Updated project metadata. The molecular basis of aortic valve degeneration (AVD) is unclear. The extracellular matrix (ECM) of the valve is in dynamic reciprocity with its surrounding microenvironment and contains molecular traits of the pathophysiological processes. We compared abundances of ECM proteins from excised valve tissues of 88 patients with isolated AVD of normal tricuspid (TAV) and congenital bicuspid aortic valves (BAV) by employing a new method for protein preparation and quantitative mass-spectrometry analysis.