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

The Biomarkers for Acute Myocardial Infarction and Heart Failure

The use of a large number of cardiovascular biomarkers, meant to complement the use of the electrocardiogram, echocardiography cardiac imaging, and clinical symptom assessment, has become a routine in clinical diagnosis, differential diagnosis, risk stratification, and prognosis and guides the management of patients with suspected cardiovascular diseases. There is a broad consensus that cardiac troponin and natriuretic peptides are the preferred biomarkers in clinical practice for the diagnosis of the acute coronary syndrome and heart failure, respectively, while the roles and possible clinical applications of several other potential biomarkers are still under study. This review mainly focuses on the recent studies of the roles and clinical applications of troponin and natriuretic peptides, which seem to be the best-validated markers in distinguishing and predicting the future cardiac events of patients with suspected cardiovascular diseases. Additionally, the review briefly discusses some of the large number of potential markers that may play a more prominent role in the future.

Pregnancy-Associated Plasma Protein A Induces Inflammatory Cytokine Expression by Activating IGF-I/PI3K/Akt Pathways

Pregnancy-associated plasma protein A (PAPP-A) was previously reported to be an inflammatory biomarker and a prognostic marker of acute coronary syndrome (ACS) and involved in the process of atherosclerosis and plaque rupture. However, the role of PAPP-A in inflammation is poorly understood. In this study, we aimed to investigate the role of PAPP-A in macrophage activation and inflammatory cytokine production. RAW264.7 macrophages were treated with or without PAPP-A. Reverse-transcriptase quantitative real-time PCR (RT-qPCR) and Western blot were performed to detect gene and protein expressions. The concentration of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in culture supernatants was determined by ELISA. Results showed that PAPP-A significantly stimulated the expression of MCP-1, TNF-α, and IL-6 at both transcriptional and translational levels in a dose-dependent and time-dependent manner. The secretion of these inflammatory cytokines by macrophages was also increased after PAPP-A treatment. Moreover, PAPP-A activated the IGF-I/PI3K/Akt signaling pathway in macrophages. The PAPP-A-mediated upregulation of MCP-1, TNF-α, and IL-6 mRNA and protein levels were strongly inhibited by PI3K inhibitors or IGF-IR siRNA, indicating that the upregulation of MCP-1, TNF-α, and IL-6 could involve the IGF-I/PI3K/Akt pathway. Together, this study demonstrates that PAPP-A activates the macrophage signaling pathway (IGF-I/PI3K/Akt), which drives the expression and production of inflammatory cytokines known to contribute to the initiation and progression of ACS. These findings indicate that PAPP-A may play a proinflammatory role in the pathophysiology of ACS and serve as a potential therapeutic target.

Pregnancy-associated plasma protein-a is associated with subclinical atherosclerosis in men with HIV infection

The pathophysiology of an early and accelerated atherosclerotic process is complex and multifactorial in HIV-infected men compared with HIV-non-infected men. Several biomarkers have been well studied in the detection of the early stage of atherosclerosis, but studies are limited in HIV-infected men. The objective of this study was to investigate the association between serum pregnancy-associated plasma protein-A (PAPP-A) and carotid intima-media wall thickness (CIMT) in asymptomatic HIV-infected men. This a case-control study group comprising 118 HIV-infected men and 60 age-matched and gender-matched HIV-non-infected men. Serum PAPP-A was measured using an ELISA kit and carotid IMT was evaluated by Doppler ultrasonography in all subjects. Statistical analysis included receiver-operating characteristic (ROC) analysis, Pearson correlation and logistic regression analysis. Serum PAPP-A level was significantly higher in HIV +CIMT+ group compared with HIV +CIMT group and HIV-CIMT- group. We found a positive correlation between PAPP-A and increased CIMT (r=0.737, p<0.0001), and a negative correlation between nadir CD4 T cell counts and increased CIMT (r=-0.526, p<0.001). In multivariate logistic regression analyses, PAPP-A, nadir CD4 T cell count and age were significantly associated with subclinical atherosclerosis (p<0.001, p=0.006 and p=0.032, respectively). In ROC analysis, PAPP-A levels of >3.70 µg/mL were associated with subclinical atherosclerosis in HIV+ men with a specificity of 100% and a sensitivity of 71% (area under the curve: 0.949, 95% CI 0.875 to 1.000, p<0.001). Serum PAPP-A level was strongly correlated with increased CIMT in HIV-infected men. PAPP-A might be used as an early biomarker to identify atherosclerosis in asymptomatic HIV-infected men.

