OBJECTIVETo assess the relationship between pregnancy associated plasma protein-A (PAPP-A) and culprit coronary plaque morphology in patients with unstable angina (UA).

METHODSSixty-eight UA patients undergoing diagnostic coronary angiography and intravascular ultrasound were included in this study. A sandwich enzyme-linked immunosorbent assay technique was used to assay the circulating PAPP-A. Plaque characteristics of culprit lesion were analyzed for UA patients with various PAPP-A levels.

RESULTSPAPP-A level was significantly higher in high-risk UA than in non-high-risk UA [(19.9 ± 20.1) mIU/L vs. (6.9 ± 5.7) mIU/L, P = 0.002]. Optimal threshold of PAPP-A to predict high-risk UA was determined as 11.0 mIU/L with a sensitivity of 78.6% and a specificity of 77.5%. Patients with higher PAPP-A level (≥ 11.0 mIU/L) was associated with larger external elastic membrane cross-sectional area, plaque area and more plaque burden compared with patients with lower PAPP-A level (all P < 0.01). Positive remodeling, attenuated plaque and plaque rupture were significantly more often in patients with higher PAPP-A than in patients with lower PAPP-A level (all P < 0.01). PAPP-A ≥ 11.0 mIU/L (OR = 5.921, P = 0.014) and attenuated plaque (OR = 7.541, P = 0.038) were independent risk predictors for high-risk UA.

CONCLUSIONSPAPP-A was associated with instability of culprit plaque in UA patients. PAPP-A ≥ 11.0 mIU/L and attenuated plaque were independent predictors for high-risk UA.