Plasma Cell-free DNA is a potential biomarker for diagnosis of calcific aortic valve disease

Introduction: Calcific aortic valve disease (CAVD) is the third most common cardiovascular disease in aging populations. Despite a growing number of biomarkers having been shown to be associated with CAVD, a marker suitable for routine testing in clinical practice is still needed. Plasma cell-free DNA (cfDNA) has been suggested as a biomarker for diagnosis and prognosis in multiple diseases. In this study, we aimed to test whether cfDNA could be used as a biomarker for the diagnosis of CAVD. Methods: Serum samples were collected from 137 diagnosed CAVD patients and 180 normal controls. The amount of cfDNA was quantified by amplifying a short fragment (ALU 115) and a long fragment (ALU 247) using qPCR. The cfDNA integrity (cfDI) was calculated as the ratio of ALU247 to ALU115. The association between CAVD and cfDI was evaluated using regression analysis. Results: CAVD patients had increased ALU 115 fragments (median, 185.14 (416.42) vs 302.83 (665.41), p<0.05) but a decreased value of cfDI (mean, 0.50 +/- 0.25 vs 0.41 +/- 0.26, p<0.01) in their serum when compared to controls. This difference was more dramatic in non-rheumatic CAVD patients (p<0.001) vs rheumatic CAVD patients (no significant difference). Similarly, CAVD patients with bicuspid aortic valve (BAV) (p<0.01) showed a greater difference than non-BAV CAVD patients (p<0.05). Linear regression and logistic regression showed that cfDI was independently and significantly associated with the presence of CAVD (95%CI, 0.096 to 0.773, p<0.05). The ROC assay revealed that cfDI combined with clinical characteristics had a better diagnostic value than cfDI alone (AUC=0.6191, p<0.001). Conclusion: cfDI may be a potential biomarker for diagnosis of CAVD.