Abstract Body (Do not enter title and authors here): Background: Bicuspid aortic valve (BAV) is the most common congenital defect affecting 1-2% of general population. It often presents with progressive AV stenosis/regurgitation and ascending aortopathy (AA) which often require surgical intervention.

Objective: We sought to report characteristics and long-term outcomes of a contemporary cohort of patients with BAV and concomitant AA.

Methods: We included 3782 patients with a documented BAV and an unrepaired AA (≥4 cm) who underwent a clinical evaluation between 1/2010 and 12/2023 at our large tertiary referral center. Patients presenting with acute aortic dissection/rupture as an initial presentation were excluded. Clinical (including aortic surgery/dissection/rupture during follow-up) and imaging data were collected. Primary outcome was all-cause mortality.

Results: Characteristics of the patients are shown in Figure 1. At 1±2.2 years from initial evaluation, 2363 (62%) patients underwent surgery (AV repair/replacement [882 {37%}], isolated ascending aortic replacement [402 {17%}] and combined AV+ascending aortic surgery [1079 {46%}]), with 6 (0.25%) in-hospital deaths. Of 2096 AV surgeries, there were 241 (12%) mechanical prostheses, 1326 (63%) bioprosthesis, 16 (1%) homografts, 44 (2%) autografts and 473 (23%) AV repairs. During a mean follow-up of 3.9±3.9 years (range 0-15 years), there were 171 deaths (4.5%), 65 (1.7%) aortic dissections and 4 (0.1%) aortic ruptures. At 1571±1405 days following an evaluation, aortic dissection/rupture occurred in 25/1419 (1.8%) unoperated and 44/2363 (1.9%) operated patients (p=ns). Of these 44 operated patients with dissection, 28 occurred in the distal aorta in those with AA replacement. On survival analysis, longer-term deaths were higher in the unoperated vs. operated patients (71/1419 [5.0%) vs. 100/2363 (4.2%), p-value 0.03, Figure 2). Longer-term deaths were similar in patients undergoing AV repair/replacement (39/843 [4.6%]) vs. isolated AA replacement (20/402 [5.0%]) vs. combined AV+AA surgery (41/1079 [3.8%]), p-value 0.69, Figure 3).

Conclusions: In a large contemporary cohort of patients with BAV and AA managed at a high-volume tertiary care center, majority eventually undergo surgery, with a very high longer-term survival and freedom from aortic dissection/rupture. There were no differences in the longer-term survival of patients getting isolated AV or aortic surgery vs. combination AV/aortic surgery.