# The Role of Paraoxonase-1 Activity, Apolipoprotein B Levels, and Apolipoprotein B/Apolipoprotein A-I Ratio as Risk Markers for Aortic Stenosis in Patients with a Bicuspid Aortic Valve

## TL;DR

This study explores how certain lipid markers predict aortic stenosis in young patients with a bicuspid aortic valve.

## Contribution

The study identifies novel associations between Apo B, Apo B/Apo AI ratio, and PON-1 activity with early aortic stenosis in bicuspid aortic valve patients.

## Key findings

- BAV patients under 45 with aortic stenosis had higher Apo B levels and Apo B/Apo AI ratio.
- Lower PON-1 arylesterase activity was observed in young BAV patients with aortic stenosis.
- Apo B levels correlated with aortic valve peak transvalvular velocity in young BAV patients.

## Abstract

The bicuspid aortic valve (BAV) is commonly associated with the early degeneration of the aortic valve. Up to 45% of BAV patients over the age of 50 develop aortic stenosis (AS). Although published data indicate a robust interplay between lipids and calcific AS in tricuspid aortic valve patients, the studies on the BAV population are lacking. We aimed to evaluate the association between selected lipid markers and the occurrence of AS in BAV patients. Methods: The study included 76 adults (21 female) with a BAV diagnosed by echocardiography, divided by age and AS diagnosis. Biochemical parameters concentrations in serum were measured: high density lipoprotein cholesterol (HDL-C) levels by standard enzymatic colorimetric tests, low density lipoprotein cholesterol (LDL-C) levels by the Friedewald formula, apolipoprotein A-I (Apo AI) and apolipoprotein B (Apo B) serum concentration by the nephelometric method, and paraoxonase-1 activity (PON-1 ASE) and arylesterase activity (PON-1 ARE) based on paraoxon and phenyl acetate hydrolysis. Results: A total of 54 patients (15 female) were more than 45 years old and 22 (6 female) were 45 or less years old. BAV patients with AS aged ≤45 had higher levels of Apo B, compared to those without AS [110.5 (102–132) vs. 95.6 (77–101) mg/d; p 0.044]. Similarly, Apo B/Apo AI ratio was higher in BAV patients with AS aged ≤45, compared to those without AS [(0.8 (0.7–1) vs. 0.6 (0.5–0.7); p 0.029]. In the group aged ≤45, Apo B showed a positive correlation with the aortic valve peak transvalvular velocity (AV Vmax) measurement (R Spearman 0.6, p 0.004). We found also that, among young BAV patients, those with AS had a lower level of PON-1 ARE compared to the cohort without AS [63.4 (52–80) vs. 85.3 (70–102); p 0.012]. We did not find any differences in lipid parameters in patients aged >45. Conclusions The metabolic link between Apo B level and Apo B/AI ratio with AS presence in BAV patients under 45 years of age suggests a significant impact of these parameters on the earlier development of AS in the BAV population. Molecules associated with high density lipoprotein and its antioxidant function, such as PON1, are valuable markers for AS development, compared to HDL-C and LDL-C levels.