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

Abstract

In recent years, an important objective of cardiovascular research has been to find new markers that would improve the risk stratification and diagnosis of patients presenting with symptoms of acute coronary syndrome (ACS). Established biomarkers for diagnosis of ACS includes troponins and creatine kinase MB (CK-MB). Pregnancy associated plasma protein A (PAPP-A) is an emerging marker which has been described as a marker of plaque instability. PAPP-A is a large metalloproteinase involved in insulin-like growth factor signaling and has been shown to be involved in pathological processes like atherosclerosis. Many studies have been published regarding release of PAPP-A in circulation during ACS. The objective of this study was to evaluate the role of PAPP-A as an early marker of ACS by comparing levels of PAPP-A in patients with acute myocardial infarction (AMI) and unstable angina (UA) with asymptomatic controls. The association of PAPP-A with markers of myocardial necrosis and the association of PAPP-A levels to the presence of risk factors for coronary artery disease was also studied. We measured PAPP-A levels in patients with AMI (30), UA (23) and asymptomatic controls (45). PAPP-A was estimated using PAPP-A US (ultra sensitive) ELISA manufactured by DRG (Germany). PAPP-A levels were significantly elevated in patients with AMI and in patients with UA (mean levels 64.26±1.05 and 36.23±1.05ng/ml respectively; p<0.001). Mean PAPP-A levels in controls were 10.68±1.04ng/ml. In UA cases PAPP-A levels were elevated when the troponin I and CK-MB levels were within the normal range. No correlation was observed between PAPP-A with markers of myocardial necrosis. PAPP-A can serve as a useful biomarker in the diagnosis of ACS, especially UA, where cardiac troponin levels and CK-MB levels are not elevated and ECG changes are inconclusive.