACS.

METHODS

The present study included normal controls (n=30), patients with stable angina (SA) (n=60) and patients with ACS, including unstable angina (UA) (n=50) and acute myocardial infarction (AMI) (n=30). Serum concentrations of PAPP-A and soluble OX40L (sOX40L) were determined with Elisa, whereas the expression of OX40L on monocytes were analyzed with flow cytometry.

RESULTS

The expression of OX40L in peripheral monocytes in patients with UA [25.6±5.5 mean fluorescence intensity (MFI)] and AMI (29.4±6.3MFI) were significantly higher than those in patients with SA (10.6±2.8MFI) and controls (11.1±3.5MFI). Both sOX40L and PAPP-A in patients with UA (15.7±4.9ng/mL, 25.4±6.8μg/mL, respectively) and AMI (17.1±5.3ng/mL, 26.3±5.6μg/mL, respectively) were significantly higher than those in patients with SA (3.4±1.4ng/mL, 9.6±2.1μg/mL, respectively) and controls (3.9±1.3ng/mL, 8.5±2.8μg/mL, respectively) (P<0.001). Interestingly, a positive correlation was found between sOX40L, membrane-bound OX40L and serum PAPP-A levels (r(1)=0.54, r(2)=0.51; P<0.0001). Both serum and membrane-bound OX40L and PAPP-A levels significantly correlated with complex coronary stenosis (r(1)=0.56, r(2)=0.55, r(3)=0.40; P<0.001).

CONCLUSION

PAPP-A level was significantly related to soluble and membrane-bound OX40L in patients with ACS. Enhanced level of serum PAPP-A and sOX40L might represent a prognostic marker for coronary disease activity.

Candidate biomarkers for the detection of coronary plaque destabilization and rupture

Identification of high-risk patients presenting with chest pain remains challenging. The use of a single biomarker or a panel of biomarkers to detect occult plaque destabilization or rupture without frank infarction would allow for appropriate triage of such patients. Current data suggest that plaque vulnerability is determined by the relationship between forces that increase the size of the lipid core and destabilize the overlying thin fibrous cap. A variety of interrelated pathways are imputed to play important roles in this process of plaque evolution, destabilization, and rupture. These mechanisms include increased systemic and local inflammation, increased oxidative stress, matrix metalloproteinase modulation, and hemodynamic variables related to altered shear stress. Select candidate biomarkers that either reflect or influence these underlying processes and may ultimately have clinical application are highlighted in this review, which focuses on emerging biomarkers to define and predict the risks associated with the complex nature of vulnerable plaque biology.

Pregnancy-associated plasma protein predicts outcomes of percutaneous coronary intervention in patients with non-ST-elevation acute coronary syndrome

OBJECTIVE

Pregnancy-associated plasma protein A (PAPP-A) may play an important role in the development of acute coronary syndrome. This study aimed to investigate the relationship between the levels of circulating PAPP-A and the mid-term outcomes of percutaneous coronary intervention (PCI) in patients with non-ST-elevation acute coronary syndrome.

METHODS

The circulating PAPP-A levels and high-sensitivity C-reactive protein before PCI were measured in 129 patients with single coronary artery stenosis. The end point of clinical follow-up was cardiac death, nonfatal myocardial infarction, target vessel revascularization, and rehospitalization for angina.

RESULTS

During the follow-up of an average of 20.3 ± 5.2 months, a cardiac event was recorded in 25 patients (19.4%). The levels of PAPP-A (29.85 ± 19.51 mIu/L vs 20.47 ± 14.33 mIu/L, P = .007) and high-sensitivity C-reactive protein (5.63 ± 2.13 mg/L vs 4.11 ± 1.28 mg/L, P = .014) in patients with cardiac events were higher than in those without cardiac events. PAPP-A ≥ 11.33 mIu/L has a strong predictive value for a combined end point (risk ratio = 4.1; 95% confidence interval, 1.0-16.2; P = .037). Patients with lower PAPP-A levels (<11.33 mIu/L) had higher event-free survivals than patients with higher PAPP-A levels (log rank = 9.334, P = .025).

CONCLUSION

Circulating PAPP-A levels predict the mid-term outcomes of PCI in patients with non-ST-elevation acute coronary syndrome and single-vessel stenosis.

