Pregnancy Associated Plasma Protein-A (PAPP-A) Levels in Acute Coronary Syndrome: A Case Control Study in a Tertiary Care Centre

Pregnancy Associated Plasma Protein-A as a Cardiovascular Risk Marker in Patients with Stable Coronary Heart Disease During 10 Years Follow-Up-A CLARICOR Trial Sub-Study

Elevated pregnancy-associated plasma protein A (PAPP-A) is associated with mortality in acute coronary syndromes. Few studies have assessed PAPP-A in stable coronary artery disease (CAD) and results are conflicting. We assessed the 10-year prognostic relevance of PAPP-A levels in stable CAD. The CLARICOR trial was a randomized controlled clinical trial including outpatients with stable CAD, randomized to clarithromycin versus placebo. The placebo group constituted our discovery cohort (n = 1.996) and the clarithromycin group the replication cohort (n = 1.975). The composite primary outcome was first occurrence of cardiovascular event or death. In the discovery cohort, incidence rates (IR) for the composite outcome were higher in those with elevated PAPP-A (IR 12.72, 95% Confidence Interval (CI) 11.0-14.7 events/100 years) compared to lower PAPP-A (IR 8.78, 8.25-9.34), with comparable results in the replication cohort. Elevated PAPP-A was associated with increased risk of the composite outcome in both cohorts (discovery Hazard Ratio (HR) 1.45, 95% CI 1.24-1.70; replication HR 1.29, 95% CI 1.10-1.52). In models adjusted for established risk factors, these trends were attenuated. Elevated PAPP-A was associated with higher all-cause mortality in both cohorts. We conclude that elevated PAPP-A levels are associated with increased long-term mortality in stable CAD, but do not improve long-term prediction of death or cardiovascular events when added to established predictors.

Pregnancy-associated plasma protein-A promotes TF procoagulant activity in human endothelial cells by Akt-NF-κB axis

Pregnancy-associated plasma protein-A (PAPP-A) is a metalloproteinase with a controversial role in pathophysiology of cardiovascular disease. It seems involved in progression of atherosclerosis and is widely represented in atherosclerotic plaque. PAPP-A plasma levels are elevated in patients with acute coronary syndromes (ACS), thus it has been suggested that it might be a prognostic marker for developing major cardiovascular events. However, the pathophysiological link(s) between PAPP-A and ACS are still unknown. Several studies have indicated that tissue factor (TF) plays a pivotal role in the pathophysiology of ACS by triggering the formation of intracoronary thrombi following endothelial injury. This study investigates whether PAPP-A, at concentrations measurable in ACS patients, might induce TF expression in human endothelial cells in culture (HUVEC). In HUVEC, PAPP-A induced TF-mRNA transcription as demonstrated by real time PCR and expression of functionally active TF as demonstrated by FACS analysis and pro-coagulant activity assay. PAPP-A induced TF expression through the activation of Akt/NF-κB axis, as demonstrated by luciferase assay and by suppression of TF-mRNA transcription as well as of TF expression/activity by Akt and NF-κB inhibitors. These data indicate that PAPP-A promotes TF expression in human endothelial cells and support the hypothesis that this proteinase, besides being involved in progression of atherosclerosis, does not represent an independent risk factor for adverse cardiovascular events, but it rather might play an "active" role in the pathophysiology of ACS as an effector molecule able to induce a pro-thrombotic phenotype in endothelial cells.

The utility of pregnancy-associated plasma protein A for determination of prognosis in a cohort of patients with coronary artery disease

Background: Pregnancy-associated plasma protein-A (PAPP-A) is discussed as a biomarker representing unstable plaques in coronary artery disease (CAD). Methods: In this study 927 patients with CAD (534 with stable angina and 393 with acute coronary syndrome [ACS]) and 217 patients without CAD and measured PAPP-A levels were included. Follow-up for a median of 5 years was documented. Results: Rising quartiles of PAPP-A concentration had a higher cardiovascular mortality in the overall cohort of patients with CAD (p = 0.002) and the cohort with ACS (p = 0.01). Patients with suspected ACS below the LOD for troponin I but elevated PAPP-A levels had an increased cardiovascular mortality. A cut-off of 11.4 IU/l identified patients with a higher mortality during follow-up. Conclusion: Rising PAPP-A levels are prognostic in patients with CAD. PAPP-A levels were especially predictive in ACS patients with troponin below 10% CV of the 99th percentile for cardiovascular mortality.