Evaluation of Serum Pregnancy Associated Plasma Protein-A & Plasma D-Dimer in Acute Coronary Syndrome

INTRODUCTION

Acute coronary syndrome (ACS), a spectrum comprising unstable angina pectoris, ST Elevated Myocardial Infarction (STEMI) & Non ST Elevated Myocardial Infarction (NSTEMI) is the major cause of presentation in Emergency Department today. Though ECG and cardiac enzymes are used for diagnosis, they mislead the diagnosis sometimes and delay in treatment initiation. This leads us to search certain new parameters which reflect the pathophysiology of ACS. Markers of plaque stability like Pregnancy Associated Plasma Protein-A and D-Dimer, a marker of ongoing thrombosis are found to be better markers in early diagnosis.

AIM

To evaluate the diagnostic competence of PAPP-A and D-Dimer in acute coronary syndrome over CK-MB and to compare with the inflammatory marker High Sensitive C-Reactive Protein (hs-CRP) which is associated with atherosclerosis.

MATERIALS AND METHODS

Fifty patients presenting with acute onset of chest pain to Emergency Department with or without ECG changes served as cases and 50 healthy people served as controls. Serum PAPP-A is measured by Enzyme Linked Immunosorbent Assay (ELISA), D-Dimer and hs-CRP by using Latex Turbidimetry method.

RESULTS

A statistical significant difference of PAPP-A and D-Dimer was noted between the ACS and controls (p < 0.001) whereas CK-MB shows no much difference (p 0.09). Statistically significant positive correlation is noted between parameters.

CONCLUSION

PAPP-A marker of plaque instability and D-Dimer marker of ongoing thrombosis are raised in acute coronary syndrome and thus can be considered as one of the marker in ACS for diagnosis.

Pregnancy-associated plasma protein-A and the vulnerable plaque

For more than a decade, pregnancy-associated plasma protein-A (PAPP-A) has been examined for its relation to acute coronary syndrome (ACS) and the vulnerable plaque. This review summarizes the current knowledge of plasma PAPP-A in relation to nonpregnant individuals focusing on patients with ACS, discusses its use as a possible biomarker for diagnosis and prognosis in ACS, briefly describes the challenges in different assay technologies and describes the effect of heparin administration on PAPP-A concentrations in plasma.

The effect of heparin on pregnancy associated plasma protein-A concentration in healthy, non-pregnant individuals

OBJECTIVES

The objective of this study was to determine the differences in pregnancy associated plasma protein-A (PAPP-A) concentrations in heparin naive and heparin treated healthy men and non-pregnant women, to find a possible difference in different age groups, and to determine the response in PAPP-A concentration to repeated injections of unfractionated heparin.

DESIGN AND METHODS

Twenty-five healthy, non-pregnant volunteers divided into five groups (determined by gender and age) received 5000 IU unfractionated heparin intravenously. Five young men received an additional 5000 IU after 90 and 180 min. Blood samples to determine PAPP-A concentration and APTT were drawn at different time points.

RESULTS

Injection of heparin elicited increase in and rapid normalization of PAPP-A concentrations in all subjects. The group of 20-30-year-old never-pregnant women had lower responses than the individuals of the four other groups. The difference was not significant (p > 0.05). Repeated injections of heparin caused additional peaks in PAPP-A concentration of about the same sizes as the first peak. We observed an increase in time to normalization of PAPP-A concentration (from 75-90 min to 90-150 min) and APTT levels with repeated injections.

CONCLUSIONS

We observed a rapid normalization of PAPP-A. Our result has a great similarity to the half-life of unfractionated heparin. This result combined with the finding of equally sized peaks in PAPP-A concentration, and that all of this was found in healthy, non-pregnant individuals, suggests that heparin might compete for a binding-site on PAPP-A or with PAPP-A itself for a common receptor in healthy arterial vessels.

Analysis of pregnancy-associated plasma protein A production in human adult cardiac progenitor cells

IGF-binding proteins (IGFBPs) and their proteases regulate IGFs bioavailability in multiple tissues. Pregnancy-associated plasma protein A (PAPP-A) is a protease acting by cleaving IGFBP2, 4, and 5, regulating local bioavailability of IGFs. We have previously shown that IGFs and IGFBPs are produced by human adult cardiac progenitor cells (haCPCs) and that IGF-1 exerts paracrine therapeutic effects in cardiac cell therapy with CPCs. Using immunofluorescence and enzyme immunoassays, we firstly report that PAPP-A is produced and secreted in surprisingly high amounts by haCPCs. In particular, the homodimeric, enzymatically active, PAPP-A is secreted in relevant concentrations in haCPC-conditioned media, while the enzymatically inactive PAPPA/proMBP complex is not detectable in the same media. Furthermore, we show that both homodimeric PAPP-A and proMBP can be detected as cell associated, suggesting that the previously described complex formation at the cell surface does not occur easily, thus positively affecting IGF signalling. Therefore, our results strongly support the importance of PAPP-A for the IGFs/IGFBPs/PAPP-A axis in CPCs biology.