A pilot study of the clinical relevance of the relationship between the serum level of pregnancy-associated plasma protein A and the degree of acute coronary syndrome

Serum levels of pregnancy-associated plasma protein-A (PAPP-A), high-sensitivity C-reactive protein (hs-CRP) and tumour necrosis factor-alpha (TNF-alpha) were measured in 70 patients with acute coronary syndrome (ACS), comprising 18 with unstable angina (UA), 37 with acute myocardial infarction (AMI) and 15 with stable angina (SA); 15 healthy controls were also included. Levels of PAPP-A were significantly higher in the UA and AMI groups than in the SA and control groups. Levels of PAPP-A were similar in the SA and control groups, and higher in the ACS patients who were cardiac troponin T-negative (comprising UA and AMI patients) than in the control and SA groups. Levels of hs-CRP and TNF-alpha were significantly higher in the SA group than in the control group, significantly higher in the UA group than in the SA and control groups, and significantly higher in the AMI group than in all other groups. Levels of PAPP-A in ACS patients were positively correlated with levels of hs-CRP and TNF-alpha. It would seem, therefore, that PAPP-A is associated with inflammation and might be used to detect plaque instability and rupture before an increase in cardiac troponin T is detectable.

Free vs Total Pregnancy-Associated Plasma Protein A (PAPP-A) as a Predictor of 1-Year Outcome in Patients Presenting with Non–ST-Elevation Acute Coronary Syndrome

Background: The free fraction of pregnancy-associated plasma protein A (FPAPP-A) was found to be the PAPP-A form released to the circulation in acute coronary syndrome (ACS). We estimated the prognostic value of FPAPP-A vs total PAPP-A (TPAPP-A) concentrations in forecasting death and nonfatal myocardial infarction (combined endpoint) in patients with non–ST-elevation ACS.

Methods: We recruited 267 patients hospitalized for symptoms consistent with non–ST-elevation ACS and followed them for 12 months. FPAPP-A, TPAPP-A, C-reactive protein (CRP), and cardiac troponin I (cTnI) were measured at admission; cTnI was also measured at 6–12 h and 24 h. Because of the recently shown interaction between PAPP-A and heparin, we excluded patients treated with any heparin preparations before the admission blood sampling.

Results: During the follow-up, 57 (21.3%) patients met the endpoint (22 deaths and 35 nonfatal myocardial infarctions). According to FPAPP-A (&lt;1.27, 1.27–1.74, &gt;1.74 mIU/L) and TPAPP-A (&lt;1.98, 1.98–2.99, &gt;2.99 mIU/L) tertiles, this endpoint was met by 12 (13.5%), 18 (20.2%), 27 (30.3%) (P = 0.02), and 17 (19.1%), 17 (19.1%), 23 (25.8%) (P = 0.54) patients, respectively. After adjusting for age, sex, diabetes, previous myocardial infarction, and ischemic electrocardiogram (ECG) findings, FPAPP-A &gt;1.74 mIU/L [risk ratio (RR) 2.0; 95% CI 1.0–4.1, P = 0.053), increased cTnI, and CRP ≥2.0 mg/L were independent predictors of an endpoint. The prognostic performance of TPAPP-A was inferior to that of FPAPP-A.

Conclusions: FPAPP-A seems to be superior as a prognostic marker compared to TPAPP-A, giving independent and additive prognostic information when measured at the time of admission in patients hospitalized for non–ST-elevation ACS.

