BACKGROUND: Bicuspid aortic valve (BAV) is a common congenital heart defect linked to abnormal valve structure and aortic dilatation. AIMS: To present BAV types and valvulo-aortopathy in the Polish population using the latest 2021 classification. METHODS: RE-BAV is a registry of adult ambulatory and hospitalized patients with BAV evaluated in echocardiographic laboratories at 23 tertiary centers in Poland (2021-2023). RESULTS: The study included 814 patients - 72.7% male, average age - mean (SD) 50 (17.4). Common symptoms included dyspnea (54.1%) and chest pain (17.5%). Hypertension (54%) was the most frequent comorbidity. Left ventricular ejection fraction was normal (median 60%, interquartile range: 55-65), but global longitudinal strain was mildly reduced - mean (SD) - 16.8% (3.7). Moderate/severe aortic stenosis was found in 34.2% and regurgitation in 44.1% (P <
0.001). The most common phenotype was typical valvulo-aortopathy (69.9%), followed by uncomplicated BAV (19.3%) and complex valvulo-aortopathy (10.8%). Among 640 patients with specified subtypes, fusion was the most frequent BAV type (79.4%), followed by 2-sinus (15.8%) and partial-fusion (4.8%) (P <
0.001 for all comparisons). Patients with the 2-sinus type were the youngest and had the least comorbidities, contrary to the partial-fusion group. Right-left cusp fusion was the most common subtype (80.4% of fusion BAV). Within the 2-sinus type the latero-lateral and antero-posterior phenotypes had similar prevalence. Aortic dilatation occurred in 63.6%, with extended aortic dilatation being most prevalent (26.3%). CONCLUSIONS: The RE-BAV registry provides updated insights into BAV phenotypes and aortopathy in the Polish population, reflecting the latest classification advancements. .