Pregnancy-associated plasma protein A predicts adverse vascular events in patients with coronary heart disease: a systematic review and meta-analysis

INTRODUCTION

Prospective studies about the association between elevated circulating pregnancy-associated plasma protein A (PAPP-A) and adverse vascular events in patients with coronary heart diseases (CHD) are inconsistent. We performed a meta-analysis to clarify this issue.

MATERIAL AND METHODS

We identified prospective studies by searching MEDLINE. The vascular outcomes included all-cause mortality, combination of all-cause mortality and non-fatal myocardial infarction (MI), and combined cardiovascular events. Prospective studies providing multivariable adjusted relative risks (RRs) and their 95% confidence intervals (CIs) of pre-mentioned outcomes were included. A random-effects model was used to calculate the pooled RRs. Subgroup and sensitivity analyses were used to explore the potential sources of heterogeneity or modifiable factors.

RESULTS

Fourteen studies with a total of 12 830 participants were included. Elevated PAPP-A level was associated with all-cause mortality (pooled RR 1.74, 95% CI: 1.45 to 2.09, p < 0.001), combined all-cause mortality and non-fatal MI (RR 1.59, 95% CI: 1.37 to 1.85, p < 0.001) and combined cardiovascular events (RR 1.50, 95% CI: 1.22 to 1.85, p < 0.001). There was no significant heterogeneity. Subgroup and sensitivity analyses showed that the positive association was not affected by follow-up term, CHD type, different assay methods of PAPP-A, or studies with less than 5 adjusted variables.

CONCLUSIONS

Elevated serum PAPP-A level is associated with adverse vascular outcomes in patients with CHD.

Pathophysiological roles and clinical importance of biomarkers in acute coronary syndrome

Early diagnosis of acute coronary syndrome (ACS) is important to guide appropriate therapy at a time when it is most likely to be of value. Accurate prognostic and risk stratification will facilitate high-risk patients to have early advanced diagnostic investigations and early appropriate interventions in a cost-effective and efficient manner, while those patients at low risk of ACS complications do not need such costly diagnostic tests and unnecessary hospital admission. Recent investigations have demonstrated that elevation of biomarkers upstream from acute-phase biomarkers, biomarkers of plaque destabilization and rupture, biomarkers of myocardial ischemia, necrosis, and dysfunction may provide an earlier assessment of patient risk and identify patients with higher risk of having an adverse event. This review provides an overview of the pathophysiology and clinical characteristics of several well-established biomarkers as well as emerging biomarkers that may have potential clinical utility in patients with ACS. Such emerging biomarkers hold promise and need to be more thoroughly evaluated before utilization in routine clinical practice.

PAPP-A in cardiac and non-cardiac conditions

Pregnancy-associated plasma protein-A (PAPP-A), a newly discovered member of insulin like growth factors (IGFs) axis, has been reported to be a biomarker in both cardiac and non-cardiac conditions. PAPP-A mainly acts as a protease cleaving IGF inhibitors - IGF binding proteins (IGFBPs), thereby setting free IGFs. In cardiac conditions, PAPP-A plays an important role in progressive atherosclerosis. As a biomarker, PAPP-A is not only sensitive, specific and early for diagnosis of acute coronary syndrome, but also an independent risk factor for all-cause mortality or combined cardiovascular events. In non-cardiac conditions, PAPP-A is a new anti-aging target. PAPP-A knock out (KO) mice have a prolonged lifespan than the wild type. In addition, PAPP-A is also a biomarker associated with malignant cancer and end stage renal disease.

Usefulness of soluble urokinase plasminogen activator receptor to predict repeat myocardial infarction and mortality in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous intervention

The plasma level of the inflammatory biomarker soluble urokinase plasminogen activator receptor (suPAR) is an independent predictor of cardiovascular disease and all-cause mortality in healthy subjects. The prognostic capability of suPAR, its temporal course, and its relation to plasma C-reactive protein (CRP) in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous intervention (PCI) is unknown. Therefore, the plasma suPAR and CRP levels were measured in 296 consecutive patients with ST-segment elevation myocardial infarction admitted for primary PCI at baseline and every 6 to 8 hours thereafter until the cardiac biomarker levels had peaked. The end points were all-cause mortality and fatal or nonfatal recurrent myocardial infarction (MI). During a median follow-up period of 5.75 years, 69 deaths and 48 nonfatal and 14 fatal recurrent MIs occurred. All-cause mortality increased significantly from 8.1% to 41.5% across increasing quartiles of suPAR levels at the end of follow-up (log-rank p <0.0001). After adjustment for other independent prognostic factors, a highly significant increase was seen in all-cause mortality (hazard ratio 1.45, 95% confidence interval, 1.19 to 1.76; p <0.001) and recurrent MI (hazard ratio 1.53, 95% confidence interval 1.16 to 2.01; p <0.01) for each standard deviation increment of suPAR levels). In contrast to plasma CRP, the suPAR levels remained stable after primary PCI. Furthermore, CRP did not predict mortality or reinfarction after adjustment for age and gender (p = 0.34). In conclusion, suPAR is a stable plasma biomarker after ST-segment elevation myocardial infarction treated with primary PCI that predicts all-cause mortality and recurrent MI.