Biomarkers in acute myocardial infarction

Myocardial infarction causes significant mortality and morbidity. Timely diagnosis allows clinicians to risk stratify their patients and select appropriate treatment. Biomarkers have been used to assist with timely diagnosis, while an increasing number of novel markers have been identified to predict outcome following an acute myocardial infarction or acute coronary syndrome. This may facilitate tailoring of appropriate therapy to high-risk patients. This review focuses on a variety of promising biomarkers which provide diagnostic and prognostic information. Heart-type Fatty Acid Binding Protein and copeptin in combination with cardiac troponin help diagnose myocardial infarction or acute coronary syndrome in the early hours following symptoms. An elevated N-Terminal Pro-B-type Natriuretic Peptide has been well validated to predict death and heart failure following a myocardial infarction. Similarly other biomarkers such as Mid-regional pro-Atrial Natriuretic Peptide, ST2, C-Terminal pro-endothelin 1, Mid-regional pro-Adrenomedullin and copeptin all provide incremental information in predicting death and heart failure. Growth differentiation factor-15 and high-sensitivity C-reactive protein predict death following an acute coronary syndrome. Pregnancy associated plasma protein A levels following chest pain predicts risk of myocardial infarction and revascularisation. Some biomarkers such as myeloperoxidase and high-sensitivity C-reactive protein in an apparently healthy population predicts risk of coronary disease and allows clinicians to initiate early preventative treatment. In addition to biomarkers, various well-validated scoring systems based on clinical characteristics are available to help clinicians predict mortality risk, such as the Thrombolysis In Myocardial Infarction score and Global Registry of Acute Coronary Events score. A multimarker approach incorporating biomarkers and clinical scores will increase the prognostic accuracy. However, it is important to note that only troponin has been used to direct therapeutic intervention and none of the new prognostic biomarkers have been tested and proven to alter outcome of therapeutic intervention. Novel biomarkers have improved prediction of outcome in acute myocardial infarction, but none have been demonstrated to alter the outcome of a particular therapy or management strategy. Randomised trials are urgently needed to address this translational gap before the use of novel biomarkers becomes common practice to facilitate tailored treatment following an acute coronary event.

Leukocyte counts, myeloperoxidase, and pregnancy-associated plasma protein a as biomarkers for cardiovascular disease: towards a multi-biomarker approach

We evaluated leukocyte counts and levels of CRP, fibrinogen, MPO, and PAPP-A in patients with stable and unstable angina pectoris, acute myocardial infarction, and healthy controls. All biomarkers were analyzed again after 6 months. Leukocyte counts and concentrations of fibrinogen, CRP, MPO, and PAPP-A were significantly increased in patients with acute myocardial infarction. Leukocyte counts and concentrations of MPO were significantly increased in patients with unstable angina pectoris compared with controls. After 6 months, leukocyte counts and MPO concentrations were still increased in patients with acute myocardial infarction when compared to controls. Discriminant analysis showed that leukocyte counts, MPO, and PAPP-A concentrations classified study group designation for acute coronary events correctly in 83% of the cases. In conclusion, combined assessment of leukocyte counts, MPO, and PAPP-A was able to correctly classify acute coronary events, suggesting that this could be a promising panel for a multibiomarker approach to assess cardiovascular risk.

Transgenic overexpression of pregnancy-associated plasma protein-A in murine arterial smooth muscle accelerates atherosclerotic lesion development

Pregnancy-associated plasma protein-A (PAPP-A) increases local IGF-I bioavailability through cleavage of inhibitory IGF binding protein (IGFBP)-4 in a variety of systems, including the cardiovascular system. To test the hypothesis that expression of PAPP-A promotes the development of atherosclerotic lesions, we generated transgenic mice that express human PAPP-A in arterial smooth muscle. Four founder lines were characterized for transgenic human PAPP-A mRNA and protein expression, IGFBP-4 protease activity, and tissue specificity. In study I, apolipoprotein E knockout (ApoE KO) mice, a well-characterized mouse model of atherosclerosis, and ApoE KO mice expressing the human PAPP-A transgene at relatively high levels (ApoE KO/Tg) were fed a high-fat diet. At harvest, aortas were dissected and opened longitudinally for en face staining of lipid-rich lesions. Lesion area was increased 3.5-fold in aortas from ApoE KO/Tg compared with ApoE KO mice (P < 0.001), but no significant difference was seen in lesion number. In study II, replacement of PAPP-A expression in arterial smooth muscle of double ApoE KO/PAPP-A KO mice resulted in a 2.5-fold increase in lesion area (P = 0.002), without an effect on lesion number. PAPP-A transgene expression was associated with a significant increase in an IGF-responsive gene (P < 0.001), suggesting increased local IGF-I action. We therefore conclude that expression of human PAPP-A localized to arterial smooth muscle accelerates lesion progression in a mouse model of atherosclerosis. These data provide further evidence for the importance of PAPP-A in the cardiovascular system and suggest PAPP-A as a potential therapeutic target in the control of atherosclerosis.

