The relationship between ECG characteristics, left ventricular (LV) diastolic function by echocardiography and Gadolinium extracellular volume fraction (ECV) in bicuspid aortic valve (BAV) are unknown. We aimed to test the hypothesis that BAV has an association with LV hypertrophy, myocardial fibrosis, and diastolic dysfunction. Cardiac magnetic resonance, ECG, and echocardiography were performed in 80 patients with BAV and 34 patients with trileaflet aortic valve (TAV). ECV was significantly higher in BAV than TAV. ECV, Sokolow-Lyon voltage, Cornell product, and e’ demonstrated significant relationships with LV end-diastolic volume index. ECV can be a useful predictor of LV remodeling in BAV.