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.

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.

Established and novel biomarkers in ST-elevation myocardial infarction

Cardiac biomarkers assist in the diagnosis of and risk stratification in acute coronary syndromes. In ST-elevation myocardial infarction (STEMI), rapid diagnosis and initiation of reperfusion via primary percutaneous coronary intervention or fibrinolysis is often based on the clinical history and presenting ECG, but measurement of biomarkers in the early and/or late phases of STEMI may allow the selection of patients who are at increased or decreased risk of subsequent complications. Although the measurement of only three biomarkers (troponin, natriuretic peptides and C-reactive protein) are currently included in practice guidelines, more than 20 other novel cardiac biomarkers have been proposed to provide improved risk stratification after a STEMI.

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.

Cardiac biomarkers - the old and the new: a review

Biomarkers are biological parameters that can be objectively measured and quantified as indicators of normal biologic processes, pathogenic processes, or responses to a therapeutic intervention. Typically thought of as disease process screening, diagnosing, or monitoring tools, biomarkers may also be used to determine disease susceptibility and eligibility for specific therapies. Cardiac biomarkers are protein components of cell structures that are released into circulation when myocardial injury occurs. They play a pivotal role in the diagnosis, risk stratification, and treatment of patients with chest pain and suspected acute coronary syndrome and those with acute exacerbations of heart failure. Cardiac markers are central to the new definition of acute myocardial infarction put forward by the American College of Cardiology and the European Society of Cardiology. Active investigation has brought forward an increasingly large number of novel candidate markers but few have withstood the test of time and become integrated into contemporary clinical care because of their readily apparent diagnostic, prognostic, or therapeutic utility.

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.

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.

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.

Temporal course of pregnancy-associated plasma protein-A in angioplasty-treated ST-elevation myocardial infarction patients and potential significance of concomitant heparin administration

Pregnancy-associated plasma protein-A (PAPP-A) is a putative plaque instability marker. In acute coronary syndromes, the disrupted culprit plaque contains abundant PAPP-A, and circulating PAPP-A levels predict clinical outcomes. Determinants of circulating PAPP-A levels, however, are not fully understood, and the potential role of concomitant heparin administration has not previously been evaluated. The purposes of the present study were to evaluate in-hospital levels of PAPP-A compared with other circulating biomarkers in patients with acute myocardial infarctions and to explore the potential impact of concomitant heparin administration on PAPP-A levels in an animal experiment. Group A comprised 84 patients with ST elevation myocardial infarctions (STEMIs) who were treated with heparin and transferred for primary percutaneous coronary intervention. Plasma samples were obtained at the time of primary percutaneous coronary intervention, twice within the next 24 hours, and subsequently daily during hospitalization. Levels of PAPP-A, troponin T, soluble cluster of differentiation 163, N-terminal-pro-brain natriuretic peptide, and high-sensitivity C-reactive protein were determined. PAPP-A levels were also determined in 2 historical cohorts not given heparin: 14 patients with STEMIs (group B) and 56 patients with non-ST elevation myocardial infarctions (group C). The impact of concomitant heparin administration on the clearance of PAPP-A from the circulation was also explored in mice. In group A, PAPP-A levels were increased in the initial plasma sample in 95% of patients presenting within 3 hours of symptom onset, whereas increased levels of troponin T, soluble cluster of differentiation 163, N-terminal-pro-brain natriuretic peptide, and high-sensitivity C-reactive protein were detectable in 45%, 15%, 50%, and 35% of patients, respectively. Compared with group A, lower levels of PAPP-A were observed in the initial plasma samples drawn in groups B (p = 0.07) and C (p <0.001) not given heparin. In the animal experiment, concomitant heparin administration resulted in increased levels of PAPP-A and delayed clearance of PAPP-A from the circulation. In conclusion, PAPP-A is markedly elevated in the earliest hours after the onset of symptoms in patients with STEMIs treated with heparin and primary percutaneous coronary intervention, and in animal studies, heparin administration is associated with a significant increase in PAPP-A levels, presumably because of the detachment of PAPP-A from the vessel wall. If future studies confirm that concomitant heparin administration also increases PAPP-A levels in humans, the prognostic role of PAPP-A in patients with STEMIs needs to be reevaluated.