Pregnancy-associated plasma protein-A, a marker for outcome in patients suspected for acute coronary syndrome

OBJECTIVES

To examine if pregnancy-associated plasma protein-A (PAPP-A) in patients with chest pain, could identify patients at risk for death or myocardial infarction.

DESIGN AND METHODS

Patients admitted with chest pain and both normal ECG and normal biomarkers were evaluated by serial measurement of PAPP-A. Main outcome measures were mortality and non-fatal myocardial infarction.

RESULTS

Median age of patients included (415) was 67years and 43% were women. The risk of death or non-fatal myocardial infarction after 3 months was 15% in the highest quartile of circulating PAPP-A compared with 3% in the lowest quartile (relative risk 3.7, p<0.01). Corresponding numbers after 1 year were 24% and 10% (relative risk 2.4, p=0.01).

CONCLUSION

In patients admitted with chest pain and both normal ECG and normal biomarkers PAPP-A seems to be valuable for predicting patients at high risk of death or non-fatal myocardial infarction.

Usefulness of pregnancy-associated plasma protein A in patients with acute coronary syndrome

To investigate whether pregnancy-associated plasma protein-A (PAPP-A) is a prognostic marker in patients admitted with high-risk acute coronary syndrome. In patients admitted with high-risk non-ST-segment elevation acute coronary syndrome (NSTE-ACS) and ST-segment elevation myocardial infarction (STEMI), risk stratification is primarily determined by the markers of myocardial necrosis and known demographic risk profiles. However, it has recently been proposed that the presence and extent of vulnerable plaques might influence the prognosis significantly. A marker for the vulnerable plaque could identify patients at high risk who would potentially benefit from intensive treatment and surveillance. Two populations of consecutive patients admitted with high-risk NSTE-ACS (n = 123) and STEMI (n = 314) were evaluated with serial measurements of PAPP-A. The incidence of mortality and nonfatal myocardial infarction was prospectively registered for 2.66 to 3.47 years. In the patients with high-risk NSTE-ACS, PAPP-A was related to the risk of nonfatal myocardial infarction (p = 0.02) and death (p = 0.03). This result was consistent on multivariate analysis of the combination of mortality or nonfatal myocardial infarction (odds ratio 2.65, 95% confidence interval 1.40 to 5.03) but not for mortality alone (p = NS). In patients with STEMI, PAPP-A was related to the risk of death (p = 0.01) but not the composite outcome of myocardial infarction and death. This was also true after adjustment for other univariate predictors of death (odds ratio 2.19, 95% confidence interval 1.16 to 4.16). In conclusion, PAPP-A seems to be valuable in predicting the outcomes of patients admitted with high-risk NSTE-ACS or STEMI.

Relationship between baseline inflammatory markers, antiplatelet therapy, and adverse cardiac events after percutaneous coronary intervention: an analysis from the clopidogrel for the reduction of events during observation trial

BACKGROUND

We evaluated patients undergoing percutaneous coronary intervention to assess the predictive value of high-sensitivity C-reactive protein (hs-CRP) and pregnancy-associated plasma protein-A (PAPP-A) on adverse cardiac outcomes and the effect of antiplatelet therapy on these outcomes.

METHODS AND RESULTS

Baseline blood samples were available on 1468 CREDO (Clopidogrel for the Reduction of Events During Observation) patients for hs-CRP testing and 1096 patients for PAPP-A testing. The 1-year primary end point was the composite incidence of death, myocardial infarction, or stroke. Patients in the highest 2 tertiles of hs-CRP had more events compared with the lowest tertile (11.4% versus 6.4%, P=0.003). Treatment with clopidogrel reduced the 1-year composite end point for patients in the highest 2 tertiles of hs-CRP (9.1% clopidogrel versus 13.5% placebo, P=0.04) but not in the lowest tertile. Elevated PAPP-A levels were associated with a trend toward more events at 1 year that did not reach statistical significance. Patients in the highest 2 tertiles of PAPP-A randomized to clopidogrel had fewer events (7.3% clopidogrel versus 13.1% placebo, P=0.01), but no benefit was seen in the lowest tertile. A 46% risk reduction with randomization to clopidogrel was seen in patients in the highest 2 tertiles of both biomarkers (8.7% versus 16.2%, P=0.02).

