P6505 Urinary desmosine, an elastin-specific degradation product is associated with maximum aortic root size and aortic z-scores in patients with bicuspid aortic valve

Background Bicuspid aortic valve (BAV) is the commonest congenital cardiac abnormality affecting up to 2% of the general population. BAV is highly diverse in phenotype however a common feature is its inherent risk of morbidity and mortality from aortic root dilatation and dissection. Aortic dilatation involves elastin degradation and desmosine is an amino acid cross-link that is released into the bloodstream and urine following elastin degradation. It is known from an earlier pilot study (DESMA) of desmosine in Marfan Syndrome (MFS) patients that plasma desmosine among patients with MFS is significantly elevated and correlates with aortic size however whether this same observation is seen in other forms of inherited aortopathies such as BAV is unclear. Objectives 1. To investigate whether patients with BAV have higher elastin degradation as indicated by plasma desmosine and urinary desmosine levels. 2. To explore the relationship between plasma and urinary desmosine levels with aortic root size in patients with BAV. Methods We measured urinary (ng/mg creatinine) and plasma desmosine (ng/mL) in 20 patients with BAV and healthy control subjects using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Aortic root size and corresponding Z-scores were measured on echocardiogram. Correlation was analysed with Spearman's rank test. Results The patients with BAV were predominantly male (n=15, 75%) with a mean age of 50.5 years ± 17.6 [SD]. All the BAV patients had normal LV systolic function and none had prior aortic root surgery or were current smokers. Nine BAV patients had treated hypertension. Compared to controls, both plasma desmosine (0.30±0.10 vs 0.26±0.075 ng/mL, p=0.01) and urinary desmosine (15.9±4.6 vs 7.2±2.8 ng/mg creatinine, p<0.001) were significantly elevated in patients with BAV. Urinary and plasma desmosine (Figure 1) were also significantly correlated (r=0.55, p=0.01). There was a significant association between urinary desmosine and maximal aortic root size and Z-scores in the BAV cohort (Figure 2) compared to controls (p=0.02), however this was not seen with plasma desmosine.