Objectives: Aortic valve stenosis (AS) causes cardiac fibrosis and left ventricular hypertrophy, and over time heart failure can occur. To date, a reliable marker to predict progression of AS or the development of heart failure is still lacking. In this study, we addressed the hypothesis that fibulin-1 levels reflect myocardial fibrosis. Methods: Patients undergoing heart surgery at the Odense University were investigated. By 2012 data on outcome were obtained. Results: In 293 patients, plasma fibulin-1 levels were measured. Patients with AS or atrial fibrillation (AF) had significantly higher fibulin-1 levels compared to those with coronary artery disease only (p = 0.005). Patients with preoperatively diagnosed chronic AF had significantly higher levels of fibulin-1 compared to those without (p = 0.004). Plasma fibulin-1 levels showed no relationship to echocardiographic size and had no impact on outcome, death or other adverse events. Conclusion: This study shows that plasma fibulin-1 levels are increased in patients with AS and AF compared to patients with coronary disease only. Our study results suggest fibulin-1, a vascular extracellular matrix (ECM) protein, as a marker of ECM turnover perhaps due to the increased myocardial stretch that is related to pressure overload.