CONCLUSIONS

Patients undergoing nonurgent percutaneous coronary intervention who have elevated hs-CRP and PAPP-A have an increased incidence of adverse cardiovascular events. The clinical benefit of adding clopidogrel to aspirin seems greater in those with increased levels of these inflammatory biomarkers.

Markers for Early Detection of Cardiac Diseases

The existing markers for myocardial necrosis, such as cardiac troponin, creatine kinase-MB, and myoglobin are thought to be released into blood following irreversible myocardial necrosis. Thus results of these tests are usually negative for patients with acute coronary syndromes (ACS) who present to the emergency department (ED) within the first 3 hours after the onset of chest pain. Given the need to make early therapeutic and triage decisions, biomarkers that can be used to diagnose and/or risk stratify ACS patients during their initial ED presentation will be important. Active research in this area has identified several classes of biomarkers that show promise for early detection of disease. These include tests for the presence of acute inflammation and infiltration (e.g., high sensitivity-C-reactive protein, myeloperoxidase), plaque instability (e.g., pregnancy-associated plasma protein-A, placental growth factor), platelet activation (e.g., whole blood choline, platelet density, CD40 ligand), and myocardial ischemia (e.g., ischemia modified albumin, free fatty acids, serum choline, and B-type natriuretic peptide). Each of these tests has demonstrated some utility for early diagnosis. However, as most lack specificity for myocardial disease, routine use may require a multi-marker approach.

Intravenous Iron Gluconate Administration Increases Circulating PAPP-A in Hemodialysis Patients

BACKGROUND

Pregnancy-associated plasma protein-A (PAPP-A) is a proatherosclerotic molecule, interrelated with oxidative stress in hemodialysis (HD) patients. As intravenous (IV) iron might enhance oxidative stress in HD patients, this study investigates circulating PAPP-A during HD session and after IV iron administration.

METHODS

In 20 HD patients, plasma PAPP-A concentration was assessed immunochemically during 2 HD sessions (prior to HD and at 60, 130, and 240 min of HD session). Sodium ferric gluconate (62.5 mg) was given IV to all patients 65 min after the start of the second HD.

RESULTS

Sixty-five min after IV iron application, there was a significant increase in plasma PAPP-A (from 36.0+/-9.9 to 79.6+/-28.9 mU/L, p<0.0001). At the end of this HD session, PAPP-A decreased significantly (p<0.0001), but still remained 1.5-fold greater compared with predialysis levels (p<0.0005).

CONCLUSION

IV iron increases circulating PAPP-A, and in this way, it might contribute to more pronounced cardiovascular complications in HD patients.

Intravenous administration of low molecular weight and unfractionated heparin elicits a rapid increase in serum pregnancy-associated plasma protein A

BACKGROUND

Pregnancy-associated plasma protein A (PAPP-A) has been suggested as a useful diagnostic and prognostic marker in acute coronary syndromes. Because low molecular weight heparin (LMWH) and unfractionated heparin (UFH) are commonly used in these cases, we analyzed the effects of intravenous administration of these heparins on serum PAPP-A concentrations.

METHODS

Serum concentrations of total and free PAPP-A were analyzed in 14 patients on chronic hemodialysis and in 10 coronary angiography patients. Ten of the dialysis patients received standard LMWH anticoagulation at the start of dialysis, and 4 were treated with a heparin-free method. Two of the patients on heparin-free hemodialysis received a reduced LMWH bolus 2 h after the start of dialysis. All angiography patients received UFH at the start of the procedure, and 1 patient received 2 extra boluses of UFH. Serum PAPP-A concentrations were analyzed before and during the dialysis session and during the coronary angiography examination.

RESULTS

A rapid increase in total PAPP-A (median, 25-fold) was seen in all patients within 5 min of administration for both LMWH and UFH boluses. This response was due to an increase in free PAPP-A in the serum. PAPP-A did not increase significantly in the patients who underwent heparin-free hemodialysis. Repeated heparin boluses induced a new PAPP-A release. In vitro addition of heparins to samples of whole blood did not increase PAPP-A concentrations.

