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Introduction: Calcific aortic valve stenosis (CAVS) is the most prevalent cardiac valvular pathology, leading to a high incidence of morbidity and mortality if left untreated. The exact pathophysiology of CAVS is largely undefined. Genetic studies have shown a strong correlation of the Lp(a) gene to developing CAVS. Lp(a) is known to be the carrier of plasma Oxidized Phosphatidylcholine and results in Lysophosphatidic acid (LPA) accumulation. The focus of the present study was to determine if OxPC and LPA in calcific human aortic valves relate with echocardiographic markers of CAVS. Methods: Aortic valves (n=98) were obtained from patients undergoing AVR. OxPC and LPA were extracted from pulverized aortic valves and analyzed using a targeted mass spectrometry approach. Lipid values are represented relative to an internal standard and normalized by homogenate and leaflet weights. The severity of calcification and aortic stenosis were measured anatomically by Echocardiographic calcification (ECC) score and hemodynamically by mean AV pressure gradient. Results: One-palmitoyl-2-(9-oxo)-nonanoyl- sn- glycero-3-phosphocholine (PONPC) was the most abundant OxPC among 58 OxPC molecules detected (49.3±3.8ng), in AV tissue. When valves were graded by ECC score, scores of 1 (no calcification) had observably attenuated amounts of mean total OxPC’s (135.3±39.3ng) compared to those with a score of 4 (severe calcification) (310.1±34.8 ng). Total valvular OxPC increased linearly with increased ECC score. Total non-fragmented OxPC’s were also significantly lower in valves with ECC scores of 1 and 2 compared to a score of 4 ( P =0.03). Six LPA species were also identified with 16:0 and 18:1 being the most prevalent. Mean AV pressure gradient had a significant, positive correlation with Total LPA amounts (r 2 =0.580, p <0.001), suggesting that elevated LPA concentrations in CAVS tissue is associated with disease severity. Conclusions: Our study is the largest lipidomics study of human aortic valve tissue demonstrating that OxPC and LPA molecules play a significant role in the etiology of CAVS and provides a novel therapeutic target for mitigating disease progression.

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