Plasma α1-antitrypsin: a neglected predictor of angiographic severity in patients with stable angina pectoris.

BACKGROUND: As an acute phase protein, α1-antitrypsin (AAT) has been extensively studied in acute coronary syndrome, but it is unclear whether a relationship exists between AAT and stable angina pectoris (SAP). The purpose of the present study was to investigate the association between AAT plasma levels and SAP. METHODS: Overall, 103 SAP patients diagnosed by coronary angiography and clinical manifestations and 118 control subjects matched for age and gender were enrolled in this case-control study. Plasma levels of AAT, high-sensitivity C-reactive protein (hsCRP), lipid profiles and other clinical parameters were assayed for all participants. The severity of coronary lesions was evaluated based on the Gensini score (GS) assessed by coronary angiography. RESULTS: Positively correlated with the GS (r = 0.564, P < 0.001), the plasma AAT level in the SAP group was significantly higher than that in the control group (142.08 ± 19.61 mg/dl vs. 125.50 ± 19.67 mg/dl, P < 0.001). The plasma AAT level was an independent predictor for both SAP (odds ratio [OR] = 1.037, 95% confidence interval [CI]: 1.020-1.054, P < 0.001) and a high GS (OR = 1.087, 95% CI: 1.051-1.124, P < 0.001) in a multivariate logistic regression model. In the receiver operating characteristic curve analysis, plasma AAT level was found to have a larger area under the curve (AUC) for predicting a high GS (AUC = 0.858, 95% CI: 0.788-0.929, P < 0.001) than that of hsCRP (AUC = 0.665, 95% CI: 0.557-0.773, P = 0.006; Z = 2.9363, P < 0.001), with an optimal cut-off value of 137.85 mg/dl (sensitivity: 94.3%, specificity: 68.2%). CONCLUSIONS: Plasma AAT levels correlate with both the presence and severity of coronary stenosis in patients with SAP, suggesting that it could be a potential predictive marker of severe stenosis in SAP patients.

The relationship between serum amyloid A and apolipoprotein A-I in high-density lipoprotein isolated from patients with coronary heart disease.

BACKGROUND: Alteration in the protein composition of high-density lipoprotein (HDL) has been proposed as a mechanism for the development of coronary heart disease (CHD). In HDL, an increase in serum amyloid A protein (SAA) accompanying the decrease in apolipoprotein A-I (apoA-I) has been found during the acute inflammation period. However, whether this phenomenon persists in CHD patients, a disease related to inflammation, is unknown. The purpose of the present study was to explore the relationship between SAA and apoA-I in HDL isolated from CHD patients. METHODS: Overall, 98 patients with confirmed stable CHD and 90 control subjects matched for age and gender were enrolled in this case-control study. Potassium bromide (KBr) density gradient ultracentrifugation was used to isolate HDL from plasma. The levels of SAA and apoA-I in the HDL samples were detected by enzyme-linked immunosorbent assay kits. Pearson's correlation and general linear models were used in the analysis. RESULTS: Compared with controls, patients with CHD had a significant decrease in the amount of apoA-I ((14.21 ± 8.44) µg/ml vs. (10.95 ± 5.95) µg/ml, P = 0.003) in HDL and a significant increase in the amount of log SAA (1.21 ± 0.46 vs. 1.51 ± 0.55, P < 0.00001). Differences were independent of age, body mass index (BMI), HDL cholesterol (HDL-C), and other factors. An independently and statistically significant positive correlation between log SAA and apoA-I in HDL was observed only in the CHD group (ß = 2.0, P = 0.026). In the general linear model, changes in log(SAA), age, age2, gender, BMI and HDL-C could explain a statistically significant 43% of the variance in apoA-I. CONCLUSIONS: This study provides direct evidence for the first time that there was an independent positive correlation between log SAA and apoA-I in the HDL of CHD patients, indicating the alteration of protein composition in HDL. However, the question of whether this alteration in HDL is associated with impairment of HDL functions requires further research.