CONCLUSIONS

Intravenous administration of heparin induces an intense and rapid increase in free PAPP-A in the serum. We recommend that this effect be considered when PAPP-A is assessed as a biomarker in acute coronary syndromes.

Association of the IGF1/pregnancy-associated plasma protein-A system and adipocytokine levels with the presence and the morphology of carotid plaques in type 2 diabetes mellitus patients with stable glycaemic control

OBJECTIVE

Pregnancy-associated plasma protein-A (PAPP-A) has been implicated in the atherosclerotic process through regulation of local expression of IGF1. In type 2 diabetes mellitus, glycaemic control has been involved in PAPP-A expression. We compared PAPP-A, IGF1, inflammatory markers and adiponectin concentrations in type 2 diabetic patients with and without carotid plaques and evaluated the relationship between these serum parameters and ultrasound carotid markers of atherosclerosis.

METHODS

We studied 125 consecutive type 2 diabetic patients. Clinical data, metabolic variables, hemostatic factors (plasma type-1 plasminogen activator inhibitor, fibrinogen), high-ultrasensitive C reactive protein (hsCRP), tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, adiponectin, IGF1 and PAPP-A were determined. Patients were classified into two groups according to the presence of carotid plaques on ultrasound. Carotid intima-media thickness (IMT) and morphology of carotid plaques were evaluated.

RESULTS

The mean age was 61.5+/-7.3 years and the mean glycated hemoglobin of 6.8+/-0.9%. A total of 60% presented carotid plaques. Both groups were homogeneous in anthropometric data, biochemical determinations and hemostatic factors. Adiponectin, hsCRP, TNF-alpha and IL-6 were similar in both groups. No differences were observed in serum PAPP-A (0.46 (0.22-0.86) vs 0.38 (0.18-0.66) mIU/l and in SDS IGF1 (-0.34+/-1.38 vs -0.67+/-1.35)) in patients with and without carotid plaques respectively. PAPP-A and IGF1 were not correlated with IMT.

CONCLUSIONS

Serum PAPP-A and IGF1 do not appear to be useful serum biomarkers for carotid atherosclerosis in type 2 diabetic patients with stable glycemic control, despite scientific evidence of their local role in atherosclerosis.

PAPP-A as a marker of increased long-term risk in patients with chest pain

OBJECTIVES

Long-term risk stratification in patients presenting with acute coronary syndromes (ACS) is possible by measuring cardiac troponin (cTn). The present study examined whether PAPP-A measured in an emergency department (ED) chest pain population in association with conventional and novel high sensitivity cTn (hs-cTnI) assays can predict long-term mortality.

METHODS

In 320 patients with cTn measurements the earliest heparinized plasma PAPP-A concentration after presentation was used for risk stratification for death by Kaplan-Meier and Cox analyses. Subgroup analyses using the earliest PAPP-A concentrations were also performed in a cohort of subjects with presentation cTnI < or = 99th percentile but with significantly changing cardiac troponin concentrations as measured by the AccuTnI assay and the hs-cTnI assay (n=45 and 120 subjects, respectively).

RESULTS

Subjects with PAPP-A concentrations in the highest tertile were at higher risk for death (HR > 2.00; p < or = 0.05 at 2 years) even after adjusting for cTnI at presentation. In the cohort with cTnI < or = 99th percentile but with changing hs-cTnI concentrations, subjects in the top PAPP-A tertile had a higher probability for death (p=0.02).

CONCLUSION

Early measurement of PAPP-A may identify chest pain patients at higher risk for long-term death. Additional prospective ACS studies are required to fully elucidate PAPP-A's role.

Biomarkers in Acute Coronary Syndrome

BACKGROUND: Evaluation of patients who present to the hospital with acute undifferentiated chest pain or other symptoms and signs suggestive of Acute Coronary Syndrome (ACS) is often a clinical challenge. The initial assessment, requiring a focused history (including risk factors analysis), a physical examination, an electrocardiogram (EKG) and serum cardiac marker determination, is time-consuming and troublesome. Recent investigations have indicated that increases in biomarkers of necrosis, inflammation, ischemia and myocardial stretch may provide earlier assessment of overall patient risk, help in identifying the adequate diagnostic and therapeutic management for each patient and allow for prevention of substantial numbers of new events. APPROACH AND CONTENT: The purpose of this review is to provide an overview of the characteristics of several biomarkers that may have potential clinical utility to identify ACS patients. Patho-physiology, analytical and clinical characteristics have been evaluated for each marker, underlying the properties for potential routine clinical use. SUMMARY: The biomarkers discussed in this review are promising and might lead to improved diagnosis and risk stratification of patients with ACS, however their clinical application requires further studies. It is important to define their clinical role as diagnostic markers, their predictive value and the specificity, standardization and detection limits of the assays.

