PO144 | KIV2 LPA POLYMORPHISM: ROLE IN BAV CLINICAL COMPLICATIONS ACCORDING TO DIFFERENT CLINICAL SETTINGS

P. Cantini¹, E. Sticchi¹, G. Barbieri¹, R. Orsi¹, A. Kura¹, F. Basso¹, A. Rogolino¹, M. Berteotti¹, S. Nistri², P. Stefàno³, R. Marcucci¹, B. Giusti¹ | ¹Atherothrombotic Diseases Center, Dep. of Experimental and Clinical Medicine, University of Florence, Careggi Hospital, Firenze, Italy; ²Cardiology Service CMSR Veneto Medica Altavilla Vicentina, Vicenza, Italy; ³Cardiac Surgery Unit, Department of Experimental and Clinical Medicine, University of Florence, Careggi Hospital, Firenze, Italy

Background and Aims. Bicuspid aortic valve (BAV) is the most common congenital cardiopathy affecting 0.5-2.0% of general population. BAV is associated with different complications such as valvular aortic stenosis, calcification, aortic insufficiency and thoracic aortic aneurysm. Beyond hemodynamic valvular impairment, dyslipidemia and elevated lipoprotein (a) [Lp(a)] levels also favour BAV progression/complications. Lp(a) levels are known to be under strict genetic control and largely influenced by LPA Kringle IV type 2 (KIV2) size polymorphism, with the repeat number inversely correlating with Lp(a) levels. Accordingly, we characterized LPA KIV2 repeats, using digital droplet PCR (ddPCR), in a cohort of Italian BAV patients.
Methods. One hundred nine subjects of Caucasian origin referred to the Regional Referral Center for Marfan syndrome and related disorders and to the Advanced Molecular Genetics Laboratory (Atherothrombotic Diseases Center, Careggi University Hospital, Florence) were enrolled. Patients were divided into two groups according to the different clinical settings: 1) patients undergoing valve replacement surgery (VRS, n=41) and 2) patients not undergoing valve replacement surgery (NVRS, n=68).
Results. NVRS and VRS patients showed, respectively, significant differences in median age (IQR) [45 (28-52) vs 66 (57–75), p<0.001] and in classical cardiovascular risk factors such as dyslipidaemia [11(16.2%) vs 19 (46.3%), p=0.0009], hypertension [20 (29.4%) vs 26 (63.4%), p=0.0007] and smoking habit [7 (10.3%) vs 23 (56.1%), p=0.0001], as well as a higher prevalence of BAV-associated complications (aortic stenosis, calcification and root/ascending aorta dilatation) in the VRS patient group, as expected. We also observed a significant difference in KIV2 repeats median number between the two groups [13 (8.1 – 22.6) in NVRS vs 33.6 (19.1 – 42.9) in VRS, p<0.001]. As concerns KIV2 repeat evaluation according to BAV clinical complications, NVRS patients with complications showed a trend towards reduction in KIV2 repeats number with respect to NVRS patients without complications [stenosis: 10.9 (7.1 – 19.9) vs 13.2 (9.2 – 24.4), p=0.341; calcification: 12.6 (7.2 – 20.3) vs 15 (9.9 – 24.5), p=0.319; root and/or ascending aorta dilatation: 11.9 (7.0 – 18.4) vs 19.4 (11.4 – 26.0), p=0.032]. In particular, higher prevalence of subjects showing a KIV2 repeat value below the distribution median value (n=18.9) in the aortic dilatation group (75.6%) with respect to those without aortic dilatation (47.8%) was observed (p=0.0310). In VRS patients, instead, no trend towards reduction in KIV2 repeats number, according to the presence or absence of BAV clinical complications, was found.
Conclusions. Our analysis suggests that in NVRS patients, younger and with a lower prevalence of traditional cardiovascular risk factors than VRS ones, higher levels of genetically determined lipoprotein (a) might contribute to the development of BAV complications and in turn to a worse prognosis. This datum, together with the observation obtained from a recent GWAS meta-analysis in which we collaborated (Thériault et al, Circulation 2026), from 17 studies in Europe and North America, of LPA among the novel loci associated with BAV, might contribute to underline LPA role in BAV predisposition and clinical complications. Data observed in VRS patients might be likely due to the not negligible impact of cardiovascular risk factors burden in influencing the phenotype severity.