For the INTERNAL group, the HAART 200 internal annuloplasty ring (CorCym, London, UK), specifically designed for BAV morphology, will be used for all patients. Intraoperative sizing for the internal ring is based on the geometric orientation and size of the non-fused cusp. A standard ball sizer is used for the measurement of the non-fused cusp to assess commissural orientation and surface area of the non-fused cusp. Sizing typically results in values of 23mm or 25mm, with other sizes being very rare. Both commissural posts of the internal annuloplasty ring are fixed using two subcommissural sutures [10]. A modified technique for placement of transannular looping sutures will be used to secure the internal ring in the subannular position, as recently published [21]. Cusp maneuvers (i.e., shaving, thinning of the raphe, central plication sutures) will be performed to achieve an effective height of 8-10 mm. When indicated (i.e., for ascending aortic diameter > 45mm or aiming to achieve t

For the EXTERNAL group, all study patients will undergo double external Dacron ring annuloplasty by simultaneous stabilization of the basal virtual ring and the STJ [22]. The surgical technique of double external annuloplasty, detailed by the Lansac group [22], involves aortic annulus sizing with a Hegar dilator to select the sizes of the external subannular annuloplasty ring and STJ ring (same size). After deep dissection of the aortic root, 6-7 2-0 pledgeted U sutures are placed circumferentially at the level of the virtual basal ring for external subannular ring implantation. Cusp maneuvers are performed similar to those in the INTERNAL group. STJ stabilization is achieved using an external STJ ring or ascending aortic replacement with a vascular tube graft (e.g., in cases with a high offspring of the right coronary artery). Treatment of the tubular ascending aorta is identical to the INTERNAL group.

For the INTERNAL group, the HAART 200 internal annuloplasty ring (CorCym, London, UK), specifically designed for BAV morphology, will be used for all patients. Intraoperative sizing for the internal ring is based on the geometric orientation and size of the non-fused cusp. A standard ball sizer is used for the measurement of the non-fused cusp to assess commissural orientation and surface area of the non-fused cusp. Sizing typically results in values of 23mm or 25mm, with other sizes being very rare. Both commissural posts of the internal annuloplasty ring are fixed using two subcommissural sutures [10]. A modified technique for placement of transannular looping sutures will be used to secure the internal ring in the subannular position, as recently published [21]. Cusp maneuvers (i.e., shaving, thinning of the raphe, central plication sutures) will be performed to achieve an effective height of 8-10 mm. When indicated (i.e., for ascending aortic diameter > 45mm or aiming to achieve th

Flow eccentricity (in percent) will be assessed using cardiac with phase-contrast imaging. Flow eccentricity is calculated based on the deviation of the flow jet from the center of the vessel lumen. Measurements will be performed pre- and post-repair to determine the percentage reduction in flow eccentricity. Measurements will be performed pre- and post-repair to determine the percentage reduction in flow eccentricity.

The regurgitation fraction (%) will be assessed using cardiac magnetic resonance imaging (CMR) with phase-contrast imaging. Regurgitation fraction is calculated as the percentage of retrograde blood flow relative to the total blood flow through the valve. Measurements will be performed at baseline (pre-repair) and after the intervention (post-repair) to evaluate changes in regurgitation fraction.

For the second primary endpoint (regurgitation fraction), the dependent variable is the post (t2 and t3) value. The study group, time post-surgery (t2 and t3), the interaction between the study group and time post-surgery measurement, and center are included as independent fixed-effect variables.

Severity will be assessed at months 6 (t2) and 12 (t3) in both study groups. The assessment is based on clinical imaging data, including transthoracic echocardiography (TTE) and cardiac MRI as available.