Present and Future Biochemical Markers for Detection of Acute Coronary Syndrome

The use of biochemical markers in the diagnosis and management of patients with acute coronary syndrome has increased continually in recent decades. The development of highly sensitive and cardiac-specific troponin assays has changed the view on diagnosis of myocardial infarction and also extended the role of biochemical markers of necrosis into risk stratification and guidance for treatment. The consensus definition of myocardial infarction places increased emphasis on cardiac marker testing, with cardiac troponin replacing creatine kinase MB as the "gold standard" for diagnosis of myocardial infarction. Along with advances in the use of more cardiac-specific markers of myocardial necrosis, biochemical markers that are involved in the progression of atherosclerotic plaques to the vulnerable state or that signal the presence of vulnerable plaques have recently been identified. These markers have variable abilities to predict the risk of an individual for acute coronary syndrome. The aim of this review is to provide an overview of the well-established markers of myocardial necrosis, with a special focus on cardiac troponin I, together with a summary of some of the potential future markers of inflammation, plaque instability, and ischemia.

Pregnancy-associated plasma protein-A (PAPP-A) and cardiovascular risk

The search for markers to improve risk prediction for individuals at risk of developing serious cardiovascular events is ongoing. New markers of coronary artery disease progression have been identified in recent years, among which, circulating levels of pregnancy-associated plasma protein-A (PAPP-A) offer an interesting profile. PAPP-A may play a role in the development of atherosclerotic lesions and represent also a marker of atheromatous plaque instability and extent of cardiovascular disease. PAPP-A has been shown to be a marker of adverse outcome in both acute coronary syndrome and stable coronary disease patients. The present article reviews currently available evidence supporting a role for PAPP-A as a marker of cardiovascular risk and discusses some of the pitfalls that may limit its use in clinical practice.

Pregnancy associated plasma protein A, a novel, quick, and sensitive marker in ST-elevation myocardial infarction

Traditional biomarkers in acute coronary syndromes reflect myocardial necrosis but not the underlying arteriosclerotic disease. Pregnancy-associated plasma protein A (PAPP-A) is a new biomarker in acute coronary syndromes that detects vulnerable plaques in arteriosclerotic disease and identifies acute coronary syndromes earlier than traditionally used biomarkers. Information regarding circulating PAPP-A levels in patients with ST elevation myocardial infarctions (STEMIs) is limited and contradictory. The aim of the present study was to describe the presence and time-related pattern of circulating PAPP-A levels in patients with STEMIs. Consecutive patients (n = 354) referred for primary percutaneous intervention because of STEMI were included in the study. Blood samples for the analysis of PAPP-A, creatine kinase-MB (CKMB), and troponin T were drawn at admission and every 6 to 8 hours until biomarkers of myocardial necrosis were consistently decreasing. PAPP-A was measured using a newly developed sandwich enzyme-linked immunosorbent assay technique based on 2 monoclonal antibodies. In total, 1,091 PAPP-A, 1,049 troponin T, and 1,016 CKMB samples were analyzed. Mean PAPP-A values at admission were significantly higher in patients with STEMIs than in those with non-ST elevation myocardial infarctions or unstable angina pectoris (27.6 vs 12.2 mIU/L, p <0.01). In samples drawn <2 hours after admission, the sensitivity of PAPP-A was superior (93%) to that of CKMB (60%) and troponin T (61%). In conclusion, PAPP-A levels are elevated in >90% of patients presenting with STEMIs if measured <6 hours after the onset of symptoms or <2 hours of primary percutaneous coronary intervention. In the early stages of STEMI, PAPP-A seems to be a more sensitive marker of myocardial infarction than CKMB and troponin T.